This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kerban, A. Articles by Sirois, J. Search for Related Content PubMed PubMed Citation Articles by Kerban, A. Articles by Sirois, J.

Human Chorionic Gonadotropin Induces an Inverse Regulation of Steroidogenic Acute Regulatory Protein Messenger Ribonucleic Acid in Theca Interna and Granulosa Cells of Equine Preovulatory Follicles¹

Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada J2S 7C6

Address all correspondence and requests for reprints to: Dr. Jean Sirois, Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, C.P. 5000, Saint-Hyacinthe, Québec, Canada J2S 7C6. E-mail: siroisje{at}medvet.umontreal.ca

The time- and gonadotropin-dependent regulation of steroidogenic acute regulatory protein (StAR) has not been characterized in vivo in preovulatory follicles of large monoovulatory species or sexually mature animals. The objectives of this study were to clone equine StAR and describe the regulation of its messenger RNA (mRNA) in equine follicles after the administration of an ovulatory dose of hCG. The screening of an equine follicle complementary DNA (cDNA) library with a mouse StAR cDNA probe revealed two forms of equine StAR that differ only in the length of their 3'-untranslated region (3'-UTR); a long form of 2918 bp and a short form of 1599 bp. The StAR long form cDNA contains a 5'-UTR of 117 bp, an open reading frame (ORF) of 855 bp, and a 3'-UTR of 1946 bp. Primer extension analysis showed that the cDNA clone lacked the first 10 bp of the primary transcript, giving a total of 127 bp for the complete StAR 5'-UTR. The ORF encodes a 285-amino acid protein that is 86–90% identical to StAR of other species characterized to date. The regulation of StAR mRNA in vivo was studied in equine preovulatory follicles isolated during estrus at 0, 12, 24, 30, 33, 36, and 39 h (n = 4–5 follicles/time point) after an ovulatory dose of hCG. Results from Northern blots showed no significant changes in StAR mRNA levels after hCG treatment when analyses were performed on intact follicle wall (theca interna with attached granulosa cells). However, Northern blots performed on isolated follicle cells revealed an unexpected regulation of StAR mRNA. In granulosa cells, StAR transcripts were undetectable at 0 h but were significantly increased at 30 h post-hCG, and this induction was associated with a rise in follicular fluid concentrations of progesterone (P < 0.05). In contrast, StAR mRNA levels were high in theca interna at 0 h, remained unchanged until 33 h post-hCG, and dropped dramatically thereafter (P < 0.05). Thus, this study describes the primary structure of equine StAR, documents the regulation of StAR mRNA in vivo in preovulatory follicles of a large monoovulatory species, and identifies a novel inverse regulation of StAR transcripts in theca interna and granulosa cells of equine follicles before ovulation.

This article has been cited by other articles:

				P. R. Manna, M. T. Dyson, and D. M. Stocco Regulation of the steroidogenic acute regulatory protein gene expression: present and future perspectives Mol. Hum. Reprod., June 1, 2009; 15(6): 321 - 333. [Abstract] [Full Text] [PDF]

				K. A. Brown, M. Dore, J. G. Lussier, and J. Sirois Human Chorionic Gonadotropin-Dependent Up-Regulation of Genes Responsible for Estrogen Sulfoconjugation and Export in Granulosa Cells of Luteinizing Preovulatory Follicles Endocrinology, September 1, 2006; 147(9): 4222 - 4233. [Abstract] [Full Text] [PDF]

				K A Brown, D Boerboom, N Bouchard, M Dore, J G Lussier, and J Sirois Human chorionic gonadotropin-dependent induction of an equine aldo-keto reductase (AKR1C23) with 20{alpha}-hydroxysteroid dehydrogenase activity during follicular luteinization in vivo. J. Mol. Endocrinol., June 1, 2006; 36(3): 449 - 461. [Abstract] [Full Text] [PDF]

				K. A. Brown, D. Boerboom, N. Bouchard, M. Dore, J. G. Lussier, and J. Sirois Human Chorionic Gonadotropin-Dependent Regulation of 17{beta}-Hydroxysteroid Dehydrogenase Type 4 in Preovulatory Follicles and Its Potential Role in Follicular Luteinization Endocrinology, April 1, 2004; 145(4): 1906 - 1915. [Abstract] [Full Text] [PDF]

				A. E. Stock, N. Bouchard, K. Brown, A. P. Spicer, C. B. Underhill, M. Dore, and J. Sirois Induction of Hyaluronan Synthase 2 by Human Chorionic Gonadotropin in Mural Granulosa Cells of Equine Preovulatory Follicles Endocrinology, November 1, 2002; 143(11): 4375 - 4384. [Abstract] [Full Text] [PDF]

				M. Kusakabe, T. Todo, H. J. McQuillan, F. W. Goetz, and G. Young Characterization and Expression of Steroidogenic Acute Regulatory Protein and MLN64 cDNAs in Trout Endocrinology, June 1, 2002; 143(6): 2062 - 2070. [Abstract] [Full Text] [PDF]

				K. A. Logan, J. L. Juengel, and K. P. McNatty Onset of Steroidogenic Enzyme Gene Expression During Ovarian Follicular Development in Sheep Biol Reprod, April 1, 2002; 66(4): 906 - 916. [Abstract] [Full Text] [PDF]

				D. Boerboom and J. Sirois Equine P450 Cholesterol Side-Chain Cleavage and 3{beta}-Hydroxysteroid Dehydrogenase/{{Delta}}5-{{Delta}}4 Isomerase: Molecular Cloning and Regulation of Their Messenger Ribonucleic Acids in Equine Follicles During the Ovulatory Process Biol Reprod, January 1, 2001; 64(1): 206 - 215. [Abstract] [Full Text]

				D. Boerboom, N. Pilon, R. Behdjani, D. W. Silversides, and J. Sirois Expression and Regulation of Transcripts Encoding Two Members of the NR5A Nuclear Receptor Subfamily of Orphan Nuclear Receptors, Steroidogenic Factor-1 and NR5A2, in Equine Ovarian Cells during the Ovulatory Process Endocrinology, December 1, 2000; 141(12): 4647 - 4656. [Abstract] [Full Text] [PDF]

				B. D. Murphy Models of Luteinization Biol Reprod, July 1, 2000; 63(1): 2 - 11. [Abstract] [Full Text]

				C. Aguirre, F. C. L. Jayes, and J. D. Veldhuis Luteinizing Hormone (LH) Drives Diverse Intracellular Calcium Second Messenger Signals in Isolated Porcine Ovarian Thecal Cells: Preferential Recruitment of Intracellular Ca2+ Oscillatory Cells by Higher Concentrations of LH Endocrinology, June 1, 2000; 141(6): 2220 - 2228. [Abstract] [Full Text] [PDF]

				F. Belin, G. Goudet, G. Duchamp, and N. Gérard Intrafollicular Concentrations of Steroids and Steroidogenic Enzymes in Relation to Follicular Development in the Mare Biol Reprod, May 1, 2000; 62(5): 1335 - 1343. [Abstract] [Full Text]

				C.L. Chaffin, G.A. Dissen, and R.L. Stouffer Hormonal regulation of steroidogenic enzyme expression in granulosa cells during the peri-ovulatory interval in monkeys Mol. Hum. Reprod., January 1, 2000; 6(1): 11 - 18. [Abstract] [Full Text] [PDF]

				D. Boerboom, A. Kerban, and J. Sirois Dual Regulation of Promoter II- and Promoter 1f-Derived Cytochrome P450 Aromatase Transcripts in Equine Granulosa Cells during Human Chorionic Gonadotropin-Induced Ovulation: A Novel Model for the Study of Aromatase Promoter Switching Endocrinology, September 1, 1999; 140(9): 4133 - 4141. [Abstract] [Full Text]