Solute carrier family 12 member 2 isoform b (NKCC1b) (NKCC1b)

Solute carrier family 12 member 2 isoform b (NKCC1b) is a brain-specific splice variant of the NKCC1 protein, encoded by the SLC12A2 gene (UniProt: P55011). This isoform is characterized by the exclusion of exon 21, which distinguishes it from the ubiquitously expressed full-length NKCC1a isoform (Vibat et al., 2001, PubMed: 11447201). NKCC1b functions as a symporter that mediates the electroneutral movement of sodium, potassium, and chloride ions into neurons, playing a pivotal role in maintaining high intracellular chloride levels during early neurodevelopment (Ben-Ari, 2002, PubMed: 12183631). This high chloride concentration is essential for the depolarizing (excitatory) action of GABA in the developing brain, a process that typically shifts to hyperpolarizing (inhibitory) as KCC2 expression increases and NKCC1 activity decreases. Dysregulation of NKCC1b expression or function is strongly associated with neurological and psychiatric disorders, including neonatal seizures, autism spectrum disorder (ASD), and schizophrenia, where an imbalance in the chloride gradient leads to impaired inhibitory neurotransmission (Lemonnier et al., 2012, PubMed: 23236382; Morita et al., 2014, PubMed: 24508565). Pharmacological targeting of NKCC1b is primarily achieved through loop diuretics such as bumetanide, which act as potent inhibitors of the cotransporter (Puskarjov et al., 2014, PubMed: 25203315). While bumetanide has shown promise in clinical trials for ASD and epilepsy, its lack of isoform specificity leads to systemic side effects, most notably diuresis and potential ototoxicity, driving the search for brain-selective NKCC1b inhibitors (Savardi et al., 2020, PubMed: 32699215).

Other names

SLC12A2 isoform 2Sodium-potassium-chloride cotransporter 1 isoform bBSC2NKCC1 splice variant b

Inhibition of the Na-K-2Cl cotransport system, preventing the inward movement of sodium, potassium, and chloride ions into the cell.