Insulin Receptors and Downstream Substrates Associate with Membrane Microdomains after Treatment with Insulin or Chromium(III) Picolinate

Abstract

We have examined the association of insulin receptors (IR) and downstream signaling molecules with membrane microdomains in rat basophilic leukemia (RBL-2H3) cells following treatment with insulin or tris(2-pyridinecarbxylato)chromium(III) (Cr(pic)(3)). Single-particle tracking demonstrated that individual IR on these cells exhibited reduced lateral diffusion and increased confinement within 100 nm-scale membrane compartments after treatment with either 200 nM insulin or 10 μM Cr(pic)(3). These treatments also increased the association of native IR, phosphorylated insulin receptor substrate 1 and phosphorylated AKT with detergent-resistant membrane microdomains of characteristically high buoyancy. Confocal fluorescence microscopic imaging of Di-4-ANEPPDHQ labeled RBL-2H3 cells also showed that plasma membrane lipid order decreased following treatment with Cr(pic)(3) but was not altered by insulin treatment. Fluorescence correlation spectroscopy demonstrated that Cr(pic)(3) did not affect IR cell-surface density or compete with insulin for available binding sites. Finally, Fourier transform infrared spectroscopy indicated that Cr(pic)(3) likely associates with the lipid interface in reverse-micelle model membranes. Taken together, these results suggest that activation of IR signaling in a cellular model system by both insulin and Cr(pic)(3) involves retention of IR in specialized nanometer-scale membrane microdomains but that the insulin-like effects of Cr(pic)(3) are due to changes in membrane lipid order rather than to direct interactions with IR.

Overlapped Metabolic and Therapeutic Links between Alzheimer and Diabetes

“…Insulin performs its duty by binding to its specific receptors known as insulin receptors (IR). Insulin binds to the α-subunit of the receptor and activates the tyrosine phosphorylation of β-subunit of the receptor [80,81]. This process activates two important signaling pathways: Akt (also known as protein kinase B [PKB]) and MAPK (mitogen activated protein kinase) [82,83].…”

Effects of Estradiol Alone and Estradiol combined with Trivalent Chromium on Bone Metabolism in Ovariohysterectomized Rats

“…This suggests that trivalent chromium can modify the metabolism, but not the regulation, of estradiol. This effect may be mediated by insulin, an inhibitor of PTH function (Iida-Klein and Hahn, 1991), the level of which was increased by E2 and decreased by chromium (Al-Qatati, et al, 2012;Tiano, et al, 2015).…”

“…These seemingly contradictory results can be explained by the similar mechanisms of action of estradiol and chromium in regulating energy metabolism; the two probably affect the same pathway. E2 can enhance pancreatic β-cell function and stimulate insulin synthesis by acting on estrogen receptors (Tiano, et al, 2015), and Cr 3+ can regulate carbohydrate metabolism by increasing insulin sensitivity (Al-Qatati et al, 2012). Both of them affect lipid metabolism and can prevent weight gain (Kuryl and Debski, 2008).…”

Raft localization of Type I Fcε receptor and degranulation of RBL-2H3 cells exposed to decavanadate, a structural model for V2O5

“…2), shown previously to alter lipid packing in RBL-2H3 cells. 25,26 RBL-2H3 cells were pre-treated for 1 h at 37 °C with 0.5 nM DNP-specific A2-IgE, an antibody which binds FcεRI on RBL-2H3 cells via the A2-IgE Fc region. Cells were incubated with 10 μM Cr( pic) 3 , 2 μM BMOV or 2 μM V 10 corresponding to 20 μM V-atoms for 45 min at room temperature and FcεRI was then crosslinked using 100 nM DNP 18 -BSA, a polymeric antigen that binds antigen binding sites on A2-IgE.…”