| First Author | Shimada BK | Year | 2021 |
| Journal | Physiol Rep | Volume | 9 |
| Issue | 6 | Pages | e14807 |
| PubMed ID | 33769701 | Mgi Jnum | J:317983 |
| Mgi Id | MGI:6808248 | Doi | 10.14814/phy2.14807 |
| Citation | Shimada BK, et al. (2021) mTOR-mediated calcium transients affect cardiac function in ex vivo ischemia-reperfusion injury. Physiol Rep 9(6):e14807 |
| abstractText | The mechanistic target of rapamycin (mTOR) is a key mediator of energy metabolism, cell growth, and survival. While previous studies using transgenic mice with cardiac-specific overexpression of mTOR (mTOR-Tg) demonstrated the protective effects of cardiac mTOR against ischemia-reperfusion (I/R) injury in both ex vivo and in vivo models, the mechanisms underlying the role of cardiac mTOR in cardiac function following I/R injury are not well-understood. Torin1, a pharmacological inhibitor of mTOR complex (mTORC) 1 and mTORC2, significantly decreased functional recovery of LV developed pressure in ex vivo I/R models (p < 0.05). To confirm the role of mTOR complexes in I/R injury, we generated cardiac-specific mTOR-knockout (CKO) mice. In contrast to the effects of Torin1, CKO hearts recovered better after I/R injury than control hearts (p < 0.05). Interestingly, the CKO hearts had exhibited irregular contractions during the reperfusion phase. Calcium is a major factor in Excitation-Contraction (EC) coupling via Sarcoplasmic Reticulum (SR) calcium release. Calcium is also key in opening the mitochondrial permeability transition pore (mPTP) and cell death following I/R injury. Caffeine-induced SR calcium release in isolated CMs showed that total SR calcium content was lower in CKO than in control CMs. Western blotting showed that a significant amount of mTOR localizes to the SR/mitochondria and that GSK3-beta phosphorylation, a key factor in SR calcium mobilization, was decreased. These findings suggest that cardiac mTOR located to the SR/mitochondria plays a vital role in EC coupling and cell survival in I/R injury. |
