Cloning and Expression Analysis of Testis-Specific Cyclic 3′,5′-Adenosine Monophosphate-Responsive Element Modulator Activators in the Nonhuman Primate (Macaca fascicularis): Comparison with Other Primate and Rodent Species1

Abstract

The cAMP-responsive element modulator (CREM) gene encodes a transcription factor that is essential for spermatogenesis. In mouse testis, several CREM repressors and activators have been identified. In contrast to the situation for the mouse, however, little is known about CREM isoforms in the primate testis. We analyzed CREM isoforms and mRNA expression in a clinically relevant primate model, the cynomolgus monkey (Macaca fascicularis). A cDNA library was generated from monkey testis; and two activator isoforms (tau2 with and without exon gamma) were identified, which displayed high sequence identity to mouse and human isoforms. The insertion of exon gamma was observed for the first time in the primate testis. CREM activator expression was confined to the testis, where it was seen in late pachytene spermatocytes and round spermatids in specific spermatogenic stages, as revealed by in situ hybridization. Comparison of the mRNA and the recently described protein expression indicated a lack of translational delay of CREM expression. Comparative analysis of testicular CREM expression by reverse transcription-polymerase chain reaction yielded several transcripts in the rat, mouse, hamster, and marmoset; two transcripts in cynomolgus and rhesus monkeys; and one transcript in men. These findings suggest an evolutionary trend from multiple activator isoforms to a single activator transcript in men.

Krüppel-like factor 4, a “pluripotency transcription factor” highly expressed in male postmeiotic germ cells, is dispensable for spermatogenesis in the mouse

“…the last stage before spermiation. CREM is strongly expressed in round spermatids (Behr et al, 2000; Behr and Weinbauer, 2001) and essential for spermiogenesis (Blendy et al, 1996; Nantel et al, 1996). Since both genes are co-expressed in round spermatids and since we found by TRED analysis (Jiang et al, 2007; Zhao et al, 2005) three putative KLF4 binding sites in the Crem promoter (TRED promoter ID 62523; CACCC motif (Garrett-Sinha et al, 1996) at position −261 to −265; RRGGYGY motif (Shields and Yang, 1998) at positions −225 to −231 and −748 to −754), we tested by immunohistochemistry whether the lack of KLF4 influenced CREM expression in spermatids.…”

Dynamic Regulation of Histone H3 Methylation at Lysine 4 in Mammalian Spermatogenesis1

“…The common marmoset, Callithrix jacchus, has been used intensively for many years as a nonhuman primate model to describe the physiology of testicular development and function [33,[57][58][59][60]. Importantly, the marmoset shows striking similarities to the organization of the human seminiferous epithelium [61].…”

Transplantation of Wild-Type Spermatogonia Leads to Complete Spermatogenesis in Testes of Cyclic 3′,5′-Adenosine Monophosphate Response Element Modulator-Deficient Mice1

“…There is also strong evidence for the importance of CREM during the development and maturation of the male germ cells in primates [3,6]. The transcription factor CREM is expressed in germ cells and Sertoli cells [3,[6][7][8][9]. The CREM gene consists of several exons encoding different functional domains of the CREM protein [10,[24][25][26].…”

“…Male CREM knockout mice are deficient in all CREM proteins and show a round spermatid maturation arrest (RSMA) [4,5]. However, exact cellular targets causing this defect are still unknown because CREM proteins are expressed in both germ cells and Sertoli cells [6][7][8][9]. CREM appears to regulate the expression of several target genes that are necessary for spermiogenesis [3,10].…”