C1q/tumor necrosis factor‐related protein‐6 attenuates TNF‐α‐induced apoptosis in salivary acinar cells via AMPK/SIRT1‐modulated miR‐34a‐5p expression

Abstract

C1q/tumor necrosis factor‐related protein‐6 (CTRP6) is a newly identified adipokine involved in diverse biological processes. However, its role in salivary glands remains unknown. Here, we demonstrated that CTRP6 was mainly distributed in the nuclei, apicolateral membranes, and cytoplasm of human submandibular glands (SMGs), serous cells of parotid glands, and ducts and apicolateral membranes of serous cells in rats and mice. CTRP6 inhibited the apoptosis rate and reversed the increased levels of cleaved caspase 3, caspase 8, caspase 9, and cytochrome C and the decreased Bcl‐2 expression induced by tumor necrosis factor (TNF)‐α in both SMG‐C6 cells and cultured human SMG tissues. Microarray analysis identified 43 differentially expressed microRNAs (miRNAs) in the SMGs of nonobese diabetic mice. miR‐34a‐5p was selected due to its upregulation by TNF‐α, which was abolished by CTRP6. The miR‐34a‐5p inhibitor promoted whereas the miR‐34a‐5p mimic suppressed the effects of CTRP6 on TNF‐α‐induced apoptosis. CTRP6 increased AMP‐activated protein kinase (AMPK) phosphorylation and reversed TNF‐α‐induced SIRT1 downregulation in salivary cells. AraA, an AMPK inhibitor, reversed the effects of CTRP6 on TNF‐α‐induced alterations in the levels of SIRT1, miR‐34a‐5p, Bcl‐2, and cleaved caspase 3 in vitro and ex vivo, whereas activating AMPK by AICAR reversed the decrease in SIRT1 expression and increase in miR‐34a‐5p expression induced by TNF‐α. Inhibition of SIRT1 by EX527 suppressed the effects of CTRP6 on TNF‐α‐induced changes in miR‐34a‐5p and apoptosis‐related proteins. Our findings indicate that salivary glands are novel sites for CTRP6 synthesis and secretion. CTRP6 protects acinar cells against TNF‐α‐induced apoptosis via AMPK/SIRT1‐modulated miR‐34a‐5p expression.

High Glucose Reduces the Paracellular Permeability of the Submandibular Gland Epithelium via the MiR-22-3p/Sp1/Claudin Pathway

“…The rat SMG acinar cell line SMG-C6 (a kind gift from Dr David O. Quissell) was cultured in DMEM/F12 (1:1 mixture) as previously described [23]. In high-glucose (HG) experiments, cells were incubated in normal medium supplemented with D-glucose at a final concentration of 25 mmol/L.…”

“…All participants signed an informed consent document before tissue collection. Fresh SMGs were transported, cut, and incubated with or without HG medium for the indicated times, as described previously [23].…”

Composition and regulation of the immune microenvironment of salivary gland in Sjögren’s syndrome

“…TNF-induced apoptosis occurs through the binding of TNF type I receptors (TNFR1), which contain death domains that transmit apoptotic signals through caspase activation ( 160 ). In addition, TNFα significantly increased the levels of caspase 3, 8, 9 and cytochrome C, leading to a decrease in the level of Bcl-2 and induced apoptosis of SMG-C6 cells and human SMG tissues ( 161 ). Caspase 3 is considered the most important executor of apoptosis, and caspase 8 initiates the death receptor pathway of apoptosis.…”

“…To determine the role of these miRNAs in TNFα -induced acinar cell apoptosis, real-time PCR was used to measure their expression levels after cells were incubated with TNFα for a specified period of time. The results showed that TNFα could induce significantly increased levels of Mir-34a-5p, Mir-34a-3p, Mir-200b-5p and Mir-200b-3p simultaneously, while leT-7a-5P expression remained unchanged ( 161 ).…”

Tetrahydroxy stilbene glycoside attenuates endothelial cell premature senescence induced by H2O2 through the microRNA-34a/SIRT1 pathway

“…It has been reported that miR-34a increases with aging in vessels and induces senescence and the acquisition of the senescence-associated secretory phenotype (SASP) in ECs 7 – 9 . SIRT1 has been revealed that it could be regulated by miR-34a 10 . miR-34a inhibits SIRT1 through a miR-34a binding site with the 3’UTR of SIRT1 11 , 12 .…”