Abstract 16096: Snf1-Related Kinase Inhibits Cell Proliferation Through Upregulated Calcyclin Binding Protein and Reduced Beta-Catenin Signaling
Introduction: Snf1-related kinase (SNRK) is a mammalian serine-threonine kinase with sequence similarity to the AMP-activated kinase alpha subunit. SNRK localizes to the cytoplasm and nucleus, however, its primary function is not well-characterized. We hypothesized that SNRK alters expression of genes involved in cell proliferation.
Results: Gene array in HEK293 cells demonstrated that SNRK overexpression increased levels of genes involved in cell cycle control and DNA synthesis compared to GFP control. In the array, SNRK upregulated calcyclin binding protein (CacyBP), which is a member of a ubiquitin ligase complex that targets beta-catenin protein for degradation. We verified that SNRK overexpression increased CacyBP mRNA and protein and reduced beta-catenin protein compared to GFP and SNRK kinase mutant, and SNRK downregulation reduced CacyBP and increased beta-catenin. Because beta-catenin is a pro-proliferation signaling modulator, we measured the effects of SNRK on cell proliferation. SNRK decreased DNA synthesis and proliferation by 46.94±5.79% in HEK293 and by 24.84±2.15% in HCT116 cells, while its downregulation increased proliferation by 19.19±3.93% in HEK293 and 33.12±5.67% in RKO cells. CacyBP downregulation reversed the effects of SNRK on proliferation arrest and DNA synthesis, demonstrating that CacyBP signaling is a primary mechanism by which SNRK reduces cell proliferation. Furthermore, SNRK decreased beta-catenin nuclear localization and target transcription of c-Myc and cyclin D1. Beta-catenin downregulation eradicated the effects of SNRK knockdown on proliferation, showing that beta-catenin signaling is also an essential downstream mediator of the effects of SNRK on proliferation.
Conclusions: Our results indicate that SNRK inhibits cell proliferation and DNA synthesis through CacyBP upregulation and beta-catenin degradation, resulting in reduced downstream proliferation signaling. These findings provide a novel function for SNRK, and suggest it may be therapeutically targeted to modify proliferation or beta-catenin signaling during many different cell processes including vascular smooth muscle cell and stem cell proliferation, fibroblast growth, and heart development.
- © 2011 by American Heart Association, Inc.