Valproic acid decreases vascular smooth muscle cell proliferation via protein phosphatase 2A-mediated p70 S6 kinase inhibition. 2022

Hansol Lee, and Yun-Jin Hwang, and Jung-Hyun Park, and Du-Hyong Cho
Department of Pharmacology, Yeungnam University College of Medicine, 170 Hyunchung-ro, Nam-gu, Daegu, 42415, South Korea.

Valproic acid (VPA) has been used to treat epilepsy and bipolar disorder. Although the abnormal proliferation of vascular smooth muscle cells (VSMCs) is a well-established contributor to the development of various vascular diseases including atherosclerosis, the effect of VPA on VSMC proliferation and its mechanism of action have not been fully revealed. Herein, we investigated the molecular mechanism by which VPA inhibits rat VSMC proliferation. VPA dose-dependently decreased VSMC proliferation, which was accompanied by the dose-dependent decrease in phosphorylation of p70 S6 kinase (p70S6K) at Thr389 (p-p70S6K-Thr389), and overexpression of the p70S6K-T389E mutant gene significantly reversed VPA-inhibited VSMC proliferation. Co-treatment with okadaic acid, a specific protein phosphatase 2A (PP2A) inhibitor, significantly restored p-p70S6K-Thr389. Furthermore, knockdown of PP2Ac gene expression by siRNA significantly reversed VPA-inhibited p-p70S6K-Thr389 and VSMC proliferation. Confocal microscopic analyses and co-immunoprecipitation results clearly showed that the physical binding of p70S6K and PP2Ac was promoted by VPA. Valpromide, a VPA's structural derivative with no histone deacetylase (HDAC) inhibition activity, as well as VPA and sodium butyrate, an HDAC inhibitor similar to VPA, decreased VSMC proliferation and p-p70S6K-Thr389, indicating that HDAC is not involved in VPA-inhibited VSMC proliferation. Finally, the inhibitory effects of VPA on p-p70S6K-Thr389 and VSMC proliferation were reiterated in a platelet-derived growth factor (PDGF)-induced in vitro atherosclerosis model. In conclusion, our results demonstrate that VPA decreased cell proliferation via PP2A-mediated inhibition of p-p70S6K-Thr389 in basal and PDGF-stimulated VSMCs. The results suggest that VPA could be used in the treatment and prevention of atherosclerosis and in-stent restenosis.

UI MeSH Term Description Entries
D009131 Muscle, Smooth, Vascular The nonstriated involuntary muscle tissue of blood vessels. Vascular Smooth Muscle,Muscle, Vascular Smooth,Muscles, Vascular Smooth,Smooth Muscle, Vascular,Smooth Muscles, Vascular,Vascular Smooth Muscles
D010982 Platelet-Derived Growth Factor Mitogenic peptide growth hormone carried in the alpha-granules of platelets. It is released when platelets adhere to traumatized tissues. Connective tissue cells near the traumatized region respond by initiating the process of replication. Platelet Derived Growth Factor,Factor, Platelet-Derived Growth,Growth Factor, Platelet-Derived
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014635 Valproic Acid A fatty acid with anticonvulsant and anti-manic properties that is used in the treatment of EPILEPSY and BIPOLAR DISORDER. The mechanisms of its therapeutic actions are not well understood. It may act by increasing GAMMA-AMINOBUTYRIC ACID levels in the brain or by altering the properties of VOLTAGE-GATED SODIUM CHANNELS. Dipropyl Acetate,Divalproex,Sodium Valproate,2-Propylpentanoic Acid,Calcium Valproate,Convulsofin,Depakene,Depakine,Depakote,Divalproex Sodium,Ergenyl,Magnesium Valproate,Propylisopropylacetic Acid,Semisodium Valproate,Valproate,Valproate Calcium,Valproate Sodium,Valproic Acid, Sodium Salt (2:1),Vupral,2 Propylpentanoic Acid
D015398 Signal Transduction The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway. Cell Signaling,Receptor-Mediated Signal Transduction,Signal Pathways,Receptor Mediated Signal Transduction,Signal Transduction Pathways,Signal Transduction Systems,Pathway, Signal,Pathway, Signal Transduction,Pathways, Signal,Pathways, Signal Transduction,Receptor-Mediated Signal Transductions,Signal Pathway,Signal Transduction Pathway,Signal Transduction System,Signal Transduction, Receptor-Mediated,Signal Transductions,Signal Transductions, Receptor-Mediated,System, Signal Transduction,Systems, Signal Transduction,Transduction, Signal,Transductions, Signal
D049109 Cell Proliferation All of the processes involved in increasing CELL NUMBER including CELL DIVISION. Cell Growth in Number,Cellular Proliferation,Cell Multiplication,Cell Number Growth,Growth, Cell Number,Multiplication, Cell,Number Growth, Cell,Proliferation, Cell,Proliferation, Cellular
D050197 Atherosclerosis A thickening and loss of elasticity of the walls of ARTERIES that occurs with formation of ATHEROSCLEROTIC PLAQUES within the ARTERIAL INTIMA. Atherogenesis,Atherogeneses,Atheroscleroses
D051381 Rats The common name for the genus Rattus. Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus
D054648 Protein Phosphatase 2 A phosphoprotein phosphatase subtype that is comprised of a catalytic subunit and two different regulatory subunits. At least two genes encode isoforms of the protein phosphatase catalytic subunit, while several isoforms of regulatory subunits exist due to the presence of multiple genes and the alternative splicing of their mRNAs. Protein phosphatase 2 acts on a broad variety of cellular proteins and may play a role as a regulator of intracellular signaling processes. PPP2CA Phosphatase,PPP2CB Phosphatase,Protein Phosphatase 2, Catalytic Subunit,Protein Phosphatase 2, Catalytic Subunit, alpha Isoform,Protein Phosphatase 2, Catalytic Subunit, beta Isoform,Protein Phosphatase 2, Regulatory Subunit,Protein Phosphatase 2, Regulatory Subunit A, alpha Isoform,Protein Phosphatase 2, Regulatory Subunit A, beta Isoform,Protein Phosphatase 2, Regulatory Subunit B, alpha Isoform,Protein Phosphatase 2, Regulatory Subunit B, beta Isoform,Protein Phosphatase 2, Regulatory Subunit B, delta Isoform,Protein Phosphatase 2, Regulatory Subunit B, gamma Isoform,Protein Phosphatase 2A, Catalytic Subunit, alpha Isoform,Protein Phosphatase 2A, Catalytic Subunit, beta Isoform,Protein Phosphatase 2A, Regulatory Subunit A , alpha Isoform,Protein Phosphatase 2A, Regulatory Subunit A, beta Isoform,Protein Phosphatase 2A, Regulatory Subunit B, alpha Isoform,Protein Phosphatase 2A, Regulatory Subunit B, beta Isoform,Protein Phosphatase 2A, Regulatory Subunit B, delta Isoform,Protein Phosphatase 2A, Regulatory Subunit B, gamma Isoform,Protein Phosphatase-2A,Serine Threonine Protein Phosphatase 2A Catalytic Subunit beta Isoform,Serine-Threonine-Protein Phosphatase 2A Catalytic Subunit alpha Isoform,Phosphatase, PPP2CA,Phosphatase, PPP2CB,Protein Phosphatase 2A,Serine Threonine Protein Phosphatase 2A Catalytic Subunit alpha Isoform

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