Collagen IV-mediated signalling is involved in progenitor Leydig cell proliferation.
In rats, during postnatal Leydig cell development, the progenitor Leydig cells (PLC) proliferate actively during days 14-21 of postnatal life. Luteinizing hormone (LH) is known to stimulate Leydig cell proliferation and oestradiol 17beta inhibits this process. In order to identify the molecules involved in Leydig cell proliferation, differentially expressed genes in proliferating and non-proliferating PLC isolated from vehicle and oestradiol 17beta-treated rats respectively, were analysed by differential display reverse transcription polymerase chain reaction (DD-RT-PCR). Results revealed that the expression of collagen IV alpha4 (Col IV alpha4), a subunit of extracellular matrix (ECM) protein collagen IV, was down regulated in PLC isolated from oestradiol 17beta-treated rats. Studies on stage specific expression of Col IV alpha4 during Leydig cell development revealed that this transcript is abundantly expressed at the stage where Leydig cell proliferation is maximal and the expression of this transcript decreased during differentiation of Leydig cells, which is associated with loss of proliferation. These observations suggest that Col IV alpha4 is important for PLC proliferation. Stimulation of PLC proliferation in vitro in the presence collagen IV provides additional support for the conclusion that collagen IV-mediated signalling is involved in PLC proliferation. Further studies revealed that active forms of focal adhesion kinase (FAK) and mitogen activated protein kinase 1/2 (MAPK 1/2), the intracellular signalling molecules that are known to mediate ECM protein signalling are present only in proliferating forms of Leydig cells and are absent in non-proliferating Leydig cells. These results suggest that collagen IV-mediated signalling is involved in PLC proliferation.
Anbalagan
M
M
Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India.
Rao
A Jagannadha
AJ
D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D049109:Cell Proliferation / Q000187:drug effects; D024141:Collagen Type IV / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000235:genetics; D004958:Estradiol / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D020869:Gene Expression Profiling; D007985:Leydig Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*
D024141:Collagen Type IV; D012333:RNA, Messenger; D004958:Estradiol; D004247:DNA; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D048049:Extracellular Signal-Regulated MAP Kinases