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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 -
Frontiers in Physiology 2024Vascular endothelial cells line the inner surface of all blood vessels, where they are exposed to polarized mechanical forces throughout their lifespan. Both basal... (Review)
Review
Vascular endothelial cells line the inner surface of all blood vessels, where they are exposed to polarized mechanical forces throughout their lifespan. Both basal substrate interactions and apical blood flow-induced shear stress regulate blood vessel development, remodeling, and maintenance of vascular homeostasis. Disruption of these interactions leads to dysfunction and vascular pathologies, although how forces are sensed and integrated to affect endothelial cell behaviors is incompletely understood. Recently the endothelial cell nucleus has emerged as a prominent force-transducing organelle that participates in vascular mechanotransduction, via communication to and from cell-cell and cell-matrix junctions. The LINC complex, composed of SUN and nesprin proteins, spans the nuclear membranes and connects the nuclear lamina, the nuclear envelope, and the cytoskeleton. Here we review LINC complex involvement in endothelial cell mechanotransduction, describe unique and overlapping functions of each LINC complex component, and consider emerging evidence that two major SUN proteins, SUN1 and SUN2, orchestrate a complex interplay that extends outward to cell-cell and cell-matrix junctions and inward to interactions within the nucleus and chromatin. We discuss these findings in relation to vascular pathologies such as Hutchinson-Gilford progeria syndrome, a premature aging disorder with cardiovascular impairment. More knowledge of LINC complex regulation and function will help to understand how the nucleus participates in endothelial cell force sensing and how dysfunction leads to cardiovascular disease.
PubMed: 38831796
DOI: 10.3389/fphys.2024.1411995 -
Science China. Life Sciences Mar 2024Cullin-RING E3 ubiquitin ligases (CRLs), the largest family of multi-subunit E3 ubiquitin ligases in eukaryotic cells, represent core cellular machinery for executing...
Cullin-RING E3 ubiquitin ligases (CRLs), the largest family of multi-subunit E3 ubiquitin ligases in eukaryotic cells, represent core cellular machinery for executing protein degradation and maintaining proteostasis. Here, we asked what roles Cullin proteins play in human mesenchymal stem cell (hMSC) homeostasis and senescence. To this end, we conducted a comparative aging phenotype analysis by individually knocking down Cullin members in three senescence models: replicative senescent hMSCs, Hutchinson-Gilford Progeria Syndrome hMSCs, and Werner syndrome hMSCs. Among all family members, we found that CUL2 deficiency rendered hMSCs the most susceptible to senescence. To investigate CUL2-specific underlying mechanisms, we then applied CRISPR/Cas9-mediated gene editing technology to generate CUL2-deficient human embryonic stem cells (hESCs). When we differentiated these into hMSCs, we found that CUL2 deletion markedly accelerates hMSC senescence. Importantly, we identified that CUL2 targets and promotes ubiquitin proteasome-mediated degradation of TSPYL2 (a known negative regulator of proliferation) through the substrate receptor protein APPBP2, which in turn down-regulates one of the canonical aging marker-P21, and thereby delays senescence. Our work provides important insights into how CRL2-mediated TSPYL2 degradation counteracts hMSC senescence, providing a molecular basis for directing intervention strategies against aging and aging-related diseases.
Topics: Humans; Carrier Proteins; Cellular Senescence; Cullin Proteins; Mesenchymal Stem Cells; Ubiquitin-Protein Ligases; Ubiquitins
PubMed: 38170390
DOI: 10.1007/s11427-023-2451-3 -
Journal of Cachexia, Sarcopenia and... Jun 2024Sarcopenia is characterized by loss of skeletal muscle mass and function, and is a major risk factor for disability and independence in the elderly. Effective medication...
BACKGROUND
Sarcopenia is characterized by loss of skeletal muscle mass and function, and is a major risk factor for disability and independence in the elderly. Effective medication is not available. Dietary restriction (DR) has been found to attenuate aging and aging-related diseases, including sarcopenia, but the mechanism of both DR and sarcopenia are incompletely understood.
METHODS
In this study, mice body weight, fore and all limb grip strength, and motor learning and coordination performance were first analysed to evaluate the DR effects on muscle functioning. Liquid chromatography-mass spectrometry (LC-MS) was utilized for the metabolomics study of the DR effects on sarcopenia in progeroid DNA repair-deficient Ercc1 and Xpg mice, to identify potential biomarkers for attenuation of sarcopenia.
RESULTS
Muscle mass was significantly (P < 0.05) decreased (13-20%) by DR; however, the muscle quality was improved with retained fore limbs and all limbs grip strength in Ercc1 and Xpg mice. The LC-MS results revealed that metabolites and pathways related to oxidative-stress, that is, GSSG/GSH (P < 0.01); inflammation, that is, 9-HODE, 11-HETE (P < 0.05), PGE, PGD, and TXB (P < 0.01); and muscle growth (PGF) (P < 0.01) and regeneration stimulation (PGE) (P < 0.05) are significantly downregulated by DR. On the other hand, anti-inflammatory indicator and several related metabolites, that is, β-hydroxybutyrate (P < 0.01), 14,15-DiHETE (P < 0.0001), 8,9-EET, 12,13-DiHODE, and PGF (P < 0.05); consumption of sources of energy (i.e., muscle and liver glycogen); and energy production pathways, that is, glycolysis (glucose, glucose-6-P, fructose-6-P) (P < 0.01), tricarboxylic acid cycle (succinyl-CoA, malate) (P < 0.001), and gluconeogenesis-related metabolite, alanine (P < 0.01), are significantly upregulated by DR. The notably (P < 0.01) down-modulated muscle growth (PGF) and regeneration (PGE) stimulation metabolite and the increased consumption of glycogen in muscle and liver may be related to the significantly (P < 0.01) lower body weight and muscle mass by DR. The downregulated oxidative stress, pro-inflammatory mediators, and upregulated anti-inflammatory metabolites resulted in a lower energy expenditure, which contributed to enhanced muscle quality together with upregulated energy production pathways by DR. The improved muscle quality may explain why grip strength is maintained and motor coordination and learning performance are improved by DR in Ercc1 and Xpg mice.
CONCLUSIONS
This study provides fundamental supporting information on biomarkers and pathways related to the attenuation of sarcopenia, which might facilitate its diagnosis, prevention, and clinical therapy.
Topics: Animals; Mice; Sarcopenia; Metabolomics; Aging, Premature; Metabolome; Mice, Knockout; Disease Models, Animal; DNA Repair; Male; Caloric Restriction; Muscle, Skeletal; DNA-Binding Proteins; Endonucleases
PubMed: 38689513
DOI: 10.1002/jcsm.13433 -
American Journal of Medical Genetics.... Sep 2023Atypical progeroid syndromes (APS) are premature aging syndromes caused by pathogenic LMNA missense variants, associated with unaltered expression levels of lamins A and...
A recurrent homozygous LMNA missense variant p.Thr528Met causes atypical progeroid syndrome characterized by mandibuloacral dysostosis, severe muscular dystrophy, and skeletal deformities.
Atypical progeroid syndromes (APS) are premature aging syndromes caused by pathogenic LMNA missense variants, associated with unaltered expression levels of lamins A and C, without accumulation of wild-type or deleted prelamin A isoforms, as observed in Hutchinson-Gilford progeria syndrome (HGPS) or HGPS-like syndromes. A specific LMNA missense variant, (p.Thr528Met), was previously identified in a compound heterozygous state in patients affected by APS and severe familial partial lipodystrophy, whereas heterozygosity was recently identified in patients affected by Type 2 familial partial lipodystrophy. Here, we report four unrelated boys harboring homozygosity for the p.Thr528Met, variant who presented with strikingly homogeneous APS clinical features, including osteolysis of mandibles, distal clavicles and phalanges, congenital muscular dystrophy with elevated creatine kinase levels, and major skeletal deformities. Immunofluorescence analyses of patient-derived primary fibroblasts showed a high percentage of dysmorphic nuclei with nuclear blebs and typical honeycomb patterns devoid of lamin B1. Interestingly, in some protrusions emerin or LAP2α formed aberrant aggregates, suggesting pathophysiology-associated clues. These four cases further confirm that a specific LMNA variant can lead to the development of strikingly homogeneous clinical phenotypes, in these particular cases a premature aging phenotype with major musculoskeletal involvement linked to the homozygous p.Thr528Met variant.
Topics: Humans; Aging, Premature; Syndrome; Lipodystrophy, Familial Partial; Clavicle; Mutation; Progeria; Muscular Dystrophies; Dysostoses; Lamin Type A
PubMed: 37387251
DOI: 10.1002/ajmg.a.63335 -
Nucleus (Austin, Tex.) Dec 2023Several related progeroid disorders are caused by defective post-translational processing of prelamin A, the precursor of the nuclear scaffold protein lamin A, encoded...
Several related progeroid disorders are caused by defective post-translational processing of prelamin A, the precursor of the nuclear scaffold protein lamin A, encoded by . Prelamin A undergoes farnesylation and additional modifications at its C-terminus. Subsequently, the farnesylated C-terminal segment is cleaved off by the zinc metalloprotease ZMPSTE24. The premature aging disorder Hutchinson Gilford progeria syndrome (HGPS) and a related progeroid disease, mandibuloacral dysplasia (MAD-B), are caused by mutations in and , respectively, that result in failure to process the lamin A precursor and accumulate permanently farnesylated forms of prelamin A. The farnesyl transferase inhibitor (FTI) lonafarnib is known to correct the aberrant nuclear morphology of HGPS patient cells and improves lifespan in children with HGPS. Importantly, and in contrast to a previous report, we show here that FTI treatment also improves the aberrant nuclear phenotypes in MAD-B patient cells with mutations in (P248L or L425P). As expected, lonafarnib does not correct nuclear defects for cells with lamin A processing-proficient mutations. We also examine prelamin A processing in fibroblasts from two individuals with a prevalent laminopathy mutation -R644C. Despite the proximity of residue R644 to the prelamin A cleavage site, neither R644C patient cell line shows a prelamin A processing defect, and both have normal nuclear morphology. This work clarifies the prelamin A processing status and role of FTIs in a variety of laminopathy patient cells and supports the FDA-approved indication for the FTI Zokinvy for patients with processing-deficient progeroid laminopathies, but not for patients with processing-proficient laminopathies.
Topics: Child; Humans; Lamin Type A; Progeria; Enzyme Inhibitors; Mutation; Lipodystrophy; Fibroblasts; Transferases; Metalloendopeptidases; Membrane Proteins
PubMed: 38050983
DOI: 10.1080/19491034.2023.2288476 -
Aging Cell Jun 2024Hutchinson-Gilford progeria syndrome (HGPS) is a rare and fatal disease manifested by premature aging and aging-related phenotypes, making it a disease model for aging....
Hutchinson-Gilford progeria syndrome (HGPS) is a rare and fatal disease manifested by premature aging and aging-related phenotypes, making it a disease model for aging. The cellular machinery mediating age-associated phenotypes in HGPS remains largely unknown, resulting in limited therapeutic targets for HGPS. In this study, we showed that mitophagy defects impaired mitochondrial function and contributed to cellular markers associated with aging in mesenchymal stem cells derived from HGPS patients (HGPS-MSCs). Mechanistically, we discovered that mitophagy affected the aging-associated phenotypes of HGPS-MSCs by inhibiting the STING-NF-ĸB pathway and the downstream transcription of senescence-associated secretory phenotypes (SASPs). Furthermore, by utilizing UMI-77, an effective mitophagy inducer, we showed that mitophagy induction alleviated aging-associated phenotypes in HGPS and naturally aged mice. Collectively, our results uncovered that mitophagy defects mediated the aging-associated markers in HGPS, highlighted the function of mitochondrial homeostasis in HGPS progression, and suggested mitophagy as an intervention target for HGPS and aging.
Topics: Progeria; Mitophagy; Humans; Mice; Animals; Aging; Cellular Senescence
PubMed: 38482753
DOI: 10.1111/acel.14143 -
Cell and Tissue Research Oct 2023Cardiovascular diseases, atherosclerosis, and strokes are the most common causes of death in patients with Hutchinson-Gilford progeria syndrome (HGPS). The LMNA variant...
Cardiovascular diseases, atherosclerosis, and strokes are the most common causes of death in patients with Hutchinson-Gilford progeria syndrome (HGPS). The LMNA variant c.1824C > T accounts for ~ 90% of HGPS cases. The detailed molecular mechanisms of Lamin A in the heart remain elusive due to the lack of appropriate in vitro models. We hypothesize that HGPS patient's induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMCs) will provide a model platform to study the cardio-pathologic mechanisms associated with HGPS. To elucidate the effects of progerin in cardiomyocytes, we first obtained skin fibroblasts (SFs) from a de-identified HGPS patient (hPGP1, proband) and both parents from the Progeria Research Foundation. Through Sanger sequencing and restriction fragment length polymorphism, with the enzyme EciI, targeting Lamin A, we characterized hPGP1-SFs as heterozygous mutants for the LMNA variant c.1824 C > T. Additionally, we performed LMNA exon 11 bisulfite sequencing to analyze the methylation status of the progeria cells. Furthermore, we reprogrammed the three SFs into iPSCs and differentiated them into iCMCs, which gained a beating on day 7. Through particle image velocimetry analysis, we found that hPGP1-iCMCs had an irregular contractile function and decreased cardiac-specific gene and protein expressions by qRT-PCR and Western blot. Our progeria-patient-derived iCMCs were found to be functionally and structurally defective when compared to normal iCMCs. This in vitro model will help in elucidating the role of Lamin A in cardiac diseases and the cardio-pathologic mechanisms associated with progeria. It provides a new platform for researchers to study novel treatment approaches for progeria-associated cardiac diseases.
Topics: Humans; Progeria; Lamin Type A; Myocytes, Cardiac; Cell Differentiation; Heart Diseases
PubMed: 37572165
DOI: 10.1007/s00441-023-03813-2 -
Remodeling of the Cardiac Extracellular Matrix Proteome During Chronological and Pathological Aging.Molecular & Cellular Proteomics : MCP Jan 2024Impaired extracellular matrix (ECM) remodeling is a hallmark of many chronic inflammatory disorders that can lead to cellular dysfunction, aging, and disease...
Impaired extracellular matrix (ECM) remodeling is a hallmark of many chronic inflammatory disorders that can lead to cellular dysfunction, aging, and disease progression. The ECM of the aged heart and its effects on cardiac cells during chronological and pathological aging are poorly understood across species. For this purpose, we first used mass spectrometry-based proteomics to quantitatively characterize age-related remodeling of the left ventricle (LV) of mice and humans during chronological and pathological (Hutchinson-Gilford progeria syndrome (HGPS)) aging. Of the approximately 300 ECM and ECM-associated proteins quantified (named as Matrisome), we identified 13 proteins that were increased during aging, including lactadherin (MFGE8), collagen VI α6 (COL6A6), vitronectin (VTN) and immunoglobulin heavy constant mu (IGHM), whereas fibulin-5 (FBLN5) was decreased in most of the data sets analyzed. We show that lactadherin accumulates with age in large cardiac blood vessels and when immobilized, triggers phosphorylation of several phosphosites of GSK3B, MAPK isoforms 1, 3, and 14, and MTOR kinases in aortic endothelial cells (ECs). In addition, immobilized lactadherin increased the expression of pro-inflammatory markers associated with an aging phenotype. These results extend our knowledge of the LV proteome remodeling induced by chronological and pathological aging in different species (mouse and human). The lactadherin-triggered changes in the proteome and phosphoproteome of ECs suggest a straight link between ECM component remodeling and the aging process of ECs, which may provide an additional layer to prevent cardiac aging.
Topics: Humans; Proteome; Endothelial Cells; Heart; Aging; Extracellular Matrix; Extracellular Matrix Proteins
PubMed: 38141925
DOI: 10.1016/j.mcpro.2023.100706 -
Zhonghua Er Ke Za Zhi = Chinese Journal... Feb 2024To analyze the nutritional status of progeria, and to provide reference for scientific nutritional management of progeria. This cross-sectional study included 15...
To analyze the nutritional status of progeria, and to provide reference for scientific nutritional management of progeria. This cross-sectional study included 15 children with progeria who were treated at Children's Hospital, Zhejiang University School of Medicine, between April 2022 and May 2023. Data of medical history, physical examination, laboratory tests, dietary survey and body composition were collected and analyzed. Among 15 patients there were 7 males and 8 females, aged 7.8 (2.3, 10.8) years. Twelve of the 15 patients exhibited signs of malnutrition. A 24-hour dietary survey was carried out in 14 of them. The daily energy intake of 11 cases was below recommended levels. Carbohydrate intake was insufficient in 10 cases, protein intake was insufficient in 7 cases, and fat intake was insufficient in 12 cases. Deficiencies in calcium, magnesium, iron and zinc were noted in 13, 13, 9 and 10 cases, respectively. Body composition was determined by dual-energy X-ray absorptiometry in 8 cases, and the bone mineral density was below average in 5 of them. Malnutrition, characterized by reduced energy intake, micronutrient deficiencies, and alteration in body composition, is prevalent in children with progeria. Regular routine nutritional assessment and proper interventions may benefit their long-term health status.
Topics: Male; Child; Female; Humans; Nutritional Status; Progeria; Cross-Sectional Studies; Malnutrition; Energy Intake
PubMed: 38264818
DOI: 10.3760/cma.j.cn112140-20230928-00230