Abstract
The PSMD14 (POH1, also known as Rpn11/MPR1/S13/CepP1) protein within the 19S complex (19S cap; PA700) is responsible for substrate deubiquitination during proteasomal degradation. The role of PSMD14 in cell proliferation and senescence was explored using siRNA knockdown in carcinoma cell lines. Our results reveal that down-regulation of PSMD14 by siRNA transfection had a considerable impact on cell viability causing cell arrest in the G0-G1 phase, ultimately leading to senescence. The molecular events associated with decreased cell proliferation, cell cycle arrest and senescence include down-regulation of cyclin B1-CDK1-CDC25C, down-regulation of cyclin D1 and up-regulation of p21(/Cip) and p27(/Kip1). Most notably, phosphorylation of the retinoblastoma protein was markedly reduced in PSMD14 knockdown cells. A comparative study with PSMB5, a subunit of the 20S proteasome, revealed that PSMB5 and PSMD14 have different effects on cell cycle, senescence and associated molecular events. These data support the view that the 19S and 20S subunits of the proteasome have distinct biological functions and imply that targeting 19S and 20S would have distinct molecular consequences on tumor cells.
MeSH terms
-
CDC2 Protein Kinase / genetics
-
CDC2 Protein Kinase / metabolism
-
Cell Cycle / genetics*
-
Cell Line, Tumor
-
Cell Proliferation
-
Cell Survival / genetics
-
Cellular Senescence / genetics*
-
Cyclin B1 / genetics
-
Cyclin B1 / metabolism
-
Cyclin D1 / genetics
-
Cyclin D1 / metabolism
-
Cyclin-Dependent Kinase Inhibitor Proteins / genetics
-
Cyclin-Dependent Kinase Inhibitor Proteins / metabolism
-
DNA / analysis
-
Epithelial Cells / cytology
-
Epithelial Cells / metabolism
-
Fibroblasts / cytology
-
Fibroblasts / metabolism
-
G1 Phase / genetics
-
Gene Expression / genetics
-
HeLa Cells
-
Humans
-
Phosphorylation / genetics
-
Proteasome Endopeptidase Complex / deficiency*
-
Proteasome Endopeptidase Complex / genetics
-
Proteasome Endopeptidase Complex / metabolism
-
RNA, Small Interfering / genetics
-
Resting Phase, Cell Cycle / genetics
-
Retinoblastoma Protein / genetics
-
Retinoblastoma Protein / metabolism
-
Sulfotransferases / metabolism
-
Trans-Activators / deficiency*
-
Trans-Activators / genetics
-
Trans-Activators / metabolism
-
Transfection
-
Ubiquitinated Proteins / metabolism
-
Up-Regulation / genetics
-
beta-Galactosidase / metabolism
-
cdc25 Phosphatases / genetics
-
cdc25 Phosphatases / metabolism
Substances
-
CCNB1 protein, human
-
CCND1 protein, human
-
Cyclin B1
-
Cyclin-Dependent Kinase Inhibitor Proteins
-
PSMD14 protein, human
-
RNA, Small Interfering
-
Retinoblastoma Protein
-
Trans-Activators
-
Ubiquitinated Proteins
-
Cyclin D1
-
DNA
-
CDC2 Protein Kinase
-
Sulfotransferases
-
alcohol sulfotransferase
-
CDC25C protein, human
-
cdc25 Phosphatases
-
beta-Galactosidase
-
PSMB5 protein, human
-
Proteasome Endopeptidase Complex