Structural and functional basis of inositol hexaphosphate stimulation of NHEJ through stabilization of Ku-XLF interaction.

The classical Non-Homologous End Joining (c-NHEJ) pathway is the predominant process in mammals for repairing endogenous, accidental or programmed DNA Double-Strand Breaks. c-NHEJ is regulated by several accessory factors, post-translational modifications, endogenous chemical agents and metabolites. The metabolite inositol-hexaphosphate (IP6) stimulates c-NHEJ by interacting with the Ku70-Ku80 heterodimer (Ku).

Pre-RNA splicing in metabolic homeostasis and liver disease.

The liver plays a key role in sensing nutritional and hormonal inputs to maintain metabolic homeostasis. Recent studies into pre-mRNA splicing and alternative splicing (AS) and their effects on gene expression have revealed considerable transcriptional complexity in the liver, both in health and disease. While the contribution of these mechanisms to cell and tissue identity is widely accepted, their role in physiological and pathological contexts within tissues is just beginning to be appreciated.

Cryo-EM structure of a DNA-PK trimer: higher order oligomerisation in NHEJ.

The ability of humans to maintain the integrity of the genome is imperative for cellular survival. DNA double-strand breaks (DSBs) are considered the most critical type of DNA lesion, which can ultimately lead to diseases including cancer. Non-homologous end joining (NHEJ) is one of two core mechanisms utilized to repair DSBs.

PAXX binding to the NHEJ machinery explains functional redundancy with XLF.

Nonhomologous end joining is a critical mechanism that repairs DNA double-strand breaks in human cells. In this work, we address the structural and functional role of the accessory protein PAXX [paralog of x-ray repair cross-complementing protein 4 (XRCC4) and XRCC4-like factor (XLF)] in this mechanism. Here, we report high-resolution cryo-electron microscopy (cryo-EM) and x-ray crystallography structures of the PAXX C-terminal Ku-binding motif bound to Ku70/80 and cryo-EM structures of PAXX bound to two alternate DNA-dependent protein kinase (DNA-PK) end-bridging dimers, mediated by either Ku80 or XLF.

Cryo-EM of NHEJ supercomplexes provides insights into DNA repair.

Non-homologous end joining (NHEJ) is one of two critical mechanisms utilized in humans to repair DNA double-strand breaks (DSBs). Unrepaired or incorrect repair of DSBs can lead to apoptosis or cancer. NHEJ involves several proteins, including the Ku70/80 heterodimer, DNA-dependent protein kinase catalytic subunit (DNA-PKcs), X-ray cross-complementing protein 4 (XRCC4), XRCC4-like factor (XLF), and ligase IV.

Stages, scaffolds and strings in the spatial organisation of non-homologous end joining: Insights from X-ray diffraction and Cryo-EM.

Non-homologous end joining (NHEJ) is the preferred pathway for the repair of DNA double-strand breaks in humans. Here we describe three structural aspects of the repair pathway: stages, scaffolds and strings. We discuss the orchestration of DNA repair to guarantee robust and efficient NHEJ.

Dimers of DNA-PK create a stage for DNA double-strand break repair.

DNA double-strand breaks are the most dangerous type of DNA damage and, if not repaired correctly, can lead to cancer. In humans, Ku70/80 recognizes DNA broken ends and recruits the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to form DNA-dependent protein kinase holoenzyme (DNA-PK) in the process of non-homologous end joining (NHEJ). We present a 2.

Druggable binding sites in the multicomponent assemblies that characterise DNA double-strand-break repair through non-homologous end joining.

Non-homologous end joining (NHEJ) is one of the two principal damage repair pathways for DNA double-strand breaks in cells. In this review, we give a brief overview of the system including a discussion of the effects of deregulation of NHEJ components in carcinogenesis and resistance to cancer therapy. We then discuss the relevance of targeting NHEJ components pharmacologically as a potential cancer therapy and review previous approaches to orthosteric regulation of NHEJ factors.