Abstract: Objective To study the effect of protein tyrosine phosphatase non-receptor type 12 (PTPN12) in regulating cardiac
HERG channel currents. Methods The plasmids pcDNA3.1-PTPN12-RFP and herg mutant constructed by PCR technique were
transfected into HEK293 cells via Lipofectamine 2000, and the cells stably expressing PTPN12 selected with G418 were
identified by Western blotting with anti-PTPN12 antibody. HERG channel current in cells expressing HERG alone (HEK293/
HERG cells), cells overexpressing PTPN12 (HEK293/HERG cells transfected with pCDNA3.1-PTPN12-RFP), PAO-treated cells
(PTPN12/HERG cells treated with PAO), and herg mutant cells (HEK293/HERGY327A-Y700A-Y845A cells transfected with
pcDNA3.1-PTPN12-RFP) were recorded by patch-clamp technique. Results The plasmids pcDNA3.1-PTPN12-RFP and herg
mutant were successfully constructed, and the stable expressing cell lines were established. Red fluorescence was obversed in
HEK293/HERG cells transfected with pcDNA3.1-PTPN12-RFP, and the protein expression of PTPN12 was detected.
Overexpression of PTPN12 significantly decreased HERG current density in HEK293/HERG cells, and this change was
significantly weakened in the inhibitor group and herg mutant group. Conclusion PTPN12 negatively regulates cardiac HERG
channel cerrent possibly by decreasing the phosphorylation level of HERG tyrosine residues. This finding provides further
insight into the regulatory mechanism of HERG channel and the pathogenesis of long QT syndrome.