Exendin-4 protects bone marrow-derived mesenchymal stem cells against oxygen/glucose and serum deprivation-induced apoptosis through the activation of the cAMP/PKA signaling pathway and the attenuation of ER stress

Int J Mol Med. 2016 Apr;37(4):889-900. doi: 10.3892/ijmm.2016.2509. Epub 2016 Feb 29.

Abstract

Exendin-4 (ex-4) is a long-acting glucagon-like peptide-1 receptor (GLP-1R) agonist which exerts beneficial effects on glycemic control and promotes cell viability. In the present study, we investigated the anti-apoptotic effects of ex-4, as well as the potential mechanisms responsible for these effects in rat bone marrow-derived mesenchymal stem cells (BM-MSCs) under conditions of oxygen, glucose and serum deprivation (OGD). The apoptosis of the MSCs was induced by subjecting the cells to OGD conditions for 4 h and was detected by Annexin V/PI and Hoechst 33258 staining. The MSCs were pre-conditioned with ex-4 for 12 h prior to being subjected to OGD conditions, and the expression levels of an apoptotic marker (cleaved caspase-3), endoplasmic reticulum (ER) stress markers [phosphorylated (p-)protein kinase RNA-like endoplasmic reticulum kinase (PERK), PERK, binding immunoglobulin protein (BIP), activating transcription factor 4 (ATF-4) and C/EBP homologous protein (CHOP)], as well as those of a survival marker (Bcl-2) were measured by western blot analysis. Furthermore, the mRNA levels of ATF-4 and CHOP were determined by RT-qPCR. ELISA was used to examine the activity of intracellular cAMP. Moreover, the GLP-1R antagonist, exendin9-39 (ex9-39), the protein kinase A (PKA) inhibitor, H89, and small interfering RNA (siRNA) targeting rat ATF-4 and CHOP were co-incubated with the MSCs. The apoptotic rate was markedly diminished following pre-conditioning with ex-4 in a dose‑dependent manner (P<0.05). The ER stress markers, p-PERK, BIP, ATF-4 and CHOP, were upregulated in the cells subjected to OGD conditions. Ex-4 pre-conditioning significantly decreased the mRNA and protein levels of ATF-4 and CHOP (P<0.05), and increased the activity of intracellular cAMP (P<0.05). Furthermore, the anti-apoptotic effects of ex-4 were almost reversed by treatment with either H89 or ex9-39 (P<0.05); transfection with siRNA-CHOP significantly reduced the apoptotic rate of the MSCs and did not impair the cytoprotective effects of ex-4. Taken together, these findings suggest that ex-4 protects rat BM-MSCs from OGD-induced apoptosis through the activation of the PKA/cAMP pathway and the attenuation of the ER stress signaling pathway. Ex-4 may thus prove to be a therapeutic agent with the potential to improve the viability of MSCs in the ischemic milieu, and consequently, to optimize the therapeutic effects of MSC therapy in acute myocardial infarction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Cyclic AMP / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Endoplasmic Reticulum Stress / drug effects*
  • Enzyme Activation / drug effects
  • Exenatide
  • Glucose / metabolism
  • Hypoglycemic Agents / pharmacology*
  • Male
  • Mesenchymal Stem Cells / metabolism
  • Oxygen / metabolism*
  • Peptides / pharmacology*
  • Protective Agents / pharmacology*
  • Rats, Sprague-Dawley
  • Signal Transduction / drug effects
  • Venoms / pharmacology*

Substances

  • Hypoglycemic Agents
  • Peptides
  • Protective Agents
  • Venoms
  • Exenatide
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Glucose
  • Oxygen