H2AX Is Required for Cell Cycle Arrest via the p53/p21 Pathway

Abstract

Phosphorylation of H2AX (␥H2AX) is an early sign of DNA damage induced by replication stalling. However, the role of H2AX in the repair of this type of DNA damage is still unclear. In this study, we used an inactivated adeno-associated virus (AAV) to induce a stalled replication fork signal and investigate the function of ␥H2AX. The cellular response to AAV provides a unique model to study ␥H2AX function, because the infection causes pannuclear H2AX phosphorylation without any signs of damage to the host genome. We found that pannuclear ␥H2AX formation is a result of ATR overactivation and diffusion but is independent of ATM. The inhibition of H2AX with RNA interference or the use of H2AX-deficient cells showed that ␥H2AX is dispensable for the formation and maintenance of DNA repair foci induced by stalled replication. However, in the absence of H2AX, the AAV-containing cells showed proteosome-dependent degradation of p21, followed by caspase-dependent mitotic catastrophe. In contrast, H2AX-proficient cells as well as H2AX-complemented H2AX؊/؊ cells reacted by increasing p21 levels and arresting the cell cycle. The results establish a new role for H2AX in the p53/p21 pathway and indicate that H2AX is required for p21-induced cell cycle arrest after replication stalling.

Glucose oscillations, more than constant high glucose, induce p53 activation and a metabolic memory in human endothelial cells

“…2c), which is involved in apoptosis [18]; p21 (Fig. 2d), involved in the regulation of growth and cellular senescence [20]; and TIGAR (Fig. 2e), involved in apoptosis and the regulation of glucose metabolism [22].…”

“…Activation of p53 triggers upregulation of genes involved in apoptosis, such as PUMA (p53 upregulated mediator of apoptosis; also known as BBC3) and PTEN (phosphatase and tensin homologue) [18,19], and in senescence, such as p21 (also known as CDKN1A) [20], and of its feedback inhibitor, murine double minute oncoprotein (MDM2) [21]. Recently, it has also been shown that p53 regulates glucose metabolism via Tp53-induced glycolysis and apoptosis regulator (TIGAR) [22] and insulin sensitivity via PTEN, the main negative regulator of phosphorylation of the serine/threonine protein kinase AKT [17].…”

HIF mediated and DNA damage independent histone H2AX phosphorylation in chronic hypoxia

“…Moreover, diffuse and pan-nuclear γ H2AX staining has been found to occur upon non-ionizing UV-C irradiation, independent of DNA-DSBs (Marti et al , 2006 ). Infection with inactivated adeno-associated virus has been shown to lead to replication fork stalling and a diffuse γ H2AX nuclear staining, which is essential for subsequent cell-cycle arrest in the absence of DNA damage (Fragkos et al , 2009 ). However, the mechanism behind this diffuse γ H2AX distribution pattern as well as its functional relevance are currently unknown.…”

The Capsid Proteins of Aleutian Mink Disease Virus Activate Caspases and Are Specifically Cleaved during Infection

“…The plate was placed in a Hoefer UVC 500 UV cross-linker (Hoefer Inc.) for UV irradiation at a dose of 720 mJ/cm 2 (25,32). To ensure that most of the cells were infected, CrFK cells were infected with the UV-inactivated virus at an MOI of 3 FFU/cell.…”