A novel mutation in GPD1­L associated with early repolarization syndrome via modulation of cardiomyocyte fast sodium currents.

ABSTRACT

Early repolarization syndrome (ERS) is associated with genetic mutations, but the role of the glycerol­3­phosphate dehydrogenase 1­like (GPD1­L) mutation remains unclear. The aim of the present study was to investigate the role and potential underlying mechanism of GPD1­L mutation P112L in the pathogenesis of ERS. Whole­genome sequencing was performed on samples from a family with ERS, and the gene sequencing results were analyzed using bioinformatics. 293 cells were transfected with wild­type (WT) or mutant­type (MT) GPD1­L and SCN5A plasmids. Successful transfection of GPD1­L in 293 cells was verified by western blotting. Whole­cell patch­clamp recording, confocal microscopic observation and western blotting were used to uncover the potential mechanism of GPD1­L P112L in ERS. The results of western blotting indicated that the expression of the GPD1­L protein was lower in the MT group compared with that in the WT group, but the mock group did not express the GPD1­L protein. The whole­cell patch­clamp recording results indicated that the activation current density of INa (at ­30 mV) was ~60% lower in the MT group compared with the WT group (P<0.01). The mutation caused the inactivation voltage to move in a negative direction by ~3 mV compared with that of the WT group. However, there were no significant between­group differences in the steady activation, steady inactivation, and steady recovery of INa. Confocal microscopy demonstrated that MT GPD1­L was less expressed near the cell membrane and more expressed in the cytoplasm compared with WT GPD1­L. Both WT and MT GPD1­L were highly expressed in the cytoplasm and in small amounts in the nucleus. In conclusion, the GPD1­L P112L mutation decreased INa activation and GPD1­L cell expression, including in the region near the cell membrane. These results suggest that GPD1­L P112L may be a pathogenic genetic mutation associated with ERS.