Liao, L.-D. | Search bioRxiv

bioRxiv2023

CHAF1A promotes the translesion DNA synthesis pathway in response to DNA replication stress

The translesion DNA synthesis (TLS) pathway mediated by proliferating cell nuclear antigen (PCNA) monoubiquitination is an essential mechanism by which cancer cells bypass DNA damage caused by DNA replication stress to maintain genomic stability and cell survival. Chromatin assembly factor 1 subunit A (CHAF1A) traditionally promotes histone assembly during DNA replication. Here, we revealed that CHAF1A is a novel regulator of the TLS pathway. High expression of CHAF1A is significantly associated with poor prognosis in cancer patients. CHAF1A promotes fork restart under DNA replication stress and maintains genome integrity. CHAF1A enhances the interaction between PCNA and E3 ubiquitin protein ligase RAD18 and promotes PCNA monoubiquitination, thereby promoting the recruitment of Y-family DNA polymerase Pol {eta} and enhancing cancer cell resistance to stimuli that trigger replication fork blockade. Mechanistically, CHAF1A-mediated PCNA monoubiquitination is independent of CHAF1A-PCNA interaction. CHAF1A interacts with both RAD18 and replication protein A2 (RPA2), mediating RAD18 binding on chromatin in response to DNA replication stress. Taken together, these findings improve our understanding of the mechanisms that regulate the TLS pathway and provide insights into the relationship between CHAF1A and the malignant progression of cancers.

cell biology↗

bioRxiv2022

LOXL2-dependent deacetylation of aldolase A induces metabolic reprogramming and tumor progression

Lysyl-oxidase like-2 (LOXL2) regulates extracellular matrix remodeling and promotes tumor invasion and metastasis. Altered metabolism is a core hallmark of cancer, however, it remains unclear whether and how LOXL2 contributes to tumor metabolism. Here, we found that LOXL2 and its catalytically inactive L2{Delta}13 splice variant also function as novel deacetylases that trigger metabolic reprogramming during malignant transformation. Integrated transcriptomic and metabolomic analysis revealed that L2{Delta}13-overexpressing transgenic mice displayed perturbed glucose and lipid metabolism, which was associated with increased hepatic fibrosis and enhanced formation of precancerous lesions induced by chemical carcinogens, such as carbon tetrachloride and N-nitrosomethylbenzylamine. Furthermore, both LOXL2 and L2{Delta}13 boosted glucose metabolism of esophageal tumor cells, thereby facilitating tumor cell proliferation in vitro and in vivo. Mechanistically, LOXL2 and L2{Delta}13 interacted physically with several glycolic proteins including aldolase A to enhance their enzymatic activities and mobilization from the actin cytoskeleton. Using SILAC followed by proteomic analysis, we identified LOXL2 as a deacetylase targeting metabolic proteins in esophageal cancer. Importantly, both LOXL2 and L2{Delta}13 directly catalyzed the deacetylation of aldolase A at K13, resulting in enhanced glycolysis which subsequently reprogramed tumor metabolism and promoted tumor progression. High level expression of LOXL2/L2{Delta}13 combined with decreased acetylation of aldolase-K13 predicted poor clinical outcome in patients with esophageal cancer. In summary, we have characterized a novel molecular mechanism that mediates the pro-tumorigenic activity of LOXL2 independently of its classical amine oxidase activity. These findings may enable the future development of therapeutic agents targeting the metabolic machinery via LOXL2 or L2{Delta}13.

cell biology↗