Abstract:SummaryArf/p53 pathway protects the cells against DNA damage induced by acute stress. This characteristic is the responsible for its tumor suppressor activity. Moreover, it regulates the chronic type of stress associated with aging. This is the basis of its anti‐aging activity. Indeed, increased gene dosage of Arf/p53 displays elongated longevity and delayed aging. At a cellular level, it has been recently shown that increased dosage of Arf/p53 delays age‐associated stem cell exhaustion and the subsequent decl… Show more
Ezh2 is an histone methyltransferase (HMT) that catalyzes H3K27me3 and functions in TH1, TH2, and Treg cells primarily via HMT activity. Here we show that Ezh2 ablation impairs T follicular helper (TFH) cell differentiation and activation of the TFH transcription program. In TFH cells, most Ezh2-occupied genomic sites, including the Bcl6 promoter, are associated with H3K27ac rather than H3K27me3. Mechanistically, Ezh2 is recruited by Tcf1 to directly activate Bcl6 transcription, with this function requiring Ezh2 phosphorylation at Ser21. Meanwhile, Ezh2 deploys H3K27me3 to repress Cdkn2a expression in TFH cells, where aberrantly upregulated p19Arf, a Cdkn2a protein product, triggers TFH cell apoptosis and antagonizes Bcl6 function via protein-protein interaction. Either forced expression of Bcl6 or genetic ablation of p19Arf in Ezh2-deficient cells improves TFH cell differentiation and helper function. Thus, Ezh2 orchestrates TFH-lineage specification and function maturation by integrating phosphorylation-dependent transcriptional activation and HMT-dependent gene repression.
Ezh2 is an histone methyltransferase (HMT) that catalyzes H3K27me3 and functions in TH1, TH2, and Treg cells primarily via HMT activity. Here we show that Ezh2 ablation impairs T follicular helper (TFH) cell differentiation and activation of the TFH transcription program. In TFH cells, most Ezh2-occupied genomic sites, including the Bcl6 promoter, are associated with H3K27ac rather than H3K27me3. Mechanistically, Ezh2 is recruited by Tcf1 to directly activate Bcl6 transcription, with this function requiring Ezh2 phosphorylation at Ser21. Meanwhile, Ezh2 deploys H3K27me3 to repress Cdkn2a expression in TFH cells, where aberrantly upregulated p19Arf, a Cdkn2a protein product, triggers TFH cell apoptosis and antagonizes Bcl6 function via protein-protein interaction. Either forced expression of Bcl6 or genetic ablation of p19Arf in Ezh2-deficient cells improves TFH cell differentiation and helper function. Thus, Ezh2 orchestrates TFH-lineage specification and function maturation by integrating phosphorylation-dependent transcriptional activation and HMT-dependent gene repression.
“…Moreover, it regulates the chronic type of stress associated with aging. Indeed, decreased gene dosage of p53 displays elongated longevity and delayed aging [ 58 ]. Previous studies indicated that TERT suppression-induced DNA damage and apoptosis was in a p53-dependent way [ 59 ].…”
Catalpol, an iridoid glucoside, has been found present in large quantities in the root of Rehmannia glutinosa L. and showed a strong antioxidant capacity in the previous study. In the present work, the protective effect of catalpol against AS via inhibiting oxidative stress, DNA damage, and telomere shortening was found in LDLr−/− mice. This study also shows that activation of the peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α)/telomerase reverse transcriptase (TERT) pathway, which is the new link between mitochondria and telomere, was involved in the protective effects of catalpol. Further, by using PGC-1α or TERT siRNA in oxLDL-treated macrophages, it is proved that catalpol reduced oxidative stress, telomere function, and related DNA damage at least partly through activating the PGC-1α/TERT pathway. Moreover, dual luciferase activity assay-validated catalpol directly enhanced PGC-1α promoter activity. In conclusion, our study revealed that the PGC-1α/TERT pathway might be a possible therapeutic target in AS and catalpol has highly favorable characteristics for the treatment of AS via modulating this pathway.
“…Therefore, it seems that CYLD, like other well-known tumor suppressor proteins such as Ink4a, Arf and PTEN, acts as a tumor suppressor in a variety of malignancies. It is interesting that these other renowned tumor suppressors develop important additional roles protecting from aging [14–16]. However, the possible role of CYLD as an aging guard has not been yet investigated.…”
CYLD is a deubiquitinating enzyme known for its role as a tumor suppressor whose mutation leads to skin appendages tumors and other cancers. In this manuscript we report that the tumor suppressor CYLD, similarly to other renowned tumor suppressor genes, protects from premature aging and cancer. We have generated transgenic mice expressing the mutant CYLDC/S protein, lacking its deubiquitinase function, under the control of the keratin 5 promoter, the K5-CYLDC/S mice. These mice express the transgene in different organs, including those considered to be more susceptible to aging, such as skin and thymus. Our results show that K5-CYLDC/S mice exhibit epidermal, hair follicle, and sebaceous gland alterations; and, importantly, they show signs of premature aging from an early age. Typically, 3-month-old K5-CYLDC/S mice exhibit a phenotype characterized by alopecia and kyphosis, and, the histological examination reveals that transgenic mice show signs of accelerated aging in numerous organs such as skin, thymus, pancreas, liver and lung. Additionally, they spontaneously develop tumors of diverse origin. Over-activation of the NF-κB pathway, along with hyperactivation of Akt, JNK and c-Myc, and chronic inflammation, appear as the mechanisms responsible for the premature aging of the K5-CYLDC/S mice.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
