title: RNA interference-mediated survivin gene knockdown induces growth arrest and reduced migration of vascular smooth muscle cells.
abstract: Survivin (SVV) is a multifunctional protein that has been implicated in the development of neointimal hyperplasia. Nuclear SVV is essential for mitosis, whereas in mitochondria SVV has a cytoprotective function. Here, we investigated the effects of RNA interference (RNAi)-mediated SVV knockdown on cell cycle kinetics, apoptosis, migration, and gene expression in primary cultured vascular smooth muscle cells (VSMCs) from the human saphenous vein. Primary Human VSMCs were obtained from saphenous veins and cultured under standard conditions. SVV knockdown was achieved by either small interfering RNA or lentiviral transduction of short hairpin RNA, reducing SVV gene expression by quantitative PCR (>75%, P < 0.01) without a loss of cell viability. Subcellular fractionation revealed that RNAi treatment effectively targeted the nuclear SVV pool, whereas the larger mitochondrial pool was much less sensitive to transient knockdown. Both p53 and p27 protein levels were notably increased. SVV RNAi treatment significantly blocked VSMC proliferation in response to serum and PDGF-AB, arresting VSMC growth. Cell cycle analysis revealed an increased G(2)/M fraction consistent with a mitotic defect; 4',6-diamidino-2-phenylindole staining confirmed an increased frequency of polyploid and abnormal nuclei. In a transwell assay, SVV knockdown reduced migration to PDGF-AB, and actin-phalloidin staining revealed disorganized actin filaments and polygonal cell shape. However, apoptosis (DNA content and annexin V flow cytometry) was not directly induced by SVV RNAi, and sensitivity to apoptotic agonists (e.g., staurosporine and cytokines) was unchanged. In conclusion, RNAi-mediated SVV knockdown in VSMCs leads to profound cell cycle arrest at G(2)/M and impaired chemotaxis without cytotoxicity. The regulation of mitosis and apoptosis in VSMC involves differentially regulated subcellular pools of SVV. Thus, treatment of VSMC with RNAi targeting SVV might limit the response to vascular injury without destabilizing the vessel wall.
authors.affiliation: Division of Vascular and Endovascular Surgery, Laboratory for Accelerated Vascular Research, University of California, San Francisco, CA 94143, USA.
authors.forename: Christoph S
authors.initials: CS
authors.lastname: Nabzdyk
authors.forename: Hope
authors.initials: H
authors.lastname: Lancero
authors.forename: Khanh P
authors.initials: KP
authors.lastname: Nguyen
authors.forename: Sherveen
authors.initials: S
authors.lastname: Salek
authors.forename: Michael S
authors.initials: MS
authors.lastname: Conte
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D017209:Apoptosis; D059447:Cell Cycle Checkpoints; D049109:Cell Proliferation; D002478:Cells, Cultured; D002633:Chemotaxis; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D006801:Humans; D006965:Hyperplasia; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000473:pathology; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D034622:RNA Interference; D012501:Saphenous Vein / Q000378:metabolism / Q000473:pathology; D000077022:Survivin; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: C107489:BIRC5 protein, human; C436291:CDKN1B protein, human; D051034:Inhibitor of Apoptosis Proteins; D010982:Platelet-Derived Growth Factor; D000077022:Survivin; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C095477:platelet-derived growth factor AB; D050760:Cyclin-Dependent Kinase Inhibitor p27