Lysophosphatidic acid and adenylyl cyclase inhibitor increase proliferation of senescent human diploid fibroblasts by inhibiting adenosine monophosphate-activated protein kinase.
This study was designed to elucidate the molecular mechanism underlying lysophosphatidic acid (LPA) and adenylyl cyclase inhibitor SQ22536 (ACI)-induced senescent human diploid fibroblast (HDF) proliferation. Because adenosine monophosphate (AMP)-activated protein kinase (AMPK) is known to inhibit cell proliferation, we examined the phosphorylation status of AMPK and p53 and the expression level of p21(waf1/cip1) after treating HDFs with LPA and ACI. Phosphorylation of AMPKalpha on threonine-172 (p-Thr172-AMPKalpha) increases its catalytic activity but phosphorylation on serine-485/491 (p-Ser485/491-AMPKalpha) reduces the accessibility of the Thr172 phosphorylation site thereby inhibiting its catalytic activity. LPA increased p-Ser485/491-AMPKalpha, presumably by activating cAMP-dependent protein kinase (PKA). However, ACI reduced p-Thr172-AMPKalpha by inhibiting the LKB signaling. Our data demonstrated that both LPA and ACI inhibit the catalytic activity of AMPKalpha and p53 by differentially regulating phosphorylation of AMPKalpha, causing increased senescent cell proliferation. These findings suggest that the proliferation potential of senescent HDFs can be modulated through the regulation of the AMPK signaling pathway.
Rhim
Ji-Heon
JH
Department of Biochemistry and Molecular Biology, Aging and Apoptosis Research Center, Seoul National University College of Medicine, 28 Yon-gon-dong, Chongno-Gu, Seoul, South Korea.
Jang
Ik-Soon
IS
Song
Kye-Yong
KY
Ha
Moon-Kyung
MK
Cho
Sung-Chun
SC
Yeo
Eui-Ju
EJ
Park
Sang Chul
SC
D055372:AMP-Activated Protein Kinases; D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology; D019938:Cyclin D1 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004171:Diploidy; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology*; D008954:Models, Biological; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D016196:S Phase / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D000067956:Adenylyl Cyclase Inhibitors; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; D008246:Lysophospholipids; D009097:Multienzyme Complexes; D019938:Cyclin D1; C017759:9-(tetrahydro-2-furyl)-adenine; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D055372:AMP-Activated Protein Kinases; D000225:Adenine; C032881:lysophosphatidic acid