Localization of Cellular Retinol-Binding Protein mRNA in Rat Testis and Epididymis and its Stage-Dependent Expression during the Cycle of the Seminiferous Epithelium1

Abstract

Anatomical localization of cellular retinol-binding protein (CRBP) mRNA was examined in normal rat testis and epididymis and also in retinoid-deficient rat testis. In situ hybridization was performed with 35S-labeled rat CRBP cRNA probes on frozen tissue sections. In normal testis, CRBP mRNA was mainly localized in the Sertoli cells and to some extent in peritubular cells. A distinct cyclic variation of the relative levels of hybridizable CRBP mRNA was observed during the spermatogenic cycle. The peak of CRBP mRNA content was seen in the stages of the cycle that preceded those in which peak CRBP protein content had been observed previously in our laboratory by immunohistochemistry. No appreciable amount of CRBP mRNA was observed in the interstitial space or in the lumen of the tubules. CRBP mRNA displayed the same anatomical localization in the retinoid-deficient testis, but the level of hybridizable CRBP mRNA was substantially reduced. A strong hybridization signal for CRBP mRNA was seen in proximal epididymis and was strikingly localized in the ductular epithelium. CRBP mRNA was not detectable in the distal portion of the epididymis. These studies provide information about the cell-specific expression of CRBP synthesis within the testis and epididymis and about its cyclic variation and regulation.

Cellular expression of retinal dehydrogenase types 1 and 2: Effects of vitamin A status on testis mRNA

“…Moreover, germ cells of vitamin A-suf®cient rats express CRBP, RoDH1, and RoDH2 mRNA much less intensely relative to Sertoli cell expression Schmitt and Ong, 1993;Zhai et al, 1997;Akmal et al, 1998). Similarly, undetectable RALDH mRNA expression in Sertoli cells of vitamin A-suf®cient rats was not expected, because Sertoli cells synthesize RA in vitro and in culture and express CRBP, RoDH1, and RoDH2 intensely (Porter et al, 1983;Kato et al, 1985;Rajan et al, 1990;Zhai et al, 1997). Lack of mRNA detection does not necessarily indicate lack of expression, however.…”

Retinoids and spermatogenesis: Lessons from mutant mice lacking the plasma retinol binding protein

“…First, the expression patterns of retinoic acid receptors, retinoic acid synthesizing enzymes, and other retinoid binding proteins in the testis differ between the rat (Akmal et al, 1997;Zhai et al, 2001;Rajan et al, 1990) and the mouse (Vernet et al, 2006). Second, the outcome of VAD in the seminiferous epithelium differs between these species: in VAD rats, spermatogenesis is arrested at the preleptotene spermatocyte stage (Huang and Humbree, 1979;Huang et al, 1990;Ismail et al, 1990), whereas in VAD mice, it is arrested at the spermatogonia stage (Huang and Hembree, 1979;Gaemers et al, 1997).…”

Retinoic Acid Metabolism and Signaling Pathways in the Adult and Developing Mouse Testis

“…Rbp1) inactivation dramatically reduces the retinyl ester stores (2). Both of these proteins are expressed in the rat testis (25,26,60). Thus, we used ISH to identify the cell types expressing them in the adult mouse testis.…”

“…The ROL-binding proteins, CRBP1 and CRBP2, are both involved in ROL storage in vivo (2,24). In the adult rat testis, CRBP1 is localized mainly in Sertoli cells (25,26), whereas CRBP2 is not expressed (27,28). As for RA-binding proteins, CRABP1 and CRABP2, their actual functions remain controversial (23,29,30).…”