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1.
Nat Commun ; 10(1): 4364, 2019 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-31554793

RESUMO

Phosphatidylinositol 3-kinase-gamma (PI3Kγ) is highly expressed in leukocytes and is an attractive drug target for immune modulation. Different experimental systems have led to conflicting conclusions regarding inflammatory and anti-inflammatory functions of PI3Kγ. Here, we report a human patient with bi-allelic, loss-of-function mutations in PIK3CG resulting in absence of the p110γ catalytic subunit of PI3Kγ. She has a history of childhood-onset antibody defects, cytopenias, and T lymphocytic pneumonitis and colitis, with reduced peripheral blood memory B, memory CD8+ T, and regulatory T cells and increased CXCR3+ tissue-homing CD4 T cells. PI3Kγ-deficient macrophages and monocytes produce elevated inflammatory IL-12 and IL-23 in a GSK3α/ß-dependent manner upon TLR stimulation. Pik3cg-deficient mice recapitulate major features of human disease after exposure to natural microbiota through co-housing with pet-store mice. Together, our results emphasize the physiological importance of PI3Kγ in restraining inflammation and promoting appropriate adaptive immune responses in both humans and mice.

2.
Front Immunol ; 10: 2000, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31507602

RESUMO

Interleukin-2-inducible T cell kinase (ITK) is critical for T cell signaling and cytotoxicity, and control of Epstein-Barr virus (EBV). We identified a patient with a novel homozygous missense mutation (D540N) in a highly conserved residue in the kinase domain of ITK who presented with EBV-positive lymphomatoid granulomatosis. She was treated with interferon and chemotherapy and her disease went into remission; however, she has persistent elevation of EBV DNA in the blood, low CD4 T cells, low NK cells, and nearly absent iNKT cells. Molecular modeling predicts that the mutation increases the flexibility of the ITK kinase domain impairing phosphorylation of the protein. Stimulation of her T cells resulted in reduced phosphorylation of ITK, PLCγ, and PKC. The CD8 T cells were moderately impaired for cytotoxicity and degranulation. Importantly, addition of magnesium to her CD8 T cells in vitro restored cytotoxicity and degranulation to levels similar to controls. Supplemental magnesium in patients with mutations in another protein important for T cell signaling, MAGT1, was reported to restore EBV-specific cytotoxicity. Our findings highlight the critical role of ITK for T cell activation and suggest the potential for supplemental magnesium to treat patients with ITK deficiency.

3.
Dig Dis Sci ; 63(5): 1192-1199, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29484573

RESUMO

BACKGROUND: Advances in genomics have facilitated the discovery of monogenic disorders in patients with unique gastro-intestinal phenotypes. Syndromic diarrhea, also called tricho-hepato-enteric (THE) syndrome, results from deleterious mutations in SKIV2L or TTC37 genes. The main features of this disorder are intractable diarrhea, abnormal hair, facial dysmorphism, immunodeficiency and liver disease. AIM: To report on a patient with THE syndrome and present the genetic analysis that facilitated diagnosis. METHODS: Whole-exome sequencing (WES) was performed in a 4-month-old female with history of congenital diarrhea and severe failure to thrive but without hair anomalies or dysmorphism. Since the parents were first-degree cousins, the analysis focused on an autosomal recessive model. Sanger sequencing was used to validate suspected variants. Mutated protein structure was modeled to assess the effect of the mutation on protein function. RESULTS: We identified an autosomal recessive C.1891G > A missense mutation (NM_006929) in SKIV2L gene that was previously described only in a compound heterozygous state as causing THE syndrome. The mutation was determined to be deleterious in multiple prediction models. Protein modeling suggested that the mutation has the potential to cause structural destabilization of SKIV2L, either through conformational changes, interference with the protein's packing, or changes at the protein's interface. CONCLUSIONS: THE syndrome can present with a broad range of clinical features in the neonatal period. WES is an important diagnostic tool in patients with congenital diarrhea and can facilitate diagnosis of various diseases presenting with atypical features.


Assuntos
DNA Helicases/genética , Diarreia Infantil/genética , Retardo do Crescimento Fetal/genética , Doenças do Cabelo/genética , Mutação de Sentido Incorreto , Diarreia Infantil/diagnóstico , Facies , Feminino , Retardo do Crescimento Fetal/diagnóstico , Marcadores Genéticos , Doenças do Cabelo/diagnóstico , Humanos , Lactente , Sequenciamento Completo do Exoma
5.
J Exp Med ; 214(7): 1949-1972, 2017 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-28606988

RESUMO

MDA5 is a cytosolic sensor of double-stranded RNA (ds)RNA including viral byproducts and intermediates. We studied a child with life-threatening, recurrent respiratory tract infections, caused by viruses including human rhinovirus (HRV), influenza virus, and respiratory syncytial virus (RSV). We identified in her a homozygous missense mutation in IFIH1 that encodes MDA5. Mutant MDA5 was expressed but did not recognize the synthetic MDA5 agonist/(ds)RNA mimic polyinosinic-polycytidylic acid. When overexpressed, mutant MDA5 failed to drive luciferase activity from the IFNB1 promoter or promoters containing ISRE or NF-κB sequence motifs. In respiratory epithelial cells or fibroblasts, wild-type but not knockdown of MDA5 restricted HRV infection while increasing IFN-stimulated gene expression and IFN-ß/λ. However, wild-type MDA5 did not restrict influenza virus or RSV replication. Moreover, nasal epithelial cells from the patient, or fibroblasts gene-edited to express mutant MDA5, showed increased replication of HRV but not influenza or RSV. Thus, human MDA5 deficiency is a novel inborn error of innate and/or intrinsic immunity that causes impaired (ds)RNA sensing, reduced IFN induction, and susceptibility to the common cold virus.


Assuntos
Helicase IFIH1 Induzida por Interferon/genética , Mutação , Infecções por Picornaviridae/genética , Infecções por Picornaviridae/virologia , Rhinovirus/fisiologia , Antivirais/farmacologia , Sequência de Bases , Células Cultivadas , Pré-Escolar , Análise Mutacional de DNA/métodos , Feminino , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/virologia , Expressão Gênica/efeitos dos fármacos , Genes Recessivos/genética , Heterozigoto , Homozigoto , Interações Hospedeiro-Patógeno , Humanos , Helicase IFIH1 Induzida por Interferon/deficiência , Interferons/farmacologia , Masculino , Linhagem
6.
Nat Genet ; 49(8): 1192-1201, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28628108

RESUMO

Few monogenic causes for severe manifestations of common allergic diseases have been identified. Through next-generation sequencing on a cohort of patients with severe atopic dermatitis with and without comorbid infections, we found eight individuals, from four families, with novel heterozygous mutations in CARD11, which encodes a scaffolding protein involved in lymphocyte receptor signaling. Disease improved over time in most patients. Transfection of mutant CARD11 expression constructs into T cell lines demonstrated both loss-of-function and dominant-interfering activity upon antigen receptor-induced activation of nuclear factor-κB and mammalian target of rapamycin complex 1 (mTORC1). Patient T cells had similar defects, as well as low production of the cytokine interferon-γ (IFN-γ). The mTORC1 and IFN-γ production defects were partially rescued by supplementation with glutamine, which requires CARD11 for import into T cells. Our findings indicate that a single hypomorphic mutation in CARD11 can cause potentially correctable cellular defects that lead to atopic dermatitis.


Assuntos
Proteínas Adaptadoras de Sinalização CARD/genética , Dermatite Atópica/genética , Mutação em Linhagem Germinativa , Guanilato Ciclase/genética , Sistema ASC de Transporte de Aminoácidos/metabolismo , Estudos de Coortes , Análise Mutacional de DNA , Dermatite Atópica/imunologia , Feminino , Genes Dominantes , Glutamina/metabolismo , Humanos , Células Jurkat , Ativação Linfocitária , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Antígenos de Histocompatibilidade Menor/metabolismo , Complexos Multiproteicos/metabolismo , NF-kappa B/metabolismo , Linhagem , Linfócitos T/imunologia , Linfócitos T/metabolismo , Serina-Treonina Quinases TOR/metabolismo
7.
N Engl J Med ; 377(1): 52-61, 2017 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-28657829

RESUMO

BACKGROUND: Studies of monogenic gastrointestinal diseases have revealed molecular pathways critical to gut homeostasis and enabled the development of targeted therapies. METHODS: We studied 11 patients with abdominal pain and diarrhea caused by early-onset protein-losing enteropathy with primary intestinal lymphangiectasia, edema due to hypoproteinemia, malabsorption, and less frequently, bowel inflammation, recurrent infections, and angiopathic thromboembolic disease; the disorder followed an autosomal recessive pattern of inheritance. Whole-exome sequencing was performed to identify gene variants. We evaluated the function of CD55 in patients' cells, which we confirmed by means of exogenous induction of expression of CD55. RESULTS: We identified homozygous loss-of-function mutations in the gene encoding CD55 (decay-accelerating factor), which lead to loss of protein expression. Patients' T lymphocytes showed increased complement activation causing surface deposition of complement and the generation of soluble C5a. Costimulatory function and cytokine modulation by CD55 were defective. Genetic reconstitution of CD55 or treatment with a complement-inhibitory therapeutic antibody reversed abnormal complement activation. CONCLUSIONS: CD55 deficiency with hyperactivation of complement, angiopathic thrombosis, and protein-losing enteropathy (the CHAPLE syndrome) is caused by abnormal complement activation due to biallelic loss-of-function mutations in CD55. (Funded by the National Institute of Allergy and Infectious Diseases and others.).


Assuntos
Antígenos CD55/genética , Ativação do Complemento/genética , Proteínas do Sistema Complemento/metabolismo , Mutação , Enteropatias Perdedoras de Proteínas/genética , Trombose/genética , Antígenos CD55/sangue , Criança , Pré-Escolar , Ativação do Complemento/efeitos dos fármacos , Inativadores do Complemento/farmacologia , Feminino , Homozigoto , Humanos , Imunoglobulina A/sangue , Lactente , Intestino Delgado/patologia , Masculino , Linhagem , Enteropatias Perdedoras de Proteínas/complicações , Estatísticas não Paramétricas , Síndrome , Linfócitos T/metabolismo
9.
J Exp Med ; 214(1): 91-106, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-28011864

RESUMO

In this study, we describe four patients from two unrelated families of different ethnicities with a primary immunodeficiency, predominantly manifesting as susceptibility to Epstein-Barr virus (EBV)-related diseases. Three patients presented with EBV-associated Hodgkin's lymphoma and hypogammaglobulinemia; one also had severe varicella infection. The fourth had viral encephalitis during infancy. Homozygous frameshift or in-frame deletions in CD70 in these patients abolished either CD70 surface expression or binding to its cognate receptor CD27. Blood lymphocyte numbers were normal, but the proportions of memory B cells and EBV-specific effector memory CD8+ T cells were reduced. Furthermore, although T cell proliferation was normal, in vitro-generated EBV-specific cytotoxic T cell activity was reduced because of CD70 deficiency. This reflected impaired activation by, rather than effects during killing of, EBV-transformed B cells. Notably, expression of 2B4 and NKG2D, receptors implicated in controlling EBV infection, on memory CD8+ T cells from CD70-deficient individuals was reduced, consistent with their impaired killing of EBV-infected cells. Thus, autosomal recessive CD70 deficiency is a novel cause of combined immunodeficiency and EBV-associated diseases, reminiscent of inherited CD27 deficiency. Overall, human CD70-CD27 interactions therefore play a nonredundant role in T and B cell-mediated immunity, especially for protection against EBV and humoral immunity.


Assuntos
Linfócitos B/imunologia , Ligante CD27/deficiência , Infecções por Vírus Epstein-Barr/complicações , Doença de Hodgkin/etiologia , Síndromes de Imunodeficiência/complicações , Adolescente , Adulto , Ligante CD27/genética , Linfócitos T CD8-Positivos/imunologia , Criança , Citotoxicidade Imunológica , Feminino , Herpesvirus Humano 4/imunologia , Humanos , Memória Imunológica , Masculino , Mutação , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/fisiologia
10.
Nat Genet ; 48(12): 1564-1569, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27749843

RESUMO

Elevated basal serum tryptase levels are present in 4-6% of the general population, but the cause and relevance of such increases are unknown. Previously, we described subjects with dominantly inherited elevated basal serum tryptase levels associated with multisystem complaints including cutaneous flushing and pruritus, dysautonomia, functional gastrointestinal symptoms, chronic pain, and connective tissue abnormalities, including joint hypermobility. Here we report the identification of germline duplications and triplications in the TPSAB1 gene encoding α-tryptase that segregate with inherited increases in basal serum tryptase levels in 35 families presenting with associated multisystem complaints. Individuals harboring alleles encoding three copies of α-tryptase had higher basal serum levels of tryptase and were more symptomatic than those with alleles encoding two copies, suggesting a gene-dose effect. Further, we found in two additional cohorts (172 individuals) that elevated basal serum tryptase levels were exclusively associated with duplication of α-tryptase-encoding sequence in TPSAB1, and affected individuals reported symptom complexes seen in our initial familial cohort. Thus, our findings link duplications in TPSAB1 with irritable bowel syndrome, cutaneous complaints, connective tissue abnormalities, and dysautonomia.


Assuntos
Dor Crônica/genética , Doenças do Tecido Conjuntivo/genética , Variações do Número de Cópias de DNA/genética , Disautonomia Familiar/genética , Gastroenteropatias/genética , Prurido/genética , Dermatopatias/genética , Triptases/sangue , Triptases/genética , Adolescente , Adulto , Idoso , Criança , Dor Crônica/sangue , Dor Crônica/enzimologia , Doenças do Tecido Conjuntivo/sangue , Doenças do Tecido Conjuntivo/enzimologia , Disautonomia Familiar/sangue , Disautonomia Familiar/enzimologia , Feminino , Gastroenteropatias/sangue , Gastroenteropatias/enzimologia , Humanos , Masculino , Pessoa de Meia-Idade , Prurido/sangue , Prurido/enzimologia , Dermatopatias/sangue , Dermatopatias/enzimologia , Adulto Jovem
11.
Nat Med ; 21(7): 719-29, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26121196

RESUMO

The cytokine interleukin-12 (IL-12) was thought to have a central role in T cell-mediated responses in inflammation for more than a decade after it was first identified. Discovery of the cytokine IL-23, which shares a common p40 subunit with IL-12, prompted efforts to clarify the relative contribution of these two cytokines in immune regulation. Ustekinumab, a therapeutic agent targeting both cytokines, was recently approved to treat psoriasis and psoriatic arthritis, and related agents are in clinical testing for a variety of inflammatory disorders. Here we discuss the therapeutic rationale for targeting these cytokines, the unintended consequences for host defense and tumor surveillance and potential ways in which these therapies can be applied to treat additional immune disorders.


Assuntos
Imunidade , Inflamação/imunologia , Interleucina-12/metabolismo , Interleucina-23/metabolismo , Terapia de Alvo Molecular , Animais , Humanos , Vigilância Imunológica , Inflamação/patologia , Interleucina-12/antagonistas & inibidores , Interleucina-23/antagonistas & inibidores
12.
Nature ; 477(7365): 482-5, 2011 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-21938067

RESUMO

Overexpression of sirtuins (NAD(+)-dependent protein deacetylases) has been reported to increase lifespan in budding yeast (Saccharomyces cerevisiae), Caenorhabditis elegans and Drosophila melanogaster. Studies of the effects of genes on ageing are vulnerable to confounding effects of genetic background. Here we re-examined the reported effects of sirtuin overexpression on ageing and found that standardization of genetic background and the use of appropriate controls abolished the apparent effects in both C. elegans and Drosophila. In C. elegans, outcrossing of a line with high-level sir-2.1 overexpression abrogated the longevity increase, but did not abrogate sir-2.1 overexpression. Instead, longevity co-segregated with a second-site mutation affecting sensory neurons. Outcrossing of a line with low-copy-number sir-2.1 overexpression also abrogated longevity. A Drosophila strain with ubiquitous overexpression of dSir2 using the UAS-GAL4 system was long-lived relative to wild-type controls, as previously reported, but was not long-lived relative to the appropriate transgenic controls, and nor was a new line with stronger overexpression of dSir2. These findings underscore the importance of controlling for genetic background and for the mutagenic effects of transgene insertions in studies of genetic effects on lifespan. The life-extending effect of dietary restriction on ageing in Drosophila has also been reported to be dSir2 dependent. We found that dietary restriction increased fly lifespan independently of dSir2. Our findings do not rule out a role for sirtuins in determination of metazoan lifespan, but they do cast doubt on the robustness of the previously reported effects of sirtuins on lifespan in C. elegans and Drosophila.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiologia , Proteínas de Drosophila/genética , Drosophila melanogaster/fisiologia , Histona Desacetilases/genética , Longevidade/fisiologia , Sirtuínas/genética , Envelhecimento/genética , Envelhecimento/fisiologia , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Restrição Calórica , Cruzamentos Genéticos , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Feminino , Expressão Gênica , Histona Desacetilases/metabolismo , Longevidade/genética , Masculino , RNA Mensageiro/análise , RNA Mensageiro/genética , Sirtuínas/metabolismo
13.
Mol Syst Biol ; 6: 399, 2010 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-20706209

RESUMO

Insulin/IGF-1 signaling controls metabolism, stress resistance and aging in Caenorhabditis elegans by regulating the activity of the DAF-16/FoxO transcription factor (TF). However, the function of DAF-16 and the topology of the transcriptional network that it crowns remain unclear. Using chromatin profiling by DNA adenine methyltransferase identification (DamID), we identified 907 genes that are bound by DAF-16. These were enriched for genes showing DAF-16-dependent upregulation in long-lived daf-2 insulin/IGF-1 receptor mutants (P=1.4e(-11)). Cross-referencing DAF-16 targets with these upregulated genes (daf-2 versus daf-16; daf-2) identified 65 genes that were DAF-16 regulatory targets. These 65 were enriched for signaling genes, including known determinants of longevity, but not for genes specifying somatic maintenance functions (e.g. detoxification, repair). This suggests that DAF-16 acts within a relatively small transcriptional subnetwork activating (but not suppressing) other regulators of stress resistance and aging, rather than directly regulating terminal effectors of longevity. For most genes bound by DAF-16::DAM, transcriptional regulation by DAF-16 was not detected, perhaps reflecting transcriptionally non-functional TF 'parking sites'. This study demonstrates the efficacy of DamID for chromatin profiling in C. elegans.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/fisiologia , Fatores de Transcrição Forkhead/metabolismo , Perfilação da Expressão Gênica/métodos , Longevidade/fisiologia , DNA Metiltransferases Sítio Específica (Adenina-Específica)/metabolismo , Fatores de Transcrição/metabolismo , Animais , Sítios de Ligação , Cromatina/metabolismo , Metilação de DNA , Regulação da Expressão Gênica no Desenvolvimento , Longevidade/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
14.
Genes Dev ; 22(23): 3236-41, 2008 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-19056880

RESUMO

The superoxide radical (O(2)(-)) has long been considered a major cause of aging. O(2)(-) in cytosolic, extracellular, and mitochondrial pools is detoxified by dedicated superoxide dismutase (SOD) isoforms. We tested the impact of each SOD isoform in Caenorhabditis elegans by manipulating its five sod genes and saw no major effects on life span. sod genes are not required for daf-2 insulin/IGF-1 receptor mutant longevity. However, loss of the extracellular Cu/ZnSOD sod-4 enhances daf-2 longevity and constitutive diapause, suggesting a signaling role for sod-4. Overall, these findings imply that O(2)(-) is not a major determinant of aging in C. elegans.


Assuntos
Envelhecimento , Caenorhabditis elegans/metabolismo , Estresse Oxidativo , Superóxido Dismutase/genética , Superóxidos/metabolismo , Animais , Caenorhabditis elegans/fisiologia , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/fisiologia , Deleção de Genes , Isoenzimas/fisiologia , Expectativa de Vida , Modelos Biológicos , Receptor de Insulina/fisiologia , Superóxido Dismutase/fisiologia
15.
Genetics ; 178(2): 931-46, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18245374

RESUMO

The DAF-2 insulin/IGF-1 receptor regulates development, metabolism, and aging in the nematode Caenorhabditis elegans. However, complex differences among daf-2 alleles complicate analysis of this gene. We have employed epistasis analysis, transcript profile analysis, mutant sequence analysis, and homology modeling of mutant receptors to understand this complexity. We define an allelic series of nonconditional daf-2 mutants, including nonsense and deletion alleles, and a putative null allele, m65. The most severe daf-2 alleles show incomplete suppression by daf-18(0) and daf-16(0) and have a range of effects on early development. Among weaker daf-2 alleles there exist distinct mutant classes that differ in epistatic interactions with mutations in other genes. Mutant sequence analysis (including 11 newly sequenced alleles) reveals that class 1 mutant lesions lie only in certain extracellular regions of the receptor, while class 2 (pleiotropic) and nonconditional missense mutants have lesions only in the ligand-binding pocket of the receptor ectodomain or the tyrosine kinase domain. Effects of equivalent mutations on the human insulin receptor suggest an altered balance of intracellular signaling in class 2 alleles. These studies consolidate and extend our understanding of the complex genetics of daf-2 and its underlying molecular biology.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Insulina/genética , Receptor IGF Tipo 1/genética , Receptor de Insulina/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Dados de Sequência Molecular , Família Multigênica , Mutação , Filogenia
16.
Genome Biol ; 8(7): R132, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17612391

RESUMO

BACKGROUND: To what extent are the determinants of aging in animal species universal? Insulin/insulin-like growth factor (IGF)-1 signaling (IIS) is an evolutionarily conserved (public) regulator of longevity; yet it remains unclear whether the genes and biochemical processes through which IIS acts on aging are public or private (that is, lineage specific). To address this, we have applied a novel, multi-level cross-species comparative analysis to compare gene expression changes accompanying increased longevity in mutant nematodes, fruitflies and mice with reduced IIS. RESULTS: Surprisingly, there is little evolutionary conservation at the level of individual, orthologous genes or paralogous genes under IIS regulation. However, a number of gene categories are significantly enriched for genes whose expression changes in long-lived animals of all three species. Down-regulated categories include protein biosynthesis-associated genes. Up-regulated categories include sugar catabolism, energy generation, glutathione-S-transferases (GSTs) and several other categories linked to cellular detoxification (that is, phase 1 and phase 2 metabolism of xenobiotic and endobiotic toxins). Protein biosynthesis and GST activity have recently been linked to aging and longevity assurance, respectively. CONCLUSION: These processes represent candidate, regulated mechanisms of longevity-control that are conserved across animal species. The longevity assurance mechanisms via which IIS acts appear to be lineage-specific at the gene level (private), but conserved at the process level (or semi-public). In the case of GSTs, and cellular detoxification generally, this suggests that the mechanisms of aging against which longevity assurance mechanisms act are, to some extent, lineage specific.


Assuntos
Evolução Molecular , Perfilação da Expressão Gênica , Fator de Crescimento Insulin-Like I/genética , Insulina/genética , Longevidade/genética , Envelhecimento/genética , Animais , Caenorhabditis elegans/genética , Drosophila/genética , Glutationa Transferase/genética , Camundongos , Biossíntese de Proteínas/genética , Transdução de Sinais
17.
Mech Ageing Dev ; 127(5): 458-72, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16522328

RESUMO

The longevity of the Caenorhabditis elegans diapausal dauer larva greatly exceeds that of the adult. Dauer formation and adult ageing are both regulated by insulin/IGF-1 signaling (IIS). Reduced IIS, e.g. by mutation of the daf-2 insulin/IGF-1 receptor gene, increases adult lifespan. This may reflect mis-expression in the adult of dauer longevity-assurance processes. Since IIS plays a central role in the regulation of metabolism, metabolic alterations shared by dauer larvae and daf-2 adults represent candidate mechanisms for lifespan determination. We have conducted a detailed comparison of transcript profile data from dauers and daf-2 mutant adults, focusing on expression of metabolic pathway genes. Our results imply up-regulation in both dauers and daf-2 mutant adults of gluconeogenesis, glyoxylate pathway activity, and trehalose biosynthesis. Down-regulation of the citric acid cycle and mitochondrial respiratory chain occurs in dauers, but not daf-2 adults. However, the F(1) ATPase inhibitor was up-regulated in both, implying enhanced homeostasis in conditions where mitochondria are stressed. Overall, the data implies increased conversion of fat to carbohydrate, and conservation of ATP stocks in daf-2 mutant adults, suggesting a state of increased energy availability. We postulate that this fuels increased somatic maintenance activity, as suggested by the disposable soma theory.


Assuntos
Proteínas de Caenorhabditis elegans/fisiologia , Regulação da Expressão Gênica , Mutação , Receptor de Insulina/fisiologia , Animais , Caenorhabditis elegans , Proteínas de Caenorhabditis elegans/metabolismo , Ácido Cítrico/metabolismo , Ciclo do Ácido Cítrico , Transporte de Elétrons , Fatores de Transcrição Forkhead , Gluconeogênese , Glicólise , Modelos Biológicos , Análise de Sequência com Séries de Oligonucleotídeos , ATPases Translocadoras de Prótons/metabolismo , Receptor de Insulina/metabolismo , Transdução de Sinais , Fatores de Transcrição , Trealose/metabolismo , Triglicerídeos/metabolismo , Regulação para Cima
18.
Mech Ageing Dev ; 127(12): 922-36, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17216712

RESUMO

The longevity of the Caenorhabditis elegans diapausal dauer larva greatly exceeds that of the adult. Dauer formation and adult ageing are both regulated by insulin/IGF-1 signalling (IIS). Reduced IIS, e.g. by mutation of the daf-2 insulin/IGF-1 receptor gene, increases adult lifespan. This may reflect mis-expression in the adult of dauer longevity-assurance processes. Since IIS plays a central role in the regulation of metabolism, metabolic alterations shared by dauer larvae and daf-2 adults represent candidate mechanisms for lifespan determination. We have conducted a detailed comparison of transcript profile data from dauers and daf-2 mutant adults, focusing on expression of metabolic pathway genes. Our results imply up-regulation in both dauers and daf-2 mutant adults of gluconeogenesis, glyoxylate pathway activity, and trehalose biosynthesis. Down-regulation of the citric acid cycle and mitochondrial respiratory chain occurs in dauers, but not daf-2 adults. However, the F1 ATPase inhibitor was up-regulated in both, implying enhanced homeostasis in conditions where mitochondria are stressed. Overall, the data implies increased conversion of fat to carbohydrate, and conservation of ATP stocks in daf-2 mutant adults, suggesting a state of increased energy availability. We postulate that this fuels increased somatic maintenance activity, as suggested by the disposable soma theory.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Metabolismo Energético/genética , Longevidade/genética , Mutação , Receptor de Insulina/genética , Transdução de Sinais/genética , Animais , Larva/genética
19.
Mech Ageing Dev ; 126(3): 381-7, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15664624

RESUMO

Our recent survey of genes regulated by insulin/IGF-1 signaling (IIS) in Caenorhabditis elegans suggests a role for a number of gene classes in longevity assurance. Based on these findings, we propose a model for the biochemistry of longevity assurance and ageing, which is as follows. Ageing results from molecular damage from highly diverse endobiotic toxins. These are stochastic by-products of diverse metabolic processes, of which reactive oxygen species (ROS) are likely to be only one component. Our microarray analysis suggests a major role in longevity assurance of the phase 1, phase 2 detoxification system involving cytochrome P450 (CYP), short-chain dehydrogenase/reductase (SDR) and UDP-glucuronosyltransferase (UGT) enzymes. Unlike superoxide and hydrogen peroxide detoxification, this system is energetically costly, and requires the excretion from the cell of its products. Given such costs, its activity may be selected against, as predicted by the disposable soma theory. CYP and UGT enzymes target lipophilic molecular species; insufficient activity of this system is consistent with age-pigment (lipofuscin) accumulation during ageing. We suggest that IIS-regulated longevity assurance involves: (a) energetically costly detoxification and excretion of molecular rubbish, and (b) conservation of existing proteins via molecular chaperones. Given the emphasis in this theory on investment in cellular waste disposal, and on protein conservation, we have dubbed it the green theory.


Assuntos
Fator de Crescimento Insulin-Like I/fisiologia , Insulina/fisiologia , Longevidade/fisiologia , Transdução de Sinais/fisiologia , Animais , Regulação da Expressão Gênica/fisiologia , Humanos , Longevidade/genética , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/genética
20.
J Biol Chem ; 279(43): 44533-43, 2004 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-15308663

RESUMO

In the nematode Caenorhabditis elegans, formation of the long-lived dauer larva and adult aging are both controlled by insulin/insulin-like growth factor-1 signaling. Potentially, increased adult life span in daf-2 insulin/insulin-like growth factor-1 receptor mutants results from mis-expression in the adult of a dauer larva longevity program. By using oligonucleotide microarray analysis, we identified a dauer transcriptional signature in daf-2 mutant adults. By means of a nonbiased statistical approach, we identified gene classes whose expression is altered similarly in dauers and daf-2 mutants, which represent potential determinants of life span. These include known determinants of longevity; the small heat shock protein/alpha-crystallins are up-regulated in both milieus. The cytochrome P450, short-chain dehydrogenase/reductase, UDP-glucuronosyltransferase, and glutathione S-transferase (in daf-2 mutants) gene classes were also up-regulated. These four gene classes act together in metabolism and excretion of toxic endobiotic and xenobiotic metabolites. This suggests that diverse toxic lipophilic and electrophilic metabolites, disposed of by phase 1 and phase 2 drug metabolism, may be the major determinants of the molecular damage that causes aging. In addition, we observed down-regulation of genes linked to nutrient uptake, including nhx-2 and pep-2. These work together in the uptake of dipeptides in the intestine, implying dietary restriction in daf-2 mutants. Some gene groups up-regulated in dauers and/or daf-2 were enriched for certain promoter elements as follows: the daf-16-binding element, the heat shock-response element, the heat shock-associated sequence, or the hif-1-response element. By contrast, the daf-16-associated element was enriched in genes down-regulated in dauers and daf-2 mutants. Thus, particular promoter elements appear longevity-associated or aging associated.


Assuntos
Proteínas de Caenorhabditis elegans/fisiologia , Receptor de Insulina/fisiologia , Fatores de Transcrição/fisiologia , Transcrição Genética , Envelhecimento , Animais , Caenorhabditis elegans , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Bases de Dados como Assunto , Drosophila , Fatores de Transcrição Forkhead , Regulação da Expressão Gênica , Glutationa Transferase/metabolismo , Longevidade , Modelos Biológicos , Modelos Químicos , Mutação , Análise de Sequência com Séries de Oligonucleotídeos , Oligonucleotídeos/química , Regiões Promotoras Genéticas , RNA/metabolismo , Receptor de Insulina/genética , Transdução de Sinais , Fatores de Tempo , Fatores de Transcrição/genética , Regulação para Cima
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