The integrity of genome is a prerequisite for healthy life. Indeed, defects in DNA repair have been associated with several human diseases, including tissue-fibrosis, neurodegeneration and cancer. Despite decades of extensive research, the spatio-mechanical processes of double-strand break (DSB)-repair, especially the auxiliary factor(s) that can stimulate accurate and timely repair, have remained elusive. Here, we report an ATM-kinase dependent, unforeseen function of the nuclear isoform of the Receptor for Advanced Glycation End-products (nRAGE) in DSB-repair. RAGE is phosphorylated at Serine376 and Serine389 by the ATM kinase and is recruited to the site of DNA-DSBs via an early DNA damage response. nRAGE preferentially co-localized with the MRE11 nuclease subunit of the MRN complex and orchestrates its nucleolytic activity to the ATR kinase signaling. This promotes efficient RPA2S4-S8 and CHK1S345 phosphorylation and thereby prevents cellular senescence, IPF and carcinoma formation. Accordingly, loss of RAGE causatively linked to perpetual DSBs signaling, cellular senescence and fibrosis. Importantly, in a mouse model of idiopathic pulmonary fibrosis (RAGE−/−), reconstitution of RAGE efficiently restored DSB-repair and reversed pathological anomalies. Collectively, this study identifies nRAGE as a master regulator of DSB-repair, the absence of which orchestrates persistent DSB signaling to senescence, tissue-fibrosis and oncogenesis.
The clinical symptoms of diabetic neuropathy (DN) manifest in a time dependent manner as a positive symptoms (i. e. pain, hypersensitivity, tingling, cramps, cold feet etc.) during its early stages and by a loss of function (i. e. loss of sensory perception, delayed wound healing etc.) predominating in the later stages. Elevated blood glucose alone cannot explain the development and progression of DN and the lowering of blood glucose is insufficient in preventing and/or reversing neuropathy in patients with type 2 diabetes. Recently it has been shown that the endogenous reactive metabolite methylglyoxal (MG) can contribute to the gain of function via post-translational modification in DN of neuronal ion channels involved in chemosensing and action potential generation in nociceptive nerve endings. Dicarbonyls, such as MG, that are elevated in diabetic patients, modify DNA as well as extra- and intracellular proteins, leading to the formation of advanced glycation endproducts (AGEs). Increased formation of AGEs leads to increased cellular stress, dysfunction and ultimately cell death. The interaction of AGE-modified proteins through cell surface receptors, such as RAGE, can lead to increased cellular activation and sustained inflammatory responses, which are the molecular hallmarks of the later, degenerative, stages of DN. The direct and indirect effects of dicarbonyls on nerves or neuronal microvascular network provides a unifying mechanism for the development and progression of DN. Targeting the accumulation of MG and/or prevention of RAGE interactions may therefore provide new, more effective, therapeutic approaches for the treatment of DN.
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