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Nature Cell Biology Feb 2024The mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth, metabolism and autophagy. Multiple pathways modulate mTORC1 in response to...
The mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth, metabolism and autophagy. Multiple pathways modulate mTORC1 in response to nutrients. Here we describe that nucleus-cytoplasmic shuttling of p300/EP300 regulates mTORC1 activity in response to amino acid or glucose levels. Depletion of these nutrients causes cytoplasm-to-nucleus relocalization of p300 that decreases acetylation of the mTORC1 component raptor, thereby reducing mTORC1 activity and activating autophagy. This is mediated by AMP-activated protein kinase-dependent phosphorylation of p300 at serine 89. Nutrient addition to starved cells results in protein phosphatase 2A-dependent dephosphorylation of nuclear p300, enabling its CRM1-dependent export to the cytoplasm to mediate mTORC1 reactivation. p300 shuttling regulates mTORC1 in most cell types and occurs in response to altered nutrients in diverse mouse tissues. Interestingly, p300 cytoplasm-nucleus shuttling is altered in cells from patients with Hutchinson-Gilford progeria syndrome. p300 mislocalization by the disease-causing protein, progerin, activates mTORC1 and inhibits autophagy, phenotypes that are normalized by modulating p300 shuttling. These results reveal how nutrients regulate mTORC1, a cytoplasmic complex, by shuttling its positive regulator p300 in and out of the nucleus, and how this pathway is misregulated in Hutchinson-Gilford progeria syndrome, causing mTORC1 hyperactivation and defective autophagy.
Topics: Humans; Mice; Animals; Mechanistic Target of Rapamycin Complex 1; Progeria; Active Transport, Cell Nucleus; Regulatory-Associated Protein of mTOR; Amino Acids; Lamin Type A
PubMed: 38267537
DOI: 10.1038/s41556-023-01338-y -
Journal of Cell Science Aug 2006Three mammalian nuclear lamin proteins, lamin B(1), lamin B(2) and the lamin A precursor, prelamin A, undergo canonical farnesylation and processing at CAAX motifs. In... (Review)
Review
Three mammalian nuclear lamin proteins, lamin B(1), lamin B(2) and the lamin A precursor, prelamin A, undergo canonical farnesylation and processing at CAAX motifs. In the case of prelamin A, there is an additional farnesylation-dependent endoproteolysis, which is defective in two congenital diseases: Hutchinson-Gilford progeria (HGPS) and restrictive dermopathy (RD). These two diseases arise respectively from defects in the prelamin A substrate and the enzyme (ZmpSte24) that processes it. Recent work has shed light on the roles of the lamin proteins and the enzymes involved in their farnesylation-dependent maturation. Other experimental work, including mouse model studies, have examined the possibility that farnesyl transferase inhibitors can represent effective treatment for HGPS. However, there are concerns about their use for this purpose given the potential for alternative prenylation pathways.
Topics: Animals; Enzyme Inhibitors; Farnesyltranstransferase; Humans; Lamins; Lipoproteins; Membrane Proteins; Metalloendopeptidases; Metalloproteases; Progeria; Protein Prenylation; Skin Abnormalities; Syndrome
PubMed: 16899817
DOI: 10.1242/jcs.03156 -
Aging Nov 2012
Review
Topics: Aging; Aging, Premature; Animals; Humans; NF-kappa B; Progeria
PubMed: 23211391
DOI: 10.18632/aging.100502 -
Stem Cell Research & Therapy Sep 2016Laminopathy is a disease closely related to deficiency of the nuclear matrix protein lamin A/C or failure in prelamin A processing, and leads to accumulation of the... (Review)
Review
Laminopathy is a disease closely related to deficiency of the nuclear matrix protein lamin A/C or failure in prelamin A processing, and leads to accumulation of the misfold protein causing progeria. The resultant disrupted lamin function is highly associated with abnormal nuclear architecture, cell senescence, apoptosis, and unstable genome integrity. To date, the effects of loss in nuclear integrity on the susceptible organ, striated muscle, have been commonly associated with muscular dystrophy, dilated cardiac myopathy (DCM), and conduction defeats, but have not been studied intensively. In this review, we aim to summarize recent breakthroughs in an in vivo laminopathy model and in vitro study using patient-specific human induced pluripotent stem cells (iPSCs) that reproduce the pathophysiological phenotype for further drug screening. We describe several in-vivo transgenic mouse models to elucidate the effects of Lmna H222P, N195K mutations, and LMNA knockout on cardiac function, in terms of hemodynamic and electrical signal propagation; certain strategies targeted on stress-related MAPK are mentioned. We will also discuss human iPSC cardiomyocytes serving as a platform to reveal the underlying mechanisms, such as the altered mechanical sensation in electrical coupling of the heart conduction system and ion channel alternation in relation to altered nuclear architecture, and furthermore to enable screening of drugs that can attenuate this cardiac premature aging phenotype by inhibition of prelamin misfolding and oxidative stress, and also enhancement of autophagy protein clearance and cardiac-protective microRNA.
Topics: Animals; Cardiomyopathy, Dilated; Cardiotonic Agents; Gene Expression; Genomic Instability; Heart Conduction System; Humans; Induced Pluripotent Stem Cells; Lamin Type A; Mice; Mice, Transgenic; Models, Cardiovascular; Mutation; Myocytes, Cardiac; Progeria; Protein Folding; Proteostasis Deficiencies
PubMed: 27649756
DOI: 10.1186/s13287-016-0401-5 -
Cellular and Molecular Life Sciences :... Nov 2014Cellular senescence, a permanent state of cell cycle arrest accompanied by a complex phenotype, is an essential mechanism that limits tumorigenesis and tissue damage. In... (Review)
Review
Cellular senescence, a permanent state of cell cycle arrest accompanied by a complex phenotype, is an essential mechanism that limits tumorigenesis and tissue damage. In physiological conditions, senescent cells can be removed by the immune system, facilitating tumor suppression and wound healing. However, as we age, senescent cells accumulate in tissues, either because an aging immune system fails to remove them, the rate of senescent cell formation is elevated, or both. If senescent cells persist in tissues, they have the potential to paradoxically promote pathological conditions. Cellular senescence is associated with an enhanced pro-survival phenotype, which most likely promotes persistence of senescent cells in vivo. This phenotype may have evolved to favor facilitation of a short-term wound healing, followed by the elimination of senescent cells by the immune system. In this review, we provide a perspective on the triggers, mechanisms and physiological as well as pathological consequences of senescent cells.
Topics: Cell Transformation, Neoplastic; Cellular Senescence; DNA Damage; Extracellular Matrix; Humans; Neoplasms; Progeria; Signal Transduction; Werner Syndrome
PubMed: 25080110
DOI: 10.1007/s00018-014-1691-3 -
Aging Cell Jan 2021Hutchinson-Gilford progeria syndrome (HGPS) causes premature aging in children, with adipose tissue, skin and bone deterioration, and cardiovascular impairment. In HGPS...
Hutchinson-Gilford progeria syndrome (HGPS) causes premature aging in children, with adipose tissue, skin and bone deterioration, and cardiovascular impairment. In HGPS cells and mouse models, high levels of interleukin-6, an inflammatory cytokine linked to aging processes, have been detected. Here, we show that inhibition of interleukin-6 activity by tocilizumab, a neutralizing antibody raised against interleukin-6 receptors, counteracts progeroid features in both HGPS fibroblasts and Lmna progeroid mice. Tocilizumab treatment limits the accumulation of progerin, the toxic protein produced in HGPS cells, rescues nuclear envelope and chromatin abnormalities, and attenuates the hyperactivated DNA damage response. In vivo administration of tocilizumab reduces aortic lesions and adipose tissue dystrophy, delays the onset of lipodystrophy and kyphosis, avoids motor impairment, and preserves a good quality of life in progeroid mice. This work identifies tocilizumab as a valuable tool in HGPS therapy and, speculatively, in the treatment of a variety of aging-related disorders.
Topics: Aging; Animals; Humans; Interleukin-6; Mice; Progeria
PubMed: 33393189
DOI: 10.1111/acel.13285 -
Methods (San Diego, Calif.) Mar 2019Protein-protein interactions are essential for cellular structure and function. To delineate how the intricate assembly of protein interactions contribute to cellular...
Protein-protein interactions are essential for cellular structure and function. To delineate how the intricate assembly of protein interactions contribute to cellular processes in health and disease, new methodologies that are both highly sensitive and can be applied at large scale are needed. Here, we develop HiPLA (high-throughput imaging proximity ligation assay), a method that employs the well-established antibody-based proximity ligation assay in a high-throughput imaging screening format as a novel means to systematically visualize protein interactomes. Using HiPLA with a library of antibodies targeting nuclear proteins, we probe the interaction of 60 proteins and associated post-translational modifications (PTMs) with the nuclear lamina in a model of the premature aging disorder Hutchinson-Gilford progeria syndrome (HGPS). We identify a subset of proteins that differentially interact with the nuclear lamina in HGPS. Using HiPLA in combination with quantitative indirect immunofluorescence, we find that the majority of differential interactions are accompanied by corresponding changes in expression of the interacting protein. Taken together, HiPLA offers a novel approach to probe cellular protein-protein interaction at a large scale and reveals mechanistic insights into the assembly of protein complexes.
Topics: Cell Nucleus; Humans; Lamin Type A; Mutation; Progeria; Protein Interaction Mapping; Protein Precursors
PubMed: 30419336
DOI: 10.1016/j.ymeth.2018.11.004 -
Cellular & Molecular Biology Letters Mar 2011Laminopathies are rare human degenerative disorders with a wide spectrum of clinical phenotypes, associated with defects in the main protein components of the nuclear... (Review)
Review
Laminopathies are rare human degenerative disorders with a wide spectrum of clinical phenotypes, associated with defects in the main protein components of the nuclear envelope, mostly in the lamins. They include systemic disorders and tissue-restricted diseases. Scientists have been trying to explain the pathogenesis of laminopathies and find an efficient method for treatment for many years. In this review, we discuss the current state of knowledge about laminopathies, the molecular mechanisms behind the development of particular phenotypes, and the prospects for stem cell and/or gene therapy treatments.
Topics: Genetic Diseases, Inborn; Genetic Therapy; Humans; Lamins; Lipodystrophy; Muscular Diseases; Nuclear Envelope; Progeria
PubMed: 21225470
DOI: 10.2478/s11658-010-0038-9 -
Microbiology and Molecular Biology... Sep 2012The mating pheromone a-factor secreted by Saccharomyces cerevisiae is a farnesylated and carboxylmethylated peptide and is unusually hydrophobic compared to other... (Review)
Review
The mating pheromone a-factor secreted by Saccharomyces cerevisiae is a farnesylated and carboxylmethylated peptide and is unusually hydrophobic compared to other extracellular signaling molecules. Mature a-factor is derived from a precursor with a C-terminal CAAX motif that directs a series of posttranslational reactions, including prenylation, endoproteolysis, and carboxylmethylation. Historically, a-factor has served as a valuable model for the discovery and functional analysis of CAAX-processing enzymes. In this review, we discuss the three modules comprising the a-factor biogenesis pathway: (i) the C-terminal CAAX-processing steps carried out by Ram1/Ram2, Ste24 or Rce1, and Ste14; (ii) two sequential N-terminal cleavage steps, mediated by Ste24 and Axl1; and (iii) export by a nonclassical mechanism, mediated by the ATP binding cassette (ABC) transporter Ste6. The small size and hydrophobicity of a-factor present both challenges and advantages for biochemical analysis, as discussed here. The enzymes involved in a-factor biogenesis are conserved from yeasts to mammals. Notably, studies of the zinc metalloprotease Ste24 in S. cerevisiae led to the discovery of its mammalian homolog ZMPSTE24, which cleaves the prenylated C-terminal tail of the nuclear scaffold protein lamin A. Mutations that alter ZMPSTE24 processing of lamin A in humans cause the premature-aging disease progeria and related progeroid disorders. Intriguingly, recent evidence suggests that the entire a-factor pathway, including all three biogenesis modules, may be used to produce a prenylated, secreted signaling molecule involved in germ cell migration in Drosophila. Thus, additional prenylated signaling molecules resembling a-factor, with as-yet-unknown roles in metazoan biology, may await discovery.
Topics: Animals; Drosophila; Humans; Mating Factor; Peptides; Progeria; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Signal Transduction
PubMed: 22933563
DOI: 10.1128/MMBR.00010-12 -
Cells Apr 2023Hutchinson-Gilford Progeria Syndrome (HGPS) is an ultra-rare human premature aging disorder that precipitates death because of cardiac disease. Almost all cases of HGPS...
Hutchinson-Gilford Progeria Syndrome (HGPS) is an ultra-rare human premature aging disorder that precipitates death because of cardiac disease. Almost all cases of HGPS are caused by aberrant splicing of the gene that results in the production of a mutant Lamin A protein termed progerin. In our previous study, treatment with Progerinin has been shown to reduce progerin expression and improve aging phenotypes in vitro and in vivo HGPS models. In this record, cardiac parameters (stroke volume (SV), ejection fraction (EF), fractional shortening (FS), etc.) were acquired in and mice fed with either a vehicle diet or a Progerinin diet by echocardiography (from 38 weeks to 50 weeks at various ages), and then the cardiac function was analyzed. We also acquired the tissue samples and blood serum of and mice for pathological analysis at the end of echocardiography. From these data, we suggest that the administration of Progerinin in the HGPS model mouse can restore cardiac function and correct arterial abnormalities. These observations provide encouraging evidence for the efficacy of Progerinin for cardiac dysfunction in HGPS.
Topics: Mice; Humans; Animals; Progeria; Aging, Premature; Aging; Phenotype
PubMed: 37174632
DOI: 10.3390/cells12091232