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bioRxiv · 10.1101/2024.03.11.583535

Small molecule modulation of insulin receptor-insulin like growth factor-1 receptor heterodimers in human endothelial cells

Myers, C. G.·Viswambharan, H.·Haywood, N.·Bridge, K.·Turvey, S. J.·Armstrong, T.·Lunn, L.·Meakin, P. J.·Clavane, E. M.·Beech, D. J.·Cubbon, R. M.·Wheatcroft, S. B.·McPhillie, M. J.·Issad, T.·Fishwick, C. W.·Kearney, M. T.·Simmons, K. J.
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Abstract

ObjectivesThe insulin receptor (IR) and insulin like growth factor-1 receptor (IGF-1R) are heterodimers consisting of two extracellular -subunits and two transmembrane {beta} -subunits. Insulin {beta} and insulin like growth factor-1 {beta} hemi-receptors can heterodimerize to form hybrids composed of one IR {beta} and one IGF-1R {beta}. The function of hybrids in the endothelium is unclear. We sought insight by developing a small molecule capable of reducing hybrid formation in endothelial cells. MethodsWe performed a high-throughput small molecule screening, based on a homology model of hybrid structure. Endothelial cells were studied using western blotting and qPCR to determine the effects of small molecules that reduced hybrid formation. ResultsOur studies unveil a first-in-class quinoline-containing heterocyclic small molecule that reduces hybrids by >50% in human umbilical vein endothelial cells (HUVECs) with no effects on insulin or insulin like growth factor-1 receptors. This small molecule reduced expression of the negative regulatory p85 subunit of phosphatidylinositol 3-kinase, increased basal phosphorylation of the downstream target Akt and enhanced insulin/insulin-like growth factor-1 and shear stress-induced serine phosphorylation of Akt. In primary saphenous vein endothelial cells (SVEC) from patients with type 2 diabetes mellitus undergoing coronary artery bypass (CABG) surgery, hybrid receptor expression was greater than in patients without type 2 diabetes mellitus. The small molecule significantly reduced hybrid expression in SVEC from patients with type 2 diabetes mellitus. ConclusionsWe identified a small molecule that decreases the formation of IR: IGF-1R hybrid receptors in human endothelial cells, without significant impact on the overall expression of IR or IGF-1R. In HUVECs, reduction of IR: IGF-1R hybrid receptors leads to an increase in insulin-induced serine phosphorylation of the critical downstream signalling kinase, Akt. The underpinning mechanism appears, at least in part to involve the attenuation of the adverse effect of IR: IGF-1R hybrid receptors on PI3-kinase signalling. HighlightsO_LIWe have discovered a small molecule (HI) that inhibits insulin receptor/IGF-1 receptor hybrid formation. C_LIO_LIHI reveals previously unrecognised actions of insulin receptor/IGF-1 receptor hybrids distinct to insulin and IGF-1 receptors in endothelial cells. C_LIO_LITreatment of endothelial cells with HI enhances activity of the downstream signalling kinase Akt due to inhibitory regulation via PI3-K. C_LI

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Myers, C. G., Viswambharan, H., Haywood, N., Bridge, K., Turvey, S. J., Armstrong, T., Lunn, L., Meakin, P. J., Clavane, E. M., Beech, D. J., Cubbon, R. M., Wheatcroft, S. B., McPhillie, M. J., Issad, T., Fishwick, C. W., Kearney, M. T., Simmons, K. J.. 2024-03-12. Small molecule modulation of insulin receptor-insulin like growth factor-1 receptor heterodimers in human endothelial cells. https://doi.org/10.1101/2024.03.11.583535

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