SIRT6 regulated nucleosomal occupancy affects Hexokinase 2 expression

To understand the molecular association between inflammation and dysregulated metabolism in glioblastoma, the effect of IL-1 beta on Hexokinase 2 (HK2) expression was investigated. IL-1 beta induced HK2 expression was accompanied by heightened SIRT6 and MZF1 levels. IL-1 beta mediated overall decrease in chromatin compactness on HK2 promoter involved diminished nucleosomal occupancy around the most labile region bearing MZF1 sites. Importantly, SIRT6 and MZF1 served as negative regulators of HK2. Ectopic SIRT6 induced formation and recruitment of MZF1-SIRT6 complex to MZF1 site was concomitant with increased nucleosomal occupancy. The function of SIRT6 as co-repressor of MZF1 was inconspicuous in cells treated with IL-1 beta alone, as IL-1 beta-induced HIF-1 alpha prevented SIRT6 availability for interaction with MZF1. Taken together, SIRT6 over-expression establishes a condition whereby reconfiguration of the HK2 promoter chromatin structure makes it receptive to interaction with MZF1/SIRT6 complex, thereby favouring a regulatory state conducive to diminished transcription.