Small-molecule inhibition of BRDT for male contraception. Small-molecule inhibition of BRDT for male contraception. Matzuk MM 2012 et al.
A pharmacologic approach to male contraception remains a longstanding challenge in medicine. Toward this objective, we explored the spermatogenic effects of a selective small-molecule inhibitor (JQ1) of the bromodomain and extraterminal (BET) subfamily of epigenetic reader proteins. Here, we report potent inhibition of the testis-specific member BRDT, which is essential for chromatin remodeling during spermatogenesis. Biochemical and crystallographic studies confirm that occupancy of the BRDT acetyl-lysine binding pocket by JQ1 prevents recognition of acetylated histone H4. Treatment of mice with JQ1 reduced seminiferous tubule area, testis size, and spermatozoa number and motility without affecting hormone levels. Although JQ1-treated males mate normally, inhibitory effects of JQ1 evident at the spermatocyte and round spermatid stages cause a complete and reversible contraceptive effect. These data establish a new contraceptive that can cross the blood:testis boundary and inhibit bromodomain activity during spermatogenesis, providing a lead compound targeting the male germ cell for contraception.
/////////////////////////
NCBI Summary:
BRDT is similar to the RING3 protein family. It possesses 2 bromodomain motifs and a PEST sequence (a cluster of proline, glutamic acid, serine, and threonine residues), characteristic of proteins that undergo rapid intracellular degradation. The bromodomain is found in proteins that regulate transcription. Several transcript variants encoding multiple isoforms have been found for this gene. [provided by RefSeq, Jun 2011]
General function
Transcription factor
Comment
Cellular localization
Nuclear
Comment
Ovarian function
Oocyte maturation
Comment
Identification of differential gene expression in germinal vesicle vs. metaphase II mouse oocytes by using annealing control primers. Yoon SJ 2005 et al.
By using a new innovative technology, annealing control primer-polymerase chain reaction (ACP-PCR), we identified genes that are differentially expressed in immature GV vs. in mature MII mouse oocytes. The results of the present study will be valuable in understanding the components of oocyte maturation and provide a basis for studies of human oocyte maturation.
Interestingly, we identified two genes previously reported as testis-specific genes, Fsrg3 and TEMO, as oocyte-expressed genes (20, 21 and 22). Fsrg3, also known as BRDT, is involved in chromatin remodeling, and TEMO is a marker for Sertoli cell?germ cell interactions, but its specific function is unknown. Characterization of the expression and function of these genes in oocyte maturation should be addressed.
In conclusion, this is the first report identifying genes that are differentially expressed in GV and MII oocytes using the new ACP technology. The results of the present study with the mouse model will be valuable in understanding the mechanisms of oocyte maturation and will provide a basis for studies of human oocyte maturation.
Expression regulated by
Comment
Ovarian localization
Oocyte
Comment
Bromodomain testis-specific protein is expressed in mouse oocyte and evolves faster than its ubiquitously expressed paralogs BRD2, -3, and -4. Paillisson A et al. By using in silico methods in a previous study, we identified 100 oocyte-specific genes and 150 genes, enriched in the mouse oocyte. Interestingly, approximately half of the oocyte-specific genes tend to cluster on mouse chromosomes as if they have recently duplicated during evolution. In this study, we focused our attention on mouse BRDT, which belongs to a family of four structurally related proteins characterized by two N-terminal bromodomains and one C-terminal extraterminal domain (ET domain), defining the BET family. In mammals, BRD2, -3, and -4 are ubiquitously expressed, whereas BRDT expression was shown to be restricted to the testis. We were interested to know whether there was a correlation between the evolutionary rate and the specificity of expression of these four paralogous genes. First, we show by RT-PCR and in situ hybridization that BRDT is also expressed in mouse oocyte. Moreover, phylogenetic analyses show that the BRDT germ cell-specific orthology group clearly evolves faster than its ubiquitously expressed paralogs BRD2, BRD3, and BRD4. This suggests that there is a relationship between the evolution of these four groups of orthology and their tissue specificity of expression.
Follicle stages
Comment
Genomewide discovery and classification of candidate ovarian fertility genes in the mouse. Gallardo TD et al. Female infertility syndromes are among the most prevalent chronic health disorders in women, but their genetic basis remains unknown because of uncertainty regarding the number and identity of ovarian factors controlling the assembly, preservation, and maturation of ovarian follicles. To systematically discover ovarian fertility genes en masse, we employed a mouse model (Foxo3) in which follicles are assembled normally but then undergo synchronous activation. We developed a microarray-based approach for the systematic discovery of tissue-specific genes and, by applying it to Foxo3 ovaries and other samples, defined a surprisingly large set of ovarian factors (n = 348, approximately 1% of the mouse genome). This set included the vast majority of known ovarian factors, 44% of which when mutated produce female sterility phenotypes, but most were novel. Comparative profiling of other tissues, including microdissected oocytes and somatic cells, revealed distinct gene classes and provided new insights into oogenesis and ovarian function, demonstrating the utility of our approach for tissue-specific gene discovery. This study will thus facilitate comprehensive analyses of follicle development, ovarian function, and female infertility. This is an oocyte-specific gene.