Study On The Self-renewal Mechanism Of Female Germline Stem Cells Mediated By Cadherin 22 And The Usage Of Melation For Fertility Maintenance

Germline stem cells are adult stem cells what are capable of self-renewal,as well as the production of gametes by differentiation to pass their genetic material to future generations.Germline stem cells include spermatogonial stem cells in male,and female germline stem cell or oogonial stem cells in female.The reproductive health of germline stem cells,as well as the ability of self-renewal and differentiation,directly determines the individual's reproductive ability,but the molecular mechanisms underlying self-renewal and differentiation of germline stem cells are not yet clear.This article discusses the characteristics of germline stem cells in three different directions,their relevance and importance in the field of biomedicine,livestock husbandry,and agricultural economy.Firstly,the female germline stem cells were used as research objects to study the related regulatory molecules and signaling pathways of fate regulation of female germline stem cells,and then focus on the perspective of fertility protection of spermatogonial stem cells to explore the fertility of spermatogonial stem cells in the process of chemical therapy with reproductive hormones.The mechanism of protection of fertility and the established mouse model provide a theoretical basis in the clinic.And finally discusses the protection mechanism of melatonin on porcine spermatogonial stem cells in the toxic effects of zearalenone in the agricultural industry.The study provides a good reference for its application in agriculture.In the first part of this study,we demonstrated that the CDH22 is an important membrane protein regulating mouse female germline stem cells.It has been reported that CDH22 can encode two splicing in rat,in which the short splicing can promote the self-renewal of spermatogonial stem cells via to PI3K-AKT and JAK-STAT pathways,but there is no interaction with ?-catenin.However,we found that CDH22 can only encode one type of protein in mice and that it can regulate its self-renewal in the female germline stem cells through the interaction with JAK2,PI3K,and ?-catenin.At the same time,we confirmed that GDNF can regulate the self-renewal of female germline stem cells via GFRal receptors,and revealed that AKT3 is a pivotal factor that regulates the signaling pathway of female germline stem cells self-renewal.Both CDH22 and GFRal require the regulation of AKT3 expression via PI3K and SFK.AKT3 also regulate the self-renewal and maintenance in female germline stem cells.In the second part of this study,we studied the protective effect of hormones on spermatogonial stem cells in the chemotherapy induced reproductive toxicity.We first analyzed the chemotherapeutic drugs busulfan and its damaging effects on the reproductive system,especially toxic damage to spermatogonial stem cells,and found that busulfan can induce accumulation of reactive oxygen species in spermatogonial stem cells and activating ATM-P53 signaling pathway in spermatogonial stem cells.ATM-P53 signaling pathway induces apoptosis of spermatogonial stem cells and blocks self-renewal.We demonstrated that P53 is an important molecule that induces apoptosis of sperrnatogonial stem cells by using P53 knockout mice.After intraperitoneal injection by busulfan in P53-deficient mice,spermatogonial stem cells were protect by P53 loss.Then we compared the effects of FSH,LH,DHT,E2,and melatonin on the protection of spermatogonial stem cells in the presence of busulfan and found that melatonin had the best palliative effect.Then we compared the method of intraperitoneal injection drugs,and we found that continuous injection of melatonin can effectively alleviate busulfan damage to spermatogonial stem cells.Finally,we confirmed that melatonin can neutralize the reactive oxygen species produced by busulfan in spermatogonial stem cells.And spermatogonial stem cell can avoid busulfan-induced P53-mediated apoptosis and prevented loss of fertility.In the last part of this study,we isolated porcine spermatogonial stem cells(pSSCs)and explored the role of melatonin on protection of germline stem cells in the agricultural field.Zearalenone is a major food contaminant that not only has estrogenic toxicity but also can cause oxidative stress in germ cells.We used pSSCs s as a model to study the protective effect of melatonin on porcine spermatogonial stem cells under the toxic effects of zearalenone.Purified pSSCs were obtained by differential adherence.Using neonatal piglets Sertoli cell as feeder layers,we have been cultivating pSSCs in vitro for one month.Then we added zearalenone and melatonin in cultured pSSCs and found that melatonin could protect zearalenone induced apoptosis in pSSCs,and preliminarily confirmed that melatonin alleviated zearalenone induced reactive oxygen species as a molecular mechanism for protecting pSSCs.In summary,this study used mice and livestock pigs as model animals to deeply study the mechanism of self-renewal of germline stem cells,and the effect of melatonin on fertility protection.The theoretical support provided by the molecular mechanisms of stem cell in vitro maintenance.And microenvironment interaction studies provide a valuable reference for the application of fertility protection in clinical chemotherapy,also provide a basis for clinical treatment and diagnosis.The maintenance of fertility in male animals provides new ideas for animal husbandry production.