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Updated: Sep 4, 2025

Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions
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HSP70 protects H9C2 cells from hypoxia and reoxygenation injury through STIM1/IP3R

TianYu Liu1,2, Zhaodong Juan2, Bin Xia1

  • 1The First Affiliated Hospital of Weifang Medical University, Weifang People's Hospital Cardiovascular Surgery, Weifang, 261000, China.

Cell Stress & Chaperones
|July 16, 2022
PubMed

Insights

Heat shock protein 70 (HSP70) protects heart cells from injury by reducing calcium overload and apoptosis. This study shows HSP70 inhibits STIM1/IP3R signaling, offering a new therapeutic target for myocardial ischemia-reperfusion injury.

Area of Science:

  • Cardiovascular Biology
  • Cellular Stress Response
  • Molecular Cardiology

Background:

  • Myocardial ischemia-reperfusion (I/R) injury is a major cause of heart disease.
  • Calcium overload and apoptosis are key contributors to I/R injury.
  • Heat shock protein 70 (HSP70) shows potential cardioprotective effects, but its mechanism is unclear.

Purpose of the Study:

  • To investigate if HSP70 protects H9C2 cardiomyocytes against hypoxia/reoxygenation (H/R) injury.
  • To determine if HSP70 modulates the STIM1/IP3R calcium signaling pathway.
  • To elucidate the role of HSP70 in regulating calcium overload and apoptosis.

Main Methods:

  • H9C2 cells were subjected to H/R to model I/R injury.
  • HSP70 was overexpressed in H9C2 cells.
  • STIM1 was silenced using siRNA.
  • Cell viability, lactate dehydrogenase (LDH) release, apoptosis, intracellular calcium levels, and protein expression (STIM1, IP3R, Bcl-2, BAX) were assessed.

Main Results:

  • H/R significantly decreased H9C2 cell viability and increased LDH release and apoptosis.
  • HSP70 overexpression attenuated H/R-induced cell injury, reduced apoptosis, and lowered intracellular calcium levels.
  • HSP70 overexpression inhibited the expression of STIM1 and IP3R.
  • Silencing STIM1 mimicked the protective effects of HSP70, increasing cell viability and Bcl-2 expression while decreasing apoptosis and BAX expression.

Conclusions:

  • HSP70 exerts a protective effect against H/R-induced cardiomyocyte injury.
  • HSP70 abrogates intracellular calcium overload by inhibiting STIM1/IP3R upregulation.
  • This mechanism reduces apoptosis and alleviates myocardial I/R injury, highlighting HSP70 as a potential therapeutic target.

Keywords:
Cell apoptosisGlucose deprivationHeat shock protein 70Inositol 1,4,5-triphosphate receptorMyocardial ischemia–reperfusion injuryOxygen deprivationStromal interaction molecule 1

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