Synaptotagmins family affect glucose transport in retinal pigment epithelial cells through their ubiquitination-mediated degradation and glucose transporter-1 regulation

Figure 3 Ca²⁺ signaling is required for the increased glucose uptake by ARPE-19 cells in high glucose conditions. A: A Cell Counting Kit-8 assay was used to determine cell viability; B: Flow cytometry was used to determine apoptosis; C: Intracellular Ca²⁺ levels were determined by flow cytometry; D: The Ca²⁺ signaling pathway-related proteins CAMK4 and p-CREB were detected via Western blot; E: The glucose transporter was detected via Western blot; F: The membrane translocation of GlUT1 was examined by immunofluorescence analysis; G: ELISA was used to measure the levels of inflammatory factors [tumour necrosis factor alpha, interleukin (IL)-1β, and IL-6]; H: ELISA was used to measure the level of glucose uptake. ^aP < 0.001, vs the NC group; ^bP < 0.01, ^cP < 0.01, ^dP < 0.001 vs the HG group. GLUT1: Glucose transporter-1; TNF-α: Tumour necrosis factor alpha; IL: Interleukin.