The neuronal K+Cl− co-transporter 2 (Slc12a5) modulates insulin secretion

• DOI: 10.1038/s41598-017-01814-0
• Publication Date: 2017-05-04T17:43:54Z
• Authors: Shams Kursan; Timothy S. McMillen; Pavani Beesetty; Eduardo Dias-Junior; Mohammed M. Almut...; Abu A. Sajib; J. Ashot Kozak; Lydia Aguilar-Bryan; Mauricio Di Fulvio
• Keywords: Medical Sciences; Medical Physiology; Biochemistry; Gene; Mice; Endocrinology; Diabetes mellitus; KATP Channels; Insulin-Secreting Cells; Insulin Secretion; Endocrine system; Medicine and Health Sciences; Insulin; Internal medicine; Neurons; 0303 health sciences; Symporters; Q; R; Life Sciences; Medical Cell Biology; Pyridazines; Chemistry; Enteroendocrine cell; K Cl- Cotransporters; Glibenclamide; Medicine; Islet; Cell biology; Science; Pancreatic islets; Molecular Mechanisms of Aquaporins in Physiology and Disease; Transporter; Article; Cell Line; 03 medical and health sciences; Biochemistry, Genetics and Molecular Biology; Sulfonylurea receptor; Health Sciences; Animals; Humans; Amino Acid Sequence; Pancreatic Islet Dysfunction and Regeneration; Molecular Biology; Biology; Secretion; Base Sequence; Endocrine and Autonomic Systems; Neurosciences; Neuron; Glucagon; Hormone; Intracellular; Alternative Splicing; Thiazoles; Glucose; Medical Neurobiology; Calcium; Surgery; Neuroendocrine Regulation of Appetite and Body Weight; Physiological Processes; Neuroscience

AbstractIntracellular chloride concentration ([Cl−]i) in pancreatic β-cells is kept above electrochemical equilibrium due to the predominant functional presence of Cl− loaders such as the Na+K+2Cl− co-transporter 1 (Slc12a2) over Cl−extruders of unidentified nature. Using molecular cloning, RT-PCR, Western blotting, immunolocalization and in vitro functional assays, we establish that the “neuron-specific” K+Cl− co-transporter 2 (KCC2, Slc12a5) is expressed in several endocrine cells of the pancreatic islet, including glucagon secreting α-cells, but particularly in insulin-secreting β-cells, where we provide evidence for its role in the insulin secretory response. Three KCC2 splice variants were identified: the formerly described KCC2a and KCC2b along with a novel one lacking exon 25 (KCC2a-S25). This new variant is undetectable in brain or spinal cord, the only and most abundant known sources of KCC2. Inhibition of KCC2 activity in clonal MIN6 β-cells increases basal and glucose-stimulated insulin secretion and Ca2+ uptake in the presence of glibenclamide, an inhibitor of the ATP-dependent potassium (KATP)-channels, thus suggesting a possible mechanism underlying KCC2-dependent insulin release. We propose that the long-time considered “neuron-specific” KCC2 co-transporter is expressed in pancreatic islet β-cells where it modulates Ca2+-dependent insulin secretion.