Functions of promyelocytic leukaemia zinc finger (Plzf) in male germline stem cell development and differentiation.

Promyelocytic leukaemia zinc finger (Plzf), also known as zinc finger and BTB domain containing 16 (ZBTB16) or zinc-finger protein 145 (ZFP145), is a critical zinc finger protein of male germline stem cells (mGSCs). Multiple lines of evidence indicate that Plzf has a central role in the development, differentiation and maintenance of many stem cells, including mGSCs, and Plzf has been validated as an essential transcription factor for mammalian testis development and spermatogenesis. This review summarises current literature focusing on the significance of Plzf in maintaining and regulating self-renewal and differentiation of mGSCs, especially goat mGSCs. The review summarises evidence of the specificity of Plzf expression in germ cell development stage, the known functions of Plzf and the microRNA-mediated mechanisms that control Plzf expression in mGSCs.

LIN28A activates the transcription of NANOG in dairy goat male germline stem cells.

LIN28A serves as a crucial marker of dairy goat male germline stem cells (GmGSCs). In our previous study, we demonstrated that LIN28A promotes proliferation, self-renewal, and maintains the stemness of GmGSCs. Here, we found that LIN28A could activate the transcription of NANOG in a let-7g independent manner. We cloned the 5' upstream of two NANOG genes which were located on chromosome 15 ( NANOG-ch15) and chromosome 5 ( NANOG-ch5), respectively, and then examined their promoter activities and promoter methylation levels. Results showed that NANOG-ch15 is a pseudogene whereas NANOG-ch5 is active in Capra hircus. Bioinformatics analysis indicated that the 5' upstream region of NANOG-ch5 does not have typical CpG islands but contains several CG enrichment regions and several LIN28A binding sites. Deletion analysis suggested that NANOG-ch5 promoter can be activated by LIN28A directly binding to the site -210 but not by the indirect effect from the inhibition of let-7g, which is known to be downregulated by LIN28A. Mechanistically, LIN28A recruits and interacts with 5-methylcytosine-dioxygenase Ten-Eleven translocation 1 (TET1) to NANOG-ch5 gene promoter binding sites to orchestrate 5-methylcytosine and 5-hydroxymethylcytosine dynamics. These results revealed the role of LIN28A in NANOG transcriptional regulation via epigenetic DNA modifications to maintain the stemness of GmGSC.

miR-19b-3p integrates Jak-Stat signaling pathway through Plzf to regulate self-renewal in dairy goat male germline stem cells.

Jak-Stat pathway is the first pathway identified to stimulate spermatogonial stem cells (SSCs) self-renewal and maintenance activity. Recent studies have showed that stat3 a crucial gene implicated in this pathway can regulate self-renewal in male germline stem cell. In our previous study, we demonstrated that miR-19b-3p induces cell proliferation and reduces heterochromatin through Plzf which also regulates the balance between cell self-renewal and differentiation. Because miRNA can target several genes and to understand more about Plzf, a crucial transcription factor of SSCs, we performed microarray and found that miR-19b-3p integrate Jak-Stat through Plzf to regulate cell self-renewal. Our results demonstrated that miR-19b-3p induces Jak-Stat when Plzf is downregulated; overexpression of Plzf reversed the trend and shown an existence of feedback (-/+) between Plzf and GHR. The cell self-renewal markers CD49f, GFRα1, Oct4 and cKIT analyzed in the both groups miR-19b-3p and Plzf-overexpressing compared to their respective control confirm miR-19b-3p regulates cell pluripotency and self-renewal in goat male germline stem cells through Plzf. Together our finding revels that miR-19b-3p control Jak-Stat signaling through Plzf.

Triptolide induces growth inhibition and apoptosis of human laryngocarcinoma cells by enhancing p53 activities and suppressing E6-mediated p53 degradation.

Triptolide, an active compound extracted from Chinese herb Leigongteng (Tripterygium wilfordii Hook F.), shows a broad-spectrum of anticancer activity through its cytotoxicity. However, the efficacy of triptolide on laryngocarcinoma rarely been evaluated, and the mechanism by which triptolide-induced cellular apoptosis is still not well understood. In this study, we found that triptolide significantly inhibited the laryngocarcinoma HEp-2 cells proliferation, migration and survivability. Triptolide induces HEp-2 cell cycle arrest at the G1 phase and apoptosis through intrinsic and extrinsic pathways since both caspase-8 and -9 are activated. Moreover, triptolide enhances p53 expression by increasing its stability via down-regulation of E6 and E6AP. Increased p53 transactivates down-stream target genes to initiate apoptosis. In addition, we found that short time treatment with triptolide induced DNA damage, which was consistent with the increase in p53. Furthermore, the cytotoxicity of triptolide is decreased by p53 knockdown or use of caspases inhibitor. In conclusion, our results demonstrated that triptolide inhibits cell proliferation and induces apoptosis in laryngocarcinoma cells by enhancing p53 expression and activating p53 functions through induction of DNA damage and suppression of E6 mediated p53 degradation. These studies indicate that triptolide is a potential anti-laryngocarcinoma drug.