Reversal of mitochondrial defects with CSB-dependent serine protease inhibitors in patient cells of the progeroid Cockayne syndrome

Abstract

UV-sensitive syndrome (UV S S) and Cockayne syndrome (CS) are human disorders caused by CSA or CSB gene mutations; both conditions cause defective transcription-coupled repair and photosensitivity. Patients with CS also display neurological and developmental abnormalities and dramatic premature aging, and their cells are hypersensitive to oxidative stress. We report CSA/CSB-dependent depletion of the mitochondrial DNA polymerase-γ catalytic subunit (POLG1), due to HTRA3 serine protease accumulation in CS, but not in UV s S or control fibroblasts. Inhibition of serine proteases restored physiological POLG1 levels in either CS fibroblasts and in CSB-silenced cells. Moreover, patient-derived CS cells displayed greater nitroso-redox imbalance than UV S S cells. Scavengers of reactive oxygen species and peroxynitrite normalized HTRA3 and POLG1 levels in CS cells, and notably, increased mitochondrial oxidative phosphorylation, which was altered in CS cells. These data reveal critical deregulation of proteases potentially linked to progeroid phenotypes in CS, and our results suggest rescue strategies as a therapeutic option.Cockayne syndrome | premature ageing | serine protease | DNA polymerase gamma | mtSSB

Cockayne syndrome group A and B proteins converge on transcription-linked resolution of non-B DNA

“…Interestingly, the observed mitochondrial changes with increased mitochondrial membrane potential and oxygen consumption suggest that the changes are not caused by primary mitochondrial dysfunction but rather by a secondary compensatory response due to nuclear changes, as proposed previously (35,36). This is in agreement with a number of previous studies showing similar mitochondrial changes as a response to nuclear DNA damage whereas studies in nonisogenic cell lines in the context of Cockayne syndrome have been inconclusive (7,10,(37)(38)(39)(40)(41). Notably, G4-forming DNA sequences, which are abundant in rDNA, appear to be potent obstacles to transcription in CSA-or CSB-deficient cells, and these structures activate PARP1 in vitro and in vivo.…”

“…The disease is caused by mutations in either the ERCC8 (CSA) or ERCC6 (CSB) genes, which encode proteins that are thought to be involved in DNA repair, transcription, and chromatin remodeling (3)(4)(5). Recent work has demonstrated mitochondrial dysfunction in cell and animal models deficient in CSB (6)(7)(8)(9)(10). The disease mechanism may involve persistent activation of a DNA damage response orchestrated by the enzyme poly-ADP ribosepolymerase 1 (PARP1) leading to loss of NAD + and increased lactate production (8,11), features that are also observed in normal aging (12)(13)(14).…”

How Research on Human Progeroid and Antigeroid Syndromes Can Contribute to the Longevity Dividend Initiative

“…Oxidative stress and mitochondrial dysfunction have also been associated with the Cockayne syndrome and have been shown to be related to depletion of the catalytic subunit of DNA polymerase gamma, the enzyme responsible for replicating mitochondrial DNA. That depletion was associated with the accumulation of a serine protease; of great potential therapeutic significance, the phenotype could be reversed by a serine protease inhibitor (Chatre et al 2015). …”

DNA repair deficiency sensitizes lung cancer cells to NAD+ biosynthesis blockade

“…DNA repair deficiency sensitizes lung cancer cells to NAD + biosynthesis blockade Mehdi Touat, 1,2,3 Tony Sourisseau, 1 Nicolas Dorvault, 1,4 Roman M. Chabanon, 1,4 Marlène Garrido, 1,4 Daphné Morel, 1,4 Dragomir B. Krastev, 5 Ludovic Bigot, 1 Julien Adam, 1,6 Jessica R. Frankum, 5 Sylvère Durand, 7 Clement Pontoizeau, 8,9,10 Sylvie Souquère, 11 Mei-Shiue Kuo, 1 Sylvie Sauvaigo, 12 Faraz Mardakheh, 13 Alain Sarasin, 14 Ken A. Olaussen, 1,15 Luc Friboulet, 1 Frédéric Bouillaud, 16 Gérard Pierron, 11 Alan Ashworth, 17 Anne Lombès, 16 Christopher J. Lord,5 Jean-Charles Soria, 1,2,15 and Sophie Postel-Vinay (8,9).…”

“…PARP1, whose activation catabolizes a significant amount of NAD + (7,12), is the most abundant nuclear protein of the PARP family and serves as sensor to DNA damage (6). Deciphering and exploiting interactions between these 2 hallmarks of cancer -namely DNA ery could contribute to alterations in mitochondrial function and energy metabolism (7)(8)(9)(10)(11). Mouse models of xeroderma pigmentosum group A (XPA) and Cockayne syndrome group B (CSB) display aberrant activation of the DNA repair enzymes PARPs with concomitant depletion of nicotinamide adenine dinucleotide (NAD + ) and mitochondrial dysfunction, which can be partly rescued by Figure 1.…”