title: A RNA interference screen identifies the protein phosphatase 2A subunit PR55gamma as a stress-sensitive inhibitor of c-SRC.
abstract: Protein Phosphatase type 2A (PP2A) represents a family of holoenzyme complexes with diverse biological activities. Specific holoenzyme complexes are thought to be deregulated during oncogenic transformation and oncogene-induced signaling. Since most studies on the role of this phosphatase family have relied on the use of generic PP2A inhibitors, the contribution of individual PP2A holoenzyme complexes in PP2A-controlled signaling pathways is largely unclear. To gain insight into this, we have constructed a set of shRNA vectors targeting the individual PP2A regulatory subunits for suppression by RNA interference. Here, we identify PR55gamma and PR55delta as inhibitors of c-Jun NH(2)-terminal kinase (JNK) activation by UV irradiation. We show that PR55gamma binds c-SRC and modulates the phosphorylation of serine 12 of c-SRC, a residue we demonstrate to be required for JNK activation by c-SRC. We also find that the physical interaction between PR55gamma and c-SRC is sensitive to UV irradiation. Our data reveal a novel mechanism of c-SRC regulation whereby in response to stress c-SRC activity is regulated, at least in part, through loss of the interaction with its inhibitor, PR55gamma.
authors: Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Pieter J A
authors: PJ
authors: Eichhorn
authors: Menno P
authors: MP
authors: Creyghton
authors: Kevin
authors: K
authors: Wilhelmsen
authors: Hans
authors: H
authors: van Dam
authors: René
authors: R
authors: Bernards
mesh_terms: D019943:Amino Acid Substitution; D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects; D001483:Base Sequence; D000081247:CSK Tyrosine-Protein Kinase; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D014162:Transfection; D014466:Ultraviolet Rays; D019061:src-Family Kinases
chemical_list: D017931:DNA Primers; C517192:PPP2R2C protein, human; D011518:Proto-Oncogene Proteins; D012694:Serine; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D048031:JNK Mitogen-Activated Protein Kinases; D054648:Protein Phosphatase 2