Activation of an AMP-activated protein kinase is involved in post-diapause development of Artemia franciscana encysted embryos.
BACKGROUND
Cysts of Artemia can remain in a dormant state for long periods with a very low metabolic rate, and only resume their development with the approach of favorable conditions. The post-diapause development is a very complicated process involving a variety of metabolic and biochemical events. However, the intrinsic mechanisms that regulate this process are unclear.


RESULTS
Herein we report the specific activation of an AMP-activated protein kinase (AMPK) in the post-diapause developmental process of Artemia. Using a phospho-AMPKalpha antibody, AMPK was shown to be phosphorylated in the post-diapause developmental process. Results of kinase assay analysis showed that this phosphorylation is essential for AMPK activation. Using whole-mount immunohistochemistry, phosphorylated AMPK was shown to be predominantly located in the ectoderm of the early developed embryos in a ring shape; however, the location and shape of the activation region changed as development proceeded. Additionally, Western blotting analysis on different portions of the cyst extracts showed that phosphorylated AMPKalpha localized to the nuclei and this location was not affected by intracellular pH. Confocal microscopy analysis of immunofluorescent stained cyst nuclei further showed that AMPKalpha localized to the nuclei when activated. Moreover, cellular AMP, ADP, and ATP levels in developing cysts were determined by HPLC, and the results showed that the activation of Artemia AMPK may not be associated with cellular AMP:ATP ratios, suggesting other pathways for regulation of Artemia AMPK activity.


CONCLUSIONS
Together, we report evidence demonstrating the activation of AMPK in Artemia developing cysts and present an argument for its role in the development-related gene expression and energy control in certain cells during post-diapause development of Artemia.
Zhu
Xiao-Jing
XJ
Institute of Cell Biology and Genetics, College of Life Sciences, Zijingang Campus, Zhejiang University, Hangzhou, Zhejiang 310058, PR China. xiao_jingzhu@hotmail.com
Dai
Jie-Qiong
JQ
Tan
Xin
X
Zhao
Yang
Y
Yang
Wei-Jun
WJ
D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001156:Artemia / Q000196:embryology / Q000201:enzymology*; D015153:Blotting, Western; D002384:Catalysis; D002467:Cell Nucleus / Q000201:enzymology; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000201:enzymology* / Q000378:metabolism; D004789:Enzyme Activation; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D005982:Glutathione Transferase; D055372:AMP-Activated Protein Kinases