Induction of endothelin-2 expression by luteinizing hormone and hypoxia: possible role in bovine corpus luteum formation.
The pattern and regulation of endothlin-2 (EDN2) expression and its putative roles in bovine ovaries were investigated. EDN2 mRNA was determined in corpus luteum (CL) and during folliculoluteal transition induced by GnRH in vivo. EDN2 was elevated only in the early CL and was not present in older CL. In the young CL, EDN2 mRNA was identified mainly in luteal cells but not endothelial cells that expressed the EDN1 gene. Similarly, in preovulatory follicles, EDN2 was expressed in the granulosa cells (GCs) and not in the vascular theca interna. LH and hypoxia are two major stimulants of CL formation. Therefore, GCs were cultured with bovine LH, under hypoxic conditions. GCs incubated with bovine LH resulted in increased EDN2 mRNA 42 h later. CoCl2, a hypoxia-mimicking agent, elevated EDN2 in GCs in a dose-dependent manner. Incubation of the human GC line (Simian virus 40 large T antigen) under low oxygen tension (1%) augmented EDN2 6 and 24 h later. In these two cell types, along with EDN2, hypoxia augmented VEGF. EDN2 induced in GCs changes that characterize the developing CL: cell proliferation as well as up-regulation of vascular endothelial growth factor and cyclooxygenase-2 (mRNA and protein levels). Human chorionic gonadotropin also up-regulated these two genes. Small interfering RNA targeting EDN-converting enzyme-1 effectively reduced its mRNA levels. This treatment, expected to lower the mature EDN2 peptide production, inhibited VEGF mRNA levels and GC numbers. Together these data suggest that elevated EDN2 in the early bovine CL, triggered by LH surge and hypoxia, may facilitate CL formation by promoting angiogenesis, cell proliferation, and differentiation.
Klipper
Eyal
E
Department of Animal Sciences, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
Levit
Anat
A
Mastich
Yonit
Y
Berisha
Bajram
B
Schams
Dieter
D
Meidan
Rina
R
D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D003338:Corpus Luteum / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019333:Endothelin-2 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D020868:Gene Silencing; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism* / Q000494:pharmacology; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D019333:Endothelin-2; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; D007987:Gonadotropin-Releasing Hormone; D003035:Cobalt; D007986:Luteinizing Hormone; C018021:cobaltous chloride