Heterochromatin Protein 1 (HP1) inhibits stem cell proliferation induced by ectopic activation of the Jak/STAT pathway in the Drosophila testis

Functional Analysis of Forkhead Transcription Factor Fd59a in the Spermatogenesis of Drosophila melanogaster

Spermatogenesis is critical for insect reproduction and is regulated by many different genes. In this study, we found that Forkhead transcription factor Fd59a functions as a key factor in the spermatogenesis of Drosophila melanogaster. Fd59a contains a conversed Forkhead domain, and it is clustered to the FoxD subfamily with other FoxD members from some insect and vertebrate species. Mutations in Fd59a caused swelling in the apical region of the testis. More importantly, fewer mature sperm were present in the seminal vesicle of Fd59a mutant flies compared to the control flies, and the fertility of Fd59a2/2 mutant males was significantly lower than that of the control flies. Immunofluorescence staining showed that the homeostasis of the testis stem cell niche in Fd59a2/2 mutant and Fd59a RNAi flies was disrupted and the apoptosis of sperm bundles was increased. Furthermore, results from RNA sequencing and qRT-PCR suggested that Fd59a can regulate the expression of genes related to reproductive process and cell death. Taken together, our results indicated that Fd59a plays a key role in the spermatogenesis of Drosophila.

Canonical and non-canonical functions of STAT in germline stem cell maintenance

BACKGROUND

Maintenance of the Drosophila male germline stem cells (GSCs) requires activation of the Janus kinase/signal transducer and activators of transcription (JAK/STAT) pathway by niche signals. The precise role of JAK/STAT signaling in GSC maintenance, however, remains incompletely understood.

RESULTS

Here, we show that, GSC maintenance requires both canonical and non-canonical JAK/STAT signaling, in which unphosphorylated STAT (uSTAT) maintains heterochromatin stability by binding to heterochromatin protein 1 (HP1). We found that GSC-specific overexpressing STAT, or even the transcriptionally inactive mutant STAT, increases GSC number and partially rescues the GSC-loss mutant phenotype due to reduced JAK activity. Furthermore, we found that both HP1 and STAT are transcriptional targets of the canonical JAK/STAT pathway in GSCs, and that GSCs exhibit higher heterochromatin content.

CONCLUSIONS

These results suggest that persistent JAK/STAT activation by niche signals leads to the accumulation of HP1 and uSTAT in GSCs, which promote heterochromatin formation important for maintaining GSC identity. Thus, the maintenance of Drosophila GSCs requires both canonical and non-canonical STAT functions within GSCs for heterochromatin regulation.

CG6015 controls spermatogonia transit-amplifying divisions by epidermal growth factor receptor signaling in Drosophila testes

Spermatogonia transit-amplifying (TA) divisions are crucial for the differentiation of germline stem cell daughters. However, the underlying mechanism is largely unknown. In the present study, we demonstrated that CG6015 was essential for spermatogonia TA-divisions and elongated spermatozoon development in Drosophila melanogaster. Spermatogonia deficient in CG6015 inhibited germline differentiation leading to the accumulation of undifferentiated cell populations. Transcriptome profiling using RNA sequencing indicated that CG6015 was involved in spermatogenesis, spermatid differentiation, and metabolic processes. Gene Set Enrichment Analysis (GSEA) revealed the relationship between CG6015 and the epidermal growth factor receptor (EGFR) signaling pathway. Unexpectedly, we discovered that phosphorylated extracellular regulated kinase (dpERK) signals were activated in germline stem cell (GSC)-like cells after reduction of CG6015 in spermatogonia. Moreover, Downstream of raf1 (Dsor1), a key downstream target of EGFR, mimicked the phenotype of CG6015, and germline dpERK signals were activated in spermatogonia of Dsor1 RNAi testes. Together, these findings revealed a potential regulatory mechanism of CG6015 via EGFR signaling during spermatogonia TA-divisions in Drosophila testes.

Epigenetic regulation of drosophila germline stem cell maintenance and differentiation

Gametogenesis is one of the most extreme cellular differentiation processes that takes place in Drosophila male and female germlines. This process begins at the germline stem cell, which undergoes asymmetric cell division (ACD) to produce a self-renewed daughter that preserves its stemness and a differentiating daughter cell that undergoes epigenetic and genomic changes to eventually produce haploid gametes. Research in molecular genetics and cellular biology are beginning to take advantage of the continually advancing genomic tools to understand: (1) how germ cells are able to maintain their identity throughout the adult reproductive lifetime, and (2) undergo differentiation in a balanced manner. In this review, we focus on the epigenetic mechanisms that address these two questions through their regulation of germline-soma communication to ensure germline stem cell identity and activity.

You-Gui-Yin improved the reproductive dysfunction of male rats with chronic kidney disease via regulating the HIF1α-STAT5 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

You-Gui-Yin (YGY) is a famous Chinese traditional medicine compound that has been used to treat renal function diseases for more than 300 years. It is recorded in Jing Yue Quanshu, which was written by a famous medical scientist named Jiebing Zhang in the Ming Dynasty.

AIM OF THE STUDY

Reproductive dysfunction is one of the most serious complications of chronic kidney disease (CKD). The aim of this study was to observe the effect of You-Gui-Yin (YGY) on reproductive dysfunction of male rats with adenine-induced CKD and to determine if any effects occurred via regulation of the HIF1α-STAT5 pathway.

MATERIALS AND METHODS

UPLC-Q-TOF-MS was used to detect the main medicinal components and conduct quality control of YGY. A total of 60 rats were randomly divided into 2 groups: the NC group (10 rats) and the CKD model group (50 rats). The CKD model rats was established by administration of adenine 150 mg kg^-1 orally for 14 days. After that, the CKD rats were randomly divided into 5 groups: the CKD group, YGY (10 g kg^-1 group, 20 g kg^-1 group, 40 g kg^-1 group) and the GUI-LU-ER-XIAN-JIAO (GL) 10 g kg^-1 group with 10 rats in each group. From the 15th day to the 45th day rats were given 150 mg kg^-1 adenine orally every other day to maintain the model (except in the NC group). The YGY groups and the GL group were orally administered the relevant drug once per day for 30 days. The NC group and the CKD group were orally administered an equal volume of normal saline for 30 days. On the 45th day, the rats' sexual behavior index was tested. On the 46th day, the rats were sacrificed. Biochemical indexes, histopathological changes of the kidneys and testes, sperm morphology, sperm abnormality rate, and key proteins in the HIF1α-STAT5 pathway in the kidney and testis were detected.

RESULTS

Thirteen components in the YGY extract were identified by UPLC-Q-TOF-MS for quality control of the YGY extract. The results of the biochemical and physiological tests validated the success of inducing CKD accompanied by reproductive dysfunction in rats. YGY significantly retarded the CKD progression and improved the hormone levels of male CKD rats. Sexual behavior tests showed YGY can significantly improve CKD rats' sexual function. In addition, the pathological changes of the kidney and testis, sperm abnormality rate and sperm morphological abnormalities of the CKD rats were reduced by YGY. Furthermore, decreased expression of HIF1α and EPO, and increased expression of p-EPOR (Tyr368), p-JAK2 (Tyr570) and p-STAT5 (Ser725) were observed in the kidney and the testis of the CKD rats. The YGY extract dramatically increased the expression of HIF1α and EPO, and decreased the expression of p-EPOR (Tyr368), p-JAK2 (Tyr570) and p-STAT5 (Ser725) to regulate key proteins in the HIF1α-STAT5 pathway of the kidney and testis.

CONCLUSIONS

YGY has obvious reversal effects on the abnormal symptoms of adenine-induced CKD and the abnormal symptoms of rats with hypothyroidism and male reproductive hypotension. Its mechanism is related to its ability to regulate the HIF1α-STAT5 pathway.