Cell Proliferation and Cytotoxic Studies of Vernonia amygdalina on Vascular Smooth Muscle Cells and HT 29 Cell Lines

Leptin, one of the adipocyte-secreted peptides, is involved in the control of appetite and body weight. Several studies have demonstrated that plasma leptin levels are elevated in obese subjects and are positively correlated with body weight. The arterial endothelin (ET) system plays an important role in the regulation of vascular tone, and ET-1 overexpression may be involved in the pathogenesis of the hypertension associated with insulin resistance. This study was performed to explore the regulatory effects of leptin on ET receptor expression and ET binding in A10 vascular smooth muscle cells (VSMCs) by use of Northern blotting, immunoblotting, and a 125I-labeled ET-1 binding assay. The effect of leptin on ET receptor-mediated cell proliferation was also tested. The results showed that leptin caused a significant increase in [125I]-ET-1 binding, which was time- and dose-dependent. Immunoblotting showed that expression of the ET type A receptor (ETAR) in leptin (10−7 M)-treated cells was increased by up to 2.3-fold compared with controls. Levels of ETAR mRNA measured by Northern blotting were also increased by up to 2.2-fold in leptin (10−7 M)-treated cells. Pretreatment with an ERK inhibitor, PD-98059 (2.5 × 10−5 M), blocked the leptin-induced increase in 125I-ET-1 binding. Finally, ET-1 (10−7 M)-stimulated cell proliferation was enhanced by leptin (10−7 M) pretreatment, with a maximal increase of twofold compared with controls. In conclusion, leptin increases ETAR expression in VSMCs in a time- and dose-dependent manner. This effect is ERK dependent and is associated with increased ET-1-stimulated cell proliferation. These findings provide support for roles for leptin and the ET system in the pathogenesis of obesity-associated hypertension.

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Tyrphostin inhibition of ATP-stimulated DNA synthesis, cell proliferation and Fos-protein expression in vascular smooth muscle cells

British Journal of Pharmacology ◽

10.1111/j.1476-5381.1996.tb15502.x ◽

1996 ◽

Vol 118 (4) ◽

pp. 1028-1034 ◽

Cited By ~ 21

Author(s):

David Erlinge ◽

Markus Heilig ◽

Lars Edvinsson

Keyword(s):

Cell Proliferation ◽

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Protein Expression ◽

Smooth Muscle Cells ◽

Dna Synthesis ◽

Vascular Smooth Muscle Cells ◽

Muscle Cells ◽

Fos Protein

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Orai1 and Ca2+-independent phospholipase A2 are required for store-operated Icat-SOC current, Ca2+ entry, and proliferation of primary vascular smooth muscle cells

AJP Cell Physiology ◽

10.1152/ajpcell.00312.2011 ◽

2012 ◽

Vol 302 (5) ◽

pp. C748-C756 ◽

Cited By ~ 13

Author(s):

Bo Yang ◽

Tomasz Gwozdz ◽

Joanna Dutko-Gwozdz ◽

Victoria M. Bolotina

Keyword(s):

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cells ◽

Dna Synthesis ◽

Phospholipase A2 ◽

Cell Lines ◽

Vascular Smooth Muscle Cells ◽

Muscle Cells ◽

Multiple Functions

Store-operated Ca2+ entry (SOCE) is important for multiple functions of vascular smooth muscle cells (SMC), which, depending of their phenotype, can resemble excitable and nonexcitable cells. Similar to nonexcitable cells, Orai1 was found to mediate Ca2+-selective (CRAC-like) current and SOCE in dedifferentiated cultured SMC and smooth muscle-derived cell lines. However, the role of Orai1 in cation-selective store-operated channels (cat-SOC), which are responsible for SOCE in primary SMC, remains unclear. Here we focus on primary SMC, and assess the role of Orai1 and Ca2+-independent phospholipase A2 (iPLA2β, or PLA2G6) in activation of cat-SOC current ( Icat-SOC), SOCE, and SMC proliferation. Using molecular, electrophysiological, imaging, and functional approaches, we demonstrate that molecular knockdown of either Orai1 or iPLA2β leads to similar inhibition of the whole cell cat-SOC current and SOCE in primary aortic SMC and results in significant reduction in DNA synthesis and impairment of SMC proliferation. This is the first demonstration that Orai1 and iPLA2β are equally important for cat-SOC, SOCE, and proliferation of primary aortic SMC.

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