Project description:Description Somatic mutation rates are inversely correlated with life span in mouse, guinea pig, blind mole-rat, naked mole-rat, and humans. DNA mutations in somatic cells have been implicated in the causation of aging, with longer-lived species having a higher capacity to maintain genome sequence integrity than shorter-lived species. In an attempt to directly test this hypothesis, we used single-cell whole-genome sequencing to analyze spontaneous and bleomycin-induced somatic mutations in lung fibroblasts of four rodent species with distinct maximum life spans, including mouse, guinea pig, blind mole-rat, and naked mole-rat, as well as humans. As predicted, the mutagen-induced mutation frequencies inversely correlated with species-specific maximum life span, with the greatest difference observed between the mouse and all other species. These results suggest that long-lived species are capable of processing DNA damage in a more accurate way than short-lived species.
| S-EPMC8550225 | biostudies-literature
Project description:Maintenance of genome sequence integrity in long and short-lived rodent species.
Project description:Rapid protein degradation enables cells to quickly modulate protein abundance in response to stimuli. Previous studies have generally sought to delineate basic features of proteome turnover. A focused map of short-lived proteins, however, remains a missing piece of the human proteome. To begin to address this, we combined cycloheximide chase assays with advanced high-throughput quantitative proteomics to map short-lived proteins in four genetically distinct human cell lines. Apparent half-lives of ≤ 8 hr were measured for 1,017 proteins. Systematic analyses revealed general properties of short-lived proteins (e.g., enriched in substrate recognition subunits of E3 ubiquitin ligase complexes, thermally instable, evolutionarily younger). We further quantified 103 proteins with widely different stabilities among cell lines. Of these, we show that truncated forms of ATRX and GMDS were expressed in U2OS and HCT116 cells, respectively, which had shorter half-lives than their full-length counterparts. This study provides a large-scale resource of human short-lived proteins in cultured cells, leading to untapped avenues of protein regulation for therapeutic intervention.
Project description:CD8 effector T cells with a CD127hi KLRG1- phenotype are considered precursors to the long-lived memory pool, while KLRG1+ CD127low cells are viewed as short-lived effectors. Nevertheless, we and others have shown that a KLRG1+ CD127low population persists into the memory phase and that these T cells (termed long-lived effector cells or LLEC) display robust protective function during acute re-challenge with bacteria or viruses. Whether these T cells represent a true memory population or are instead a remnant effector cell population that failed to undergo initial contraction has remained unclear. Here, we show that LLEC from mice express a distinct phenotypic and transcriptional signature that shares characteristics of both early effectors and long-lived memory cells. Furthermore, we find that LLEC are exclusively derived from day 12 KLRG1+ effector cells. Our work challenges the concept that the KLRG1+ CD127low population is dominated by short-lived cells and shows that KLRG1 downregulation is not a prerequisite to become a long-lived protective memory T cell.
Project description:Chronic infections such as HIV, tuberculosis and malaria in humans are associated with the appearance of atypical memory B cells in peripheral blood. It has been suggested that these B cells do not function normally as memory cells, and thus may be responsible for poor acquisition of immunity and maintenance of chronic infections. Studies on these cells in human infections are limited by the lack of accessibility to lymphoid organs, and relevant mouse models would be valuable to investigate their development, functional capacities, and role. To investigate Plasmodium-specific memory B-cell responses during malaria, we generated an immunoglobin heavy chain knock-in mouse with a B-cell receptor that recognizes the merozoite surface protein (MSP)-1 of the rodent malaria parasite, Plasmodium chabaudi. Using this mouse and a P. chabaudi infection initiated by infected mosquito bites we show that antigen-specific B cells with many characteristics of human atypical memory B cells are generated. These cells are immunoglobulin class-switched and express, among others, the cell surface molecules CD11c, CD11b, FCRL5, and some inhibitory receptors including PD1 and LAIR-1, as well as the transcription factor T-bet. Antigen-specific atypical memory B cells are detected side-by-side with classical memory B cells during chronic blood-stage infection. Whereas classical memory B cells persist after complete infection clearance, atypical memory B cells are short-lived and disappear from the spleen at the resolution of chronic infection. Short-lived Plasmodium-specific atypical B cells also appear transiently after immunization with a TLR7/8 ligand and MSP-1. Our data suggest that these atypical memory B cells are not a subset of memory B cells, but rather antigen-experienced activated cells, and part of a normal ongoing response. Their persistence over weeks in malaria and other infections may be a consequence of continued and chronic antigenic stimulation.
Project description:Targeted proTargeted protein degradation has recently emerged as a novel option in drug discovery. Natural protein half-life is expected to affect the efficacy of degrading agents, but it has not been systematically explored to what extent it influences target protein degradation. Using mathematical modelling of protein degradation, we demonstrate that the natural half-life of a target protein has a dramatic effect on the level of protein degradation induced by a PROTAC which can pose significant hurdles to screening efforts. Moreover, we show that upon screening for degraders of short-lived proteins, agents that stall protein synthesis, such as GSPT1 degraders and generally cytotoxic compounds, deceptively appear as protein degrading agents. This is exemplified by the disappearance of short-lived proteins such as MCL1 and MDM2 upon GSPT1 degradation and upon treatment with cytotoxic agents such as doxorubicin. These findings have implications for target selection as well as for the type of control experiments required before concluding that a novel agent works as a bone-fide targeted protein degrader. tein degradation has recently emerged as a novel option in drug discovery. Natural protein half-life is expected to affect the efficacy of degrading agents, but it has not been systematically explored to what extent it influences target protein degradation. Using mathematical modelling of protein degradation, we demonstrate that the natural half-life of a target protein has a dramatic effect on the level of protein degradation induced by a PROTAC which can pose significant hurdles to screening efforts. Moreover, we show that upon screening for degraders of short-lived proteins, agents that stall protein synthesis, such as GSPT1 degraders and generally cytotoxic compounds, deceptively appear as protein degrading agents. This is exemplified by the disappearance of short-lived proteins such as MCL1 and MDM2 upon GSPT1 degradation and upon treatment with cytotoxic agents such as doxorubicin. These findings have implications for target selection as well as for the type of control experiments required before concluding that a novel agent works as a bone-fide targeted protein degrader.