Constitutive regulation of the Insl3 gene in rat Leydig cells.
Insulin-like factor 3 (Insl3) is a major new product of the Leydig cells in all mammalian species so far examined. The rat Insl3 gene is encoded by two exons in close juxtaposition to the Jak3 gene. Using RT-PCR analysis we now show that in the rat testis it is expressed as both major and minor splice variants, the former encoding the normal protein, the latter a truncated peptide comprising a C-terminally extended B-domain. Both transcripts are produced in constant relative amounts uniquely in the Leydig cells of the postnatal testis and in no other testicular cell type. Rat Insl3 protein is also expressed only in Leydig cells after postnatal day 30. Although specific mRNA is present at earlier times, corresponding protein is not detected. Semi-quantitative RT-PCR analysis of Insl3 transcripts in the mouse MA-10 tumour Leydig cell-line under a wide range of stimulation regimes shows that in an acute context, the Insl3 gene is expressed absolutely constitutively. This is confirmed by transfection and electrophoretic mobility shift (EMSA) analysis of the rat Insl3 gene promoter, wherein the importance of three putative SF-1 responsive elements is underscored, although these appear to differ in their relative importance from their counterparts in the mouse Insl3 gene.
Sadeghian
Helen
H
Institute for Hormone and Fertility Research, University of Hamburg, Germany.
Anand-Ivell
Ravinder
R
Balvers
Marga
M
Relan
Vandana
V
Ivell
Richard
R
D000818:Animals; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation / Q000502:physiology*; D018398:Homeodomain Proteins / Q000378:metabolism; D007328:Insulin / Q000096:biosynthesis* / Q000235:genetics; D053616:Janus Kinase 3; D007985:Leydig Cells / Q000166:cytology / Q000502:physiology*; D008297:Male; D051379:Mice; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D020218:Response Elements / Q000502:physiology*; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000378:metabolism
D018398:Homeodomain Proteins; D007328:Insulin; C507936:Jak3 protein, rat; C084797:Leydig insulin-like protein; D011506:Proteins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D011505:Protein-Tyrosine Kinases; C507935:Jak3 protein, mouse; D053616:Janus Kinase 3