ABSTRACT
Migration and proliferation of smooth muscle cells (SMC) contribute to neointimal formation after arterial injury. However, the relation between migration and proliferation in these cells is obscure. To discriminate between migration and proliferation, we employed a migration assay of SMC at different phases of the cell cycle. Serum-deprived SMC were synchronized in different phases of the cell cycle by addition of serum for various periods of time. Migration induced by platelet-derived growth factor B-chain homodimer was maximal in SMC that were predominantly in the late G(1) (G(1b)) phase. In addition, in nonsynchronized SMC, 65-75% of SMC that had migrated were in the G(1b) phase. Phosphorylated myosin light chain was enriched around the cell periphery in SMC in the G(1b) phase compared with SMC in the other cell cycle phases. Interestingly, the Triton X-100-insoluble fraction of myosin was remarkably decreased in G(1b)-enriched SMC. These findings suggest that migratory activity of SMC may be coupled with the G(1b) phase. The phosphorylation and retention of myosin might explain some of the properties responsible for increased migration.
Subject(s)
Cell Movement/physiology , G1 Phase/physiology , Muscle, Smooth, Vascular/cytology , Muscle, Smooth, Vascular/metabolism , Actins/chemistry , Actins/metabolism , Animals , Becaplermin , Cell Adhesion/physiology , Cell Movement/drug effects , Cells, Cultured , Cytoskeletal Proteins/metabolism , DNA/metabolism , Fibronectins/metabolism , Flow Cytometry , Focal Adhesion Kinase 1 , Focal Adhesion Protein-Tyrosine Kinases , Humans , Interphase/physiology , Muscle, Smooth, Vascular/drug effects , Myosin Light Chains/chemistry , Myosin Light Chains/metabolism , Octoxynol/chemistry , Octoxynol/pharmacology , Paxillin , Phosphoproteins/metabolism , Phosphorylation/drug effects , Platelet-Derived Growth Factor/pharmacology , Protein-Tyrosine Kinases/metabolism , Proto-Oncogene Proteins c-sis , RNA/metabolism , Rabbits , Solubility/drug effectsABSTRACT
Self-aggregates of a synthetic cadmium chlorin possessing 3(1)-hydroxyl and 13-carbonyl groups were prepared in dried thin film. The solid film was characterized by visible and infrared absorption spectroscopies at both transmission and reflection modes. The spectra given by the two different modes were essentially the same and resembled those in the extramembranous antennas of green photosynthetic bacteria. The circular dichroism and resonance Raman spectra also supported the similarity between the artificial self-aggregates and the natural systems. Electron diffraction of the aggregated film by transmission electron microscopy indicated the presence of an orderly structure with a 6.4-A interval, which was estimated for the close Cd-Cd distance of the stacking in the self-aggregates. The in vitro self-assembly in the solid state is a good structural model for the in vivo antenna.
Subject(s)
Cadmium/chemistry , Photosynthetic Reaction Center Complex Proteins/chemistry , Porphyrins/chemistry , Bacteria/chemistry , Circular Dichroism , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Structure , Porphyrins/chemical synthesis , Spectrum Analysis, RamanABSTRACT
Dehydroepiandrosterone (DHEA) and its sulfate (DHEA-S) are the most abundant steroids in humans, and their serum concentrations progressively decrease with age. Although relationships between DHEA(-S) and many age-related illnesses have been postulated, the mechanisms for their effects remain unknown, and specific receptors for these molecules have not been identified. In this paper, to investigate the role of DHEA(-S) in atherogenesis, we studied the proliferation and migration of a rabbit vascular smooth muscle cell line, SM-3, in the presence of DHEA(-S). Cellular proliferation was inhibited by DHEA-S, and to a lesser extent by DHEA. Modified Boyden's chamber assays revealed that DHEA-S inhibited the migration of SM-3 cells toward PDGF-BB. In cell attachment assays, DHEA-S inhibited the attachment of SM3 cells to fibronectin. It was suggested that the inhibitory effect of DHEA-S for SM-3 proliferation and migration was due to the decreased interaction with fibronectin. Scatchard analysis revealed the presence of two populations of DHEA-S binding sites in the nuclear fraction, and a smaller number in the cytosolic fraction. Since the dissociation constant of the higher affinity site was similar to the serum DHEA-S concentration in humans (Kd = 5.8 microM), this binding site could be functional under physiologic conditions. These findings suggest that there may be receptor-mediated anti-atherogenic actions of DHEA-S.
Subject(s)
Cell Movement/drug effects , Dehydroepiandrosterone Sulfate/pharmacology , Muscle, Smooth, Vascular/cytology , Animals , Arteriosclerosis/metabolism , Arteriosclerosis/physiopathology , Cell Division/drug effects , Cells, Cultured , RabbitsABSTRACT
In vascular smooth muscle cells (SMCs), proliferation and migration contribute to lesion formation after arterial injury. In the cell cycle, several cyclin-dependent kinases (cdks) inhibitors are implicated in the regulating of cyclin-cdk activity such as p21Cip1, p16Ink4 and p27Kip1. Although Cip1 inhibits SMC proliferation, its effects on SMC migration are unknown. To test the hypothesis that Cip1 inhibits SMCs migration and proliferation, we transfected the Cip1 gene into a strain of rabbit aortic SMCs (SM3 cells). Both the spreading and the attachment of Cip1-transfected SM3 cells to extracellular matrices (ECMs) were inhibited compared to that of vector-transfected cells. In the modified Boyden's chamber assay the effect of fibronectin on the migratory activity of Cip1-transfected SM3 cells was significantly less than that of vector transfected cells in response to PDGF-BB. These data suggested that Cip1 inhibited both the migration and proliferation of SMC.
