PT  - JOURNAL ARTICLE
AU  - Nicola M. Blythe
AU  - Vasili Stylianidis
AU  - Melanie J. Ludlow
AU  - Hamish T. J. Gilbert
AU  - Elizabeth L. Evans
AU  - Kevin Cuthbertson
AU  - Richard Foster
AU  - Joe Swift
AU  - Jing Li
AU  - Mark J. Drinkhill
AU  - Frans A. van Nieuwenhoven
AU  - Karen E. Porter
AU  - David J. Beech
AU  - Neil A. Turner
TI  - Stimulation of cardiac fibroblast Piezo1 channels opposes myofibroblast differentiation and induces IL-6 secretion via Ca<sup>2+</sup>-mediated p38 MAP kinase activation
AID  - 10.1101/603456
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 603456
4099  - http://biorxiv.org/content/early/2019/04/10/603456.short
4100  - http://biorxiv.org/content/early/2019/04/10/603456.full
AB  - Piezo1 is a mechanosensitive cation channel with widespread physiological importance; however its role in the heart is poorly understood. Cardiac fibroblasts are responsible for preserving the structural integrity of the myocardium and play a key role in regulating its repair and remodeling following stress or injury. We investigated expression and function of Piezo1 in cultured human and mouse cardiac fibroblasts. RT-PCR studies confirmed expression of Piezo1 mRNA in cardiac fibroblasts at similar levels to endothelial cells. Fura-2 intracellular Ca2+ measurements validated Piezo1 as a functional ion channel that was activated by the Piezo1 agonist, Yoda1. Yoda1-induced Ca2+ entry was inhibited by Piezo1 blockers (gadolinium, ruthenium red) and the Ca2+ response was reduced proportionally by Piezo1 siRNA knockdown or in cells from Piezo1+/− mice. Investigation of Yoda1 effects on selected remodeling genes indicated that Piezo1 activation opposed cardiac fibroblast differentiation; data confirmed by functional collagen gel contraction assays. Piezo1 activation using Yoda1 or mechanical stretch also increased the expression of interleukin-6 (IL-6), a mechanosensitive pro-hypertrophic and pro-fibrotic cytokine, in a Piezo1-dependent manner. Multiplex kinase activity profiling combined with kinase inhibitor studies and phospho-specific western blotting, established that Piezo1 activation stimulated IL-6 secretion via a pathway involving p38 MAP kinase, downstream of Ca2+ entry. In summary, this study reveals that cardiac fibroblasts express functional Piezo1 channels coupled to reduced myofibroblast activation and increased secretion of paracrine signaling molecules that can modulate cardiac remodeling.α-SMA,α-smooth muscle actin;CDK,cyclin-dependent kinase;DMSO,dimethylsulfoxide;ECM,extracellular matrix;ERK,extracellular signal-regulated kinases;Gapdh/GAPDH,glyceraldehyde-3-phosphate dehydrogenase;HEK,human embryonic kidney;Het,heterozygous;HUVECs,human umbilical vein endothelial cells;IL,interleukin;JNK,c-Jun N-terminal kinase;MACS,magnetic antibody cell separation;MAPK,mitogen-activated protein kinase;MMP,matrix metalloproteinase;SBS,standard bath solution;STK,Serine-Threonine Kinase;WT,wild-type.