Effect of Rosolic acid on endothelial dysfunction under ER stress in pancreatic microenvironment

Abstract

Endothelial cell (EC) dysfunction is the underlying cause for the development of several pathologies, and the interdependency between the pancreatic β-cells and ECs has been established in the pathophysiology of diabetes. ECs release several factors that govern the expression of genes involved in the proliferation, physiology, and survival of the β-cells. Of the known factors that collapse this intricately balanced system, endothelial dysfunction is the crucial condition that manifests as the causative factor for micro and macrovascular diseases. Our earlier studies demonstrated that activation of nuclear factor erythroid-related factor (Nrf2) renders protection to the ECs experiencing ER stress. In this study, using a co-culture system, the crosstalk between pancreatic cells under ER stress and ECs and the effect of a novel Nrf2 activator Rosolic Acid (RA), on the crosstalk was investigated. ECs pre-treated with different concentrations RA and co-cultured with thapsigargin-induced ER stressed pancreatic β-cells showed increased levels of Nrf2 and its downstream targets such as heme oxygenase-1 (HO-1) and NADPH-quinone oxidoreductase-1 (NQO-1), and reduction of ER stress evinced by the decreased levels of glucose-regulated protein (GRP) 78 and C/ERB homologous protein (CHOP). The sensitization of ECs using RA, offered protection to pancreatic cells against ER stress as displayed by increased intracellular insulin and upregulated expression of cell survival and proliferative genes BCl2 and PDX-1. In addition, RA treatment resulted in elevated levels of various angiogenic factors, while inflammatory (TNF-α and IL-1β) and apoptotic markers (CXCL10 and CCL2) decreased. RA treatment normalized the levels of 115 proteins of the 277, which were differentially regulated as revealed by proteomic studies of ER stressed pancreatic β-cells in co-culture conditions. These findings clearly indicate the role of small molecule activators of Nrf2 not only in restoring the functioning of pancreatic cells but also in increasing the cell mass. Further, the study impinges on the strategies that can be developed to balance the pancreatic microenvironment, leading to the restoration of β-cell mass and their normophysiology in diabetic patients.

Keywords:

• Endothelial dysfunction
• ER stress
• rosolic acid
• Nrf2
• co-culture

Author contributions

KMR, PR and TSU conceived and designed the experiment. KNA, KS and MRG performed the experiment and drafted the manuscript. KNA, PR, DA and KMR analyzed the data. KMR, DVLS and PR contributed to the discussion and reviewed the manuscript. All the authors have approved the manuscript.

Disclosure statement

We declare that we have no competing financial interests and personal relationships with other people or organizations that can inappropriately influence our work. There is no professional or other personal interests of any nature or kind in any product, service, and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled.

Additional information

Funding

The authors gratefully acknowledge the financial support by the Science and Engineering Research Board (SERB) (Grant no. EMR/2016/006196), Government of India. The authors gratefully acknowledge the facilities provided by “SRM-DBT Partnership Platform for Contemporary Research Services and Skill Development in Advanced Life Sciences Technologies” [Grant No. BT/PR12987/INF/22/205/2015]. This work was funded by the Researchers Supporting Project number RSP-2020/165, King Saud University, Riyadh, Saudi Arabia.