Regulation of pendrin by pH: dependence on glycosylation.

[pendred syndrome]

Mutations in the anion exchanger pendrin are responsible for Pendred syndrome , an autosomal recessive disease characterized by deafness and goitre . Pendrin is highly expressed in kidney collecting ducts , where it acts as a chloride /bicarbonate exchanger and thereby contributes to the regulation of acid-base homoeostasis and blood pressure . The present study aimed to characterize the intrinsic properties of pendrin . Mouse pendrin was transfected in HEK (human embryonic kidney ) 293 and OKP (opossum kidney proximal tubule ) cells and its activity was determined by monitoring changes in the intracellular pH induced by variations of transmembrane anion gradients . Combining measurements of pendrin activity with mathematical modelling we found that its affinity for Cl-, HCO 3 - and OH - varies with intracellular pH , with increased activity at low intracellular pH . Maximal pendrin activity was also stimulated at low extracellular pH , suggesting the presence of both intracellular and extracellular proton regulatory sites . We identified five putative pendrin glycosylation sites , only two of which are used . Mutagenesis-induced disruption of pendrin glycosylation did not alter its cell-surface expression or polarized targeting to the apical membrane and basal activity , but fully abrogated its sensitivity to extracellular pH . The hither to unknown regulation of pendrin by external pH may constitute a key mechanism in controlling ionic exchanges across the collecting duct and inner ear .

Diseases
Validation

Diseases presenting "blood pressure" symptom

acute rheumatic fever

adrenal incidentaloma

alpha-thalassemia

cadasil

congenital adrenal hyperplasia

congenital diaphragmatic hernia

cushing syndrome

fabry disease

familial mediterranean fever

lymphangioleiomyomatosis

pendred syndrome

proteus syndrome

scrub typhus

systemic capillary leak syndrome

thoracic outlet syndrome

typhoid

von hippel-lindau disease

werner syndrome

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