title: Enhanced store-operated Ca2+influx and ORAI1 expression in ventricular fibroblasts from human failing heart.
abstract: Excessive cardiac fibrosis, characterized by increased collagen-rich extracellular matrix (ECM) deposition, is a major predisposing factor for mechanical and electrical dysfunction in heart failure (HF). The human ventricular fibroblast (hVF) remodeling mechanisms that cause excessive collagen deposition in HF are unclear, although reports suggest a role for intracellular free Ca2+in fibrosis. Therefore, we determined the association of differences in cellular Ca2+dynamics and collagen secretion/deposition between hVFs from failing and normal (control) hearts. Histology of left ventricle sections (Masson trichrome) confirmed excessive fibrosis in HF versus normal.In vitro, hVFs from HF showed increased secretion/deposition of soluble collagen in 48 h of culture compared with control [85.9±7.4 µg/106cells vs 58.5±8.8 µg/106cells,P<0.05; (Sircol™ assay)]. However, collagen gene expressions (COL1A1andCOL1A2; RT-PCR) were not different. Ca2+imaging (fluo-3) of isolated hVFs showed no difference in the thapsigargin-induced intracellular Ca2+release capacity (control 16±1.4% vs HF 17±1.1%); however, Ca2+influx via store-operated Ca2+entry/Ca2+release-activated channels (SOCE/CRAC) was significantly (P≤0.05) greater in HF-hVFs (47±3%) compared with non-failing (35±5%). Immunoblotting forICRACchannel components showed increased ORAI1 expression in HF-hVFs compared with normal without any difference in STIM1 expression. The Pearson's correlation coefficient for co-localization of STIM1/ORAI1 was significantly (P<0.01) greater in HF (0.5±0.01) than control (0.4±0.01) hVFs. The increase in collagen secretion of HF versus control hVFs was eliminated by incubation of hVFs with YM58483 (10 µM), a selective ICRACinhibitor, for 48 h (66.78±5.87 µg/106cells vs 55.81±7.09 µg/106cells,P=0.27). In conclusion, hVFs from HF have increased collagen secretion capacity versus non-failing hearts and this is related to increase in Ca2+entry via SOCE and enhanced expression of ORAI, the pore-forming subunit. Therapeutic inhibition of SOCE may reduce the progression of cardiac fibrosis/HF.
authors.affiliation: Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, Milwaukee, WI 53215, USA.
authors.forename: Gracious R
authors.initials: GR
authors.lastname: Ross
authors.affiliation: Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, Milwaukee, WI 53215, USA.
authors.forename: Tanvir
authors.initials: T
authors.lastname: Bajwa
authors.affiliation: Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, Milwaukee, WI 53215, USA.
authors.forename: Stacie
authors.initials: S
authors.lastname: Edwards
authors.affiliation: Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, Milwaukee, WI 53215, USA.
authors.forename: Larisa
authors.initials: L
authors.lastname: Emelyanova
authors.affiliation: Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, Milwaukee, WI 53215, USA.
authors.forename: Farhan
authors.initials: F
authors.lastname: Rizvi
authors.affiliation: Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, Milwaukee, WI 53215, USA.
authors.forename: Ekhson L
authors.initials: EL
authors.lastname: Holmuhamedov
authors.affiliation: Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, WI 53215, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Werner
authors.affiliation: Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, WI 53215, USA.
authors.forename: Francis X
authors.initials: FX
authors.lastname: Downey
authors.affiliation: Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, WI 53215, USA.
authors.forename: A Jamil
authors.initials: AJ
authors.lastname: Tajik
authors.affiliation: Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, Milwaukee, WI 53215, USA publishing44@aurora.org.|Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, WI 53215, USA.
authors.forename: Arshad
authors.identifier: http://orcid.org/0000-0002-0221-8017
authors.initials: A
authors.lastname: Jahangir
keywords: Calcium; Cardiac fibrosis; Heart failure; Store-operated Ca2+ entry