Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.12 (PKG)
 2,515 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rat smooth muscle cells (SMCs) stably transfected with the gene for the phenotype regulating protein cyclic guanosine monophosphate-dependent protein kinase (PKG) were used as a cell source in the preparation of three-dimensional (3D) collagen type I vascular constructs. PKG-transfected cells expressed severalfold higher levels of the contractile protein smooth muscle alpha-actin (SMA), relative to untransfected SMCs, both in monolayer culture and in 3D gels. The proliferation rate of PKG-transfected cells was lower than that of untransfected cells in both culture geometries. Three-dimensional collagen constructs made with PKG-transfected cells compacted to a similar degree as those made with untransfected cells, and this compaction could be augmented by biochemical stimulation with platelet-derived growth factor BB (PDGF) or transforming growth factor beta(1) (TGF). Application of cyclic mechanical strain to tubular collagen gels seeded with PKG-transfected cells resulted in a higher degree of gel compaction and circumferential matrix alignment, relative to statically grown controls, but cell proliferation and SMA expression were not affected. These results show that genetic modification of SMCs can be used as a tool to control cell function in vascular tissue engineering, and that the function of such cells can be further modulated by application of biochemical and mechanical stimulation.
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PMID:Genetic modification of smooth muscle cells to control phenotype and function in vascular tissue engineering. 1500 45

Pericytes exert an important influence on the control of retinal blood flow; however, little is known regarding the molecular basis of retinal pericyte excitability. The purpose of this study was to elucidate the signaling pathway of how prostacyclin (PGI2), an important endogenous regulator of retinal blood flow, stimulates potassium channel activity in retinal pericytes. Retinal pericytes were isolated from porcine eyeballs and plated on glass coverslips. Immunocytochemistry was performed to verify expression of the pericyte-specific ganglioside marker, 3G5 and smooth muscle alpha-actin. Activity of the large-conductance, voltage- and calcium-activated potassium (BKCa) channel was measured in retinal pericytes via single-channel patch-clamp, and channel identification was confirmed via biophysical and pharmacological characterization. PGI2 (10 microM) or beraprost (30 microM; more stable prostacyclin analog) dramatically stimulated the activity of BKCa channels isolated in cell-attached patches. These experiments strongly suggested that PGI2 stimulated BKCa channel activity via a diffusible second messenger. Similarly, chlorophenylthio (CPT)-cAMP (100 microM; membrane permeable cAMP derivative) induced a significant increase in BKCa channel activity; however, inhibition of the cAMP-dependent protein kinase (PKA) with 300 nM KT5720 could not reverse the stimulatory effect of either PGI2 or CPT-cAMP. In contrast, activation of BK(Ca) channels with either CPT-cAMP or PGI2 was abolished by 300 nM KT5823 (n=5, p<0.01), an inhibitor of the cGMP-dependent protein kinase (PKG). In addition, PGI2-stimulated channel activity was also attenuated by Rp-8-CPT-cGMPS, which inhibits PKG activity via a different mechanism. These findings demonstrate that prostacyclin, the most abundant prostanoid in the retinal circulation, is a potent stimulator of BKCa channel activity in retinal pericytes. Interestingly, this response appears to involve cAMP-stimulated cross-activation of PKG, and not PKA. Taken together, these findings could explain, at least in part, the cellular/molecular basis for PGI2-induced pericyte relaxation and augmentation of blood flow in the retina. Further, we propose PKG-dependent stimulation of BKCa channel activity as a new potential therapeutic target to combat decreased retinal blood flow seen in some disease states (e.g., diabetic retinopathy).
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PMID:PGI2 opens potassium channels in retinal pericytes by cyclic AMP-stimulated, cross-activation of PKG. 1695 50