PKA regulates HMGB1 through activation of IGFBP-3 and SIRT1 in human retinal endothelial cells cultured in high glucose
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Objective and Design
Inflammation is a key component of a number of diseases, including diabetic retinopathy. We investigated the cellular pathway by which protein kinase A (PKA) inhibited high mobility group box 1 (HMGB1).
Primary human retinal endothelial cells (REC) were grown in normal glucose (5 mM) or high glucose (25 mM). Cells in high glucose were treated with exchange protein for cAMP 1 (Epac1) and IGFBP-3 siRNA. Additional cells in high glucose were treated with forskolin, a PKA agonist, and Epac1 siRNA. Some cells were treated with a plasmid for insulin-like growth factor binding protein 3 (IGFBP-3) that does not bind IGF-1. Finally, some REC received Ex527, a sirtuin 1 (SIRT1) antagonist, prior to forskolin treatment. Protein analyses were done for HMGB1, Epac1, IGFBP-3, SIRT1, and PKA.
PKA inhibited cytoplasmic HMGB1, independent of Epac1 actions. PKA activated IGFBP-3 and SIRT1 to inhibit cytoplasmic HMGB1. High glucose inhibited SIRT1 levels and increased cytoplasmic HMGB1 in REC.
PKA requires active IGFBP-3 and SIRT1 to inhibit HMGB1 inflammatory actions in the retina vasculature. Activation of these pathways may offer new targets for therapy development.
KeywordsPKA HMGB1 SIRT1 Inflammation Retinal endothelial cells
R01EY028442 (JJS), P30EY04068 (Hazlett), and an Unrestricted Grant to the Department of Ophthalmology from Research to Prevent Blindness (Kresge Eye Institute). The funders did not influence these design or execution of these studies.
- 1.Joussen AM, Poulaki V, Le ML, et al. A central role for inflammation in the pathogenesis of diabetic retinopathy. FASEB journal: official publication of the Federation of American Societies for Experimental Biology. 2004; 18 1450–2.Google Scholar
- 6.Jiang Y, Liu L, Curtiss E, Steinle JJ. Epac1 blocks NLRP3 inflammasome to reduce IL-1beta in retinal endothelial cells and mouse retinal vasculature. Mediators Inflamm. 2017; 2017 2860956.Google Scholar
- 7.Chen C, Du J, Feng W, et al. beta-Adrenergic receptors stimulate interleukin-6 production through Epac-dependent activation of PKCdelta/p38 MAPK signalling in neonatal mouse cardiac fibroblasts. Br J Pharmacol. 2012; 166:676–88.Google Scholar
- 8.Wu H, Chen Z, Xie J, et al. High mobility group box-1: a missing link between diabetes and its complications. Mediators Inflamm. 2016; 3896147.Google Scholar
- 9.Sun X, Zeng H, Wang Q, et al. Glycyrrhizin ameliorates inflammatory pain by inhibiting microglial activation-mediated inflammatory response via blockage of the HMGB1-TLR4-NF-kB pathway. Exp Cell Res. 2018.Google Scholar
- 10.Abu El-Asrar AM, Siddiquei MM, Nawaz MI, Geboes K, Mohammad G. The proinflammatory cytokine high-mobility group box-1 mediates retinal neuropathy induced by diabetes. Mediators Inflamm. 2014; 2014 746415.Google Scholar
- 15.Cho JH, Lee YK, Chae CB. The modulation of the biological activities of mitochondrial histone Abf2p by yeast PKA and its possible role in the regulation of mitochondrial DNA content during glucose repression. Biochimica et biophysica acta. 2001; 1522:175–86.Google Scholar
- 24.Ha YM, Ham SA, Kim YM, et al. beta(1)-adrenergic receptor-mediated HO-1 induction, via PI3K and p38 MAPK, by isoproterenol in RAW 264.7 cells leads to inhibition of HMGB1 release in LPS-activated RAW 264.7 cells and increases in survival rate of CLP-induced septic mice. Biochem Pharmacol. 2011; 82:769–77.CrossRefGoogle Scholar