connexin43 (cx43)

TAT-Gap19 acetate is a specific inhibitor of connexin43 hemichannel (Cx43 HC). TAT-Gap19 acetate traverses the blood-brain barrier and alleviates liver fibrosis in mice. TAT-Gap19 acetate does not inhibit the corresponding Cx43 GJCs.

Tat-Gap 19, a peptide inhibitor of connexin43 (Cx43) hemichannels, is derived from the HIV-1 Tat protein transduction domain fused with a nine-amino acid sequence from Cx43 residues 128-136. This compound, at a concentration of 10 µM, effectively suppresses glutamate-induced ATP release in primary rat hepatocytes, indicating inhibition of Cx43 hemichannel activity. Furthermore, Tat-Gap 19 demonstrates therapeutic potential by significantly reducing infarct volume in a mouse cerebral ischemia-reperfusion injury model following middle cerebral artery occlusion (MCAO) at a dosage of 25 mg/kg. Moreover, its intraperitoneal administration at 1 mg/kg per day ameliorates fibrosis and decreases the area of hepatic stellate cells, the precursors to myofibroblasts, expressing α-smooth muscle actin (α-SMA), in a model of thioacetamide-induced liver damage. Additionally, it enhances superoxide dismutase (SOD) activity in hepatic cells from the treated mice, indicating its antioxidative benefits.

TAT-Gap19 TFA, a Cx mimetic peptide and specific connexin43 hemichannel (Cx43 HC) inhibitor, does not inhibit corresponding Cx43 gap junction channels (GJCs). It crosses the blood-brain barrier and has shown efficacy in alleviating liver fibrosis in mice [1] [2] [3].