title: Expression of stimulated by retinoic acid gene 8 (Stra8) and maturation of murine gonocytes and spermatogonia induced by retinoic acid in vitro.
abstract: Vitamin A deficiency in the mouse results in an arrest in the progression of undifferentiated spermatogonia to differentiating spermatogonia. The supplement of retinol to vitamin-A-deficient mice reinitiates spermatogenesis in a synchronous manner throughout the testes. It is unclear whether the effects of retinoids are the result of a direct action on germ cells or are indirectly mediated through Sertoli cells. The expression of Stimulated by retinoic acid gene 8 (Stra8), which is required for spermatogenesis, is directly related to the availability of retinoic acid (RA). Analysis of gene expression by microarrays revealed moderate levels of Stra8 transcript in gonocytes and high levels in A and B spermatogonia. Stra8 mRNA levels were greatly reduced or absent in germ cells once they entered meiosis. This study examined the effect of retinoic acid on cultured neonatal testes and isolated gonocytes/spermatogonia in vitro. THY1(+) and KIT(+) germ cells were isolated by magnetic-activated cell sorting from the testes of mice of different ages. Isolated germ cells were cultured and treated with either vehicle (ethanol) or RA without feeder cells. We found that 1) Stra8 is predominantly expressed in premeiotic germ cells, 2) RA stimulates gonocyte DNA replication and differentiation in cultured neonatal testes, 3) in the absence of feeder cells, RA directly induces the transition of undifferentiated spermatogonia to differentiating spermatogonia by stimulating Stra8 and Kit gene expression, 4) RA dramatically stimulates Stra8 expression in undifferentiated spermatogonia but has a lesser impact in differentiating spermatogonia, 5) endogenous Stra8 gene expression is higher in differentiating spermatogonia than in undifferentiated spermatogonia and could mediate the RA effects on spermatogonial maturation, and 6) RA stimulates a group of genes involved in the metabolism, storage, transport, and signaling of retinoids.
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhou
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Rong
authors.initials: R
authors.lastname: Nie
authors.forename: Patrick
authors.initials: P
authors.lastname: Friel
authors.forename: Debra
authors.initials: D
authors.lastname: Mitchell
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Evanoff
authors.forename: Derek
authors.initials: D
authors.lastname: Pouchnik
authors.forename: Brent
authors.initials: B
authors.lastname: Banasik
authors.forename: John R
authors.initials: JR
authors.lastname: McCarrey
authors.forename: Christopher
authors.initials: C
authors.lastname: Small
authors.forename: Michael D
authors.initials: MD
authors.lastname: Griswold
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D004261:DNA Replication / Q000187:drug effects / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D008540:Meiosis / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D012708:Sertoli Cells / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D013091:Spermatogenesis / Q000187:drug effects / Q000235:genetics*; D013093:Spermatogonia / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D014212:Tretinoin / Q000494:pharmacology*; D014801:Vitamin A / Q000378:metabolism / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D011506:Proteins; C102019:Stra8 protein, mouse; D014801:Vitamin A; D014212:Tretinoin; D019009:Proto-Oncogene Proteins c-kit