title: FHL2/SLIM3 decreases cardiomyocyte survival by inhibitory interaction with sphingosine kinase-1.
abstract: Sphingosine kinase-1 (SK1) is a key enzyme catalyzing the phosphorylation of sphingosine to sphingosine-1-phosphate (S1P). Recent studies suggest that SK1, and its product S1P, regulate diverse biological functions, including cell growth, differentiation, proliferation, and apoptosis. S1P may also play an important role in cardiac development and ischemic preconditioning, but the mechanism underlying these effects is not known. Using a yeast 2-hybrid screen with SK1 as bait and a cardiac cDNA library to identify novel proteins involved in regulating SK1 activity in cardiomyocytes, we identified the LIM-only factor FHL2 (SLIM3) as a SK1-interacting protein in both yeast and mammalian cells. FHL2, but not FHL1 or FHL3, interacted with SK1, and FHL2 colocalized with SK1 in the cytoplasm. The interaction sites with SK1 consisted of at least 4 LIM domains in FHL2, whereas the C-terminal portion of SK1 mediates the binding of FHL2 in SK1. Overexpression of FHL2 attenuated the activity and antiapoptotic effects of SK1. Indeed, endothelin-1, which is a potent survival factor in cardiomyocytes, inhibited FHL2-SK1 association and increased SK1 activity. These findings indicate that FHL2 is a novel inhibitor of SK1 activity in cardiomyocytes and suggest that targeting FHL2 for inhibition may prevent myocardial apoptosis through activation of SK1.
authors.affiliation: Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark 07103, USA. sunj1@umdnj.edu
authors.forename: Jianxin
authors.initials: J
authors.lastname: Sun
authors.forename: Guijun
authors.initials: G
authors.lastname: Yan
authors.forename: Aixia
authors.initials: A
authors.lastname: Ren
authors.forename: Bei
authors.initials: B
authors.lastname: You
authors.forename: James K
authors.initials: JK
authors.lastname: Liao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival; D019332:Endothelin-1 / Q000502:physiology; D018398:Homeodomain Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D006801:Humans; D060850:LIM-Homeodomain Proteins; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009124:Muscle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000201:enzymology / Q000502:physiology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D000099157:Sphingosine Kinase
chemical_list: D019332:Endothelin-1; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D009124:Muscle Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D034741:RNA, Small Interfering; D014157:Transcription Factors; D000099157:Sphingosine Kinase; C105987:FHL2 protein, human