MALAT1: A Pivotal lncRNA in the Phenotypic Switch of Gastric Smooth Muscle Cells via the Targeting of the miR-449a/DLL1 Axis in Diabetic Gastroparesis.

Yanjuan Wang,Yaoyao Gong,Lin Lin,Ying Zhu,Wenjie Xiong,Boqian Zhu,Ya Jiang,Yan Wang

doi:10.3389/fphar.2021.719581

Abstract

Diabetic gastroparesis (DGP) is a common complication of diabetes mellitus (DM). Our previous study suggested that the expression of the long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is closely related to DGP. However, the role of MALAT1 in DGP pathogenesis remains unclear. Here, we aim to characterize the role of MALAT1 in DGP. First, we analyzed the lncRNA expression profiles through lncRNA sequencing. Next, we detected MALAT1 expression in the stomach tissues of DGP model mice and diabetic patients. Then, we investigated the role and mechanisms of MALAT1 in the proliferation, migration, phenotypic switch, and carbachol-induced intracellular Ca2+ changes in human gastric smooth muscle cells (HGSMCs) under high glucose (HG) conditions, using short hairpin RNA technology, RNA immunoprecipitation, and dual-luciferase reporter assays. We show that MALAT1 expression was upregulated in the gastric tissues of DGP model mice, the adjacent healthy tissues collected from diabetic gastric cancer patients with DGP symptoms, and in HGSMCs cultured under HG conditions. Functionally, MALAT1 knockdown in vitro impacted the viability, proliferation, migration and promoted the phenotypic switch of HGSMCs under HG conditions. Additionally, we show that MALAT1 sponged miR-449a, regulating Delta-like ligand 1 (DLL1) expression in HGSMCs; any disturbance of the MALAT1/miR-449a/DLL1 pathway affects the proliferation, migration, phenotypic switch, and carbachol-induced Ca2+ transient signals in HGSMCs under HG conditions. Collectively, our data highlight a novel regulatory signaling pathway, the MALAT1/miR-449a/DLL1 axis, in the context of DGP.

Highlights

Diabetic gastroparesis (DGP), defined as the objectively delayed gastric emptying without mechanical obstruction, is a severe complication of diabetes mellitus (DM); it causes early satiety, nausea, vomiting, bloating, heartburn, and abdominal pain, as well as significant morbidity (Vanormelingen et al, 2013; Camilleri et al, 2017)
LncRNA sequencing was conducted in three pairs of gastric tissues from DGP mice and the respective control group to investigate the profile of long non-coding RNA (lncRNA) expression
In order to verify the reliability of the sequencing results, top ten upregulated and down-regulated candidate lncRNAs were selected for qPCR, and the results were consistent with those of the sequencing analysis (Figure 1C)

Summary

Introduction

Diabetic gastroparesis (DGP), defined as the objectively delayed gastric emptying without mechanical obstruction, is a severe complication of diabetes mellitus (DM); it causes early satiety, nausea, vomiting, bloating, heartburn, and abdominal pain, as well as significant morbidity (Vanormelingen et al, 2013; Camilleri et al, 2017). The exact prevalence of DGP remains unknown, gastric emptying disorders reportedly occur in approximately one-third of diabetic patients (De Block et al, 2006; Bharucha et al, 2019). Hyperglycemia and immune disorders, hormonal disturbances, autonomic neuropathy, autonomic or enteric neuropathy, gastric smooth muscle lesions, and injury of the interstitial cells of Cajal (ICCs) may result in DGP (Camilleri et al, 2011; Bharucha et al, 2019). The mechanisms underlying the formation of smooth muscle lesions remain unclear

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