title: Insulin-like growth factor I promotes oocyte maturation through increasing the expression and phosphorylation of epidermal growth factor receptor in the zebrafish ovary.
abstract: The resumption of oocyte meiosis is a critical step for the progression of oocyte development, which requires an intimate collaboration of a variety of hormones and growth factors. Insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF) family are well recognized to promote oocyte maturation. However, the mechanism by which they coordinate this process remains unknown. The present study demonstrated that IGF-I can increase egfr mRNA and protein levels in follicle cell culture or intact follicles. This stimulation can be significantly inhibited by IGF-IR specific inhibitor, NVP-ADW742. The inhibitors against phosphatidylinositol-3-kinase (PI3K), phosphoinositide-dependent protein kinase 1 (PDK1) and Akt also dramatically abolished IGF-I-induced egfr expression, suggesting that the classical PI3K/Akt pathway mediated the action of IGF-I in this regulation. We further found that not only was the protein level of Egfr increased, but also the phosphorylation level was enhanced by IGF-I. Unlike egfr, IGF-I failed to stimulate the expression of Egf-like ligands whereas decreased the level of protein-tyrosine phosphatase, receptor type, kappa (ptprk), a protein tyrosine phosphatase. The oocyte maturation assay further confirmed that IGF-I initiates this regulation through its cognate receptor in the follicle cells. Taken together, IGF-I promoted oocyte maturation, in part at least, through Egf-like ligands/Egfr pathway. This study sheds light on the cross-talk between two important growth factors in the zebrafish ovary and the mechanism underlying the IGF-I induction on oocyte maturation.
authors.affiliation: Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation, Ministry of Health, and Key Laboratory of Organ Transplantation, Ministry of Education, Wuhan 430030, China. Electronic address: lxie86@gmail.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Xie
authors.affiliation: Changsha Aier Eye Hospital, Changsha 410015, China.
authors.forename: Qiongyan
authors.initials: Q
authors.lastname: Tang
authors.affiliation: The Department of Infectious Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
authors.affiliation: Hubei Medical Association, Wuhan 430071, China.
authors.forename: Lianyi
authors.initials: L
authors.lastname: Chen
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D009866:Oogenesis; D010053:Ovary / Q000166:cytology* / Q000378:metabolism; D010766:Phosphorylation; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013002:Somatomedins / Q000235:genetics / Q000378:metabolism*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D013002:Somatomedins; D029961:Zebrafish Proteins; C431139:igf1 protein, zebrafish; D066246:ErbB Receptors; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2
keywords: Epidermal growth factor; Folliculogenesis; Insulin-like growth factor; Oocyte maturation; Ovary