The roles and regulation of Yes-associated protein 1 in stem cells

Yes-associated protein 1(YAP1)is a downstream effector of the Hippo signaling pathway,and it is involved in tumorigenesis,tissue repair,growth,and development.In this review,the biological roles and the mechanisms of YAP1 in mediating stem cell fate decisions are discussed,including cell proliferation,differentiation,and apoptosis.In general,YAP1 promotes the proliferation and differentiation of stem cells,including embryonic stem cells and adult stem cells.It inhibits apoptosis by binding to the transcription factors,e.g.,transcriptional enhanced associate domain(TEAD),Smad,runt-related transcription factor 1/2,p73,p63,and Erb84,to maintain tissue homeostasis.The translocalization of YAP1 in cellular nuclei and the phosphorylation in the cytoplasm work as important and unusual events for the activation of YAP1.Moreover,YAP1 serves as the crosstalk for the Hippo pathway and other signaling pathways,including the Wnt and Notch pathways.It is highlighted in this review that YAP1 is an essential regulator for stem cells that have significant applications in regenerative medicine and reproductive medicine.

Metallothionein 1E Alleviates Cadmium-induced Renal Cytotoxicity through Promoting Mitochondrial Functional Recovery

The pervasive utilization of industrial substances has escalated human exposure to cadmium(Cd),a metal associated with long-term negative health outcomes such as renal dysfunction,neurological disorders,and various cancers^([1]).Once ingested by humans,Cd interacts with cysteine-rich metallothioneins(MTs)which have metal-binding and antioxidant properties and is subsequently transported to the kidney^([2]).

OIP5 Interacts with NCK2 to Mediate Human Spermatogonial Stem Cell Self-Renewal and Apoptosis through Cell Cyclins and Cycle Progression and Its Abnormality Is Correlated with Male Infertility

Spermatogonial stem cells(SSCs)have important applications in both reproduction and regenerative medicine.Nevertheless,specific genes and signaling transduction pathways in mediating fate decisions of human SSCs remain elusive.Here,we have demonstrated for the first time that OIP5(Opa interacting protein 5)controlled the self-renewal and apoptosis of human SSCs.RNA sequencing identified that NCK2 was a target for OIP5 in human SSCs,and interestingly,OIP5 could interact with NCK2 as shown by Co-IP(co-immunoprecipitation),IP-MS(mass spectrometry),and GST pulldown assays.NCK2 silencing decreased human SSC proliferation and DNA synthesis but enhanced their apoptosis.Notably,NCK2 knockdown reversed the influence of OIP5 overexpression on human SSCs.Moreover,OIP5 inhibition decreased the numbers of human SSCs at S and G2/M phases,while the levels of numerous cell cycle proteins,including cyclins A2,B1,D1,E1 and H,especially cyclin D1,were remarkably reduced.Significantly,whole-exome sequencing of 777 patients with nonobstructive azoospermia(NOA)revealed 54 singlenucleotide polymorphism mutations of the OIP5 gene(6.95%),while the level of OIP5 protein was obviously lower in testes of NOA patients compared to fertile men.Collectively,these results implicate that OIP5 interacts with NCK2 to modulate human SSC self-renewal and apoptosis via cell cyclins and cell cycle progression and that its mutation and/or lower expression is correlated with azoospermia.As such,this study offers novel insights into molecular mechanisms underlying the fate determinations of human SSCs and the pathogenesis of NOA,and it provides new targets for treating male infertility.

Casticin Attenuates Stemness in Cervical Cancer Stem-Like Cells by Regulating Activity and Expression of DNMT1

Objective:To explore whether casticin(CAS)suppresses stemness in cancer stem-like cells(CSLCs)obtained from human cervical cancer(CCSLCs)and the underlying mechanism.Methods:Spheres from He La and Ca Ski cells were used as CCSLCs.DNA methyltransferase 1(DNMT1)activity and m RNA levels,self-renewal capability(Nanog and Sox2),and cancer stem cell markers(CD133 and CD44)were detected by a colorimetric DNMT activity/inhibition assay kit,quantitative real-time reverse transcription-polymerase chain reaction,sphere and colony formation assays,and immunoblot,respectively.Knockdown and overexpression of DNMT1 by transfection with sh RNA and c DNA,respectively,were performed to explore the mechanism for action of CAS(0,10,30,and 100 nmol/L).Results:DNMT1 activity was increased in CCSLCs compared with He La and Ca Ski cells(P<0.05).In addition,He La-derived CCSLCs transfected with DNMT1 sh RNA showed reduced sphere and colony formation abilities,and lower CD133,CD44,Nanog and Sox2 protein expressions(P<0.05).Conversely,overexpression of DNMT1 in He La cells exhibited the oppositive effects.Furthermore,CAS significantly reduced DNMT1 activity and transcription levels as well as stemness in He La-derived CCSLCs(P<0.05).Interestingly,DNMT1 knockdown enhanced the inhibitory effect of CAS on stemness.As expected,DNMT1 overexpression reversed the inhibitory effect of CAS on stemness in He La cells.Conclusion:CAS effectively inhibits stemness in CCSLCs through suppression of DNMT1 activation,suggesting that CAS acts as a promising preventive and therapeutic candidate in cervical cancer.

Generation of male germ cells in vitro from the stem cells

Infertility has become a serious disease since it affects 10%–15%of couples worldwide,and male infertility contributes to about 50%of the cases.Notably,a significant decrease occurs in the newborn population by 7.82 million in 2020 compared to 2016 in China.As such,it is essential to explore the effective methods of obtaining functional male gametes for restoring male fertility.Stem cells,including embryonic stem cells(ESCs),induced pluripotent stem cells(iPSCs),spermatogonial stem cells(SSCs),and mesenchymal stem cells(MSCs),possess the abilities of both self-renewal and differentiation into germ cells.Significantly,much progress has recently been achieved in the generation of male germ cells in vitro from various kinds of stem cells under the specified conditions,e.g.,the coculturing with Sertoli cells,three-dimensional culture system,the addition of growth factors and cytokines,and/or the overexpression of germ cell-related genes.In this review,we address the current advance in the derivation of male germ cells in vitro from stem cells based on the studies of the peers and us,and we highlight the perspectives and potential application of stem cell-derived male gametes in reproductive medicine.

The role of homozygous LOF variant of the PNLDC1 gene in oligo-astheno-teratozoospermia(OAT)and male infertility

Dear Editor,An interesting article from Zhao et al.recently published in Asian Journal of Andrology,has shown the association of a novel loss-of function(LOF)variant in PARN-like ribonuclease domain-containing exonuclease 1(PNLDCI)and male infertility,and we would like to contribute a commentary on this article.

Characterization, isolation, and culture of spermatogonial stem cells in Macaca fascicularis

Spermatogonial stem cells(SSCs)have great applications in both reproductive and regenerative medicine.Primates including monkeys are very similar to humans with regard to physiology and pathology.Nevertheless,little is known about the isolation,the characteristics,and the culture of primate SSCs.This study was designed to identify,isolate,and culture monkey SSCs.Immunocytochemistry was used to identify markers for monkey SSCs.Glial cell line-derived neurotrophic factor family receptor alpha-1(GFRAl)-enriched spermatogonia were isolated from monkeys,namely Macaca fascicularis(M.fascicularis),by two-step enzymatic digestion and magnetic-activated cell sorting,and they were cultured on precoated plates in the conditioned medium.Reverse transcription-polymerase chain reaction(RT-PCR),immunocytochemistry,and RNA sequencing were used to compare phenotype and transcriptomes in GFRAl-enriched spermatogonia between 0 day and 14 days of culture,and xenotransplantation was performed to evaluate the function of GFRAl-enriched spermatogonia.SSCs shared some phenotypes with rodent and human SSCs.GFRAl-enriched spermatogonia with high purity and viability were isolated from M.fascicularis testes.The freshly isolated cells expressed numerous markers for rodent SSCs,and they were cultured for 14 days.The expression of numerous SSC markers was maintained during the cultivation of GFRAl-enriched spermatogonia.RNA sequencing reflected a 97.3%similarity in global gene profiles between 0 day and 14 days of culture.The xenotransplantation assay indicated that the GFRAl-enriched spermatogonia formed colonies and proliferated in vivo in the recipient c-Kitw/w(W)mutant mice.Collectively,GFRAl-enriched spermatogonia are monkey SSCs phenotypically both in vitro and in vivo.This study suggests that monkey might provide an alternative to human SSCs for basic research and application in human diseases.

Exosomes:key players in cancer and potential therapeutic strategy

Exosomes are extracellular vesicles secreted by most eukaryotic cells and participate in intercellular communication.The components of exosomes,including proteins,DNA,mRNA,microRNA,long noncoding RNA,circular RNA,etc.,which play a crucial role in regulating tumor growth,metastasis,and angiogenesis in the process of cancer development,and can be used as a prognostic marker and/or grading basis for tumor patients.Hereby,we mainly summarized as followed:the role of exosome contents in cancer,focusing on proteins and noncoding RNA;the interaction between exosomes and tumor microenvironment;the mechanisms that epithelial-mesenchymal transition,invasion and migration of tumor affected by exosomes;and tumor suppression strategies based on exosomes.Finally,the application potential of exosomes in clinical tumor diagnosis and therapy is prospected,which providing theoretical supports for using exosomes to serve precise tumor treatment in the clinic.