IP3R1 regulates Ca2+ transport and pyroptosis through the NLRP3/Caspase-1 pathway in myocardial ischemia/reperfusion injury

miR-302a-3p targets FMR1 to regulate pyroptosis of renal tubular epithelial cells induced by hypoxia-reoxygenation injury

NEW FINDINGS

What is the central question of this study? How does miR-302a-3p play a role in hypoxia-reoxygenation-induced pyroptosis of renal tubular epithelial cells? What is the main finding and its importance? Hypoxia-reoxygenation treatment upregulated the expression of miR-302a-3p in HK-2 cells, and then inhibited the transcription of FMRP translational regulator 1 (FMR1), so as to promote the activation of the NLRP3 inflammasome and aggravate the pyroptosis of HK-2 cells. miR-302a-3p was used as a molecular target in this study, which provides a new theoretical basis for the treatment of renal failure.

ABSTRACT

Hypoxia-reoxygenation (H/R) induction can affect miRNA expression and then control NLR family pyrin domain containing 3 (NLRP3) inflammasome-mediated pyroptosis. This study investigated the mechanism of miR-302a-3p in H/R-induced renal tubular epithelial cell (RTEC) pyroptosis. Human HK-2 RTECs were induced by H/R. Lactate dehydrogenase content, cell activity and pyroptosis, and levels of NLRP3, GSDMD-N, caspase-1, interleukin (IL)-1β, IL-18, superoxide dismutase, and malondialdehyde were detected to verify the effect of H/R on HK-2 cells. The NLRP3 inflammasome action was evaluated after H/R-induced HK-2 cells were treated with BAY11-7082, an inflammasome inhibitor. After inhibiting miR-302a-3p expression, the changes of pyroptosis were observed. The binding relation between miR-302a-3p and FMRP translational regulator 1 (FMR1) was verified. A function-rescue experiment verified the role of FMR1 in the regulation of pyroptosis. H/R-induced HK-2 cells showed significant pyroptosis injury, and the NLRP3 inflammasome was activated. After inhibiting the NLRP3 inflammasome, H/R-induced apoptosis was inhibited. After H/R treatment, miR-302a-3p in HK-2 cells was increased, and miR-302a-3p downregulation limited H/R-induced NLRP3 inflammasome-mediated pyroptosis. FMR1 is the target of miR-302a-3p. Inhibition of FMR1 alleviated the inhibition of H/R-induced HK-2 cell pyroptosis by miR-302a-3p inhibitor. Collectively, inhibiting miR-302a-3p can weaken its targeted inhibition on FMR1, thereby inhibiting the activation of NLRP3 inflammasomes and reducing caspase-1-dependent pyroptosis in HK-2 cells.

Structure and Function of Mitochondria-Associated Endoplasmic Reticulum Membranes (MAMs) and Their Role in Cardiovascular Diseases

Abnormal function of suborganelles such as mitochondria and endoplasmic reticulum often leads to abnormal function of cardiomyocytes or vascular endothelial cells and cardiovascular disease (CVD). Mitochondria-associated membrane (MAM) is involved in several important cellular functions. Increasing evidence shows that MAM is involved in the pathogenesis of CVD. MAM mediates multiple cellular processes, including calcium homeostasis regulation, lipid metabolism, unfolded protein response, ROS, mitochondrial dynamics, autophagy, apoptosis, and inflammation, which are key risk factors for CVD. In this review, we discuss the structure of MAM and MAM-associated proteins, their role in CVD progression, and the potential use of MAM as the therapeutic targets for CVD treatment.

ERp44/CG9911 promotes fat storage in Drosophila adipocytes by regulating ER Ca2+ homeostasis

Fat storage is one of the important strategies employed in regulating energy homeostasis. Impaired lipid storage causes metabolic disorders in both mammals and Drosophila. In this study, we report CG9911, the Drosophila homolog of ERp44 (endoplasmic reticulum protein 44) plays a role in regulating adipose tissue fat storage. Using the CRISPR/Cas9 system, we generated a CG9911 mutant line deleting 5 bp of the coding sequence. The mutant flies exhibit phenotypes of lower bodyweight, fewer lipid droplets, reduced TAG level and increased expression of lipolysis related genes. The increased lipolysis phenotype is enhanced in the presence of ER stresses and suppressed by a reduction of the ER Ca²⁺. Moreover, loss of CG9911 per se results in a decrease of ER Ca²⁺ in the fat body. Together, our results reveal a novel function of CG9911 in promoting fat storage via regulating ER Ca²⁺ signal in Drosophila.