Knockdown of MBP-1 in human foreskin fibroblasts induces p53-p21 dependent senescence.
MBP-1 acts as a general transcriptional repressor. Overexpression of MBP-1 induces cell death in a number of cancer cells and regresses tumor growth. However, the function of endogenous MBP-1 in normal cell growth regulation remains unknown. To unravel the role of endogenous MBP-1, we knocked down MBP-1 expression in primary human foreskin fibroblasts (HFF) by RNA interference. Knockdown of MBP-1 in HFF (HFF-MBPsi-4) resulted in an induction of premature senescence, displayed flattened cell morphology, and increased senescence-associated beta-galactosidase activity. FACS analysis of HFF-MBPsi-4 revealed accumulation of a high number of cells in the G1-phase. A significant upregulation of cyclin D1 and reduction of cyclin A was detected in HFF-MBPsi-4 as compared to control HFF. Senescent fibroblasts exhibited enhanced expression of phosphorylated and acetylated p53, and cyclin-dependent kinase inhibitor, p21. Further analysis suggested that promyolocytic leukemia protein (PML) bodies are dramatically increased in HFF-MBPsi-4. Together, these results demonstrated that knockdown of endogenous MBP-1 is involved in cellular senescence of HFF through p53-p21 pathway.
Department of Pathology, Saint Louis University, St. Louis, Missouri, United States of America.
Asish K
AK
Ghosh
Tatsuo
T
Kanda
Robert
R
Steele
Ratna B
RB
Ray
D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D052816:Foreskin / Q000166:cytology; D016193:G1 Phase; D006801:Humans; D008297:Male; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D050759:Cyclin-Dependent Kinase Inhibitor p21; C088830:DENND4A protein, human; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53