Heather I. Cohn

GPCR signalling in hypertension: role of GRKs.

Hypertension is a prevalent condition in the developed world and disease severity is directly correlated with additional cardiovascular complications. It is estimated that 30% of the adult population in the United States has hypertension, which is classified as a systolic blood pressure > or =140 mmHg and/or a diastolic blood pressure > or =90 mmHg. A prolonged increase in afterload ultimately leads to congestive heart failure in the majority of cases. Currently, medication designed to treat hypertension is inadequate, thus new therapies need to be explored. Blood pressure is tightly regulated by blood vessel radius, which is established by hormones and/or peptides binding to GPCRs (G-protein-coupled receptors). Catecholamines and peptide hormones, such as AngII (angiotensin II), are elevated in hypertension and, therefore, signalling by these GPCRs is increased. Their signalling is tightly controlled by a class of proteins, the GRKs (GPCR kinases). Elevated levels of either GRK2 or GRK5 in both the lymphocytes and VSM (vascular smooth muscle) are associated with human hypertension and animal models of the disease. The focus of the present review is on the role GRKs, and their regulation of GPCRs, play in high blood pressure.

A phase II randomized vehicle-controlled trial of intradermal allogeneic fibroblasts for recessive dystrophic epidermolysis bullosa

BACKGROUND Chronic wounds are a major source of morbidity and mortality in generalized severe recessive dystrophic epidermolysis bullosa (RDEB-GS). OBJECTIVE This was a phase II double-blinded randomized controlled trial of intralesional allogeneic cultured fibroblasts in suspension solution versus suspension solution alone for wound healing in RDEB-GS. METHODS Adult patients with RDEB-GS were screened for chronic ulcers and reduced collagen VII expression. Up to 6 pairs of symmetric wounds were measured and biopsied at baseline, then randomized to cultured allogeneic fibroblasts in a crystalloid suspension solution with 2% albumin or suspension solution alone. Ulcer size, collagen VII protein and messenger RNA expression, anchoring fibril numbers, morphology, and inflammatory markers were measured at 2 weeks and at 3, 6, and 12 months. RESULTS All wounds healed significantly more rapidly with fibroblasts and vehicle injections, with an area decrease of 50% by 12 weeks, compared with noninjected wounds. Collagen VII expression increased to a similar degree in both study arms in wounds from 3 of 5 patients. LIMITATIONS The number of patients with RDEB-GS who met inclusion criteria was a limitation, as was 1 trial center rather than multicenter. CONCLUSIONS The injection of both allogeneic fibroblasts and suspension solution alone improved wound healing in chronic nonhealing RDEB-GS wounds independently of collagen VII regeneration. This may provide feasible therapy for wound healing in patients with RDEB-GS.

Inhibition of vascular smooth muscle G protein-coupled receptor kinase 2 enhances α1D-adrenergic receptor constriction

G protein-coupled receptor kinase 2 (GRK2) is a serine/theorinine kinase that phosphorylates and desensitizes agonist-bound G protein-coupled receptors. GRK2 is increased in expression and activity in lymphocytes and vascular smooth muscle (VSM) in human hypertension and animal models of the disease. Inhibition of GRK2 using the carboxyl-terminal portion of the protein (GRK2ct) has been an effective tool to restore compromised beta-adrenergic receptor (AR) function in heart failure and improve outcome. A well-characterized dysfunction in hypertension is attenuation of betaAR-mediated vasodilation. Therefore, we tested the role of inhibition of GRK2 using GRK2ct or VSM-selective GRK2 gene ablation in a renal artery stenosis model of elevated blood pressure (BP) [the two-kidney, one-clip (2K1C) model]. Use of the 2K1C model resulted in a 30% increase in conscious BP, a threefold increase in plasma norepinephrine levels, and a 50% increase in VSM GRK2 mRNA levels. BP remained increased despite VSM-specific GRK2 inhibition by either GRK2 knockout (GRK2KO) or peptide inhibition (GRK2ct). Although betaAR-mediated dilation in vivo and in situ was enhanced, alpha(1)AR-mediated vasoconstriction was also increased. Further pharmacological experiments using alpha(1)AR antagonists revealed that GRK2 inhibition of expression (GRK2KO) or activity (GRK2ct) enhanced alpha(1D)AR vasoconstriction. This is the first study to suggest that VSM alpha(1D)ARs are a GRK2 substrate in vivo.

Laryngo-onycho-cutaneous Syndrome

Laryngo-onycho-cutaneous (LOC) syndrome was reclassified as a subtype of junctional epidermolysis bullosa (JEB) based on clinical features similar to JEB and its association, in the majority of patients from the Punjab, with a unique mutation affecting the N terminus of the alpha3 chain of LM332. Although LOC syndrome is now a subtype of JEB(JEB-LOC) JEB-LOC has a distinct clinicopathologic appearance and molecular fingerprint. The intricacies of the JEB-LOC subtype are discussed in this article with regard to disease presentation, pathogenesis, management, and prognosis.

Inhibition of Angiotensin II Gq Signaling Augments β-Adrenergic Receptor Mediated Effects in a Renal Artery Stenosis Model of High Blood Pressure

Chronic ventricular pressure overload states, such as hypertension, and elevated levels of neurohormones (norepinephrine, angiotensin II, endothelin-1) initiate cardiac hypertrophy and dysfunction and share the property of being able to bind to Gq-coupled 7-transmembrane receptors. The goal of the current study was to determine the role of endogenous cardiac myocyte Gq signaling and its role in cardiac hypertrophy and dysfunction during high blood pressure (BP). We induced renal artery stenosis for 8 weeks in control mice and mice expressing a peptide inhibitor of Gq signaling (GqI) using a 2 kidney, 1 clip renal artery stenosis model. 8 weeks following chronic high BP, control mice had cardiac hypertrophy and depressed function. Inhibition of cardiomyocyte Gq signaling did not reverse cardiac hypertrophy but attenuated increases in a profile of cardiac profibrotic genes and genes associated with remodeling. Inhibition of Gq signaling also attenuated the loss of cardiac function. We determined that Gq signaling downstream of angiotensin II receptor stimulation negatively impacted beta-adrenergic receptor (AR) responses and inhibition of Gq signaling was sufficient to restore betaAR-mediated responses. Therefore, in this study we found that Gq signaling negatively impacts cardiac function during high BP. Specifically, we found that inhibition of AT1-Gq signaling augmented betaAR mediated effects in a renal artery stenosis model of hypertension. These observations may underlie additional, beneficial effects of angiotensinogen converting enzyme (ACE) inhibitors and angiotensin receptor antagonists observed during times of hemodynamic stress.

Responsiveness of nonHerlitz junctional epidermolysis bullosa to topical gentian violet.

Background  Gentian violet (GV), a mixture of crystal violet and methyl violet, a dye belonging to the di‐ and triaminophenylmethanes class and has been widely used for its bactericidal and fungicidal properties. To date, there have been no reports of long‐term therapeutic use of GV in epidermolysis bullosa (EB).