Biomedical Sciences ETDs

Publication Date

5-1-2015

Abstract

V-ATPase is a vacuolar (lysosome-like) ATPase-dependent proton pump necessary for maintaining pH homeostasis in the organelles of the endomembrane system. It also contributes to regulation of the cytosol pH and the extracellular pH. In specialized cells (renal intercalated cells, epididymis clear cells, and osteoclasts), V-ATPase proton transport supports urinary acidification, sperm maturation, and bone resorption. Genetic mutations of V-ATPase expressed in those tissue-specific cells cause distal renal tubular acidosis, infertility, and osteopetrosis. V-ATPases are composed of a peripheral domain (V1), which hydrolyzes ATP, and a membrane-bound domain (Vo), which transports proton. V-ATPase activity is tightly regulated in vivo by numbers of mechanisms, including reversible disassembly of the V1 and Vo domains. Glucose, the nutrient oxidized in glycolysis, modulates reversible dissociation of V-ATPase. This dissertation was aimed at understanding how subunits of phosphofructokinase-1 (α subunit and β subunit) regulate V-ATPase function. Our results showed that both subunits are important for V-ATPase activity, but β subunit displayed more significant phenotypes. Deletion of β subunit reduced glucose-dependent V1Vo reassembly and altered V-ATPase binding to its assembly factor, RAVE. We additionally investigated the mechanisms by which phosphofructokinase-1 controls V-ATPase function. We concluded that glucose-dependent V1Vo reassembly and V-ATPase function at steady state were controlled by the glycolytic flux, independently of phosphofructokinase-1. Notably, V-ATPase activation in vivo correlated with the presence of phosphoglycerate kinase at vacuolar membranes. These studies further advanced our understanding how glucose controls V-ATPase pumps in vivo.

Keywords

V-ATPase

Document Type

Dissertation

Language

English

Degree Name

Biomedical Sciences

Level of Degree

Doctoral

Department Name

Biomedical Sciences Graduate Program

First Committee Member (Chair)

Osley, Mary Ann

Second Committee Member

Garver, William S.

Third Committee Member

Lee, Samuel A.

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