Key result
Overexpression of chaperones CRT and ERP57 increased tail current density by 46% and 53%, respectively, restoring the trafficking of the mutant HERG-A561V protein in vitro.
Why the study?
Whether the maturation process of HERG protein involves key molecules derived from the calnexin/calreticulin cycle and how these molecules work remained unknown.
Overexpression of chaperones ERP57 and CRT can restore the trafficking and function of the mutant HERG-A561V protein, offering potential molecular targets for Long QT syndrome type 2.
Does not change LQTS2 management; leaves open chaperone overexpression as a hypothesis-generating target for HERG trafficking rescue.
Long QT syndrome type 2 is caused by a mutation in the human‑ether‑a‑go‑go‑related gene (HERG) gene encoding the rapidly activating delayed rectifier K‑current. HERG is a key cell membrane glycoprotein; however, whether the maturation process of HERG protein involves key molecules derived from the calnexin (CNX)/calreticulin (CRT) cycle and how these molecules work remains unknown. Using western blotting, the present study screened the key molecules CNX/CRT/endoplasmic reticulum protein 57 (ERP57) involved in this cycle, and it was revealed that the protein expression levels of CNX/CRT/ERP57 in wild‑type (WT)/A561V cells were increased compared with those in WT cells (n=3; P<0.05). Additionally, a co‑immunoprecipitation experiment was used to reveal that the ability of CNX/ERP57/CRT to interact with HERG was significantly increased in A561V and WT/A561V cells (n=3; P<0.05). A plasmid lacking the bb' domain of ERP57 was constructed and it was demonstrated that the key site of ERP57 binding to CRT and immature HERG protein is the bb' domain. The whole‑cell patch‑clamp technique detected that the tail current density increased by 46% following overexpression of CRT and by 53% following overexpression of ERP57 in WT/A561V cells. Overexpression of CRT and ERP57 could increased HERG protein levels on the membrane detected by confocal imaging. Furthermore, overexpression of ERP57 and CRT proteins could restore the HERG‑A561V mutant protein trafficking process and rescue the dominant‑negative suppression of WT. Overall, ERP57/CRT served a crucial role in the HERG‑A561V mutant protein trafficking deficiency and degradation process.
No takes yet. Share an insight, caveat, or question.
Wu et al. (2021) studied Long QT syndrome type 2 (HERG-A561V mutation). Overexpression of CRT and ERP57 vs. Heterozygous control (WT/A561V without overexpression) was evaluated on Tail current density (46% increase, p=<0.05). Overexpression of chaperones CRT and ERP57 increased tail current density by 46% and 53%, respectively, restoring the trafficking of the mutant HERG-A561V protein in vitro.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: