VEGFA and Hyperglycemia: In addition, the authors demonstrated that Müller glia may be a source of Sirt6-mediated control of VEGF expression in response to high glucose: cultured Müller glia upregulated VEGF expression in response to short interfering RNA (siRNA) knockdown of Sirt6, and hyperglycemia-induced VEGF upregulation was blocked by Sirt6 overexpression [13].