MicroRNA-144 is a circulating effector of remote ischemic preconditioning

Abstract

Remote ischemic preconditioning (rIPC) induced by cycles of transient limb ischemia and reperfusion is a powerful cardioprotective strategy with additional pleiotropic effects. However, our understanding of its underlying mediators and mechanisms remains incomplete. We examined the role of miR-144 in the cardioprotection induced by rIPC. Microarray studies first established that rIPC increases, and IR injury decreases miR-144 levels in mouse myocardium, the latter being rescued by both rIPC and intravenous administration of miR-144. Going along with this systemic treatment with miR-144 increased P-Akt, P-GSK3β and P-p44/42 MAPK, decreased p-mTOR level and induced autophagy signaling, and induced early and delayed cardioprotection with improved functional recovery and reduction in infarct size similar to that achieved by rIPC. Conversely, systemic administration of a specific antisense oligonucleotide reduced myocardial levels of miR-144 and abrogated cardioprotection by rIPC. We then showed that rIPC increases plasma miR-144 levels in mice and humans, but there was no change in plasma microparticle (50-400 nM) numbers or their miR-144 content. However, there was an almost fourfold increase in miR-144 precursor in the exosome pellet, and a significant increase in miR-144 levels in exosome-poor serum which, in turn, was associated with increased levels of the miR carriage protein Argonaute-2. Systemic release of microRNA 144 plays a pivotal role in the cardioprotection induced by rIPC. Future studies should assess the potential for plasma miR-144 as a biomarker of the effectiveness of rIPC induced by limb ischemia, and whether miR-144 itself may represent a novel therapy to reduce clinical ischemia-reperfusion injury.

Molecular Basis of Cardioprotection

“…267 Several different micro RNAs have been identified in protocols of IPC, [268][269][270][271][272] POC, 270,[272][273][274][275] and RIC 270,[276][277][278] in various species, including humans. 276,277 Unless the microarray screening data were confirmed by RT-PCR, 269,270,272,275,277 it is difficult to decide whether the identified microRNAs reflect robust data or circumstantial epiphenomena.…”

“…267 Several different micro RNAs have been identified in protocols of IPC, [268][269][270][271][272] POC, 270,[272][273][274][275] and RIC 270,[276][277][278] in various species, including humans. 276,277 Unless the microarray screening data were confirmed by RT-PCR, 269,270,272,275,277 it is difficult to decide whether the identified microRNAs reflect robust data or circumstantial epiphenomena. Likewise, unless the identified microRNAs were demonstrated to be causally related to the expression/activity of an established cardioprotective protein 268,270,274 or, even better, to IS reduction, for example, by abrogation of IS reduction by an antagonist 269,271,273,276 to an increased microRNA or exogenous administration of a decreased microRNA, 268,272 respectively, the functional relevance of the reported microRNA in cardioprotective signaling must remain unclear.…”

“…276,277 Unless the microarray screening data were confirmed by RT-PCR, 269,270,272,275,277 it is difficult to decide whether the identified microRNAs reflect robust data or circumstantial epiphenomena. Likewise, unless the identified microRNAs were demonstrated to be causally related to the expression/activity of an established cardioprotective protein 268,270,274 or, even better, to IS reduction, for example, by abrogation of IS reduction by an antagonist 269,271,273,276 to an increased microRNA or exogenous administration of a decreased microRNA, 268,272 respectively, the functional relevance of the reported microRNA in cardioprotective signaling must remain unclear. Given these criteria, several different microRNAs seem to be involved in IPC, [269][270][271][272] notably microRNA-21, which seems to be upregulated and serve a cardioprotective function.…”

Proteostasis in cardiac health and disease

“…or myocyte hypertrophic signals, or even by delivery from distant sites, as found in remote preconditioning 144,145 . In addition to exosomes, tunnelling nanotubes -long, intercellular connections of 50-700 nm in diameter prov iding membrane continuity between connected cells -have emerged as an alternative means of transfer of microRNAs and even organelles 146,147 .…”

Beneficial effects of exosomes secreted by cardiac-derived progenitor cells and other cell types in myocardial ischemia

“…Li et al (67) reported that remote ischemic preconditioning, to the opposite of IR injury, increased miR-144 levels in mouse myocardium and miR-144 precursor in exosomes. Systemic treatment with miR-144 increased P-Akt, P-GSK3β and P-p44/42 MAPK, and induced early and delayed cardioprotection resulting in improved functional recovery and decreased infarct size similar to that achieved by remote ischemic preconditioning.…”