The cardioprotective role of sirtuins is mediated in part by regulating KATP channel surface expression


TUNCAY E., Gando I., Huo J., Yepuri G., Sampler N., TURAN B., ...More

American journal of physiology. Cell physiology, vol.324, no.5, 2023 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 324 Issue: 5
  • Publication Date: 2023
  • Doi Number: 10.1152/ajpcell.00459.2022
  • Journal Name: American journal of physiology. Cell physiology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, BIOSIS, CAB Abstracts, Chimica, EMBASE, MEDLINE, Veterinary Science Database
  • Keywords: cardioprotection, heart, KATP channels, lysine-acetylation, sirtuins
  • Lokman Hekim University Affiliated: Yes

Abstract

Sirtuins are NAD+-dependent deacetylases with beneficial roles in conditions relevant to human health, including metabolic disease, type II diabetes, obesity, cancer, aging, neurodegenerative diseases, and cardiac ischemia. Since ATP-sensitive K+ (KATP) channels have cardioprotective roles, we investigated whether they are regulated by sirtuins. Nicotinamide mononucleotide (NMN) was used to increase cytosolic NAD+ levels and to activate sirtuins in cell lines, isolated rat and mouse cardiomyocytes or insulin-secreting INS-1 cells. KATP channels were studied with patch clamping, biochemistry techniques, and antibody uptake experiments. NMN led to an increase in intracellular NAD+ levels and an increase in the KATP channel current, without significant changes in the unitary current amplitude or open probability. An increased surface expression was confirmed using surface biotinylation approaches. The rate of KATP channel internalization was diminished by NMN, which may be a partial explanation for the increased surface expression. We show that NMN acts via sirtuins since the increased KATP channel surface expression was prevented by blockers of SIRT1 and SIRT2 (Ex527 and AGK2) and mimicked by SIRT1 activation (SRT1720). The pathophysiological relevance of this finding was studied using a cardioprotection assay with isolated ventricular myocytes, in which NMN protected against simulated ischemia or hypoxia in a KATP channel-dependent manner. Overall, our data draw a link between intracellular NAD+, sirtuin activation, KATP channel surface expression, and cardiac protection against ischemic damage.