CHES-1-like, the ortholog of a non-obstructive azoospermia-associated gene, blocks germline stem cell differentiation by upregulating Dpp expression inDrosophilatestis

Abstract

Azoospermia is a high risk factor for testicular germ cell tumors, whose underlying molecular mechanisms remain unknown. In a genome-wide association study to identify novel loci associated with human non-obstructive azoospermia (NOA), we uncovered a single nucleotide polymorphism (rs1887102, P=2.60 ×10−7) in a human gene FOXN3. FOXN3 is an evolutionarily conserved gene. We used Drosophila melanogaster as a model system to test whether CHES-1-like, the Drosophila FOXN3 ortholog, is required for male fertility. CHES-1-like knockout flies are viable and fertile, and show no defects in spermatogenesis. However, ectopic expression of CHES-1-like in germ cells significantly reduced male fertility. With CHES-1-like overexpression, spermatogonia fail to differentiate after four rounds of mitotic division, but continue to divide to form tumor like structures. In these testes, expression levels of differentiation factor, Bam, were reduced, but the expression region of Bam was expanded. Further reduced Bam expression in CHES-1-like expressing testes exhibited enhanced tumor-like structure formation. The expression of daughters against dpp (dad), a downstream gene of dpp signaling, was upregulated by CHES-1-like expression in testes. We found that CHES-1-like could directly bind to the dpp promoter. We propose a model that CHES-1-like overexpression in germ cells activates dpp expression, inhibits spermatocyte differentiation, and finally leads to germ cell tumors.

The FOXN3-NEAT1-SIN3A repressor complex promotes progression of hormonally responsive breast cancer

“…It has been reported that FOXN3 acts in both transcription repression (3,(8)(9)(10) and activation (11). We report in this study that FOXN3 acts as a transcription repressor and physically interacts with the SIN3A complex in human cells.…”

“…At the cellular level, FOXN3 was described as a checkpoint suppressor (CHES1) in yeast (5) and was shown to inhibit protein biosynthesis (6) or to downregulate E2F5 in human cells to control cell cycle (7). At the molecular level, although it has been reported that FOXN3 interacts with xSin3/xRPD3 in X. laevis (3) and Sin3 in Saccharomyces cerevisiae (8) and with MEN1 (9) or SKIP (10) in human cells to exert transcriptional repressive function, in Drosophila testes it was demonstrated that FOXN3 acts to activate transcription (11). Clearly, the mechanistic action of FOXN3 in mammalian cells needs further elucidation.…”

Precursor RNA processing 3 is required for male fertility, and germline stem cell self-renewal and differentiation via regulating spliceosome function in Drosophila testes

“…Previous study indicated that heterozygous mutation of bam did not lead to dramatic differentiation defects in Drosophila testes 7 . However, phenotype of differentiation defects were obviously enhanced in Bam > Prp3 RNAi; Δ86/+ testes (more point fusomes and accumulated undifferentiated germ cells), compared with Bam > Prp3 RNAi (Fig.…”

“…All flies were cultured on standard corn meal food at 25 °C 7 . Information for alleles or transgenic lines used in this study can be found as noted: Nos-Gal4 (BDSC, #4937), Tj-Gal4 (DGRC, #104055), UAS- Prp3 RNA interference (RNAi) (THFC, #TH02381.N), UAS- Prp8 RNAi (THFC, #THU1528), UAS- Prp19 RNAi (THFC, #THU1054), UAS- bam RNAi (THFC, #THU0567).…”

Identifying potential maternal genes of Bombyx mori using digital gene expression profiling

“…Decapentaplegic (Dpp) is a subgroup of bone morphogenetic protein (BMP)-type ligands which are members of the transforming growth factor-β (TGF-β) superfamily [ 43 ]. In Drosophila , CHES-1-like activated TGF-β signaling by directly binding to the Dpp promoter and up-regulating Dpp expression [ 44 ]; Dpp played a significant role in immunity and several distinct stages of Drosophila development [ 45 , 46 ]. BGIBMGA010384 was identified as BmDpp , which functioned in response to the BmNPV infection in B .…”