The inhibitor of growth (ING) gene family proteins regulate many critical cellular processes such as cell proliferation and growth, apoptosis, DNA repair, senescence, angiogenesis, and drug resistance. Their transcripts and proteins are differentially expressed in health and disease and there is evidence for developmental regulation. The vast majority of studies have characterized ING levels in the context of cancer. However, relatively little attention has been paid to the expression of ING family members in other contexts. This review summarizes the findings from human and animal model systems that provide insight into the factors influencing the expression of these important proteins. We examine the influence of cell cycle and aging as well as genotoxic stress on ING expression levels and evaluate several emerging areas of inquiry demonstrating that ING gene activity may be modulated by factors such as the p53 tumor suppressor, DNA methylation, and ING proteins themselves with external factors such as hormones, reactive oxygen species, TGFβ signalling, and other proteins of pathological significance also influencing ING levels. We then briefly discuss the influence of posttranslational modification and changes in subcellular localization as it pertains to modulation of ING expression. Understanding how ING expression is modulated represents a vital aspect of effective drug targeting strategies.
Keywords: ING1, ING2, ING3, ING4, ING5, transcript variant, regulation, protein
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