Abstract
The c-Jun N-terminal protein kinase mitogen-activated protein kinases (JNK MAPKs) are an evolutionarily conserved family of serine/threonine protein kinases involved in controlling cell growth, differentiation, and apoptosis in mammalian testis and germ cells. As a scaffold protein of the JNK pathway, JNK-interacting protein 4 (JIP4) is found in some mammalian spermatozoa and participates in certain male reproductive processes. Few have reported on the roles of JNK and JIP4 in the Chinese mitten crab Eriocheir sinensis H. Milne Edwards, 1853. Based on transcriptome sequences from the testis of E. sinensis , we successfully cloned full-length cDNAs of JNK and JIP4 (designated Es-JNK and Es-JIP4 , respectively). Western blotting showed relatively high expression of Es -JNK and Es -JIP4 proteins in the testis. Expression levels of total Es -JNK, phosphorylated Es -JNK ( Es -p-JNK), and Es -JIP4 proteins decreased gradually during spermatogenesis. Es-JNK and Es-JIP4 mRNAs were mainly localized in the nucleus from the spermatogonium stage to the secondary spermatocyte stage and were widely distributed in the nuclear cup, apical cap, acrosomal tubule, and acrosomal vesicle of spermatids. Es -JNK, Es -p-JNK, and Es -JIP4 proteins were nevertheless mainly dispersed in the cytoplasm and intercellular substance of spermatogonium and primary spermatocytes, in the nucleus of secondary spermatocytes, and in the apical cap, acrosomal tubule, acrosomal vesicle, and nuclear cup of spermatids. During the acrosome reaction induced by the calcium ionophore A23187, Es -JNK, Es -p-JNK, and Es -JIP4 proteins were found mainly expressed in the apical cap and acrosomal vesicle by immunofluorescence microscopy. The results implicate functions for Es -JNK and Es -JIP4 in spermatogenesis and the acrosome reaction in E. sinensis .
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