Project description:Heart performance declines with age. Reduced protein quality control (PQC) due to decreased function of the ubiquitin/proteasome system (UPS), autophagy, and/or chaperone-mediated protein refolding is a likely contributor to age-associated cardiac performance decline. The transcription factor FOXO participates in the regulation of genes involved PQC and a host of other processes. Here, the effect of cardiac-restricted dFOXO overexpression was investigated in Drosophila, a genetically pliable and rapidly aging model. Modest dFOXO overexpression in the heart was protective, ameliorating functional decline with age. Increased expression of genes associated predominantly with UPS relative to other PQC components accompanied dFOXO-mediated cardioprotection, which was corroborated by a significant decrease in ubiquitinated myocardial proteins. In agreement, knockdown of upregulated UPS components seemingly induced premature aging. Despite these findings, excessive dFOXO overexpression or knockdown proved detrimental to heart function and overall organismal development. This study highlights Drosophila as a model of cardiac aging and FOXO as a tightly-regulated mediator of proteostasis and heart performance over time. Two replicates of 4 different samples were analyzed. Two of these samples were controls (GMH5 x yw 1 week and GMH5 x yw 5 week).
Project description:Heart performance declines with age. Reduced protein quality control (PQC) due to decreased function of the ubiquitin/proteasome system (UPS), autophagy, and/or chaperone-mediated protein refolding is a likely contributor to age-associated cardiac performance decline. The transcription factor FOXO participates in the regulation of genes involved PQC and a host of other processes. Here, the effect of cardiac-restricted dFOXO overexpression was investigated in Drosophila, a genetically pliable and rapidly aging model. Modest dFOXO overexpression in the heart was protective, ameliorating functional decline with age. Increased expression of genes associated predominantly with UPS relative to other PQC components accompanied dFOXO-mediated cardioprotection, which was corroborated by a significant decrease in ubiquitinated myocardial proteins. In agreement, knockdown of upregulated UPS components seemingly induced premature aging. Despite these findings, excessive dFOXO overexpression or knockdown proved detrimental to heart function and overall organismal development. This study highlights Drosophila as a model of cardiac aging and FOXO as a tightly-regulated mediator of proteostasis and heart performance over time.
Project description:Increased protein misfolding and aggregation are key hallmarks of ageing and many age-related diseases. As generating and maintaining a functional proteome (proteostasis) is crucial to every cellular process, this age-related decline in proteostasis is suggested to play a primary role in the breakdown of diverse cellular subsystems during ageing. Indeed, augmented proteostasis pathways are associated with extended lifespan across different species. With the ribosome as the earliest proteostasis checkpoint, decreased protein synthesis is also a conserved mechanism that extends lifespan. Yet, it remains unclear whether ageing impacts translation after initiation. Here, we use worms and yeast to investigate how ageing influences translation elongation. We show an age-dependent increase in ribosome pausing at diverse positions in coding sequences. This pausing is conserved in both worms and yeast, particularly at Arg and polybasic regions. We further show that such pausing is associated with the age-dependent aggregation of truncated nascent proteins involved in proteostasis pathways, notably aminoacyl tRNA synthetases. Moreover, we find that impairment in clearing truncated nascent proteins is associated with decreased lifespan. These data establish elongation kinetics and co-translational quality control as critical contributors of the age-related proteostasis collapse, which may precipitate the systemic decline observed during ageing.
Project description:Skeletal muscle senescence influences whole organism aging, yet little is known on the relay of pro-longevity signals from muscles to other tissues. We performed an RNAi screen in Drosophila for muscle-released cytokines ('myokines') regulating lifespan and identified Myoglianin, the homolog of human Myostatin. Myoglianin is induced in skeletal muscles by the transcription factor Mnt and together they constitute an inter-organ signaling module that regulates lifespan, age-related muscle dysfunction, and protein synthesis across aging tissues. Both Mnt and Myoglianin activate already in young age the protective decline in protein synthesis that is typical of old age, while knock-down of Myoglianin impairs this process. Mechanistically, Mnt decreases the expression of nucleolar components in muscles while also decreasing nucleolar size in distant tissues via Myostatin/p38 MAPK signaling. Our results highlight a myokine-dependent inter-organ longevity pathway that coordinates nucleolar function and protein synthesis across aging tissues. Affymetrix microarrays were used to evaluate genome-wide expression in skeletal muscles of flies with muscle-specific overexpression of FOXO or Mnt (Affymetrix Drosophila Genome 2.0 Array). This design allowed us to identify genes and pathways induced by overexpression of FOXO and/or Mnt, and enabled us to address the degree to which FOXO-induced pathways were independent of those induced by Mnt. Three independent biological replicates from each of three groups (control, UAS-Foxo and UAS-Mnt)
Project description:Aging and the age-associated decline of the proteome is determined in part through neuronal control of evolutionarily conserved transcriptional effectors, which safeguard homeostasis under fluctuating metabolic and stress conditions by regulating an expansive proteostatic network. We have discovered the Caenorhabditis elegans homeodomain-interacting protein kinase (HPK-1) acts as a key transcriptional effector to preserve neuronal integrity, function, and proteostasis during aging. Loss of hpk-1 results in drastic dysregulation in expression of neuronal genes, including premature upregulation of genes associated with neuronal aging. During normal aging hpk-1 expression increases throughout the nervous system and in more cell-clusters than any other kinase. Within the aging nervous system, hpk-1 is co-expressed with key longevity transcription factors, including daf-16 (FOXO), hlh-30 (TFEB), skn-1 (Nrf2), and hif-1, which suggests hpk-1 expression mitigates natural age-associated physiological decline. Consistently, pan-neuronal overexpression of hpk-1 extends longevity, preserves proteostasis both within and outside of the nervous system, and improves stress resistance. Neuronal HPK-1 improves proteostasis through kinase activity. HPK-1 functions cell non-autonomously within serotonergic and GABAergic neurons to improve proteostasis in distal tissues by specifically regulating divergent components of the proteostatic network. Increased serotonergic HPK-1 enhances the heat shock response and survival to acute stress. In contrast, GABAergic HPK-1 induces basal autophagy and extends longevity. Our work establishes hpk-1 as a key neuronal transcriptional regulator that is critical for the preservation of neuronal function during aging and insight as to how the nervous system partitions acute and chronic adaptive response pathways to delay aging by maintaining organismal homeostasis.
Project description:Protein translation (PT) declines with age in invertebrates, rodents, and humans1-6. It has been assumed that elevated PT at young ages is beneficial to health and PT ends up dropping as a passive byproduct of aging. In Drosophila, we show that a transient elevation in PT during early-adulthood exerts long-lasting negative impacts on aging trajectories and proteostasis in later-life. Blocking the early-life PT elevation robustly improves life-/health-span and prevents age-related protein aggregation, whereas transiently inducing early-life PT surge in long-lived fly strains abolishes their longevity/proteostasis benefits. The early-life PT elevation triggers proteostatic dysfunction, silences stress responses, and drives age-related functional decline via juvenile hormone-lipid transfer protein axis and germline signaling. Our findings suggest that PT is adaptively suppressed after early-adulthood, alleviating later-life proteostatic burden, slowing down age-related functional decline, and improving lifespan. Our work provides a novel theoretical framework for understanding how lifetime PT dynamics shape future aging trajectories.
Project description:Protein translation (PT) declines with age in invertebrates, rodents, and humans. It has been assumed that elevated PT at young ages is beneficial to health and PT ends up dropping as a passive byproduct of aging. In Drosophila, we show that a transient elevation in PT during early-adulthood exerts long-lasting negative impacts on aging trajectories and proteostasis in later-life. Blocking the early-life PT elevation robustly improves life-/health-span and prevents age-related protein aggregation, whereas transiently inducing an early-life PT surge in long-lived fly strains abolishes their longevity/proteostasis benefits. The early-life PT elevation triggers proteostatic dysfunction, silences stress responses, and drives age related functional decline via juvenile hormone-lipid transfer protein axis and germline signaling. Our findings suggest that PT is adaptively suppressed after early-adulthood, alleviating later-life proteostatic burden, slowing down age-related functional decline, and improving lifespan. Our work provides a theoretical framework for understanding how lifetime PT dynamics shape future aging trajectories.
Project description:Skeletal muscle senescence influences whole organism aging, yet little is known on the relay of pro-longevity signals from muscles to other tissues. We performed an RNAi screen in Drosophila for muscle-released cytokines (?myokines?) regulating lifespan and identified Myoglianin, the homolog of human Myostatin. Myoglianin is induced in skeletal muscles by the transcription factor Mnt and together they constitute an inter-organ signaling module that regulates lifespan, age-related muscle dysfunction, and protein synthesis across aging tissues. Both Mnt and Myoglianin activate already in young age the protective decline in protein synthesis that is typical of old age, while knock-down of Myoglianin impairs this process. Mechanistically, Mnt decreases the expression of nucleolar components in muscles while also decreasing nucleolar size in distant tissues via Myostatin/p38 MAPK signaling. Our results highlight a myokine-dependent inter-organ longevity pathway that coordinates nucleolar function and protein synthesis across aging tissues. Affymetrix microarrays were used to evaluate genome-wide expression in skeletal muscles of flies with muscle-specific overexpression of FOXO or Mnt (Affymetrix Drosophila Genome 2.0 Array). This design allowed us to identify genes and pathways induced by overexpression of FOXO and/or Mnt, and enabled us to address the degree to which FOXO-induced pathways were independent of those induced by Mnt.
Project description:Aging is a major risk factor for impaired cardiovascular health. The aging myocardium is characterized by microcirculatory and diastolic dysfunction and increased susceptibility to arrhythmias. Nerves align with vessels during development. However, the impact of aging on the cardiac neuro-vascular interface is entirely unknown. Here, we report that aging reduces nerve density specifically in the left ventricle and dysregulates vascular-derived neuro-regulatory genes. Aging leads to a down-regulation of miR-145 and de-repression of the neuro-repulsive factor Semaphorin-3A. miR-145 deletion, which increased Sema3a expression, or endothelial Sema3a overexpression reduced axon density, thus mimicking the observed aged heart phenotype. Removal of senescent cells, which accumulated with chronological age in parallel to the decline in nerve density, rescued age-induced denervation, reduced Sema3a expression, preserved heart rate variability and reduced electrical instability. These data suggest that senescence-associated regulation of neuro-regulatory genes is associated with reduced nerve density and, thereby, contributes to age-associated cardiac dysfunction.