Identification of a novel C1q family member in color crucian carp (Carassius auratus) ovary.
Potential roles of C1q/tumor necrosis factor (TNF) superfamily proteins have been observed in vertebrate oogenesis and oocyte maturation, but no ovary-specific member has been identified so far. In this study, we have cloned and identified a novel member of C1q family with a C1q domain in the C-terminal from fully grown oocyte cDNA library of color crucian carp and demonstrated that the gene might be specifically expressed in ovary and therefore designated as Carassius auratus ovary-specific C1q-like factor, CaOC1q-like factor. It encodes a 213 amino acid protein with a 17 amino acid signal peptide. There is only one protein band of about 24.5 kDa in the extracts from phase I to phase IV oocytes, but two positive protein bands are detected in the extracts of mature eggs and fertilized eggs. Furthermore, the mobility shift of the smaller target protein band cannot be eliminated by phosphatase treatment, but the larger protein band increases its mobility on the gel after phosphatase treatment, suggesting that the larger protein might be a phosphorylated form. Immunofluorescence localization indicates that the CaOC1q-like proteins localize in cytoplasm, cytoplasm membrane and egg envelope of the oocytes at cortical granule stage and vitellogenesis stage, whereas they were compressed to cytoplasm margin in ovulated mature eggs and discharged into perivitelline space between cytoplasm membrane and egg envelope after egg fertilization. Further studies on distribution and translocation mechanism of the CaOC1q-like factor will be benefit to elucidate the unique function in oogenesis, oocyte maturation and egg fertilization.
Chen
Bo
B
State Key Laboratory of Freshwater Ecology and Biotechnology, Wuhan Center for Developmental Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Gui
Jianfang
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D015922:Complement C1q / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004531:Eggs / Q000032:analysis; D005260:Female; D005306:Fertilization; D015723:Gene Library; D006054:Goldfish / Q000378:metabolism*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D010053:Ovary / Q000166:cytology / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D015922:Complement C1q