Biology subjects

Passos, J. F.

Publications and source records attributed to Passos, J. F..

7 recordsLinked to original sources

bioRxiv2023

A mitochondria-regulated p53-CCF circuit integrates genome integrity with inflammation

Genomic instability and inflammation are distinct hallmarks of aging, but the connection between them is poorly understood. Understanding their interrelationship will help unravel new mechanisms and therapeutic targets of aging and age-associated diseases. Here we report a novel mechanism directly linking genomic instability and inflammation in senescent cells through a mitochondria-regulated molecular circuit driven by p53 and cytoplasmic chromatin fragments (CCF). We show, through activation or inactivation of p53 by genetic and pharmacologic approaches, that p53 suppresses CCF accumulation and the downstream inflammatory senescence-associated secretory phenotype (SASP), without affecting cell cycle arrest. p53 activation suppressed CCF formation by promoting DNA repair, and this is reflected in maintenance of genomic integrity, particularly in subtelomeric regions, as shown by single cell genome resequencing. Activation of p53 in aged mice by pharmacological inhibition of MDM2 reversed signatures of aging, including age- and senescence-associated transcriptomic signatures of inflammation and age-associated accumulation of monocytes and macrophages in liver. Remarkably, mitochondria in senescent cells suppressed p53 activity by promoting CCF formation and thereby restricting ATM-dependent nuclear DNA damage signaling. These data provide evidence for a mitochondria-regulated p53 signaling circuit in senescent cells that controls DNA repair, genome integrity, and senescence- and age-associated inflammation. This pathway is immunomodulatory in mice and a potential target for healthy aging interventions by small molecules already shown to activate p53.

cell biology↗

bioRxiv2022

Inactivation of histone chaperone HIRA unmasks a link between normal embryonic development of melanoblasts and maintenance of adult melanocyte stem cells

Histone chaperone HIRA is thought to play a role in both early development and aging, but little is known about connections between the two processes. Here, we explore this relationship using a lineage-specific knockout mouse model, TyrCre::Hirafl/fl, in which HIRA is deficient in the pigmentary system consisting of embryonic melanoblasts, postnatal melanocytes and melanocyte stem cells (McSCs). Hira knockout leads to reduced melanoblast numbers during embryogenesis, but wild type numbers of melanocytes at birth, normally functioning juvenile and young adult McSCs, and only a very mildly hypopigmented first hair coat. However, on closer analysis, Hira knockout melanocytic cells of newborn mice exhibit molecular markers characteristic of cell aging and proliferative deficits. As they age, TyrCre::Hirafl/fl mice display marked defects in McSC maintenance and premature hair graying. Importantly, these defects are only observed when HIRA is inactivated during embryogenesis, not post-natally. This genetic model illustrates how normal embryonic development lays the foundation for maintenance of adult tissue specific stem cells and so suppression of degenerative phenotypes of aging.

developmental biology↗

bioRxiv2020

Cytoplasmic innate immune sensing by the caspase-4 non-canonical inflammasome promotes cellular senescence.

Cytoplasmic recognition of microbially derived lipopolysaccharides (LPS) in human cells is elicited by the inflammatory cysteine aspartic proteases caspase-4 and caspase-5, which activate non-canonical inflammasomes inducing a form of inflammatory programmed cell death termed pyroptosis. Here we show that LPS mediated activation of the non-canonical inflammasome also induces cellular senescence and the activation of tumour suppressor stress responses in human diploid fibroblasts. Interestingly, this LPS-induced senescence is dependent on caspase-4, the pyroptotic effector protein gasdermin-D and the tumour suppressor protein p53. Also, experiments with a catalytically deficient mutant suggest that caspase-4 proteolytic activity is not necessary for its role in senescence. Furthermore, we found that the caspase-4 non-canonical inflammasome is induced and assembled during Ras-mediated oncogene-induced senescence (OIS). Moreover, targeting caspase-4 in OIS showed that the non-canonical inflammasome is critical for SASP activation and contributes to reinforcing the cell cycle arrest in OIS. Finally, we observed that caspase-4 induction occurs in vivo in models of tumour suppression and ageing. Altogether, we are unveiling that cellular senescence is induced by cytoplasmic microbial LPS recognition by the caspase-4 non-canonical inflammasome and that this pathway is conserved in the senescence program induced by oncogenic stress.

cell biology↗

bioRxiv2020

Clearance of senescent cells during cardiac ischemia-reperfusion injury improves heart recovery following myocardial infarction

A key component of cardiac ischemia-reperfusion injury (IRI) is the increased generation of reactive oxygen species, leading to enhanced inflammation and tissue dysfunction in patients following intervention for myocardial infarction. In this study we hypothesized that oxidative stress, due to ischemia-reperfusion, induces senescence which contributes to the pathophysiology of cardiac IRI. We demonstrate that IRI induces cellular senescence in both cardiomyocytes and interstitial cell populations and treatment with the senolytic drug navitoclax after ischemia-reperfusion improves left ventricular function, increases myocardial vascularization, and decreases scar size. SWATH-MS based proteomics reveal that biological processes associated with fibrosis and inflammation, that were increased following ischemia-reperfusion, were attenuated upon senescent cell clearance. Furthermore, navitoclax treatment reduced the expression of proinflammatory, profibrotic and anti-angiogenic cytokines, including interferon gamma-induced protein-10, TGF-{beta}3, interleukin-11, interleukin-16 and fractalkine. Our study provides proof-of-concept evidence that cellular senescence contributes to impaired heart function and adverse remodeling following cardiac ischemia-reperfusion. We also establish that post-IRI senescent cells play a considerable role in the inflammatory response. Subsequently, senolytic treatment, at a clinically feasible time point, attenuates multiple components of this response and improves clinically important parameters. Thus, cellular senescence represents a potential novel therapeutic avenue to improve patient outcomes following cardiac ischemia-reperfusion.

cell biology↗

bioRxiv2019

Temporal inhibition of autophagy reveals segmental reversal of aging with increased cancer risk

Autophagy is an important cellular degradation pathway with a central role in metabolism as well as basic quality control, two processes inextricably linked to aging. A decrease in autophagy is associated with increasing age, yet it is unknown if this is causal in the aging process, and whether autophagy restoration can counteract these aging effects. Here we demonstrate that systemic autophagy inhibition induces the premature acquisition of age-associated phenotypes and pathologies in mammals. Remarkably, autophagy restoration provides a near complete recovery of morbidity and a significant extension of lifespan, however, at the molecular level this rescue appears incomplete. Importantly autophagy-restored mice still succumb earlier due to an increase in spontaneous tumor formation. Thus our data suggest that chronic autophagy inhibition confers an irreversible increase in cancer risk and uncovers a biphasic role of autophagy in cancer development being both tumor suppressive and oncogenic, sequentially.

cancer biology↗

bioRxiv2018

The innate immune sensor Toll-like receptor 2 controls the senescence-associated secretory phenotype.

Cellular senescence is a stress response program characterised by a robust cell cycle arrest and the induction of a pro-inflammatory senescence-associated secretory phenotype (SASP) that is triggered through an unknown mechanism. Here, we show that during oncogene-induced senescence (OIS), the Toll-like receptor TLR2 and its partner TLR10 are key mediators of senescence in vitro and in murine models. TLR2 promotes cell cycle arrest by regulating the tumour suppressors p53-p21CIP1, p16INK4a and p15INK4b, and regulates the SASP through the induction of the acute-phase serum amyloids A1 and A2 (A-SAA) that, in turn, function as the damage associated molecular patterns (DAMPs) signalling through TLR2 in OIS. Finally, we found evidence that the cGAS-STING cytosolic DNA sensing pathway primes TLR2 and A-SAA expression in OIS. In summary, we report that innate immune sensing of senescence-associated DAMPs by TLR2 controls the SASP and reinforces the cell cycle arrest program in OIS.

cell biology↗

bioRxiv2018

Length-independent telomere damage drives cardiomyocyte senescence

Ageing is the biggest risk factor for cardiovascular health and is associated with increased incidence of cardiovascular disease. Cellular senescence, a process driven in part by telomere shortening, has been implicated in age-related tissue dysfunction. Here, we address the question of how senescence is induced in rarely dividing/post-mitotic cardiomyocytes and investigate if clearance of senescent cells attenuates age related cardiac dysfunction. During ageing, human and murine cardiomyocytes acquire a senescent-like phenotype characterised by persistent DNA damage at telomere regions that can be driven by mitochondrial dysfunction, and crucially can occur independently of cell-division and telomere length. Length-independent telomere damage in cardiomyocytes activates the classical senescence-inducing pathways, p21CIP and p16INK4a and results in a non-canonical senescence-associated secretory phenotype. Pharmacological or genetic clearance of senescent cells in mice alleviates myocardial hypertrophy and fibrosis, detrimental features of cardiac ageing, and promotes cardiomyocyte regeneration. Our data describes a mechanism by which senescence can occur and contribute to ageing in post-mitotic tissues.

cell biology↗