The chloride anion as a signalling effector

Abstract

The specific role of the chloride anion (Cl−) as a signalling effector or second messenger has been increasingly recognized in recent years. It could represent a key factor in the regulation of cellular homeostasis. Changes in intracellular Cl− concentration affect diverse cellular functions such as gene and protein expression and activities, post-translational modifications of proteins, cellular volume, cell cycle, cell proliferation and differentiation, membrane potential, reactive oxygen species levels, and intracellular/extracellular pH. Cl− also modulates functions in different organelles, including endosomes, phagosomes, lysosomes, endoplasmic reticulum, and mitochondria. A better knowledge of Cl− signalling could help in understanding the molecular and metabolic changes seen in pathologies with altered Cl− transport or under physiological conditions. Here we review relevant evidence supporting the role of Cl− as a signalling effector.