The dynamic clustering of insulin receptor underlies its signaling and is disrupted in insulin resistance

Abstract

Insulin receptor (IR) signaling is central to normal metabolic control and is dysregulated in metabolic diseases such as type 2 diabetes. We report here that IR is incorporated into dynamic clusters at the plasma membrane, in the cytoplasm and in the nucleus of human hepatocytes and adipocytes. Insulin stimulation promotes further incorporation of IR into these dynamic clusters in insulin-sensitive cells but not in insulin-resistant cells, where both IR accumulation and dynamic behavior are reduced. Treatment of insulin-resistant cells with metformin, a first-line drug used to treat type 2 diabetes, can rescue IR accumulation and the dynamic behavior of these clusters. This rescue is associated with metformin’s role in reducing reactive oxygen species that interfere with normal dynamics. These results indicate that changes in the physico-mechanical features of IR clusters contribute to insulin resistance and have implications for improved therapeutic approaches.

Influence of metabolic stress and metformin on synaptic protein profile in SH‐SY5Y‐derived neurons

“…Synaptophysin (Cell Signaling #5461 (Wu et al., 2018)), NeuN (Cell Signaling #24307 (Tang et al., 2021)), PSD‐95 (post‐synaptic marker, Cell Signaling #36233 (Shui et al., 2022)), Homer‐1 (post‐synaptic marker, SC‐136358 (Wang et al., 2014)), SNAP‐25 (Cell signaling #5308 (Polishchuk et al., 2023)), VAMP2 (Cell signaling #13508 (Arrojo et al., 2019)) were measured as synaptic and neuronal markers. Total IR α (Cell signaling #74118 (Dall'Agnese et al., 2022)), total IR β (Cell signaling #23413 (Dall'Agnese et al., 2022)), IRS1 S636 (Cell signaling #2388 (Uddin et al., 2019)), total IRS1 (Cell signaling #2390 (Tang et al., 2019)), mTOR S2448 (Cell signaling #2971 (Luo et al., 2022)), total mTOR (Cell signaling #2972 (Luo et al., 2022)), Akt T308 (Cell signaling #9275 (Mathieu et al., 2019)), Akt S473 (Cell signaling #4058 (Marko et al., 2020)), and total Akt (Cell signaling #4685 (Marko et al., 2020)) were measured as markers of insulin signaling. Ponceau S, α ‐tubulin (Cell signaling #2144 (Mertins et al., 2021)), GAPDH (Abcam ab8245 (Luo et al., 2023)) or β ‐Actin (Abcam ab8227 (Moll et al., 2023)) were utilized as loading controls.…”

Targeting PI3K/AKT signaling pathway in obesity

“…Downstream signals of PI3K are mediated by multiple serine/threonine (Ser/Thr) kinases, including phosphoinositide-dependent protein kinase 1 (PDK1), AKT, mammalian target of rapamycin complex (mTORC), protein kinase C (PKC), ribosomal protein S6 kinase (S6K), AKT substrate of 160 kDa (AS160) and glycogen synthase kinase 3 (GSK3), which regulate the activity of various transcriptional factors, such as Forkhead box protein O1 (FOXO1), peroxisome proliferator-activated receptors (PPARs), PPARγ coactivator-1 alpha (PGC1α), and sterol regulatory element-binding proteins (SREBPs). These promote the metabolic actions of insulin on glucose, lipid, and mitochondrial metabolism, as well as effects on cell proliferation, differentiation, growth and apoptosis [30][31][32][33][34][35][36][37].…”

“…The expansion of fat stores in obesity is often associated with a lowgrade inflammation, caused by the infiltration of pro-inflammatory immune cells [77][78][79], and elevated non-esterified fatty acids serum levels, which both contribute to the development of IR. The FFA-mediated IR involves the activation of the Toll-like receptor 4/nuclear factor kappa B (NFκB) pathway [80], while inhibition of the signaling downstream of the insulin receptor is the primary mechanism of inflammatory IR development [35,79]. The elevated oxidative stress present in obesity is disrupting the insulin receptor clustering that is another mechanism decreasing the insulin sensitivity in adipose and hepatic tissues [35].…”

“…The FFA-mediated IR involves the activation of the Toll-like receptor 4/nuclear factor kappa B (NFκB) pathway [80], while inhibition of the signaling downstream of the insulin receptor is the primary mechanism of inflammatory IR development [35,79]. The elevated oxidative stress present in obesity is disrupting the insulin receptor clustering that is another mechanism decreasing the insulin sensitivity in adipose and hepatic tissues [35]. Notably, activation of multiple Ser/Thr kinases by inflammatory or stress stimuli is likely involved in the blockade of PI3K signaling downstream the insulin receptor [81].…”

Multi-layered proteomics identifies insulin-induced upregulation of the EphA2 receptor via the ERK pathway and dependent on low IGF1R level

“…Hepatic insulin resistance primarily impairs PI3K-AKT signaling [2]. The relationship between IR levels and insulin resistance is unclear, with some studies reporting reduced IR levels in insulin-resistant states [13]- [16] and others observing no significant differences between insulin-sensitive and insulin-resistant groups [17], [18]. Studies have shown that changes in subcellular localization of IR may play a role in hepatic insulin resistance [17].…”