Project description:Gametogenesis involves active protein synthesis and heavily relies on proteostasis. How animals regulate germline proteostasis at the organismal level is poorly understood. Our recent work in C. elegans indicates that germline development requires coordinated activities between insulin/IGF-1 signaling and HSF-1, the transcriptional activator of many molecular chaperones in stress and physiological conditions. In this study, we show that HSF-1 is important for germline proteostasis at ambient temperature. Depletion of HSF-1 from germ cells impairs chaperone gene expression, causing protein degradation and aggregation and, consequently, declines in fecundity and gamete quality. Reduced insulin/IGF-1 signaling confers germ cells' tolerance to limited protein folding capacity and proteotoxic stress by lowering ribosome biogenesis and translation. Interestingly, regulation of germline proteostasis by insulin/IGF-1 signaling occurs non-cell-autonomously. Our data suggest that insulin/IGF-1 signaling controls the expression of the evolutionarily conserved intestinal peptide transporter PEPT-1 via its downstream transcription factor FOXO/DAF-16, therefore allowing dietary proteins to be incorporated into an amino acid pool that fuels ribosomal biogenesis and translation in the germline. We propose that this pathway plays a critical role in regulating germline protein synthesis, which must be at balance with HSF-1-dependent protein folding to achieve proteostasis in gametogenesis.
Project description:Transcriptional profiling of human acute myeloid leukemia cells lines HEL and SET2 transduced with an IGF1R shRNA and miR-125a sponge. AIRAPL (arsenite-inducible regulatory particle-associated protein-like) is an evolutionarily conserved regulator of cellular proteostasis linked to longevity in nematodes, but whose biological function in mammals is unknown. We show herein that AIRAPL-deficient mice develop a fully-penetrant myeloproliferative neoplastic process. Proteomic analysis of AIRAPL-deficient mice revealed that this protein exerts its antineoplastic function through the regulation of the insulin/IGF-1 signaling pathway. We demonstrate that AIRAPL interacts with newly synthesized insulin-related growth factor-1 receptor (IGF1R) polypeptides, promoting their ubiquitination and proteasome-mediated degradation. Accordingly, genetic and pharmacological IGF1R inhibitory strategies prevent the hematological disease found in AIRAPL-deficient mice as well as in mice carrying the JAK2-V617F mutation, which demonstrates the causal involvement of this pathway in the pathogenesis of myeloproliferative neoplasms. Consistent with its proposed role as a tumor suppressor of myeloid transformation, AIRAPL expression is widely abrogated in human myeloproliferative disorders. Collectively, these findings support the oncogenic relevance of proteostasis deregulation in hematopoietic cells, and unveil novel therapeutic targets for these frequent hematological neoplasias.
Project description:A hallmark of aging is immunosenescence, a decline in immune function that appeared to be inevitable. Surprisingly, here we show that genetic inhibition of DAF-2/insulin/IGF-1 receptor drastically delays immunosenescence and even rejuvenates immunity in C. elegans. We find that p38 mitogen activated protein kinase (PMK-1), a key determinant of immunosenescence in wild-type, is dispensable for this rejuvenated immunity. Instead, we demonstrate that longevity-promoting DAF-16/FOXO and heat-shock transcription factor 1 (HSF-1) increase immunocompetence in old daf-2(-) animals. The up-regulation of DAF-16/FOXO and HSF-1 decreases the expression of zip-10/bZip transcription factor, which in turn down-regulates ins-7, an agonistic insulin-like peptide, for further reduction in insulin/IGF-1 signaling (IIS). Thus, reduced IIS bypasses immunosenescence and rejuvenates immunity via up-regulating anti-aging transcription factors that regulate an endocrine insulin-like peptide through a positive feedback mechanism. Because many functions of IIS are conserved across phyla, our study may lead to developing strategies for immune rejuvenation in humans.
Project description:Exposure to adverse nutritional and metabolic environments during critical periods of development can exert long-lasting effects on health outcomes of an individual and its descendants. Although such metabolic programming has been observed in multiple species and in response to distinct nutritional stressors, conclusive insights into signaling pathways and mechanisms responsible for initiating, mediating and manifesting changes to metabolism and behavior across generations remain scarce. By employing a multigenerational starvation paradigm in C. elegans, we show that starvation-induced changes in DAF-16/FoxO activity, the main downstream target of insulin/IGF-1 receptor signaling, are responsible for metabolic programming phenotypes. Tissue-specific depletion of DAF-16/FoxO during distinct developmental time points further demonstrates that DAF-16/FoxO acts in somatic tissues, but not directly in the germline, to both initiate and manifest metabolic programming. In conclusion, our study deciphers multifaceted and critical roles of highly conserved insulin/IGF-1 receptor signaling in determining health outcomes and behavior across generations.
Project description:In this project we asked how reducing the activity of the insulin/IGF signaling (IIS) cascade by knocking down the expression of daf-2, affects global protein SUMOylation of C. elegans. We found that among other proteins, IIS reduction lowers the SUMOylation of CAR-1, a protein that negatively regulates the activity of the worm’s notch receptor, GLP-1. Thus, the knockdown of car-1 hyper-activates GLP-1, shortens lifespan and exposes the worm to toxic protein aggregation (proteotoxicity). In contrast, the expression of a SUMOylation resistant CAR-1 (K185R) promotes longevity and protects model nematodes from proteotoxicity.
Project description:Gametogenesis involves active protein synthesis and is proposed to rely on proteostasis. Our previous work in C. elegans indicates that germline development requires coordinated activities of insulin/IGF-1 signaling (IIS) and HSF-1, the central regulator of the heat shock response. However, the downstream mechanisms were not identified. Here, we show that depletion of HSF-1 from germ cells impairs chaperone gene expression, causing protein degradation and aggregation and, consequently, reduced fecundity and gamete quality. Conversely, reduced IIS confers germ cell resilience to HSF-1 depletion-induced protein folding defects and various proteotoxic stresses. Surprisingly, this effect was not mediated by an enhanced stress response, which underlies longevity in low IIS conditions, but by reduced ribosome biogenesis and translation rate. We found that IIS activates the expression of intestinal peptide transporter PEPT-1 by alleviating its repression by FOXO/DAF-16, allowing dietary proteins to be efficiently incorporated into an amino acid pool that fuels germline protein synthesis. Our data suggest this non-cell-autonomous pathway is critical for proteostasis regulation during gametogenesis.
Project description:Exome sequencing of short SGA children with IGF-I and insulin resistance. Collaboration with Professor David Dunger, University of Cambridge. Funded by NIHR.
Project description:How lifespan and the rate of aging are set is a key problem in biology. Small RNAs are conserved molecules that impact diverse biological processes through the control of gene expression. However, in contrast to miRNAs, the role of endo-siRNAs in aging remains unexplored. Here, by combining deep sequencing and genomic and genetic approaches in C. elegans, we reveal an unprecedented role for endo-siRNA molecules in the maintenance of proteostasis and lifespan extension in germline-less animals. Furthermore, we identify an endo-siRNA-regulated tyrosine phosphatase, which limits the longevity of germline-less animals by restricting the activity of the heat shock transcription factor HSF-1. Altogether, our findings point to endo-siRNAs as a link between germline removal and the HSF-1 proteostasis and longevity-promoting somatic pathway. This establishes a role for endo siRNAs in the aging process and identifies downstream genes and physiological processes that are regulated by the endo siRNAs to affect longevity.
Project description:How lifespan and the rate of aging are set is a key problem in biology. Small RNAs are conserved molecules that impact diverse biological processes through the control of gene expression. However, in contrast to miRNAs, the role of endo-siRNAs in aging remains unexplored. Here, by combining deep sequencing and genomic and genetic approaches in C.CaenorhabditisC. elegans elegans, we reveal an unprecedented role for endo-siRNA molecules in the maintenance of proteostasis and lifespan extension in germline-less animals. Furthermore, we identify an endo-siRNA-regulated tyrosine phosphatase, which limits the longevity of germline-less animals by restricting the activity of the heat shock transcription factor HSF-1. Altogether, our findings point to endo-siRNAs as a link between germline removal and the HSF-1 proteostasis and longevity-promoting somatic pathway. This establishes a role for endo siRNAs in the aging process and identifies downstream genes and physiological processes that are regulated by the endo siRNAs to affect longevity.