Loss‐ and Gain‐of‐Function Mutations in the Type 1 IP3 Receptor (IP3R1) Affect Myogenic Constriction of Cerebral Resistance Arteries in Response to Intraluminal Pressure

Emilin1 (E1) is a protein of the extracellular matrix regulating TGFβ bioavailability through proTGFβ proteolysis. E1 KO mice are hypertensive with increased TGFβ activation. As E1 is expressed in vessels from embryonic life to adulthood, is still unknown whether the E1 KO phenotype results from a developmental defect or lack of homeostatic role in the adult. To dissect this issue, we used a conditional gene targeting inactivating E1 in smooth muscle cells (SMCs) of adult mice, by the use of E1flox/flox and tamoxifen (TAM) inducible Cre recombinase specific for SMCs. When E1fl/fl mice carrying the Smmhc-CreERT2 were given TAM blood pressure significantly increased (SBP: 123±2 vs basal condition 104±3;***p< 0.001) as well as myogenic tone (MT) of resistance arteries (16.3±0.7 vs basal condition 11.4±0.1 % at 125 mmHg). How increased TGFβ signaling in SMCs could determine an increased MT is still unknown. Relevant to this, we found that the higher TGFβ signaling in E1 KO SMCs stimulates heparin binding epidermal growth factor (HB-EGF) and subsequent transactivation of the EGF receptor, a mechanism typically implied in potentiating MT. When mesenteric resistance arteries from E1 were subjected to step-increases in intraluminal pressure, EGFR inhibition rescued the increased MT. At the molecular level, TGFβ-induced EGFR transactivation resulted into the activation of transient receptor potential classical type 6 (TRPC6) and melastatin type 4 (TRPM4) channels. To put our data into translational perspective, we measured MT of resistance arteries isolated from hypertensive patients and normotensive subjects, finding increased MT (HT 16.4±0.7; NT 11±0.4;***p< 0.001) and TGFβ signaling in the former group. By using a neutralizing anti-TGFβ or an anti-EGFR we found a normalization of the increased MT (HT+anti-TGFβ 11±1.3; NT+anti-TGFβ 11.2±1.2;***p< 0.001 and HT+anti-EGFR 9±0.6; NT+anti-EGFR 10.8±1.1;***p< 0.001), thus confirming the relevance of TGFβ-EGFR pathway in humans. Taken together these data suggest that primary increase of MT induced by TGFβ-EGFR transactivation can cause hypertension and that higher TGFβ signaling and MT are common alterations of resistance arteries of hypertensive patients.

Download Full-text

Pressure-Induced Myogenic Responses in Human Isolated Cerebral Resistance Arteries

Stroke ◽

10.1161/01.str.27.12.2287 ◽

1996 ◽

Vol 27 (12) ◽

pp. 2287-2291 ◽

Cited By ~ 31

Author(s):

Sarah J. Wallis ◽

John Firth ◽

William R. Dunn

Keyword(s):

Resistance Arteries ◽

Myogenic Responses ◽

Cerebral Resistance

Download Full-text

Caveolin-1 and caveolin-3 regulate Ca2+ homeostasis of single smooth muscle cells from rat cerebral resistance arteries

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00669.2006 ◽

2007 ◽

Vol 293 (1) ◽

pp. H204-H214 ◽

Cited By ~ 12

Author(s):

T. Kamishima ◽

T. Burdyga ◽

J. A. Gallagher ◽

J. M. Quayle

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Removal Rate ◽

Muscle Cells ◽

Amino Acid Residues ◽

Resistance Arteries ◽

Inhibitory Peptide ◽

Caveolin 1 ◽

Domain Peptide ◽

Cerebral Resistance

The role of caveolins, signature proteins of caveolae, in arterial Ca2+ regulation is unknown. We investigated modulation of Ca2+ homeostasis by caveolin-1 and caveolin-3 using smooth muscle cells from rat cerebral resistance arteries. Membrane current and Ca2+ transients were simultaneously measured with voltage-clamped single cells. Membrane depolarization triggered Ca2+ current and increased intracellular Ca2+ concentration ([Ca2+]i). After repolarization, elevated [Ca2+]i returned to the resting level. Ca2+ removal rate was determined from the declining phase of the Ca2+ transient. Application of caveolin-1 antibody or caveolin-1 scaffolding domain peptide, corresponding to amino acid residues 82–101 of caveolin-1, significantly slowed Ca2+ removal rate at a measured [Ca2+]i of 250 nM, with little effect at a measured [Ca2+]i of 600 nM. Application of caveolin-3 antibody or caveolin-3 scaffolding domain peptide, corresponding to amino acid residues 55–74 of caveolin-3, also significantly slowed Ca2+ removal rate at a measured [Ca2+]i of 250 nM, with little effect at a measured [Ca2+]i of 600 nM. Likewise, application of calmodulin inhibitory peptide, autocamtide-2-related inhibitory peptide, and cyclosporine A, inhibitors for calmodulin, Ca2+/calmodulin-dependent protein kinase II, and calcineurin, also significantly inhibited Ca2+ removal rate at a measured [Ca2+]i of 250 nM but not at 600 nM. Application of cyclopiazonic acid, a sarcoplasmic reticulum Ca2+ ATPase inhibitor, also significantly inhibited Ca2+ removal rate at a measured [Ca2+]i of 250 nM but not at 600 nM. Our results suggest that caveolin-1 and caveolin-3 are important in Ca2+ removal of resistance artery smooth muscle cells.

Download Full-text

Effects of Age and Exercise Training on Nitric Oxide Bioavailability in Cerebral Resistance Arteries

Medicine & Science in Sports & Exercise ◽

10.1249/00005768-200611001-00015 ◽

2006 ◽

Vol 38 (Suppl 1) ◽

pp. S4

Author(s):

Rafael A. Reyes ◽

Kathryn E. Nichol ◽

Scott A. Spier ◽

Amanda LeBlanc ◽

Judy Muller-Delp

Keyword(s):

Nitric Oxide ◽

Exercise Training ◽

Resistance Arteries ◽

Cerebral Resistance ◽

Nitric Oxide Bioavailability

Download Full-text

Disorders of the calcium-sensing receptor and partner proteins: insights into the molecular basis of calcium homeostasis

Journal of Molecular Endocrinology ◽

10.1530/jme-16-0124 ◽

2016 ◽

Vol 57 (3) ◽

pp. R127-R142 ◽

Cited By ~ 81

Author(s):

Fadil M Hannan ◽

Valerie N Babinsky ◽

Rajesh V Thakker

Keyword(s):

G Protein ◽

Hormone Secretion ◽

Urinary Calcium ◽

Calcium Excretion ◽

Loss Of Function ◽

Mineral Density ◽

Gain Of Function ◽

Type 3

The extracellular calcium (Ca2+o)-sensing receptor (CaSR) is a family C G protein-coupled receptor, which detects alterations in Ca2+o concentrations and modulates parathyroid hormone secretion and urinary calcium excretion. The central role of the CaSR in Ca2+o homeostasis has been highlighted by the identification of mutations affecting the CASR gene on chromosome 3q21.1. Loss-of-function CASR mutations cause familial hypocalciuric hypercalcaemia (FHH), whereas gain-of-function mutations lead to autosomal dominant hypocalcaemia (ADH). However, CASR mutations are only detected in ≤70% of FHH and ADH cases, referred to as FHH type 1 and ADH type 1, respectively, and studies in other FHH and ADH kindreds have revealed these disorders to be genetically heterogeneous. Thus, loss- and gain-of-function mutations of the GNA11 gene on chromosome 19p13.3, which encodes the G-protein α-11 (Gα11) subunit, lead to FHH type 2 and ADH type 2, respectively; whilst loss-of-function mutations of AP2S1 on chromosome 19q13.3, which encodes the adaptor-related protein complex 2 sigma (AP2σ) subunit, cause FHH type 3. These studies have demonstrated Gα11 to be a key mediator of downstream CaSR signal transduction, and also revealed a role for AP2σ, which is involved in clathrin-mediated endocytosis, in CaSR signalling and trafficking. Moreover, FHH type 3 has been demonstrated to represent a more severe FHH variant that may lead to symptomatic hypercalcaemia, low bone mineral density and cognitive dysfunction. In addition, calcimimetic and calcilytic drugs, which are positive and negative CaSR allosteric modulators, respectively, have been shown to be of potential benefit for these FHH and ADH disorders.

Download Full-text

Endoplasmic reticulum Ca2+ content decrease by PKA-dependent hyperphosphorylation of type 1 IP3 receptor contributes to prostate cancer cell resistance to androgen deprivation

Cell Calcium ◽

10.1016/j.ceca.2015.02.004 ◽

2015 ◽

Vol 57 (4) ◽

pp. 312-320 ◽

Cited By ~ 16

Author(s):

Benoît Boutin ◽

Nicolas Tajeddine ◽

Giovanni Monaco ◽

Jordi Molgo ◽

Didier Vertommen ◽

...

Keyword(s):

Prostate Cancer ◽

Endoplasmic Reticulum ◽

Cancer Cell ◽

Prostate Cancer Cell ◽

Androgen Deprivation ◽

Cell Resistance ◽

Ip3 Receptor

Download Full-text

The vascular renin-angiotensin system contributes to blunted vasodilation induced by transient high pressure in human adipose microvessels

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00055.2014 ◽

2014 ◽

Vol 307 (1) ◽

pp. H25-H32 ◽

Cited By ~ 13

Author(s):

Matthew J. Durand ◽

Shane A. Phillips ◽

Michael E. Widlansky ◽

Mary F. Otterson ◽

David D. Gutterman

Keyword(s):

Polyethylene Glycol ◽

Enzyme Inhibitor ◽

Renin Angiotensin System ◽

Intraluminal Pressure ◽

Ang Ii ◽

Angiotensin System ◽

Renin Angiotensin ◽

Pressure Sensitive ◽

Endothelial Denudation

Increased intraluminal pressure can reduce endothelial function in resistance arterioles; however, the mechanism of this impairment is unknown. The purpose of this study was to determine the effect of local renin-angiotensin system inhibition on the pressure-induced blunting of endothelium-dependent vasodilation in human adipose arterioles. Arterioles (100–200 μm) were dissected from fresh adipose surgical specimens, cannulated onto glass micropipettes, pressurized to an intraluminal pressure of 60 mmHg, and constricted with endothelin-1. Vasodilation to ACh was assessed at 60 mmHg and again after a 30-min exposure to an intraluminal pressure of 150 mmHg. The vasodilator response to ACh was significantly reduced in vessels exposed to 150 mmHg. Exposure of the vessels to the superoxide scavenger polyethylene glycol-SOD (100 U/ml), the ANG II type 1 receptor antagonist losartan (10−6 mol/l), or the angiotensin-converting enzyme inhibitor captopril (10−5 mol/l) prevented the pressure-induced reduction in ACh-dependent vasodilation observed in untreated vessels. High intraluminal pressure had no effect on papaverine-induced vasodilation or ANG II sensitivity. Increased intraluminal pressure increased dihydroethidium fluorescence in cannulated vessels, which could be prevented by polyethylene glycol-SOD or losartan treatment and endothelial denudation. These data indicate that high intraluminal pressure can increase vascular superoxide and reduce nitric oxide-mediated vasodilation via activation of the vascular renin-angiotensin system. This study provides evidence showing that the local renin-angiotensin system in the human microvasculature may be pressure sensitive and contribute to endothelial dysfunction after acute bouts of hypertension.

Download Full-text