Expression of Retinoic Acid Synthesizing Enzymes, Aldh1a1, Aldh1a2 and Aldh1a3 in Canine Testis During Post-Natal Development

Spermatogenesis is a highly regulated process of cell division and differentiation. Sperm production is organized temporally and spatially and is carefully controlled by several signaling molecular processes. Among these signaling events, retinoic acid (RA) signaling is considered as indispensable since the RA promotes spermatogonial differentiation, adhesion of germ cells to Sertoli cells, and release of mature spermatids into the lumen of seminiferous tubules. Evidence suggests that RA induces expression of the critical pre-meiosis gene, Stra8, in germ cells of pubertal testis and adult testis. To appropriately activate the retinoid signaling pathway during spermatogenesis, optimal testicular RA level is necessary. The suitable testicular RA level is maintained via RA synthesis and degradation. The metabolism of RA is tightly regulated by a group of RA synthesizing- and degrading-enzymes. The retinaldehyde dehydrogenase enzymes (ALDH1A1, ALDH1A2 and ALDH1A3) are responsible for the oxidation of RA precursors to produce RA. The goal of the study was to investigate the expression pattern of the retinoic acid synthesizing enzymes ALDH1A1 (XM_533525), ALDH1A2 (XM_535494) and ALDH1A3 (XM_003638965) in canine testis during post-natal development at both mRNA and protein levels. Real-time polymerase chain reaction was performed to determine the relative quantity of ALDH1A1, ALDH1A2 and ALDH1A3 at mRNA level in young, peripubertal adult dog testes, and Western blotting was used to specifically detect their proteins' presence in testes ...