Sequencing and haplotype analysis of the Activator of CREM in the Testis (ACT) gene in populations of fertile and infertile males

Abstract

cAMP-responsive element modulator (CREM) is a key transcription factor in the differentiation of round spermatids into mature spermatozoa. During spermiogenesis, CREM is regulated in part by activator of CREM in the testis (ACT), which activates CREM in a phosphorylation-independent fashion. We hypothesized that the ACT gene, which is expressed exclusively in the testis, could be involved in male factor infertility in patients with idiopathic-impaired spermatogenesis. To test this hypothesis, we sequenced the coding regions and flanking intronic regions of the ACT gene in 96 azoo- or oligospermic patients and 69 fertile controls. A total of 12 single-nucleotide polymorphisms (SNPs) was identified, and four of them leading to amino acid substitutions. An association study was performed based on calculated haplotype frequencies, and statistically significant differences were found between the patient and control populations for some haplotypes. To help establish the evolutionary relationships between the haplotypes, the coding regions of both the chimpanzee and the gorilla ACT gene were sequenced and evaluated. To test whether the different haplotypes conferred a functional change to the ACT protein, a yeast two-hybrid assay was designed to test the interaction between the two most divergent ACT haplotypes and their known binding partners, CREM and KIF17b. We identified one ACT haplotype that had a 45% reduction in its interaction with CREM. Our results suggest that different haplotypes within the ACT gene may contribute to male factor subfertility.

Fhl5/Act, a CREM-binding transcriptional activator required for normal sperm maturation and morphology, is not essential for testicular gene expression

“…This result is in keeping with a previous report that the absence of Fhl5 has no effect on the expression of known CREM targets such as TNP1, PRN1 or PRN2 as assayed by PCR [19]. It also concurs with the fact that point mutations in the human ortholog of Fhl5 occur with the same frequency in fertile individuals and azoo- or oligozoospermic patients which argues against an essential role for the protein in human spermatogenesis [18,27]. It is possible that Fhl5's in vivo role as a transcriptional regulator is too subtle to be detected by whole-genome profiling using total testicular samples and that highly enriched populations of round spermatids would have to be used instead.…”

Associations of single nucleotide polymorphisms in the Pygo2 coding sequence with idiopathic oligospermia and azoospermia

“…Our laboratory has achieved previous success in the detection of mutations in a single gene (CREM) for male infertility (Christensen et al, 2006). CREM is a key transcription factor for prototype spermatid differentiation into mature sperm.…”

Functional Analysis of KIF3A and KIF3B during Spermiogenesis of Chinese Mitten Crab Eriocheir sinensis

“…KIF17 is also responsible for the transport of RNA and transcription mediators shuttling between nucleus and cytoplasm, such as ACT the activator of CREM [43], [48], [49], [50]. As for KIF3A and KIF3B, they are speculated to function in the manchette, a special microtubule-based structure, and the flagellar tail during spermatogenesis, [3], [4], [5], [36], [46]. A series of transformations related to the mobilization and the reorganization of the cytoskeleton network, the transport of intracellular organelles and complexes, and the reshaping of some organelles have relations to KIF3A and KIF3B [3], [4], [5].…”