help button home button Endocrine Society Endocrinology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Auernhammer, C. J.
Right arrow Articles by Melmed, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Auernhammer, C. J.
Right arrow Articles by Melmed, S.
Endocrinology Vol. 139, No. 5 2201-2208
Copyright © 1998 by The Endocrine Society

ARTICLES

Leukemia Inhibitory Factor Modulates Interleukin-1ß-Induced Activation of the Hypothalamo-Pituitary-Adrenal Axis1

Christoph J. Auernhammer, Vera Chesnokova and Shlomo Melmed

Division of Endocrinology and Metabolism, Cedars-Sinai Research Institute, University of California School of Medicine, Los Angeles, California 90048

Address all correspondence and requests for reprints to: Dr. Shlomo Melmed, Division of Endocrinology and Metabolism, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, B-131, Los Angeles, California 90048. E-mail: melmed{at}cshs.org


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
We have shown that leukemia inhibitory factor (LIF) is expressed in corticotroph cells and stimulates POMC gene expression and ACTH secretion in vivo and in vitro. We therefore examined the regulation of in vitro and in vivo pituitary LIF expression by cytokines known to stimulate the hypothalamo-pituitary-adrenal axis. In the corticotroph cell line AtT-20/D16v-F2, recombinant murine interleukin-1ß (IL-1ß; 0.1–10.0 ng/ml) caused a 5- to 10-fold increase in LIF messenger RNA (mRNA) levels. LIF mRNA expression was induced as early as 1 h, peaked at 2 h, and still persistently elevated above the baseline after 8 h. This effect of IL-1ß on LIF mRNA expression was abolished by preincubation with human IL-1 receptor antagonist (100 ng/ml) or antimurine IL-1ß antibody (10 µg/ml). Tumor necrosis factor-{alpha} (20 ng/ml) only modestly increased LIF mRNA, but was synergistic with IL-1ß (up to 2.5-fold). In contrast, IL-2 and IL-6 did not alter LIF mRNA. In C57BL/6 mice, ip injection of 100 ng IL-1ß increased plasma ACTH and corticosterone levels after 1 h (P < 0.02). In addition, pituitary LIF mRNA content was increased for up to 2 h in response to IL-1ß. In comparison to wild-type (+/+) B6D2F1 mice, LIF knockout mice with a deleted LIF gene (-/-) exhibited decreased plasma ACTH (631 ± 61 vs. 376 ± 50 pg/ml; P < 0.01) and corticosterone (783 ± 85 vs. 433 ± 51 ng/ml; P < 0.01) levels 1 h after ip IL-1ß administration. In conclusion, corticotroph LIF mRNA expression is specifically stimulated by IL-1ß and tumor necrosis factor-{alpha}. The attenuated hypothalamo-pituitary-adrenal response to IL-1ß in LIF knockout mice indicates that the effect of IL-1ß on ACTH secretion is modulated by LIF. Thus, LIF appears to function as an immune-neuroendocrine modulator signaling the hypothalamo-pituitary-adrenal axis.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
LEUKEMIA inhibitory factor (LIF) belongs to a common cytokine family together with oncostatin M (OSM), interleukin-6 (IL-6), IL-11, ciliary neurotropic factor (CNTF), and cardiotropin-1 (CT-1) (1, 2, 3). These cytokines act through class I cytokine receptors (2, 3), causing hetero- or homodimerization of their common signal transducer gp130 (4) and subsequent activation of JAK kinases (5). In the pituitary, Ferrara et al. first reported LIF to be secreted by bovine pituitary follicular cells (6). Recently, we reported LIF protein and LIF receptors to be expressed in pituitary tissue, especially corticotropic cells, of murine and human origins (7, 8, 9). Hypothalamic and pituitary LIF and LIF receptor messenger RNA (mRNA) expression are both significantly induced in mice in response to lipopolysaccharide endotoxin (LPS) (8). In the murine corticotroph AtT-20 cell line (10, 11) and in primary human fetal pituitary cell cultures (9), LIF stimulates POMC gene expression and ACTH secretion. Intrapituitary LIF signaling is mediated by the gp130 receptor subunit and involves tyrosyl phosphorylation of STAT1 (signal transducer and activator of transcription-1) and STAT3 (10). LIF exhibits strong transcriptional synergy with CRH on POMC mRNA expression, mediated by a common binding element in the POMC promotor region (11). In vivo, LIF injection in mice (12) as well as in nonhuman primates (13) induces acute ACTH secretion. Transgenic mice expressing pituitary-directed LIF were found to have an increased abundance of ACTH-positive pituitary cells (14). Compared to wild-type (wt) animals, LIF knockout mice mounted an attenuated ACTH response to stress (12), which could be restored by sc delivery of LIF (15).

The inflammatory cytokines IL-1{alpha}, IL-1ß, IL-6, and tumor necrosis factor-{alpha} (TNF{alpha}) are known stimulators of the hypothalamo-pituitary-adrenal (HPA) axis both in vivo and in vitro (16, 17, 18, 19). Bacterial LPS (20) and IL-1 (21) stimulate IL-6 expression in anterior pituitary cells in vitro, suggesting an indirect paracrine mechanism of action through IL-6. LPS-induced ACTH secretion in mice is attenuated by the administration of blocking antibodies against IL-1 receptor and IL-6, respectively (22, 23). In contrast, IL-1ß-deficient knockout mice exhibit normal corticosterone increases after LPS administration (24). Coadministration of either cytokine of the IL-6/LIF/OSM/IL-11/CNTF/CT-1 family with IL-1ß to CD-1 mice caused a synergistic increase in serum corticosterone levels compared with IL-1ß administration alone (25). IL-6-deficient knockout mice show the expected corticosterone increase after LPS or IL-1ß administration (25, 26). These results led to the suggestion that besides IL-6, other cytokines of the IL-6/LIF/OSM/IL-11/CNTF/CT-1 family might be involved in modulating IL-1-induced activation of the HPA axis (25).

Induction of LIF expression by IL-1{alpha}, IL-1ß, and TNF-{alpha} has previously been reported in fibroblasts (27), chondrocytes (28), endothelial cells (29), bone marrow cells (30), and endometrial cells (31). Regulation of pituitary LIF expression by cytokines has not, however, been investigated. In this study we report that IL-1ß and TNF-{alpha} stimulate pituitary LIF mRNA expression both in vitro and in vivo. However, in LIF knockout mice, IL-1ß induction of ACTH and corticosterone levels was attenuated. Therefore, LIF appears to modulate IL-1ß-induced activation of the HPA axis.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Materials
Recombinant murine (rm) IL-1ß, rmIL-2, rmIL-6, rmTNF{alpha}, DMEM, FBS, antibiotic/antimycotic, Trizol, and RadPrime were purchased from Life Technologies (Gaithersburg, MD). rmLIF, polyclonal goat antimurine LIF (anti-mLIF) antibody, polyclonal goat anti-mIL-1ß antibody, and recombinant human IL-1 receptor antagonist (IL-1RA) were obtained from R&D Systems (Minneapolis, MN). Hybond-N+ membrane was purchased from Amersham (Little Chalfont, UK). QuickHyb Rapid and salmon sperm DNA were obtained from Stratagene (La Jolla, CA). Kodak Biomax MS film was purchased from Eastman Kodak (Rochester, NY). The mouse ß-actin DECAprobe template was obtained from Ambion (Austin, TX). The pcDNA3 vector was obtained from Invitrogen (Carlsbad, CA). The Quiaex II kit was purchased from Quiagen (Chatsworth, CA). Heparinized capillary tubes were obtained from Baxter (McGaw Park, IL).

Cell culture
AtT-20/D16v-F2 cells were purchased from American Type Culture Collection (Rockville, MD). For RNA extraction, AtT-20 cells were seeded in 100-mm dishes at a density of 2 x 106 cells and incubated for 48 h in DMEM [supplemented with 10% FBS, 2 mM glutamine, and 1% (vol/vol) antibiotic/antimycotic]. Cells were preincubated for 16 h in serum-free DMEM [supplemented with 0.1% BSA, 2 mM glutamine, and 1% (vol/vol) antibiotic/antimycotic] and then incubated in fresh serum-free DMEM with or without treatment. For measurement of ACTH secretion, 1 x 104 AtT-20 cells were seeded in 48-well plates and incubated for 48 h in DMEM and for an additional 48 h in serum-depleted DMEM-medium (supplemented with 1% FBS). Then, fresh serum-depleted DMEM medium with or without treatments was added for a subsequent 24–48 h.

Isolation of RNA and Northern blot analysis
Total RNA was extracted with Trizol reagent according to the manufacturer’s instructions. For Northern blot analysis, 25 µg total RNA were separated on a 1% agarose-6.4% formaldehyde gel and transferred to a nylon membrane (Hybond-N+). RNA was cross-linked by UV light, and membranes were baked at 80 C for 2 h. Prehybridization was performed with QuickHyb Rapid at 68 C for 2 h. The 32P-labeled probe was boiled for 5 min together with 100 µg denatured salmon sperm DNA and added; hybridization was performed under the same conditions as prehybridization for 3 h. Membranes were then washed twice for 20 min under low stringency (2 x SSC-0.1% SDS, at room temperature) and once for 40 min under high stringency conditions (0.1 x SSC-0.1% SDS, at 60 C). Membranes were exposed to Kodak Biomax MS film for 1–24 h (for ß-actin) or 36–96 h (for mLIF) at -70 C.

The EcoRI-XbaI fragment of the mLIF complementary DNA (cDNA) spanning the entire coding sequence of mLIF (2–631 bp; GenBank accession no. A01690; provided by Dr. Tracy Willson, Walter Eliza Hall Institute of Medical Research, Melbourne, Australia) was cloned into a pcDNA3 vector, isolated and electrophoresed in a 1.2% agarose gel, and extracted with Quiaex II. The ß-actin DECAprobe template was the 1.076-kilobase fragment of the mouse ß-actin gene. Probes were labeled with [{alpha}-32P]CTP and Klenow enzyme using random primer labeling with RadPrime.

Animals
Male C57BL/6 mice were purchased from The Jackson Laboratory (Bar Harbor, ME) at the age of 8–12 weeks. Heterozygous LIF knockout (LIFKO) mice (32) were provided by Dr. Colin L. Stewart (Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ). Homozygous LIFKO (-/-) animals were bred on a B6D2F1 genetic background and diagnosed by PCR DNA analysis of tail biopsied tissue, as described previously (12). All animals were kept on a 0600–1800 h daytime cycle with free access to food and water, and housed five per cage. All experimental procedures were approved by the institutional animal care and use committee.

In vivo administration of IL-1ß
rmIL-1ß was dissolved in sterile PBS. Each mouse was injected with 100 ng rmIL-1ß ip between 0900–1000 h. Control animals were injected with PBS alone.

In Exp 1, C57BL/6 mice were killed 0.5, 1.0, or 2.0 h after the injection of PBS or IL-1ß, respectively. The number of animals per treatment group and time point was seven for each. After death, total trunk blood was collected on ice and stored at -70 C until measurement of plasma ACTH and corticosterone levels. Pituitary and hypothalamic tissues were immediately removed and frozen on dry ice until Northern blot analysis.

In Exp 2, 10 B6D2F1 wt (+/+) mice and 10 LIFKO (-/-) mice were anesthetized with isoflurane, and blood was drawn from the retroorbital sinus under baseline conditions. After 7 days, the same animals were injected ip with 100 ng IL-1ß, and 1.0 h after injection, blood was drawn from the retroorbital sinus under isoflurane anesthesia. IL-1 binding to the pituitary has been reported to be increased by ether anesthesia stress (33). Thus, to avoid interactions of the previous anesthesia on IL-1 binding and action, the long interval of 7 days was chosen. Blood was collected on ice and stored at -70 C until measurement of plasma ACTH and corticosterone levels.

Hormone assays and statistical analysis
Blood was collected in ice-chilled tubes containing 0.1% EDTA, and plasma was separated and stored at -70 C. Plasma ACTH (Nichols Institute Diagnostics, San Juan Capistrano, CA) and plasma corticosterone (ICN Biomedicals, Costa Mesa, CA) were measured by commercially available RIAs. The sensitivities of the ACTH and corticosterone assay were 2 pg/ml and 25 ng/ml, respectively. Inter- and intraassay control variabilities for ACTH were 7.3% and 3.1% respectively; inter- and intraassay control variabilities for corticosterone were 4.4% and 6.5%, respectively.

ACTH in culture medium was determined by a double antibody RIA (Diagnostic Products Corp., Los Angeles, CA). Inter- and intraassay control variabilities for ACTH were below 10%.

Statistical analysis was performed using the unpaired t test, and P < 0.05 was considered significant. All values are the mean ± SE.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
LIF mRNA expression in AtT-20 cells
The effects of IL-1ß on AtT-20 cell LIF mRNA levels were assessed. LIF mRNA expression in unstimulated AtT-20 cells, preincubated with serum-free DMEM medium for 16 h, was very low and close to the detection limit of Northern blot analysis. After 2-h incubation, LIF mRNA expression was strongly stimulated by IL-1ß (1.0 ng/ml), whereas TNF{alpha} (20 ng/ml) alone caused only a modest increase in LIF mRNA levels. Coincubation of IL-1ß and TNF{alpha} caused a synergistic increase in LIF mRNA expression compared with IL-1ß alone. However, IL-2 (20 ng/ml) and IL-6 (20 ng/ml) did not alter LIF mRNA expression. LIF (20 ng/ml), added alone and in coincubation with rmIL-1ß, had no effect on LIF mRNA expression (Fig. 1Go).



View larger version (54K):
[in this window]
[in a new window]
  		Figure 1. Effects of different cytokines on LIF mRNA expression in AtT-20/D16v-F2 cells. AtT-20/D16v-F2 cells were incubated as controls (lane 1) or with 1.0 ng/ml IL-1ß (lane 2), 20 ng/ml TNF{alpha} (lane 3), 20 ng/ml TNF{alpha} plus 1.0 ng/ml IL-1ß (lane 4), 20 ng/ml IL-2 (lane 5), 20 ng/ml IL-2 plus 1.0 ng/ml IL-1ß (lane 6), 20 ng/ml IL-6 (lane 7), 20 ng/ml IL-6 plus 1.0 ng/ml IL-1ß (lane 8), 20 ng/ml LIF (lane 9), and 20 ng/ml LIF plus 1.0 ng/ml IL-1ß (lane 10) for 2 h. Northern blot analysis was performed with 25 µg total RNA/lane. Top, LIF mRNA; bottom, ß-actin mRNA.

 
Incubation of AtT-20 cells with IL-1ß (1.0 ng/ml) for up to 8 h induced LIF mRNA expression as early as 1 h, peaked at 2 h, and remained persistently elevated above the baseline at 8 h (Fig. 2Go). A 2-h incubation of AtT-20 cells with increasing concentrations of IL-1ß (0.0001–10.0 ng/ml) caused a dose-dependent increase in LIF mRNA expression, with induction peaking at 10.0 ng/ml. Compared with IL-1ß, incubation with 20 ng/ml TNF{alpha} alone showed only a moderate increase in LIF mRNA expression, but coincubation of 20 ng/ml TNF{alpha} with increasing concentrations of IL-1ß (0.0001–10.0 ng/ml) had a synergistic effect on LIF mRNA expression, starting at concentrations as low as 0.01 ng/ml IL-1ß (Fig. 3Go).



View larger version (46K):
[in this window]
[in a new window]
  		Figure 2. Time course of IL-1ß-induced LIF mRNA expression in AtT-20/D16v-F2 cells. Cells were incubated with 1.0 ng/ml IL-1ß for 1.0–8.0 h. Northern blot analysis was performed with 25 µg total RNA/lane. Top, LIF mRNA; bottom, ß-actin mRNA.

 


View larger version (35K):
[in this window]
[in a new window]
  		Figure 3. Effects of different concentrations of IL-1ß (0.0001–10.0 ng/ml), alone or in combination with TNF{alpha} (20 ng/ml), on LIF mRNA expression in AtT-20/D16v-F2 cells. Cells were incubated for 2 h. Northern blot analysis was performed with 25 µg total RNA/lane. Top, LIF mRNA; bottom, ß-actin mRNA.

 
The specificity of the observed IL-1ß effects was confirmed in several ways. Coincubation of AtT-20 cells with 100 ng/ml recombinant human IL-1RA completely antagonized the effect of IL-1ß (0.1 ng/ml) on LIF mRNA expression. A decrease in IL-1ß-induced LIF mRNA expression was also observed after coincubation with anti-mIL-1ß antibody (10 µg/ml). Also, in AtT-20 cells coincubated with TNF{alpha} (20 ng/ml) and IL-1ß (0.1 ng/ml), treatment with IL-1RA or anti-mIL-1ß antibody caused a decrease in LIF mRNA expression to levels similar to those observed after stimulation with TNF{alpha} alone (Fig. 4Go).



View larger version (46K):
[in this window]
[in a new window]
  		Figure 4. Effects of human IL-1RA and anti-mIL-1ß antibody on IL-1ß-induced LIF mRNA expression in AtT-20/D16v-F2 cells. Cells were treated with human IL-1RA (100 ng/ml) or anti-mIL-1ß antibody (10.0 µg/ml). Concurrently, IL-1ß (0.1 ng/ml), alone or in combination with TNF{alpha} (20 ng/ml), was added for 2 h. Northern blot analysis was performed with 25 µg total RNA/lane. Top, LIF mRNA; bottom, ß-actin mRNA.

 
IL-1ß- and LIF-induced ACTH secretion in AtT-20 cells
The effects of IL-1ß (10 ng/ml) and LIF (10 ng/ml) on ACTH secretion in AtT-20 cells were assessed by incubation of cells for 36 h. The data shown are the mean of four independent experiments, each performed with six wells per treatment group, respectively. Incubation of AtT-20 cells with LIF resulted in doubling of the ACTH level (P < 0.001), whereas IL-1ß alone caused a more modest induction of ACTH (1.45-fold; P < 0.001). The stimulating effect of both LIF and IL-1ß on ACTH secretion was blocked by coincubation with 20 µg/ml anti-mLIF antibody (P < 0.001 and P < 0.01, respectively). Incubation with anti-mLIF antibody alone did not significantly affect baseline values (Fig. 5Go).



View larger version (31K):
[in this window]
[in a new window]
  		Figure 5. Effects of IL-1ß (10 ng/ml) and LIF (10 ng/ml) on ACTH secretion of AtT-20/D16v-F2 cells. Goat anti-mLIF antibody (20 µg/ml) or goat IgG control (20 µg/ml) were added, respectively. Cells were incubated for 36 h. All values are the mean ± SE; the basal ACTH level was taken as 1.0. The experiment shown is the average of four independently performed experiments.

 
ACTH and corticosterone levels after injection of IL-1ß into C57BL/6 mice
C57BL/6 mice were administrated either ip PBS alone or 100 ng IL-1ß. Plasma ACTH levels did not change after 0.5 h (130 ± 29 vs. 178 ± 48 pg/ml; P = NS), but increased in the IL-1ß-injected animals after 1 h (51 ± 8 vs. 286 ± 74 pg/ml; P <= 0.02) and 2 h (121 ± 49 vs. 251 ± 98 pg/ml; P = NS). Similarly, circulating corticosterone levels did not differ in PBS- or IL-1ß-treated animals at 0.5 h (180 ± 26 vs. 186 ± 19 ng/ml; P = NS), but increased in the IL-1ß-injected animals at 1 h (49 ± 13 vs. 201 ± 20 ng/ml; P <= 0.001) and 2 h (86 ± 34 vs. 395 ± 33 pg/ml; P <= 0.001; Fig. 6AGo).



View larger version (29K):
[in this window]
[in a new window]
  		Figure 6. A, Effect of IL-1ß on plasma ACTH and corticosterone levels in C57BL/6 mice. C57BL/6 mice were injected with 100 ng IL-1ß, ip, and killed after 30, 60, and 120 min. All values are the mean ± SE. *, P < 0.05; ***, P < 0.001. B, Effect of IL-1ß on LIF mRNA expression in hypothalamus and pituitary of C57BL/6 mice. C57BL/6 mice were killed untreated (lane 1) or after ip injection of PBS alone (lanes 2–4) or 100 ng IL-1ß (lanes 5–7). Mice were killed after 30 (lanes 2 and 5), 60 (lanes 3 and 6), and 120 min (lanes 4 and 7). Northern blot analysis was performed with 25 µg total RNA/lane. Top, LIF mRNA; bottom, ethidium bromide staining.

 
LIF mRNA expression in hypothalamus and pituitary after injection of IL-1ß into C57BL/6 mice
After ip injections of PBS or IL-ß, mice were killed at 0.5, 1.0, and 2.0 h, and hypothalamic and pituitary RNA were immediately extracted. Northern blot analysis of total mRNA revealed a higher basal expression of LIF mRNA in the hypothalamus than in the pituitary. However, in the hypothalamus a transient increase in LIF mRNA was observed 1 h after IL-1ß administration. In contrast, a strong increase in pituitary LIF mRNA was observed at each time point from 0.5–2 h after IL-1ß administration, with maximal expression peaking after 1 h (Fig. 6BGo).

ACTH and corticosterone levels after injection of IL-1ß to LIF knockout (-/-) mice
In previous experiments using intact unanesthetized animals, we did not observe differences in baseline ACTH and corticosterone levels between LIFKO (-/-) and B6D2F1 wt (+/+) mice (12). In both LIFKO (-/-) and B6D2F1 wt (+/+) mice, baseline ACTH levels under anesthesia were significantly elevated compared with levels in trunk blood derived from intact animals decapitated without prior anesthesia (data not shown). Although baseline ACTH levels under anesthesia differed significantly between LIFKO (-/-) and B6D2F1 wt (+/+) mice (143 ± 36 vs. 300 ± 50 pg/ml; P < 0.05), baseline corticosterone levels were similar (73 ± 15 vs. 89 ± 13 ng/ml; P = NS; Fig. 7Go). After ip injection of 100 ng IL-1ß, circulating ACTH and corticosterone levels in LIFKO (-/-) mice [ACTH, 143 ± 36 vs. 376 ± 50 pg/ml (P < 0.01); corticosterone, 73 ± 15 vs. 433 ± 51 ng/ml (P < 0.001)] and B6D2F1 wt (+/+) mice [ACTH, 300 ± 42 vs. 631 ± 61 pg/ml (P < 0.001); corticosterone, 89 ± 13 vs. 783 ± 85 ng/ml (P < 0.001)] were each elevated compared to their respective baseline levels under anesthesia. However, in response to IL-1ß, LIFKO (-/-) mice exhibited lower peak values of plasma ACTH and corticosterone than B6D2F1 wt (+/+) mice [ACTH, 376 ± 50 vs. 631 ± 61 pg/ml (P < 0.01); corticosterone, 433 ± 51 vs. 783 ± 85 ng/ml (P < 0.01); Fig. 7Go].



View larger version (14K):
[in this window]
[in a new window]
  		Figure 7. Effect of IL-1ß on plasma ACTH and corticosterone levels in LIF knockout mice vs. B6D2F1 wt mice. Blood samples were taken for baseline determinations and 1 h after ip injection of 100 ng IL-1ß under a mild isoflurane anesthesia on two different occasions, 7 days apart. All values are the mean ± SE.

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Recently, we have shown LIF mRNA and protein expression in murine and human corticotroph cells, and LIF stimulation of ACTH secretion and POMC gene expression alone and in synergy with CRH (7, 8, 9, 10, 11). In the present study, we demonstrate that IL-1ß stimulates LIF mRNA expression in murine corticotroph AtT-20 cells in a concentration- and time-dependent manner. In vivo, ip administration of IL-1ß in C57BL/6 mice caused a transient induction of pituitary LIF mRNA transcripts of approximately 4.2 kilobases (34).

Using the LIF cDNA fragment spanning the entire coding region, we could not distinguish between the soluble and extracellular matrix-associated transcript isoforms of mLIF. The two LIF isoform transcripts are only discriminated by an alternative exon 1, resulting in four different N-terminal amino acids in the extracellular matrix-associated form (35, 36). After LPS administration in mice, we showed that both soluble and matrix-associated LIF transcripts are increased in the pituitary (8).

In AtT-20 cells and in the adenohypophysis, IL-1 type I and type II receptors are expressed, allowing for specific pituitary binding of IL-1 (33, 37, 38). Although the IL-1 type I receptor is important for signal transduction, the type II receptor binds IL-1{alpha} and IL-1ß without further signal transduction (39). In our study, the stimulatory effect of IL-1ß on LIF mRNA expression could be blocked by coincubation with human IL-1RA or anti-mIL-1ß antibody, thus indicating specific signaling through the IL-1 receptor. The recombinant human IL-1RA binds to mIL-1 receptor type I with a high affinity of approximately 200 pmol/liter, whereas its affinity for IL-1 receptor type II has been shown to be about 100- to 500-fold less (39). For these studies we used final concentrations of approximately 6 pM IL-1ß and 6 nM IL-1RA, respectively.

IL-1 stimulates expression of IL-6 in anterior pituitary cells in vitro, thus suggesting its indirect paracrine mechanism of action through IL-6 (21). As IL-6-deficient knockout mice have an appropriate corticosterone increase after IL-1ß administration (25), another cytokine of the IL-6/LIF/OSM/IL-11/CNTF/CT-1 family might be involved in modulating IL-1-induced activation of the HPA axis (25). Our finding that IL-1ß induces LIF mRNA expression in AtT-20 cells shows that LIF derived from the corticotroph cell is regulated in a specific manner by this cytokine. We reasoned that the increase in corticotropic LIF mRNA expression might be a mechanism by which locally produced LIF modulates IL-1ß-induced ACTH secretion in an autocrine/paracrine manner.

Although TNF{alpha} alone had only a modest effect on LIF mRNA levels in AtT-20 cells, TNF{alpha} in combination with IL-1ß had about a 2.5-fold synergistic effect. IL-2, IL-6, and LIF itself did not alter LIF mRNA expression in these cells. A similar synergy for IL-1ß and TNF{alpha} on LIF mRNA expression has been reported in endometrial cells (31). TNF{alpha} receptor p60 and p80 mRNA has been recently reported in AtT-20 cells, and TNF{alpha} was found to stimulate ACTH secretion in these cells (40). IL-2 and IL-2 receptor are expressed in murine AtT-20 cells and human corticotropic adenomas (41), but no effect has been found on ACTH secretion in AtT-20 cells (42). IL-6 and IL-6 receptor are expressed in human ACTH-secreting tumors (43) and human fetal pituitaries (9). In AtT-20 cells, the expression of IL-6 and IL-6 receptors has, to our knowledge, not been reported, but a stimulatory effect of IL-6 on ACTH secretion has been reported after long term culture (42). Despite these previous reports indicating that IL-2 and IL-6 exert some effects on AtT-20 cells, both cytokines, in contrast to IL-1ß and TNF{alpha}, were not found to stimulate LIF mRNA expression in AtT-20 cells.

The half-life of LIF mRNA has been estimated to be only about 30 min (30). In accordance with our results, several groups have shown LIF mRNA to be very low or undetectable in unstimulated nonpituitary cells and to transiently increase after IL-1 stimulation, peaking at 1–2 h (30, 31). These findings indicate LIF mRNA expression to be under strong negative regulatory control, a phenomenon common to many cytokines (44). To exclude a negative regulatory role of LIF itself on its own mRNA expression, we showed that baseline and IL-1ß-induced LIF mRNA levels are not altered by coincubation with relatively high concentrations of LIF. A suppressive effect of dexamethasone on pituitary LIF mRNA expression has been described (45), thus implicating a negative feedback loop of glucocorticoids on pituitary LIF expression.

Demonstration of a direct action of IL-1 mediating corticotroph ACTH secretion is still controversial. Although in long term AtT-20 cell incubations (24–72 h), stimulation of ACTH by IL-1{alpha} or IL-1ß was observed, short term incubation (up to 8 h) did not alter ACTH levels (42, 46). Similarly, in primary rat anterior pituitary cell cultures, long term (8–24 h), but not short term (4 h), incubation with IL-1{alpha} or IL-1ß resulted in enhanced ACTH secretion (47, 48, 49), whereas others observed no increased ACTH secretion (50). In our study, pretreatment of AtT-20 cells in serum-depleted medium for 48 h and subsequent long term incubation with IL-1ß (10 ng/ml) for 36 h caused an approximately 1.5-fold increase in ACTH levels from baseline values. A serum-depleted preincubation period has been reported to be required for the CRH responsiveness of AtT-20 cells (51); we observed the same phenomenon with respect to IL-1ß responsiveness (data not shown). As discussed by Renner et al. (50), differences in serum washout during preincubation might be responsible for the discrepant findings of the IL-1ß effects on ACTH secretion of pituitary monolayers in vitro. In sum, the existing data suggest that the effects of IL-1ß on ACTH secretion in vitro are not short term, but are only seen during relatively long term incubations.

Baseline circulating ACTH and corticosterone values were similar in unanesthetized B6D2F1 wt (+/+) mice and LIFKO (-/-) mice (12), whereas after anesthesia, LIFKO (-/-) mice exhibited a decreased ACTH response compared to that of B6D2F1 wt (+/+) mice. This finding of LIFKO (-/-) mice showing a decreased ACTH response to isoflurane anesthesia is consistent with our previous observation of an attenuated HPA axis stress response in these animals (12). The fact that peak ACTH and corticosterone values after ip administration of IL-1ß were significantly decreased in the LIF knockout (-/-) mice compared to those in B6D2F1 wt (+/+) mice shows that LIF is a modulator of IL-1ß-induced activation of the HPA axis. However, the precise mechanism of LIF action on the HPA axis is not clear. LIF is produced by the corticotroph cell itself, suggesting an autocrine LIF effect modulating IL-1ß-induced ACTH secretion. On the other hand, several findings suggest that a paracrine mechanism of action may be operative. Levels of LIF mRNA expression in the corticotroph cell are very low, close to the detection limit of Northern blot analysis. In vitro, long term incubation of AtT-20 cells with IL-1ß caused a 1.5-fold increase in ACTH secretion. This IL-1ß-induced increase in ACTH secretion was only modestly attenuated by coincubation with anti-mLIF antibody. As IL-1-induced LIF expression has also been described in fibroblasts (27) and endothelial cells (29), a paracrine LIF action from these pituitary structures should be considered. Our contrasting findings of a marked reduction in the IL-1ß-induced activation of the HPA axis in LIF knockout mice, but anti-mLIF antibody having only a modest effect on IL-1ß-induced ACTH secretion in vitro, could be explained by paracrine in addition to autocrine LIF acting on the corticotropic cell. In the hypothalamus we observed a higher baseline expression of LIF mRNA than in the pituitary. However, systemic administration of IL-1ß caused only a modest and transient increase in hypothalamic LIF mRNA, whereas a striking increase in LIF mRNA was observed in the pituitary at all time points examined. This difference in induction of LIF mRNA may be due to the blood-brain barrier allowing only a fraction of the administered IL-1ß to be transported to the hypothalamus by a saturable transport mechanism (52).

In contrast to our observation of LIFKO (-/-) mice exhibiting a reduced response of the HPA axis to 100 ng IL-1ß, ip, a normal increase in blood corticosterone levels has been reported in IL-6 knockout mice after ip IL-1ß administration (500 ng) (25). These different findings may be caused by the following factors. The administered dosage of IL-1 was different, and the higher dose used by Benigni et al. might have caused a compensatory increase in other cytokines, e.g. LIF, allowing a redundancy to IL-6 action. Secondly, in the study of Benigni et al. only corticosterone, not ACTH, levels were measured. However, the adrenal gland can be maximally stimulated by very small amounts of ACTH, as we have observed in LIFKO (-/-) mice exposed to restraint stress, in which transiently diminished HPA axis activity can still be associated with an adrenal response (12). Thirdly, we have previously shown that the number of ACTH-positive cells was increased in the pituitary of mice bearing a LIF transgene (14), and LIF has also been shown to induce differentiation of pituitary corticotroph function in AtT-20 cells (53). Therefore, in LIFKO (-/-) mice, the lack of LIF might cause an impaired pituitary corticotroph reserve despite unchanged baseline ACTH values (12).

In conclusion, the expression of pituitary LIF mRNA is specifically stimulated by IL-1ß in vitro as well as in vivo. IL-1ß-induced activation of the HPA axis is markedly attenuated in LIF knockout mice, whereas anti-mLIF antibody has only a modest effect on IL-1ß-induced ACTH secretion in vitro. Thus, despite the phenomenon of IL-1ß-induced LIF mRNA induction in the corticotroph cell, paracrine, rather than autocrine, derived LIF may play a more important role as a modulator of IL-1ß-induced activation of the HPA axis.


   Acknowledgments
 
We gratefully acknowledge the subcloning of the mLIF fragment by Dr. Hiroki Yano (Cedars-Sinai Medical Center, Los Angeles, CA).


   Footnotes
 
1 This work was supported by a scholarship of the Deutsche Forschungsgemeinschaft (Au 139/1–1) and NIH Grant DK-501238. Back

Received November 20, 1997.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Gearing DP 1993 The leukemia inhibitory factor and its receptor. Adv Immunol 53:31–58[Medline]
  2. Hibi M, Nakajima K, Hirano T 1996 IL-6 cytokine family and signal transduction: a model of the cytokine system. J Mol Med 74:1–12[CrossRef][Medline]
  3. Taga T 1997 The signal transducer gp130 is shared by interleukin-6 family of haematopoietic and neurotrophic cytokines. Ann Med 29:63–72[Medline]
  4. Zhang XG, Gu JJ, Lu ZY, Yasukawa K, Yancopoulos GD, Turner K, Shoyab M, Taga T, Kishimoto T, Bataille R, Klein B 1994 Ciliary neurotrophic factor, interleukin 11, leukemia inhibitory factor, and oncostatin M are growth fcators for human myeloma cell lines using the interleukin 6 signal transducer gp130. J Exp Med 177:1337–1342
  5. Stahl N, Boulton TG, Farruggella T, Ip NY, Davis S, Witthuhn BA, Quelle FW, Silvennoinen O, Barbierei G, Pellegrini S, Ihle JN, Yancopoulos GD 1994 Association and activation of Jak-Tyk kinases by CNTF-LIF-OSM-IL-6ß receptor components. Science 263:92–95[Abstract/Free Full Text]
  6. Ferrara N, Winer J, Henzel WJ 1992 Pituitary follicular cells secrete an inhibitor of aortic endothelial cell growth: identification as leukemia inhibitory factor. Proc Natl Acad Sci USA 89:698–702[Abstract/Free Full Text]
  7. Akita S, Webster J, Ren SG, Takino H, Said J, Zand O, Melmed S 1995 Human and murine pituitary expression of leukemia inhibitory factor. J Clin Invest 95:1288–1298
  8. Wang Z, Ren S-G, Melmed S 1996 Hypothalamic and pituitary leukemia inhibitory factor gene expression in vivo: a novel endotoxin-inducible neuro-endocrine interface. Endocrinology 137:2947–2953[Abstract]
  9. Shimon I, Yan X, Ray DW, Melmed S 1997 Cytokine-dependent gp130 receptor subunit regulates human fetal pituitary adrenocorticotropin hormone and growth hormone secretion. J Clin Invest 100:357–363[Medline]
  10. Ray DW, Ren SG, Melmed S 1996 Leukemia inhibitory factor (LIF) stimulates proopiomelanocortin (POMC) expression in a corticotroph cell line. Role of STAT pathway. J Clin Invest 97:1852–1859[Medline]
  11. Bousquet C, Ray DW, Melmed S 1997 A common pro-opiomelanocortin-binding element mediates leukemia inhibitory factor and corticotropin-releasing hormone transcriptional synergy. J Biol Chem 272:10551–10557[Abstract/Free Full Text]
  12. Chesnokova V, Auernhammer CJ, Melmed S 1998 Murine leukemia inhibitory factor gene disruption attenuates the hypothalamo-pituitary-adrenal axis stress response. Endocrinology 139:2209–2216[Abstract/Free Full Text]
  13. Akita S, Conn PM, Melmed S 1996 Leukemia inhibitory factor (LIF) induces acute adrenocorticotrophic hormone (ACTH) secretion in fetal rhesus macaque primate: a novel dynamic test of pituitary function. J Clin Endocrinol Metab 81:4170–4178[Abstract/Free Full Text]
  14. Akita S, Readhead C, Stefaneanu L, Fine J, Tampanaru-Sarmesiu A, Kovacs K, Melmed S 1997 Pituitary-directed leukemia inhibitory factor transgene forms Rathke’s cleft cysts and impairs pituitary function. A model for human pituitary Rathke’s cysts. J Clin Invest 99:2462–2469[Medline]
  15. Akita S, Malkin J, Melmed S 1996 Disrupted murine leukemia inhibitory factor (LIF) gene attenuates adrenocorticotropic hormone (ACTH) secretion. Endocrinology 137:3140–3143[Abstract]
  16. Turnbull AV, Rivier C 1995 Regulation of the HPA axis by cytokines. Brain Behav Immun 9:253–275[CrossRef][Medline]
  17. Chrousos GP 1995 The hypothalamic-pituitary-adrenal axis and immune-mediated inflammation. N Engl J Med 332:1351–1362[Free Full Text]
  18. Besedovsky HO, Del Rey A 1996 Immune-neuro-endocrine interactions: facts and hypotheses. Endocr Rev 17:64–102[CrossRef][Medline]
  19. Ray D, Melmed S 1997 Pituitary cytokine and growth factor expression and action. Endocr Rev 18:206–228[Abstract/Free Full Text]
  20. Muramami N, Fukata J, Tsukada T, Kobayashi H, Ebisui O, Segawa H, Muro S, Imura H, Nakao K 1993 Bacterial lipopolysaccharide-induced expression of interleukin-6 messenger ribonucleic acid in the rat hypothalamus, pituitary, adrenal gland, and spleen. Endocrinology 133:2574–2578[Abstract]
  21. Spangelo BL, Jarvis WD, Judd AM, MacLeod RM 1991 Induction of interleukin-6 release by interleukin-1 in rat anterior pituitary cells in vitro: evidence for an eicosanoid-dependent mechanism. Endocrinology 129:2886–2894[Abstract]
  22. Perlstein RS, Whitnall MH, Abrams JS, Mougey EH, Neta R 1993 Synergistic roles of interleukin-6, interleukin-1, and tumor necrosis factor in the adrenocorticotropin response to bacterial lipopolysaccharide in vivo. Endocrinology 132:946–952[Abstract]
  23. Rivier C, Chizzonite R, Vale W 1989 In the mouse, the activation of the hypothalamic-pituitary-adrenal axis by a lipopolysaccharide (endotoxin) is mediated through interleukin-1. Endocrinology 125:2800–2805[Abstract]
  24. Fantuzzi G, Zheng H, Faggioni R, Benigni F, Ghezzi P, Sipe JD, Shaw AR, Dinarello CA 1996 Effect of endotoxin in IL-1ß-deficient mice. J Immunol 157:291–296[Abstract]
  25. Benigni F, Fantuzzi G, Sacco S, Sironi M, Pozzi P, Dinarello CA, Sipe JD, Poli V, Cappelletti M, Paonessa, G, Pennica D, Panayotatos N, Ghezzi P 1996 Six different cytokines that share gp130 as a receptor subunit, induce serum amyloid A and potentiate the induction of interleukin-6 and the activation of the hypothalamus-pituitary-adrenal axis by interleukin-1. Blood 87:1851–1854[Abstract/Free Full Text]
  26. Fattori E, Cappelletti M, Costa P, Sellitto C, Cantoni L, Carelli M, Faggioni R, Fantuzzi G, Ghezzi P, Poli V 1994 Defective inflammatory response in interleukin 6-deficient mice. J Exp Med 180:1243–1250[Abstract/Free Full Text]
  27. Hamilton J, Waring P, Filonzi E 1993 Induction of leukemia inhibitory factor in human synovial fibroblasts by IL-1 and tumor necrosis factor-{alpha}. J Immunol 150:1496–1502[Abstract]
  28. Campbell I, Waring P, Novak U, Hamilton J 1993 Production of leukemia inhibitory factor by human articular chondrocytes and cartilage in response to interleukin-1 and tumor necrosis factor {alpha}. Arthritis Rheum 35:790–794
  29. Grosset C, Jazwiec B, Taupin J-L, Liu H, Richard S, Mahon F-X, Reiffers J, Moreau J-F, Ripoche J 1995 In vitro biosynthesis of leukemia inhibitory factor/human interleukin for DA cells by human endothelial cells: differential regulation by interleukin-1a and glucocorticoids. Blood 86:3763–3770[Abstract/Free Full Text]
  30. Derigs H, Boswell H 1993 LIF mRNA expression is transcriptionally regulated in murine bone marrow stromal cells. Leukemia 7:630–634[Medline]
  31. Arici A, Engin O, Attar E, Olive D 1994 Modulation of leukemia inhibitory factor gene expression and protein biosynthesis in human endometrium. J Clin Endocrinol Metab 80:1908–1915[Abstract]
  32. Stewart CL, Kaspar P, Brunet LJ, Bhatt H, Gadi I, Kontgen F, Abbondanzo SJ 1992 Blastocyst implantation depends on maternal expression of leukemia inhibitory factor. Nature 359:76–79[CrossRef][Medline]
  33. Takao T, Hashimoto K, De Souza EB 1995 Modulation of interleukin-1 receptors in the neuro-endocrine-immune axis. Int J Dev Neurosci 13:167–178[CrossRef][Medline]
  34. Stahl J, Gearing DP, Willson TA, Brown MA, King JA, Gough NM 1990 Structural organization of the genes for murine and human leukemia inhibitory factor. J Biol Chem 265:8833–8841[Abstract/Free Full Text]
  35. Rathjen PD, Toth S, Willis A, Heath JK, Smith AG 1990 Differentiation inhibiting activity is produced in matrix-associated and diffusible forms that are generated by alternate promoter usage. Cell 62:1105–1114[CrossRef][Medline]
  36. Gough NM, Willson TA, Stahl J, Brown MA 1992 Molecular biology of the leukemia inhibitory factor gene. Ciba Found Symp 167:24–38[Medline]
  37. Parnet P, Brunke DL, Goujon E, Mainard JD, Biragyn A, Arkins S, Dantzer R, Kelley KW 1993 Molecular identification of two types of interleukin-1 receptors in the murine pituitary gland. J Neuroendocrinol 5:213–219[CrossRef][Medline]
  38. Bristulf J, Bartfai T 1995 Interleukin-1ß and tumor necrosis factor-{alpha} stimulate the mRNA expression of interleukin-1 receptors in mouse anterior pituitary AtT-20 cells. Neurosci Lett 187:53–56[CrossRef][Medline]
  39. Dinarello CA 1996 Biological basis for interleukin-1 in disease. Blood 87:2095–2147[Abstract/Free Full Text]
  40. Kobayashi H, Fukata J, Murakami N, Usui T, Ebisui O, Muro S, Hanaoka I, Inoue K, Imura H, Nakao K 1997 Tumor necrosis factor receptors in the pituitary cells. Brain Res 758:45–50[CrossRef][Medline]
  41. Arzt E, Stelzer G, Renner U, Lange M, Muller OA, Stalla GK 1992 Interleukin-2 and interleukin-2 receptor expression in human corticotrophic adenoma and murine pituitary cell cultures. J Clin Invest 90:1944–1951
  42. Fukata J, Usui T, Naitoh Y, Nakai Y, Imura H 1989 Effects of recombinant human interleukin-1{alpha}, -1ß, 2 and 6 on ACTH synthesis and release in the mouse pituitary tumour cell line AtT-20. J Endocrinol 122:33–39[Abstract]
  43. Velkeniers B, Vergani P, Trouillas J, D’Haens J, Hooghe RJ, Hooghe-Peters EL 1994 Expression of IL-6 mRNA in normal rat and human pituitaries and in human pituitary adenomas. J Histochem Cytochem 42:67–76[Abstract]
  44. Ye J, Young HA 1997 Negative regulation of cytokine gene transcription. FASEB J 11:825–833[Abstract]
  45. Carter DA 1995 Leukemia inhibitory factor expression in cultured rat anterior pituitary is regulated by glucocorticoids. J Neuroendocrinol 7:623–628[CrossRef][Medline]
  46. Gwosdow AR, O’Connell NA, Abou-Samra AB 1994 Interleukin-1 increases protein kinase A activity by a cAMP-independent mechanism in AtT-20 cells. Am J Physiol 266:E79–E84
  47. Kehrer P, Turnill D, Dayer J-M, Muller AF, Gaillard RC 1988 Human recombinant interleukin-1ß and -{alpha}, but not recombinant tumor necrosis factor alpha stimulate ACTH release from rat anterior pituitary cells in vitro in a prostaglandin E2 and cAMP independent manner. Neuroendocrinology 48:160–166[CrossRef][Medline]
  48. Hashimoto K, Nishioka T, Tojo C, Takao T 1995 Nitric oxide plays no role in ACTH release induced by interleukin-1ß, corticotrophin-releasing hormone, arginine vasopressin and phorbol myristate acetate in rat anterior pituitary cell cultures. Endocr J 42:435–439[Medline]
  49. van der Meer MJM, Hermus RMM, Pesman GJ, Sweep CGJF 1996 Effects of cytokines on pituitary b-endorphin and adrenal corticosterone release in vitro. Cytokine 8:238–247[CrossRef][Medline]
  50. Renner U, Newton CJ, Pagotto U, Sauer J, Arzt E, Stalla GK 1995 Involvement of interleukin-1 and interleukin-1 receptor antagonist in rat pituitary cell growth regulation. Endocrinology 136:3186–3193[Abstract]
  51. Aoki Y, Iwasaki Y, Katahira M, Oiso Y, Saito H 1997 Regulation of the rat proopiomelanocortin gene expression in AtT-20 cells. I. Effects of the common secretagogues. Endocrinology 138:1923–1929[Abstract/Free Full Text]
  52. Banks WA, Oritz L, Plotkin SR, Kastin AJ 1991 Human interleukin (IL) 1{alpha}, murine IL-1{alpha} and murine IL-1ß are transported from blood to brain in the mouse by a shared saturable mechanism. J Pharmacol Exp Ther 259:988–996[Abstract/Free Full Text]
  53. Stefana B, Ray DW, Melmed S 1996 Leukemia inhibitory factor induces differentiation of pituitary corticotroph function: an immuno-neuroendocrine phenotypic switch. Proc Natl Acad Sci USA 93:12502–12506[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 EndocrinologyHome page
D. Chida, T. Imaki, T. Suda, and Y. Iwakura
Involvement of Corticotropin-Releasing Hormone- and Interleukin (IL)-6-Dependent Proopiomelanocortin Induction in the Anterior Pituitary during Hypothalamic-Pituitary-Adrenal Axis Activation by IL-1{alpha}
Endocrinology, December 1, 2005; 146(12): 5496 - 5502.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
A. Kariagina, D. Romanenko, S.-G. Ren, and V. Chesnokova
Hypothalamic-Pituitary Cytokine Network
Endocrinology, January 1, 2004; 145(1): 104 - 112.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Cell. Biol.Home page
J.-I. Park, C. J. Strock, D. W. Ball, and B. D. Nelkin
The Ras/Raf/MEK/Extracellular Signal-Regulated Kinase Pathway Induces Autocrine-Paracrine Growth Inhibition via the Leukemia Inhibitory Factor/JAK/STAT Pathway
Mol. Cell. Biol., January 15, 2003; 23(2): 543 - 554.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
V. Chesnokova and S. Melmed
Minireview: Neuro-Immuno-Endocrine Modulation of the Hypothalamic-Pituitary-Adrenal (HPA) Axis by gp130 Signaling Molecules
Endocrinology, May 1, 2002; 143(5): 1571 - 1574.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
J. Liu, C. Lin, A. Gleiberman, K. A. Ohgi, T. Herman, H.-P. Huang, M.-J. Tsai, and M. G. Rosenfeld
Tbx19, a tissue-selective regulator of POMC gene expression
PNAS, July 5, 2001; (2001) 141234898.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
V. Chesnokova and S. Melmed
Leukemia Inhibitory Factor Mediates the Hypothalamic Pituitary Adrenal Axis Response to Inflammation
Endocrinology, November 1, 2000; 141(11): 4032 - 4040.
[Abstract] [Full Text] [PDF]

Home page
 Endocr. Rev.Home page
J. Schwartz
Intercellular Communication in the Anterior Pituitary
Endocr. Rev., October 1, 2000; 21(5): 488 - 513.
[Abstract] [Full Text]

Home page
 Physiol. Rev.Home page
A. Slominski, J. Wortsman, T. Luger, R. Paus, and S. Solomon
Corticotropin Releasing Hormone and Proopiomelanocortin Involvement in the Cutaneous Response to Stress
Physiol Rev, July 1, 2000; 80(3): 979 - 1020.
[Abstract] [Full Text] [PDF]

Home page
 Endocr. Rev.Home page
C. J. Auernhammer and S. Melmed
Leukemia-Inhibitory Factor--Neuroimmune Modulator of Endocrine Function
Endocr. Rev., June 1, 2000; 21(3): 313 - 345.
[Abstract] [Full Text]

Home page
 J. Clin. Endocrinol. Metab.Home page
S. G. Ren, J. Seliktar, X. Li, J. M. Hershman, G. D. Braunstein, and S. Melmed
In Vivo and in Vitro Regulation of Thyroid Leukemia Inhibitory Factor (LIF): Marker of Hypothyroidism
J. Clin. Endocrinol. Metab., August 1, 1999; 84(8): 2883 - 2887.
[Abstract] [Full Text]

Home page
 Proc. Natl. Acad. Sci. USAHome page
C. J. Auernhammer, C. Bousquet, and S. Melmed
Autoregulation of pituitary corticotroph SOCS-3 expression: Characterization of the murine SOCS-3 promoter
PNAS, June 8, 1999; 96(12): 6964 - 6969.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
C. J. Auernhammer and S. Melmed
Interleukin-11 Stimulates Proopiomelanocortin Gene Expression and Adrenocorticotropin Secretion in Corticotroph Cells: Evidence for a Redundant Cytokine Network in the Hypothalamo-Pituitary-Adrenal Axis
Endocrinology, April 1, 1999; 140(4): 1559 - 1566.
[Abstract] [Full Text]

Home page
 J. Biol. Chem.Home page
E. A. Ratovitski, M. R. Alam, R. A. Quick, A. McMillan, C. Bao, C. Kozlovsky, T. A. Hand, R. C. Johnson, R. E. Mains, B. A. Eipper, et al.
Kalirin Inhibition of Inducible Nitric-oxide Synthase
J. Biol. Chem., January 8, 1999; 274(2): 993 - 999.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Endocrinol.Home page
H. Yano, C. Readhead, M. Nakashima, S.-G. Ren, and S. Melmed
Pituitary-Directed Leukemia Inhibitory Factor Transgene Causes Cushing's Syndrome: Neuro-Immune-Endocrine Modulation of Pituitary Development
Mol. Endocrinol., November 1, 1998; 12(11): 1708 - 1720.
[Abstract] [Full Text]

Home page
 Mol. Endocrinol.Home page
C. J. Auernhammer, V. Chesnokova, C. Bousquet, and S. Melmed
Pituitary Corticotroph SOCS-3: Novel Intracellular Regulation of Leukemia-Inhibitory Factor-Mediated Proopiomelanocortin Gene Expression and Adrenocorticotropin Secretion
Mol. Endocrinol., July 1, 1998; 12(7): 954 - 961.
[Abstract] [Full Text]

Home page
 EndocrinologyHome page
S. Reichlin
Editorial: What's In a Name or What Does Leukemia Inhibitory Factor Have to Do with the Pituitary Gland?
Endocrinology, May 1, 1998; 139(5): 2199 - 2200.
[Full Text] [PDF]

Home page
 EndocrinologyHome page
V. Chesnokova, C. J. Auernhammer, and S. Melmed
Murine Leukemia Inhibitory Factor Gene Disruption Attenuates the Hypothalamo-Pituitary-Adrenal Axis Stress Response
Endocrinology, May 1, 1998; 139(5): 2209 - 2216.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
J. Liu, C. Lin, A. Gleiberman, K. A. Ohgi, T. Herman, H.-P. Huang, M.-J. Tsai, and M. G. Rosenfeld
Tbx19, a tissue-selective regulator of POMC gene expression
PNAS, July 17, 2001; 98(15): 8674 - 8679.
[Abstract] [Full Text] [PDF]