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Endocrinology Vol. 141, No. 12 4481-4485
Copyright © 2000 by The Endocrine Society

ARTICLES

Oxytocin Stimulates the Translocation of Oxytocinase of Human Vascular Endothelial Cells Via Activation of Oxytocin Receptors1

Hiromi Nakamura, Atsuo Itakuara, Makoto Okamura, Mitsuaki Ito, Akira Iwase, Yutaka Nakanishi, Mayumi Okada, Tetsuro Nagasaka and Shigehiko Mizutani

Maternity and Perinatal Care Center (H.N.) and Division of Pathology, Clinical Laboratory (T.N.), Nagoya University Hospital, Showa-ku, Nagoya 466-8550, Japan; and Department of Obstetrics and Gynecology, Nagoya University School of Medicine (A.I., M.O., M.I., A.I., M.O., S.M.), Showa-ku, Nagoya 466-8550, Japan

Address all correspondence and requests for reprints to: Atsuo Itakura M.D., Department of Obstetrics and Gynecology, Nagoya University School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan. E-mail: aita{at}med.nagoya-u.ac.jp


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Oxytocinase (OTase) degrades several small peptides such as oxytocin (OT), and thus plays important roles in fetal development and maintenance of human homeostasis during pregnancy. The physiological effects of OT are mediated via its receptor (OTR). Although the interactions between OT and OTR have studied extensively, the relationship to OTase remains to be clarified. It is known that human umbilical vascular endothelial cells express OTR messenger RNA; therefore, they were selected for examination of this question in the present study.

RT-PCR experiments confirmed the existence of messenger RNA for OTase, and assessment of protein levels and activity clarified that OT increases the activity of OTase at the cell surface via binding to OTR. This stimulation appears to involve translocation of OTase from cytosolic to the cell surface in response to cellular signal transduction pathways linked to the OTR. Protein kinase C stimulation significantly increased the cell surface activity of OTase, whereas its inhibition resulted in reduction.

In summary, our findings provide clear evidence that OT triggers directly OTase translocation in human umbilical vascular endothelial cells via a protein kinase C-dependent pathway coupled to OTR.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
OXYTOCIN (OT) is a nonapeptide hormone secreted mainly from the posterior pituitary gland. Its major endocrine functions are uterotonic action at parturition and in stimulating milk ejection. In addition, OT is thought to affect ovarian regulation and plays roles in control of the nervous system and other organs.

The physiological effects of OT are mediated via its receptor (OTR). Since the initial molecular cloning of OTR performed by Kimura et al. (1), studies of the action of OT via OTR have progressed. Several groups have cloned members of the family of G protein-coupled receptors including OTRs (2, 3), and it is now established that the binding of OT to OTR leads to calcium mobilization, protein kinase C (PKC) activation, and stimulation of phosphatidyl inositol turnover (4, 5, 6, 7, 8).

Fekete first discovered the ability of serum from pregnant women to destroy oxytocin in 1930 (9). Subsequently, bioassays and later biochemical assays demonstrated the inactivating enzyme to be oxytocinase (OTase) (EC 3.4.11.3). It is known that aminopeptidases that hydrolyze L-leucylß-naphthylamide (leucine aminopeptidase) or L-cystinedi-ß-naphthylamide (cystine aminopeptidase) increase in maternal sera during pregnancy and placental leucine aminopeptidase, found in the serum and placenta of pregnant women (10), proved to be identical to OTase (11). It degrades several small peptides, such as OT, arginine vasopressin (12), and angiotensin III (11), and plays important roles in fetal development and maintenance of homeostasis during pregnancy (13).

We cloned a complementary DNA (cDNA) for OTase from a human placental cDNA library, showing the enzyme to be a type II membrane-spanning zinc metalloprotease (14). We also revealed the tissue distribution of its messenger RNA (mRNA) to be broad and not limited to the placenta. In addition, our recent immunohistochemical study showed a wide distribution of the enzyme in a variety of sites other than placenta, including vascular endothelium, gastrointestinal mucosa, pancreas, bile duct, bronchial epithelium, renal tubules, sweat glands, adipocytes, and skeletal muscle (15). These studies suggested possible involvement of OTase not only in pregnancy, but also in many other physiological processes.

Indeed, it has been recently shown that OTase is involved in insulin action. A novel insulin-regulated aminopeptidase (IRAP) from GLUT4 vesicles was cloned independently from rat adipocytes and shown to be a rat homologue of OTase (16). IRAP is known to be concentrated in GLUT4-containing vesicles in basal adipocytes and redistributed to the plasma membrane in response to insulin.

Although interactions between OT and OTR have been studied extensively, their relationship to OTase has never been clarified in detail. It is established that human umbilical vascular endothelial cells (HUVECs) express OTR mRNA (17). We employed them in the present study to cast light on this issue.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Materials
OT was obtained from Wako (Osaka, Japan), and spiroindenylpiperidine camphorsulfonamide oxytocin (SCO), previously reported to be an OT antagonist, was provided by Yamanouchi Pharmaceutical Co., Ltd. (Tokyo, Japan) (18). Lysyl-aminoacyl derivatives [7-amino-4-methylocoumarin (AMC)] of AMC-glutathione were purchased from Molecular Probes, Inc. (Eugene, OR), dispase was obtained from Godo Shusei Co. (Tokyo, Japan), Humedia-EG2 was obtained from Kurabo Co. (Tokyo, Japan), DMEM from Sigma (St. Louis, MO), BSA from Roche Molecular Biochemicals (Barden, Switzerland), TRIzol reagent from Life Technologies, Inc. (Grand Island, NY), restriction and modification enzymes from Perkin-Elmer Corp. (Foster City, CA), UltraLink Immunobilized Streptavidin Plus from Pierce Chemical Co. (Rockford, IL), ECL protein biotinylation reagent biotinamidocaproate N-hydroxysuccinamide ester and ECL from Pharmacia Biotech (Aylesbury, UK), Bis-aminophenoxyetane-N,N,N',N'-tetraacetic acid (BAPTA) from Sigma (St. Louis, MO), and bisindolylmaleimide I from Calbiochem (San Diego, CA). Rapamycin, wortmannin, and phorbol 12-myristate 13-acetate (PMA) were purchased from Wako.

Cell culture
HUVECs were harvested enzymatically with dispase under sterile conditions and established in primary cell cultures in Humedia-EG2. Informed consent was obtained from all women before use. For experimental studies, primary cultures of confluent HUVEC monolayers were trypsinized and replaced onto collagen-coated tissue culture plates. After the cells were grown up to confluence, they were used within 72 h. Before use, each monolayer was inspected microscopically to ensure that only endothelial cells were present (identified by their typical cobblestone pattern). The cells were put into DMEM with 5 mg/ml BSA for 2 h and cultured at 37 C in a humidified atmosphere of 95% air/5% CO2 in all experiments.

RT-PCR experiments
Total RNA was isolated from HUVECs in 100-mm dishes using TRIzol reagent following the manufacturer’s protocol. RNA aliquots were stored at -80 C until use. A RT reaction with 1 µg total RNA was carried out with a Perkin-Elmer Corp. Gene Amp RNA PCR kit following the manufacturer’s protocol (Norwalk, CT). Thereafter, 1-µl aliquots of the RT reaction products underwent PCR reactions (initial denaturation at 95 C for 9 min, followed by 35 cycles, 95 C for 10 sec, 60 C for 1 min, 72 C for 30 sec) using specific primers for human OTase as presented in Table 1Go.


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  		Table 1. Structure of oligonucleotide primers used for amplification of OTase cDNAs

 
Measurement of aminopeptidase activity
Aminopeptidase activity was assayed by the method described previously (16) with aminoacyl derivatives of AMC as fluoregenic substrates. Membrane impermeability of lysyl-AMC-glutathione has already been confirmed, and activity of cell surface aminopeptidase was assayed at 25 C in a recording fluorescence spectrometer (model F5000, Hitachi, Tokyo, Japan) with excitation at 365 nm and emission at 455 nm in a 0.5-ml cuvette with a 5-mm path length. Aliquots (100 µl) were removed from each well, diluted with 400 µl Krebs-Ringer phosphate bicarbonate (KRPB) containing 100 mmol/liter EDTA, and kept on ice until fluorescence was measured.

Cell surface biotinylation
HUVECs in 60-mm collagen-coated dishes were treated with 10-6 mol/liter OT for 30 min or left in the basal state. The cells were washed twice with ice-cold PBS and then treated with 35 µl ECL protein biotinylation reagent biotinamidocaproate N-hydroxysuccinamide ester/ml PBS with constant shaking for 30 min at 4 C. They were then washed three times with ice-cold 50 mmol/liter glycine in PBS, to quench any untreated reagent and lysed with 50 mmol/liter Tris-HCl, pH 7.5, containing 250 mmol/liter NaCl, 1 mmol/liter EDTA, 1% Nonidet P-40, plus protease inhibitors (1 mmol/liter phenylmethylsulfonylfluoride, 1 µg/ml aprotinin, and 10 µg/ml leupeptin). The biotinylated proteins were recovered from the precleared cell lysate by incubation at 4 C with 50 µl streptavidin-agarose beads with vertical rotation for 2 h. After washing three times with lysis buffer and twice with PBS, the biotinylated proteins were eluted by boiling the beads in 100 µl SDS-PAGE sample buffer, and the eluted proteins were separated by SDS-PAGE and blotted onto nitrocellulose membranes. The membranes were incubated with antibody directed against human OTase (19), and immunoreactive proteins were stained using a chemiluminescence kit (ECL, Pharmacia Biotech) (16). Protein levels were quantified by densitometric analysis with a densitometer (Molecular Dynamics, Inc., Sunnyvale, CA).

Statistical analysis
To determine whether the increasing speed of cell surface OTase activity significantly changed, the regression slopes were statistically compared between before and after the addition of OT or detergent (20). OTase activity was expressed as a percentage of the basal value. Data are presented as the mean ± SEM. The difference in OTase activity between groups was statistically tested by one-way ANOVA with Scheffe’s test where appropriate. P < 0.05 was considered statistically significant.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Expression of OTase in HUVECs
To show whether OTase is expressed by the HUVECs, RT-PCR was carried out. Nucleotide sequencing revealed the cDNA fragment amplified with OTase primers (Table 1Go) to be identical to that for human placental OTase. The same RT-PCR protocol was applied to RNA samples extracted from primary cultured HUVECs. As shown in Fig. 1Go, the predicted 463-bp (primer type A) and 888-bp (primer type B) OTase cDNA fragments were detectable. Digestion of RT-PCR products with respective restriction enzymes also resulted in the anticipated smaller fragments.



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  		Figure 1. OTase mRNA expression in HUVECs. Total RNA isolated from HUVECs was used for RT-PCR as described in Materials and Methods. Lane 1 from the left is 1000-bp ladder control; lane 2 is the glyceraldehyde-3-phosphate dehydrogenase-positive control; lanes 3 and 4 correspond to the OTase-specific primers shown in Table 1Go (lane 3, primer type A; lane 4, primer type B), respectively. Restriction enzyme digestion of the PCR products and an appropriate enzyme produced the expected MboI digestion for RT-PCR products shown in lane 3 (280 and 183 bp; lane 5) and XbaI digestion for RT-PCR products shown in lane 4 (528 bp and 360 bp; lane 6). Lane 7 is the 100-bp ladder control.

 
OTase activity at the cell surface of HUVECs
To investigate the effects of OT on OTase activity on the cell surfaces of HUVECs, we measured OTase activity using lysyl-AMC-glutathione, which is a membrane-impermeable fluoregenic substrate for OTase, as described previously (16).

Firstly, to assess whether this assay system truly reflects the cell surface aminopeptidase activity, we assayed the enzyme activity using lysyl-AMC-glutathione with intact HUVECs, then after addition of 10-6 mol/liter OT, and finally with addition of nonionic detergent. The enzyme activity was estimated by measuring the fluorescence of aliquots taken from incubation well at 5-min intervals. In four separate experiments of this type, the activity of the OT-treated cells toward the lysyl-AMC-glutathione increased to about 4-fold that under OT-free conditions (P < 0.001). As shown in Fig. 2Go, the activity toward the lysyl-AMC-glutathione increased at least 15-fold upon solubilization of the membranes with nonionic detergent (P < 0.001). This result demonstrates that the substrate is not readily membrane permeable, as described previously.



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  		Figure 2. Cell surface aminopeptidase activity of intact HUVECs. After preincubated with MEM containing 5 mg/ml BSA for 2 h, cells were incubated with lysyl-AMC-glutathione as a membrane-impermeable substrate in KRPB on a 100-mm dish. At the indicated points, 10-6 mol/liter OT and then the nonionic detergent were added. The fluorescence values given by 100-µl aliquots of supernatant diluted with 400 µl KRPB containing 100 mmol/liter EDTA were plotted. Three separate experiments of this type gave similar results. This graph represents a typical experiment.

 
As we found an increase in OTase activity on the cell surfaces of HUVECs, we would expect OT to increase OTase, and OT and OTR to interact with each other on the cell surface of HUVECs. We therefore tested the effects of various concentrations of OT and the OTR antagonists on OTase activity. As shown in Fig. 3Go, OT significantly stimulated OTase activity on the cell surfaces of HUVECs (P < 0.05). The OTR antagonist, SCO, demonstrated clear inhibition after stimulation with 10-6 mol/liter OT.



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  		Figure 3. OT stimulation of the cell surface aminopeptidase activity of HUVECs. Cells were grown in 24-mm diameter collagen-coated dishes and measurement of aminopeptidase activity as described Materials and Methods. After preincubated with MEM containing 5 mg/ml BSA for 2 h, they were stimulated by 0, 10-10, 10-9, 10-8, 10-7, and 10-6 mol/liter OT or 10-6 mol/liter OT with 10 µmol/liter SCO for 30 min before addition of lysyl-AMC-glutathione. All values were derived from six independent experiments. Results are shown as the mean ± SEM. a, P < 0.001.

 
OT-stimulated translocation of OTase to the plasma membrane in HUVECs
To show that increased OTase activity on HUVECs in response to OT is due to the translocation of intracellular OTase, plasma membranes from basal and OT-treated HUVECs were analyzed after cell surface biotinylation by immunoblotting (Fig. 4Go). The level of OTase in the plasma membranes was about 3-fold increased in response to OT (P < 0.05).



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  		Figure 4. Biotinylation of OTase at the cell surface. Basal and 10-6 mol/liter OT-treated HUVECs were surface biotinylated as described in Materials and Methods. Samples of cell lysates were immunoprecipitated with antibodies against OTase. Biotinylation was detected by blotting with streptavidin conjugated to horseradish peroxidase. Lane 1, basal; lane 2, 10-6 mol/liter OT-treated HUVECs. Three separate experiments of this type gave similar results. This graph represents a typical experiment.

 
Signal transduction pathway involvement in translocation of OTase in HUVECs
We tested the effects of various reagents on OT stimulation of the translocation of OTase of HUVECs after checking that they did not affect the pregnancy serum OTase activity (data not shown). After preincubation of HUVECs with MEM containing 5 mg/ml BSA for 2 h, they were treated with OT alone or in the presence of various reagents for 30 min. With PKC stimulation by PMA the cell surface OTase activity was increased similar to that of OT, whereas the PKC inhibitor, bisindolylmaleimide, caused a clear decrease (Fig. 5Go). Both the phosphoinostiol 3-kinase (PI3-kinase) inhibitor, wortmannin, and the p70 S6 kinase inhibitor, rapamycin, reduced the activity by around one third. Chelation of intracellular calcium by BAPTA resulted in dramatic inhibition (Fig. 5Go).



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  		Figure 5. Effects of various inhibitors on OT stimulation of cell surface aminopeptidase activity of HUVECs. Cells were grown in 24-mm diameter collagen-coated dishes and measurement of aminopeptidase activity as described Materials and Methods. After preincubated with MEM containing 5 mg/ml BSA for 2 h, they were stimulated for 30 min by OT alone or in the presence of the various compounds before addition of lysyl-AMC-glutathione. All values were derived from six independent experiments. Results are shown as the mean ± SEM. a, P < 0.001; b, P < 0.007; c, P < 0.013.

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Our present data confirmed that HUVECs express OTase mRNA (and that OT causes increase in cell surface OTase activity, probably via interaction OTR. Furthermore our findings suggest that the receptor stimulation results in translocation of intracellular OTase to the plasma membrane via a signal transduction pathway. To our knowledge, this is the first report of such pathway involvement in the metabolism of OT at the cellular level.

Feedback, regulation of the output of a hormone as a result of the hormone’s own actions, is a ubiquitous process, but mechanisms are still unclear in many cases. We would expect that translocation of intracellular OTase in response to OT might result in increased degradation of OT at the cell membrane (21). Our present data suggest a mechanism of negative feedback of peptide hormones at the cellular level; bioactive peptides stimulate degrading protease activity on cell membranes. Indeed, we previously found that angiotensin II induces the enzyme responsible for its degradation, aminopeptidase A, in placental tissues (22). The potential for using this new pathway in the metabolism of bioactive peptides seems promising, although extensive work is still required for complete elucidation of details.

Our present data strongly suggest that the trafficking of OTase is essentially under the control of PKC and is partly due to PI3-kinase or p70 S6 kinase. In rat adipocytes, IRAP is a constituent of the vesicles that contain GLUT4. Like GLUT4, IRAP translocates to the cell surface in response to insulin. The molecular mechanism underlying this phenomenon has been interpreted as being linked to stimulation of signaling pathways from the insulin receptor. Both PI3-kinase and p70 S6 kinase lie downstream of insulin activation and possibly play key roles in the translocation of GLUT4/IRAP vesicles in rat adipocytes. Bradykinin also stimulates their trafficking (23); both signaling pathways are essentially independent of PKC activation.

Recently, cellular signal transduction pathways linked to HUVEC OTR and cell proliferation have been reported by other researchers (17). The effects of various reagents were essentially in line with the present data. An increase in Ca2+ is the hallmark of activation via OTR, and it is reasonable that the intracellular Ca2+ chelator, BAPTA, markedly inhibits trafficking of OTase. As our data showed that an increase in cell surface OTase activity is effected via the OTR, an influence of PMA would be expected. In addition, Waters et al. showed that microinjection into 3T3-L1 adipocytes of a glutathione-S-transferase fusion protein containing the cytosolic protein of IRAP-(55–82) resulted in translocation of GLUT4 and IRAP to the cell surface (24). In contrast to insulin-stimulated GLUT4 and IRAP translocation, the redistribution of GLUT4 and IRAP after injection of glutathione-S-transferase-IRAP-(55–82) was not blocked by wortmannin. This is the first report of a new pathway in the metabolism of OT. It will be very interesting to study whether this might also be applicable to other bioactive peptides, such as angiotensin II and somatostatin.

OT is known to mimic many of the effects of insulin in adipocytes, stimulating glucose oxidation, lipogenesis, and glycogen synthesis. It has been reported that these insulin-like activities are due to OT binding to the OTR and not to the insulin receptor itself (25). In terms of the trafficking of OTase, the tendencies were unexpectedly identical. Further studies are needed to elucidate the signal transduction pathways linking the insulin receptor and the OTR.

In summary, our present findings provide clear evidence that OT directly triggers OTase translocation in HUVECs via a PKC-dependent pathway coupled to the OTR.


   Acknowledgments
 
The authors are grateful to Dr. Kenji Wakai (Department of Preventive Medicine, Nagoya University School of Medicine) for valuable statistical advice.


   Footnotes
 
1 This work was supported by Grant-in-Aid 09771267 (to A.I.) from the Ministry of Education, Science, and Culture of Japan and a grant from Ogyaa Donation. Back

Received May 8, 2000.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Kimura T, Tanizawa O, Mori K, Brownstein MJ, Okayama H 1992 Structure and expression of a human oxytocin receptor. Nature 356:526–529[CrossRef][Medline]
  2. Birnbaumer M, Seibold A, Gilbert S, Ishido M, Barberris C 1992 Molecular cloning of the receptor for human antidiuretic hormone. Nature 357:333–335[CrossRef][Medline]
  3. Lolait SJ, O’Carroll AM, McBride OW, Konig M, Morel A, BrownsteinMJ 1992 Cloning and characterization of a vasopressin V2 receptor and possible link to nephrogenic diabetes insipidus. Nature 357:336–339[CrossRef][Medline]
  4. Flint AP, Leat WM, Sheldrick EL, Stewart HJ 1986 Stimulation of phosphoinositide hydrolysis by oxytocin and the mechanism by which oxytocin controls prostaglandin synthesis in the ovine endometrium. Biochem J 237:797–805[Medline]
  5. Ohmichi M, Koike K, Nohara A, Kanda Y, Sakamoto Y, Zhang ZX, Hirota K, Miyake A 1995 Oxytocin stimulates mitogen-activated protein kinase, activity in cultured human puerperal uterine myometrial cells. Endocrinology 136:2082–2087[Abstract]
  6. Thibonnier M, Conarty DM, Preston JA, Wickens PL, Berti-Mattera LN, Maretta R 1998 Molecular pharmacology of human vasopressin receptors. In: Zingg H, Bourque CW, Bichet D (eds) Vasopressin and Oxytocin: Molecular, Cellular, and Clinical Advances. Pleum Press, New York, vol 449:251–276
  7. Sanborn BM, Dodge K, Monga M, Qian A, Wang W, Yue C 1998 Molecular mechanisms regulating the effects of oxytocin on myometrial intracellular calcium. Adv Exp Med Biol 449:277–286[Medline]
  8. Thibonnier M, Berti-Mattera LN, Dulin N, Counarty DM, Maretta R 1998 Signal transduction pathways of the human V1-vascular, V2-renal, V3-pituitary vasopressin and oxytocin receptors. Prog Brain Res 119:147–161[Medline]
  9. Fekete K 1930 Beiträge zur physiologie der Graviditate. Endokrinologie 7:364–369
  10. Mizutani S, Yoshino M, Oya M 1976 Molecular cloning of the receptor for human antidiuretic hormone. Clin Biochem 9:16–18[CrossRef][Medline]
  11. Tsujimoto M, Mizutani S, Adachi H, Kimura M, Nakazato H, Tomoda Y 1992 Identification of human placental leucine aminopeptidase as oxytocinase. Arch Biochem Biophys 292:388–392[CrossRef][Medline]
  12. Mizutani S, Safwat MA, Goto K, Tsujimoto M, Nakazato H, Itakura A, Mizuno M, Kurauchi O, Kikkawa F, Tomoda Y 1995 Initiating and responsible enzyme of arginine vasopressin degradation in human placenta and pregnancy serum. Regul Pept 59:371–378[CrossRef][Medline]
  13. Yamahara N, Nomura S, Suzuki T, Itakura A, Ito M, Okamoto T, Tsujimoto M, Nakazato H, Mizutani S 2000 Placental leucine aminopeptidase/oxytocinase in maternal serum and placenta during normal pregnancy. Life Sci 21:1401–1410
  14. Rogi T, Tsujimoto M, Nakazato H, Mizutani S, Tomoda Y 1996 Human placental leucine aminopeptidase/oxytocinase. J Biol Chem 271:56–61[Abstract/Free Full Text]
  15. Nagasaka T, Nomura S, Okamura M, Tsujimoto M, Nakazato H, Oiso Y, Nakashima N, Mizutani S 1997 Immunohistochemical localization of placental leucine aminopeptidase/oxytocinase in normal human placental, fetal and adult tissues. Reprod Fertil Dev 9:1–7
  16. Ross SA, Scott HM, Morris NJ, Leung WY, Mao F, Lienhard GE, Keller SR 1996 Characterization of the insulin-regulated membrane aminopeptidase in 3T3–L1 adipocytes. J Biol Chem 271:3328–3332[Abstract/Free Full Text]
  17. Thibonnier M, Conarty DM, Preston JA, Plesnicher CL, Dweik RA, Eruzurum SC 1999 Human vascular endothelial cells express oxytocin receptors. Endocrinology 140:1301–1309[Abstract/Free Full Text]
  18. Williams PD, Anderson PS, Ball RG, Bock MG, Carroll LA, Chiu S-HL, Clineschmidt BV, Culberson JC, Erb JM, Evans BE, Fitzpatrick SL, Freid-inger RM, Kaufman MJ, Lundell GF, Murphy JS, Pawluczyk JM, Perlow DS, Pettibone DJ, Pitzenberger SM, Thompson KL, Veber DF1994 1-(((7,7-Dimethyl-2(S)-(2(S)-amino-4-(methylphenyl)butyramido)bicyclo[2.2.1]-heptan-1(S)-yl)methyl)sulfonyl)-4-(2-methylphenyl)piperazine (L-366, 899): an orally bioavailable, non-peptide oxytocin antagonist with potential utility for managing preterm labor. J Med Chem 37:565–571
  19. Nakanishi Y, Nomura S, Okada M, Ito T, Katsumata Y, Kikkawa F, Hattori A, Tsujimoto M, Mizutani S 2000 Immunoaffinity purification and characterization of native placental leucine aminopeptidase/oxytocinase from human placenta. Placenta 21:628–634[CrossRef][Medline]
  20. Armitage P, Berry G 1994 Further analysis of straight-line data. In: Armitage P, Berry G (eds) Statistical Methods in Medical Research. Blackwell, Oxford, pp 292–295
  21. Herbst JJ, Ross SA, Scott HM, Bobin SA, Morris NJ, Lienhard GE, Keller SR 1997 Insulin stimulates cell surface aminopeptidase activity toward vasopressin in adipocytes. Am J Physiol 272:E600–E606
  22. Hariyama Y, Itakura A, Okamura M, Ito M, Murata Y, Nagasaka T, Nakazato H, Mizutani S 2000 Placental aminopeptidase A as a possible barrier of angiotensin II between mother and fetus. Placenta 21:621–627[CrossRef][Medline]
  23. Kishi K, Muramoto N, Nakaya Y, Miyata I, Hagi A, Hayashi H, Ebina Y 1998 Bradykinin directly triggers GLUT4 translocation via an insulin-independent pathway. Diabetes 47:550–558[Abstract]
  24. Waters SB, D’Auria M, Martin SS, Nguyen C, Kozma LM, Luskey KL 1997 The amino terminus of insulin-responsive aminopeptidase causes Glut4 translocation in 3T3–L1 adipocytes. J Biol Chem 272:23323–23327[Abstract/Free Full Text]
  25. Hanif K, Goren HJ, Hollenberg D, Lederis K 1982 Oxytocin action. Mechanisms for insulin-like activity in isolated rat adipocytes. Mol Pharmacol 22:381–388[Abstract]



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Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals