ABSTRACT
After injury or cytokine stimulation, fibroblasts transdifferentiate into myofibroblasts, contractile cells that secrete extracellular matrix for wound healing and tissue remodeling. Here, a genome-wide screen identified TRPC6, a Ca(2+) channel necessary and sufficient for myofibroblast transformation. TRPC6 overexpression fully activated myofibroblast transformation, while fibroblasts lacking Trpc6 were refractory to transforming growth factor ß (TGF-ß) and angiotensin II-induced transdifferentiation. Trpc6 gene-deleted mice showed impaired dermal and cardiac wound healing after injury. The profibrotic ligands TGF-ß and angiotensin II induced TRPC6 expression through p38 mitogen-activated protein kinase (MAPK) serum response factor (SRF) signaling via the TRPC6 promoter. Once induced, TRPC6 activates the Ca(2+)-responsive protein phosphatase calcineurin, which itself induced myofibroblast transdifferentiation. Moreover, inhibition of calcineurin prevented TRPC6-dependent transdifferentiation and dermal wound healing. These results demonstrate an obligate function for TRPC6 and calcineurin in promoting myofibroblast differentiation, suggesting a comprehensive pathway for myofibroblast formation in conjunction with TGF-ß, p38 MAPK, and SRF.
Subject(s)
Cell Transdifferentiation , Myofibroblasts/cytology , Myofibroblasts/metabolism , TRPC Cation Channels/metabolism , Wound Healing , Animals , Dermis/cytology , Dermis/metabolism , Mice , TRPC6 Cation ChannelABSTRACT
PKCα and PKA have crucial but opposing roles in the regulation of calcium handling within myocytes. Identification of compounds that inhibit PKCα, but not PKA, are potential therapeutic targets for the treatment of heart disease. The synthesis of indolylureas are described, and a compound displaying nanomolar inhibition towards PKCα with significant selectivity over PKA has been identified.
Subject(s)
Protein Kinase C-alpha/antagonists & inhibitors , Protein Kinase Inhibitors/chemical synthesis , Urea/chemical synthesis , Urea/pharmacology , Cyclic AMP-Dependent Protein Kinases , Heart Diseases/drug therapy , Humans , Urea/chemistryABSTRACT
Mass Spectrometry (MS) has been widely reported for measuring the conversion of substrates to products for enzyme assays. These measurements are typically performed by time-consuming LC-MS to eliminate buffer salts that interfere with electrospray ionization MS. However, matrix-assisted laser desorption ionization, time-of-flight MS (MALDI-TOF MS) offers a label-free and direct readout of substrate and product, a fast sampling rate, and is tolerant of many buffer salts, reagents, and compounds that are typically found in enzyme reaction mixtures. In this report, a demonstration of how MALDI-TOF MS can be used to directly measure ratios of substrates and products to produce IC(50) curves for rapid enzyme assays and compound screening is provided. Typical reproducibility parameters were <7% RSD-a value comparable to ESI MS quantitative assays and well within the acceptable limits for screening assays. The speed of the MALDI readout is currently about 10 s per sample, thus allowing for over 7500 samples/day. From a simplicity standpoint, the enzymatic reaction mixtures are prepared by liquid handling robots, the reactions are stopped by addition of a 10 times volume of acidic matrix solution, and the samples are simultaneously transferred to MALDI target plate for analysis. Importantly, the ratios of substrate to product are of sufficient reproducibility to eliminate the need for internal standards and, thus, minimize the cost and increasing the speed of assay development.
Subject(s)
Enzyme Inhibitors/analysis , Spectrometry, Mass, Electrospray Ionization/methods , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Enzyme Inhibitors/metabolism , Inhibitory Concentration 50 , Mixed Function Oxygenases/antagonists & inhibitors , Mixed Function Oxygenases/metabolism , Phosphotransferases/antagonists & inhibitors , Phosphotransferases/metabolism , Reproducibility of Results , Tandem Mass SpectrometryABSTRACT
As higher density formats become more and more common in HTS labs, the expectations for maintaining faster, lower cost screens puts great pressure on traditional 96-well screens. In some cases higher density formats are not compatible with the assay. This seems especially true in cell-based assays. In our case, the nature of the cells' response forced us to remain in 96-well plates. In this paper, we describe the development of a luminescence reporter assay and its performance in two detection modes, flash and glow. The advantages in cost and throughput for each technique are explored, along with automation considerations. An additional new technology, the use of pins for low-volume transfers, is also briefly described because of its dramatic effect on our screen's throughput. However, it will be more thoroughly presented in a future publication. Comparing the technologies available for HTS aids in designing automated systems that meet the unique needs of each assay.
