Involvement of p90 ribosomal S6 kinase in termination of cell cycle arrest during development of Artemia-encysted embryos.
Artemia has evolved a unique developmental pattern of encysted embryos to cope with various environmental threats. Cell divisions totally cease during the preemergence developmental stage from gastrula to prenauplius. The molecular mechanism of this, however, remains unknown. Our study focuses on the involvement of p90 ribosomal S6 kinase (RSK), a family of serine/threonine kinase-mediating signal transduction downstream of mitogen-activated protein kinase cascades, in the termination of cell cycle arrest during the post-embryonic development of Artemia-encysted gastrula. With immunochemistry, morphology, and cell cycle analysis, the identified Artemia RSK was established to be specifically activated during the post-embryonic and early larval developmental stages when arrested cells of encysted embryos resumed mitoses. In vivo knockdown of RSK activity by RNA interference, kinase inhibition, and antibody neutralization consistently induced defective larvae with distinct gaps between the exoskeleton and internal tissues. In these abnormal individuals, mitoses were detected to be largely inhibited in the affected regions. These results display the requirement of RSK activity during Artemia development and suggest its role in termination of cell cycle (G(2)/M phase) arrest and promotion of mitogenesis. Our findings may, thus, provide insights into the regulation of cell division during Artemia post-embryonic development and reveal further aspects of RSK functions.
Dai
Jie-Qiong
JQ
Institute of Cell Biology and Genetics, College of Life Sciences, Zhejiang University, Zhejiang 310058, China.
Zhu
Xiao-Jing
XJ
Institute of Cell Biology and Genetics, College of Life Sciences, Zhejiang University, Zhejiang 310058, China.
Liu
Feng-Qi
FQ
College of Life Sciences, Nankai University, Tianjin 300071, China.
Xiang
Jian-Hai
JH
Institute of Oceanology, Chinese Academy of Sciences, Shandong 266071, China.
Nagasawa
Hiromichi
H
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
Yang
Wei-Jun
WJ
Institute of Cell Biology and Genetics, College of Life Sciences, Zhejiang University, Zhejiang 310058, China. Electronic address: w_jyang@cls.zju.edu.cn.
D000595:Amino Acid Sequence; D000818:Animals; D001156:Artemia / Q000166:cytology / Q000196:embryology* / Q000201:enzymology*; D002453:Cell Cycle; D004247:DNA / Q000032:analysis; D018076:DNA, Complementary; D004625:Embryo, Nonmammalian / Q000166:cytology* / Q000201:enzymology*; D047108:Embryonic Development; D004789:Enzyme Activation; D007814:Larva; D008938:Mitosis; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D034622:RNA Interference; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*
D018076:DNA, Complementary; D004247:DNA; D038744:Ribosomal Protein S6 Kinases, 90-kDa