RESUMO
BACKGROUND: DNA polymerase ß is one of the key enzymes involved in the repair of DNA damage, and its high or low expression is closely related to tumorigenesis. In a previous study on lung cancer, we found three genetic mutations in the promoter region of the Polb gene could be detected in the Han Chinese population. The purpose of this study was to explore the relationship between these mutations and thymic hyperplasia. METHODS: Genomic DNA was extracted from 59 thymic hyperplasia patients by the salting out method and used for amplification of the promoter region of the Polb gene. The Polb gene mutation and its frequency were analyzed systematically by comparing them with the deposited wild-type gene sequence in the NCBI database. The three typical mutated sequences in the promoter region of Polb gene, -196G > T, -168C > A and -188_-187insCGCCC, were then amplified and ligated to pGL4.10 vector, so as to get the vectors used for the infection of 293T cells to explore their transcription activities by dual-luciferase reporter system. RESULTS: Two types of mutations, -168C>A and-188_-187insCGCCC, were found in a significantly higher percentage in patients with thymic hyperplasia than in normal healthy people after sequencing analysis of 59 patients and 60 healthy controls. These results suggest that the two mutations may be closely related to thymic hyperplasia. in vitro functional experiments showed that-168C>A could significantly increase promoter activity, whereas -188_-187insCGCCC could significantly reduce promoter activity, suggesting that these two mutations may affect the expression level of the Polb gene in cells. CONCLUSIONS: Two types of mutations in the promoter region of the Polb gene, -168C>A and-188_-187insCGCCC, are associated with thymic hyperplasia and may become a new risk factor for this disease. KEY POINTS: SIGNIFICANT FINDINGS OF THE STUDY: Genetic mutations in the Polb gene are reported to be associated with different kinds of cancers. However, their relationship with thymic hyperplasia is still unclear. WHAT THIS STUDY ADDS: For the first time, we report that two nucleotide mutations in the promoter region of the Polb gene are closely related with thymic hyperplasia after sequencing 59 patients and 60 healthy controls in the Han Chinese population.
Assuntos
DNA Polimerase beta/genética , Hiperplasia do Timo/genética , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Hiperplasia do Timo/patologia , Adulto JovemRESUMO
Medullary thyroid carcinoma (MTC) develops from hyperplasia of thyroid C cells and represents one of the major causes of thyroid cancer mortality. Mutations in the cysteine-rich domain (CRD) of the RET gene are the most prevalent genetic cause of MTC. The current consensus holds that such cysteine mutations cause ligand-independent dimerization and constitutive activation of RET. However, given the number of the CRD mutations left uncharacterized, our understanding of the pathogenetic mechanisms by which CRD mutations lead to MTC remains incomplete. We report here that RET(C618F), a mutation identified in MTC patients, displays moderately high basal activity and requires the ligand for its full activation. To assess the biological significance of RET(C618F) in organogenesis, we generated a knock-in mouse line conditionally expressing RET(C618F) cDNA by the Ret promoter. The RET(C618F) allele can be made to be Ret-null and express mCherry by Cre-loxP recombination, which allows the assessment of the biological influence of RET(C618F) in vivo. Mice expressing RET(C618F) display mild C cell hyperplasia and increased numbers of enteric neurons, indicating that RET(C618F) confers gain-of-function phenotypes. This mouse line serves as a novel biological platform for investigating pathogenetic mechanisms involved in MTC and enteric hyperganglionosis.
Assuntos
Carcinoma Neuroendócrino/genética , Proteínas Proto-Oncogênicas c-ret/genética , Neoplasias da Glândula Tireoide/genética , Animais , Carcinoma Neuroendócrino/metabolismo , Linhagem Celular Tumoral , Sistema Nervoso Entérico/metabolismo , Sistema Nervoso Entérico/patologia , Técnicas de Introdução de Genes/métodos , Mutação em Linhagem Germinativa , Humanos , Hiperplasia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Doenças do Sistema Nervoso/genética , Doenças do Sistema Nervoso/metabolismo , Doenças do Sistema Nervoso/patologia , Proteínas Proto-Oncogênicas c-ret/biossíntese , Proteínas Proto-Oncogênicas c-ret/metabolismo , Hiperplasia do Timo/genética , Hiperplasia do Timo/metabolismo , Glândula Tireoide/metabolismo , Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/metabolismoRESUMO
BACKGROUND: Myasthenia Gravis (MG) is caused, in approximately 80% of the patients, by autoantibodies against the nicotinic acetylcholine receptor (AChR). The disease is often associated with pathological changes of the thymus: thymic epithelial tumours are present in about 10-20% of the patients, while up to 80% of the patients with early disease onset have thymic hyperplasia. Folate metabolism is required for the production of DNA precursors and for proper DNA methylation reactions, and impaired folate metabolism has been often associated with cellular growth and cancer. METHODS: We investigated if major polymorphisms of folate-related genes, namely MTHFR c.677C>T, MTR c.2756A>G, MTRR c.66A>G and TYMS TSER (a 28-bp tandem repeat in the 5' promoter enhancer region of TYMS) increase the risk of pathological changes of the thymus in AChR+ MG patients. A total of 526 AChR+ MG patients, including 132 patients with normal (involuted) thymus, 146 patients with thymic hyperplasia, and 248 patients with a thymoma were included in the study. Allele and genotype comparisons were performed among the three study groups, after correcting for multiple testing. RESULTS: The frequency of the TYMS TSER 3R allele was significantly higher in MG patients with thymic hyperplasia (P=0.004), and the TYMS TSER 3R3R genotype was significantly associated with increased risk of thymic hyperplasia [OR 2.71 (95% CI: 1.34-5.47)]. CONCLUSIONS: The 3R allele in the thymidylate synthase promoter enhancer region results in increased protein production, required for the synthesis of DNA precursors. The present study suggests that the TYMS TSER 3R allele increases the risk of thymic lymphoid hyperplasia in AChR+ MG patients.
Assuntos
Elementos Facilitadores Genéticos , Miastenia Gravis/complicações , Polimorfismo de Nucleotídeo Único , Timidilato Sintase/genética , Hiperplasia do Timo/genética , 5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/genética , Adulto , Idoso , Feminino , Ferredoxina-NADP Redutase/genética , Predisposição Genética para Doença , Humanos , Masculino , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Pessoa de Meia-Idade , Miastenia Gravis/genética , Miastenia Gravis/metabolismo , Regiões Promotoras Genéticas , Receptores Nicotínicos/metabolismo , Hiperplasia do Timo/etiologia , Hiperplasia do Timo/metabolismoRESUMO
CCDC6 was originally identified upon rearrangement with RET in human thyroid papillary carcinomas generating the RET/PTC1 oncogene. We have previously reported that CCDC6 interacts with CREB1 and represses its transcriptional activity. Since the function of at least one allele of CCDC6 is lost following RET/PTC1 rearrangements, we aimed at the generation of mice, carrying a CCDC6 mutant gene. Previous studies suggested that the coiled-coil domain of CCDC6, mainly encoded by human exon 2, is required for the protein function. Therefore, we engineered a murine Ccdc6 construct, carrying a deletion of the exon 2, that was able to exert only a mild repression on CREB1 transcriptional activity, with respect to the wild type Ccdc6. Subsequently, we generated Ccdc6-ex2 knock-in mice. These mice developed thyroid hyperplasia associated with an enhanced CREB1 activity and an increased expression of the CREB-1 regulated genes. These results strongly support a CCDC6 promoting role, ascribed to its functional impairment, in the development of thyroid papillary carcinomas harboring the RET/PTC1 oncogene.
Assuntos
Carcinoma/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteínas do Citoesqueleto/metabolismo , Hiperplasia do Timo/genética , Neoplasias da Glândula Tireoide/genética , Animais , Apoptose/genética , Carcinoma Papilar , Proliferação de Células/genética , Células Cultivadas , Proteínas do Citoesqueleto/genética , Ensaio de Desvio de Mobilidade Eletroforética , Fibroblastos , Técnicas de Inativação de Genes , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas de Fusão Oncogênica/genética , Receptores Patched , Receptor Patched-1 , Proteínas Proto-Oncogênicas c-ret/genética , Receptores de Superfície Celular/genética , Deleção de Sequência/genética , Câncer Papilífero da Tireoide , Glândula Tireoide/patologia , Transcrição Gênica/genéticaRESUMO
OBJECTIVE: Myasthenia gravis (MG), a neuromuscular disease mediated by anti-acetylcholine receptor (AChR) autoantibodies, is associated with thymic hyperplasia characterized by ectopic germinal centers that contain pathogenic antibody-producing B cells. Our thymic transcriptome study demonstrated increased expression of CCL21, a recruiter of immune cells. Accordingly, we are investigating its implication in MG pathogenesis. METHODS: The expression of CCL21 and its CCR7 receptor was analyzed by enzyme-linked immunosorbent assay and fluorescence-activated cell sorting, respectively. Chemotaxis of T and B cells to CCL21 was measured by transwell assay. The nature of the thymic cells overexpressing CCL21 was investigated by immunochemistry and laser-capture microdissection combined with real-time PCR. RESULTS: We demonstrate that CCL21 is overexpressed specifically in hyperplastic MG thymuses, whereas there is no variation in CCR7 levels on blood cells. We show that although CCL21 attracts both human T and B cells, it acts more strongly on naive B cells. CCL21 overexpression is normalized in corticoid-treated MG patients, suggesting that targeting this chemokine could represent a new selective treatment, decreasing the abnormal peripheral lymphocyte recruitment. Moreover, we locate protein and messenger RNA overexpression of CCL21 to specific endothelial vessels. Investigation of the nature of these vessels demonstrated different angiogenic processes in MG thymuses: high endothelial venule angiogenesis and lymphangiogenesis. Unexpectedly, CCL21 overexpression originates from afferent lymphatic endothelial vessels. INTERPRETATION: We postulate that thymic overexpression of CCL21 on specialized lymphatic vessels results in abnormal peripheral lymphocyte recruitment, bringing naive B cells in contact with the inflammatory environment characteristic of MG thymuses, where they can be sensitized against AChR.
Assuntos
Quimiocina CCL21/biossíntese , Regulação da Expressão Gênica/fisiologia , Vasos Linfáticos/metabolismo , Miastenia Gravis/metabolismo , Hiperplasia do Timo/metabolismo , Adolescente , Adulto , Autoanticorpos/biossíntese , Autoanticorpos/sangue , Subpopulações de Linfócitos B/metabolismo , Subpopulações de Linfócitos B/patologia , Diferenciação Celular/genética , Quimiocina CCL21/genética , Quimiocina CCL21/fisiologia , Quimiotaxia de Leucócito/genética , Feminino , Humanos , Lactente , Recém-Nascido , Vasos Linfáticos/patologia , Miastenia Gravis/genética , Miastenia Gravis/patologia , Hiperplasia do Timo/genética , Hiperplasia do Timo/patologia , Adulto JovemRESUMO
IFN-gamma(-/-)NOD.H-2h4 mice given 0.05% NaI in their water develop severe thyroid epithelial cell (thyrocyte) hyperplasia and proliferation (TEC H/P) and fibrosis. Proliferating thyrocytes of IFN-gamma(-/-) mice with TEC H/P produce TGF-beta as demonstrated by immunohistochemical staining and in situ hybridization. Strong expression of activating phosphorylated Smad-2/3 and weak expression of inhibitory Smad-7 by proliferating thyrocytes correlate with the severity of TEC H/P. Splenocytes from IFN-gamma(-/-) mice with severe TEC H/P transfer severe TEC H/P to IFN-gamma(-/-)NOD.H-2h4.SCID mice. Mice given anti-TGF-beta had markedly reduced thyrocyte proliferation and decreased fibrosis compared with mouse Ig-treated controls, suggesting that TGF-beta plays an important role in development of TEC H/P induced by activated splenocytes. Moreover, transgenic IFN-gamma(-/-)NOD.H-2h4 mice expressing TGF-beta on thyrocytes all develop fibrosis and moderate to severe TEC H/P with accelerated kinetics, directly demonstrating a role for TGF-beta in severe TEC H/P and fibrosis.
Assuntos
Células Epiteliais/metabolismo , Interferon gama/deficiência , Interferon gama/metabolismo , Hiperplasia do Timo/metabolismo , Hiperplasia do Timo/patologia , Fator de Crescimento Transformador beta/metabolismo , Animais , Anticorpos/imunologia , Proliferação de Células , Células Epiteliais/citologia , Fibrose/genética , Fibrose/metabolismo , Fibrose/patologia , Interferon gama/genética , Camundongos , Camundongos Endogâmicos NOD , Camundongos Knockout , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Receptor do Fator de Crescimento Transformador beta Tipo II , Receptores de Fatores de Crescimento Transformadores beta/metabolismo , Proteína Smad2/metabolismo , Proteína Smad3/metabolismo , Baço/imunologia , Baço/metabolismo , Hiperplasia do Timo/genética , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/imunologiaRESUMO
Tumor suppressor p53 is essential for checkpoint control in response to a variety of genotoxic stresses. DNA damage leads to phosphorylation on the Ser/Thr-Pro motifs of p53, which facilitates interaction with Pin1, a pSer/pThr-Pro-specific peptidyl prolyl isomerase. Pin1 is required for the timely activation of p53, resulting in apoptosis or cell cycle arrest. To investigate the physiological relationship between Pin1 and p53, we created Pin1-/-p53-/- mice. These p53-deficient mice spontaneously developed lymphomas, mainly of thymic origin, as well as generalized lymphoma infiltration into other organs, including the liver, kidneys and lungs. Ablation of Pin1, in addition to p53, accelerated the thymic hyperplasia, but the thymocytes in these Pin1-/-p53-/- mice did not infiltrate other organs. The thymocytes in 12-week-old Pin1-/-p53-/- mice were CD4(-)CD8(-) (double negative) and had significantly higher levels of the intracellular form of Notch1 (NIC) than the thymocytes of p53-/- or wild-type mice. Presenilin-1, a cleavage enzyme for NIC generation from full-length Notch1 was increased in the thymocytes of Pin1-/-p53-/- mice. Pin1 depletion also inhibited the degradation of NIC by proteasomes. These results suggest that both Pin1 and p53 control the normal proliferation and differentiation of thymocytes by regulating the NIC level.
Assuntos
Peptidilprolil Isomerase/deficiência , Receptor Notch1/metabolismo , Linfócitos T/metabolismo , Hiperplasia do Timo/metabolismo , Proteína Supressora de Tumor p53/deficiência , Animais , Western Blotting , Feminino , Citometria de Fluxo , Líquido Intracelular/química , Masculino , Camundongos , Camundongos Knockout , Peptidilprolil Isomerase de Interação com NIMA , Presenilina-1/metabolismo , Linfócitos T/imunologia , Hiperplasia do Timo/genética , Hiperplasia do Timo/patologia , Proteína Supressora de Tumor p53/genéticaRESUMO
OBJECTIVE: To present the prenatal diagnosis of an interstitial 22q11.2 deletion involving a ring 22 chromosome associated with truncus arteriosus and a hypoplastic thymus. CASE: Following the sonographic diagnosis of a cystic hygroma at 12 weeks of gestation, chromosome analysis revealed a ring 22 chromosome. RESULTS: Ring chromosomes typically result in the deletion of genetic material from the distal long and short arms of the affected chromosome. The presence of an interstitial deletion in a ring chromosome is therefore unusual. FISH analysis revealed an unexpected deletion involving the TUPLE1 gene in the DiGeorge/Velocardiofacial syndrome region in 22q11.2. Maternal chromosome analysis revealed the cause of the apparent interstitial deletion, a paracentric inversion in the long arm of chromosome 22, resulting in the distal long arm of 22q being located adjacent to the centromere and the proximal end being located near the telomere. The fetus was subsequently diagnosed with truncus arteriosus and a hypoplastic thymus, consistent with DiGeorge syndrome. CONCLUSION: The ring chromosome 22 found in the fetus appears to have been derived from a rearrangement of the mother's inverted 22, resulting in ring formation and loss of the end of the distal long arm of the inverted 22, including the TUPLE1 locus, causing DiGeorge syndrome in the fetus. The apparent interstitial deletion was actually a terminal deletion in a maternally inherited rearranged chromosome 22.
Assuntos
Anormalidades Múltiplas , Aberrações Cromossômicas , Cromossomos Humanos Par 22/genética , Hiperplasia do Timo/genética , Persistência do Tronco Arterial/genética , Aborto Eugênico , Adolescente , Amostra da Vilosidade Coriônica , Deleção Cromossômica , Inversão Cromossômica , Evolução Fatal , Feminino , Humanos , Hibridização in Situ Fluorescente , Linfangioma Cístico/diagnóstico por imagem , Linfangioma Cístico/embriologia , Gravidez , Complicações na Gravidez , Cromossomos em Anel , Cariotipagem Espectral , Persistência do Tronco Arterial/patologia , Ultrassonografia Pré-NatalRESUMO
Myasthenia gravis (MG) is an autoimmune disease mainly caused by antiacetylcholine receptor autoantibodies (seropositive (SP) disease) or by Abs against unknown autoantigenic target(s) (seronegative (SN) disease). Thymectomy is usually beneficial although thymic hyperplasia with ectopic germinal centers is mainly observed in SP MG. To understand the role of thymus in the disease process, we compared the thymic transcriptome of non-MG adults to those of SP patients with a low or high degree of hyperplasia or SN patients. Surprisingly, an overexpression of MHC class II, Ig, and B cell marker genes is observed in SP but also SN MG patients. Moreover, we demonstrate an overexpression of CXCL13 in all MG thymuses leading probably to the generalized B cell infiltration. However, we find different chemotactic properties for MG subgroups and, especially, a specific overexpression of CCL21 in hyperplastic thymuses triggering most likely ectopic germinal center development. Besides, SN patients present a peculiar signature with an abnormal expression of genes involved in muscle development and synaptic transmission, but also genes implicated in host response, suggesting that viral infection might be related to SN MG. Altogether, these results underline differential pathogenic mechanisms in the thymus of SP and SN MG and propose new research areas.
Assuntos
Quimiocinas CC/metabolismo , Expressão Gênica , Miastenia Gravis/genética , Timo/fisiologia , Hiperplasia do Timo/genética , Adulto , Autoanticorpos/sangue , Quimiocina CCL21 , Feminino , Perfilação da Expressão Gênica , Humanos , Masculino , Miastenia Gravis/sangue , Miastenia Gravis/imunologia , Análise de Sequência com Séries de Oligonucleotídeos , Hiperplasia do Timo/sangue , Hiperplasia do Timo/imunologiaRESUMO
Anti-CV2 antibodies (AB) react with the developmentally regulated neural proteins CRMPs and particularly with CRMP5. They occur with small cell lung cancer (SCLC) and thymoma. SCLCs universally express CRMP5. We investigated the expression of CRMPs in thymoma and thymus. In thymoma, none of the CRMPs were detected by immunohistochemistry in tumorous epithelial cells with specific antibodies including CRMP5 but an antibody reacting with a peptide common to the CRMPs labeled a 66-kDa protein in Western blot of rat brain, thymus, and thymoma extracts. Thus, the normal CRMP5 is probably not expressed by tumorous epithelial cells. These results indicate that the mechanisms leading to CRMP5 autoimmunization are different in SCLC and thymoma.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Expressão Gênica/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Timoma/metabolismo , Timo/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Animais Recém-Nascidos , Northern Blotting/métodos , Western Blotting/métodos , Cerebelo/metabolismo , Humanos , Hidrolases , Imuno-Histoquímica/métodos , Proteínas Associadas aos Microtúbulos , Proteínas do Tecido Nervoso/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Timoma/genética , Hiperplasia do Timo/genética , Hiperplasia do Timo/patologiaRESUMO
OBJECTIVE: To study the genetic pathogenesis of myasthenia gravis (MG) caused by cytotoxic T lymphocyte associated antigen-4 (CTLA-4) gene polymorphisms and regulation function of transcription factor. METHODS: ELISA assay was used to determine the expression level of serum sCTLA-4 in MG. Four single nucleotide polymorphisms (SNPs) of CTLA-4 at exon 1 +49, promoter -318, -1661, -1772 were analyzed by restriction fragment length polymorphism (RFLP). Transcription factor nuclear factor 1(NF-1) and c/EBPbeta binding site were confirmed by chromatin immunoprecipitation(CHIP) assay. RESULTS: It was found that the frequencies of the GG+49 genotype and G+49 allele are higher in MG patients with thymoma than those in patients of thymic hyperplasia and normal thymus subgroups. T/C-318 is not correlated with MG. The frequency of CT-1772 genotype is significantly higher in MG patients, especially in MG patients with thymoma, when compared with that in healthy controls. Meanwhile, the frequency of the G-1661 allele and GG-1661 genotype is lower in MG patients. Linkage disequilibrium (LD) between each SNPs in promoter -1772, -1661, -318 and coding sequence 1 (CDS 1) +49 is apparent. sCTLA-4 levels in patients' sera are correlated with the haplotype and genotype. T/C-1772 and A/G-1661 SNPs change the sequence of transcription factor NF-1 and c/EBPbeta binding sites. DNA variants lose site-specific binding activity of transcription factor regulated by lectin ConA and PHA. CONCLUSION: There are strong positive linkages among four SNPs. C/T-1772 and A/G-1661 polymorphisms can result in inefficient transcription of CTLA-4 gene. T>C-1772 mutation also affects gene splicing. These SNPs may constitute a factor of susceptibility to disease.
Assuntos
Antígenos de Diferenciação/genética , Miastenia Gravis/genética , Polimorfismo de Nucleotídeo Único , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígenos CD , Antígenos de Diferenciação/sangue , Proteína beta Intensificadora de Ligação a CCAAT/genética , Proteínas Estimuladoras de Ligação a CCAAT/genética , Antígeno CTLA-4 , Éxons , Feminino , Frequência do Gene , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Miastenia Gravis/imunologia , Fatores de Transcrição NFI , Mutação Puntual , Polimorfismo de Fragmento de Restrição , Regiões Promotoras Genéticas , Timoma/genética , Hiperplasia do Timo/genética , Neoplasias do Timo/genética , Fatores de Transcrição/genéticaRESUMO
The cytotoxic T lymphocyte associated protein 4 (CTLA-4) gene (Ctla-4) is a candidate gene for autoimmune disease. We here report results of two single nucleotide polymorphisms (SNPs) in the Ctla-4, a +49 A/G SNP in CDS1 and a C/T promoter SNP at position -318. There were no differences in these two SNPs between patients and healthy individuals. The frequency of allele G and genotype G/G at position +49 in CDS1 was increased in patients with thymoma when compared with patients with normal and hyperplastic thymic histopathology. Patients with the G/G genotype had signs of immune activation manifested as higher levels of serum IL-1beta and higher percentage of CD28(+) T lymphocytes. There was a strong linkage between the 86bp allele in the 3'-UTR and the A(+49) allele in CDS1. Our results suggest that the SNP at position +49 in CDS1 might be associated with the manifestations of MG.
Assuntos
Antígenos de Diferenciação/genética , Imunoconjugados , Miastenia Gravis/genética , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas , Regiões 3' não Traduzidas , Abatacepte , Antígenos CD , Antígenos CD28/análise , Antígeno CTLA-4 , Feminino , Frequência do Gene , Genótipo , Humanos , Interleucina-1/sangue , Interleucina-12/sangue , Desequilíbrio de Ligação , Masculino , Miastenia Gravis/imunologia , Suécia , Linfócitos T/imunologia , Timoma/genética , Hiperplasia do Timo/genética , Neoplasias do Timo/genéticaRESUMO
In the thymus, the relationship between lymphofollicular hyperplasia and mucosa-associated lymphoid tissue (MALT)-type lymphoma is uncertain. We analyzed 14 cases with a diagnosis of thymic follicular hyperplasia in patients with connective tissue disease (n = 2), myasthenia gravis (n = 11), or both (n = 1). In 11 cases, well-defined reactive lymphoid follicles were surrounded by a continuous layer of medullary epithelial cells. A polyclonal rearrangement of the immunoglobulin heavy chain gene (IgH) was observed. In 3 cases, ill-defined lymphoid follicles with sheets of centrocytic-like B cells disrupting the medullary cytokeratin epithelial network were observed on certain sections. These cells expressed the phenotypic features of memory B cells with CD20, CD79a, and bcl-2 positivity and CD5, CD10, CD23, and bcl-6 negativity, and a monoclonal rearrangement of the IgH gene was detected. Appropriate sampling, cytokeratin staining, and molecular analyses may help to identify early MALT-type lymphoma developing in the setting of thymic lymphofollicular hyperplasia.
Assuntos
Linfoma de Zona Marginal Tipo Células B/patologia , Timo/patologia , Hiperplasia do Timo/patologia , Adulto , Antígenos CD/imunologia , Diagnóstico Diferencial , Feminino , Rearranjo Gênico do Linfócito B , Humanos , Cadeias Pesadas de Imunoglobulinas/genética , Linfoma de Zona Marginal Tipo Células B/genética , Linfoma de Zona Marginal Tipo Células B/imunologia , Masculino , Pessoa de Meia-Idade , Mucosa/patologia , Hiperplasia do Timo/genética , Hiperplasia do Timo/imunologiaRESUMO
BACKGROUND: MG is an autoimmune disease of the neuromuscular junction. MG with thymus hyperplasia has been associated with, but not genetically linked to, the HLA-DR3 haplotype. OBJECTIVE: To re-evaluate the association of HLA with MG in 656 patients with generalized disease and to test linkage of HLA to MG with thymus hyperplasia. METHOD: Patients were genotyped for HLA-DRB1. Data analysis included case-control comparisons after subgrouping patients by thymus histopathology. The transmission of parental alleles to MG offspring with thymus hyperplasia was studied in simplex families using the transmission/disequilibrium test (TDT) as a test of linkage. RESULTS: MG with thymus hyperplasia was positively associated with DR3 (OR = 4.5, p = 1 x 10(-6)) and negatively associated with DR7 (OR = 0.28, p = 1 x 10(-6)), based on both case-control comparisons and TDT. No association was detected with thymomas. Conversely, patients who lacked thymus anomalies but expressed anti-titin antibodies (ATA) had an increase of DR7 (OR = 2.08, p = 4 x 10(-3)) and a decrease of DR3 (OR = 0.33, p = 9 x 10(-3)). CONCLUSIONS: The authors established linkage of HLA to MG and thymus hyperplasia, defining the MYAS1 locus. Moreover, DR3 and DR7, or closely linked genes, have opposing effects on MG phenotypes. Nonthymomatous patients with ATA may be a pathogenetically distinct subset of MG patients.
Assuntos
Antígeno HLA-DR3/genética , Desequilíbrio de Ligação , Proteínas Musculares/imunologia , Miastenia Gravis/genética , Miastenia Gravis/imunologia , Proteínas Quinases/imunologia , Adulto , Autoanticorpos/análise , Estudos de Casos e Controles , Conectina , Feminino , Heterogeneidade Genética , Genótipo , Antígenos HLA-DR/genética , Cadeias HLA-DRB1 , Humanos , Masculino , Miastenia Gravis/patologia , Fenótipo , Timo/patologia , Hiperplasia do Timo/genética , Hiperplasia do Timo/imunologia , Hiperplasia do Timo/patologiaRESUMO
Tumorigenic pituitary tumor transforming gene (PTTG) is a mammalian homolog of Xenopus securin that inhibits chromatid separation, is overexpressed in many human tumor types, and mediates transcriptional activation. Loss of yeast securin Pds1p or Drosophila securin pimples is lethal. Here we show that mice lacking PTTG (PTTG -/-) are, surprisingly, viable and fertile; but they have testicular and splenic hypoplasia, thymic hyperplasia, and thrombocytopenia. PTTG -/- mouse embryo fibroblasts exhibited aberrant cell cycle progression with prolonged G2-M phase and binucleated and multinucleated nuclei with increased aneuploidy. PTTG -/- mouse embryo fibroblast metaphases contained quadriradial, triradial, and chromosome breaks, as well as premature centromere division. The results show that PTTG functions to maintain chromosome stability, cell cycle progression, and appropriate cell division. Moreover, mammalian sister chromatid separation, an important transition in the cell cycle, is likely regulated by mechanisms in addition to securin.
Assuntos
Proteínas de Neoplasias/genética , Baço/patologia , Testículo/patologia , Trombocitopenia/genética , Hiperplasia do Timo/genética , Animais , Linfócitos T CD4-Positivos , Linfócitos T CD8-Positivos , Ciclo Celular/genética , Centrômero/genética , Aberrações Cromossômicas , Feminino , Masculino , Camundongos , Camundongos Mutantes , Proteínas de Neoplasias/metabolismo , Securina , Hiperplasia do Timo/patologiaRESUMO
Gadd45a-null mice generated by gene targeting exhibited several of the phenotypes characteristic of p53-deficient mice, including genomic instability, increased radiation carcinogenesis and a low frequency of exencephaly. Genomic instability was exemplified by aneuploidy, chromosome aberrations, gene amplification and centrosome amplification, and was accompanied by abnormalities in mitosis, cytokinesis and growth control. Unequal segregation of chromosomes due to multiple spindle poles during mitosis occurred in several Gadd45a -/- cell lineages and may contribute to the aneuploidy. Our results indicate that Gadd45a is one component of the p53 pathway that contributes to the maintenance of genomic stability.
Assuntos
Proteínas/genética , Animais , Apoptose/genética , Ciclo Celular/genética , Ciclo Celular/fisiologia , Divisão Celular/genética , Transformação Celular Neoplásica/genética , Senescência Celular , Centrossomo/metabolismo , Embrião de Mamíferos/citologia , Feminino , Fibroblastos/citologia , Fibroblastos/fisiologia , Fase G1 , Raios gama/efeitos adversos , Deleção de Genes , Genes ras/genética , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neoplasias/etiologia , Neoplasias/genética , Fenótipo , Proteínas/fisiologia , Hiperplasia do Timo/genética , Hiperplasia do Timo/patologia , Proteínas GADD45RESUMO
To obtain genetic markers linked to a specific genetic locus, genomic subtraction with a DNA pool of backcross or F2 intercross animals with a specific genotype at the locus is known to be effective. To determine whether the pooling strategy is also effective for isolation of genetic markers linked to a quantitative phenotype that can potentially be controlled by multiple genetic loci, we tested the ability of representational difference analysis (RDA) to isolate genetic markers linked to the thymus enlargement observed in the BUF/Mna (BUF) rat. This is known to be controlled by single major and minor genes, Ten1 and Ten2, on Chromosomes (Chrs) 1 and 13, respectively, both of which have dose effects on the normal WKY/Ncj (WKY) allele. DNA from an inbred WKY rat was used as the tester, and the driver was prepared from a DNA pool of 12 (WKY x BUF)F1 x BUF backcross rats with high thymus ratios (thymus weight/body weight), expected to have dominance of the BUF allele in the responsible loci. By two RDA series with the restriction enzymes BglII and BamHI, respectively, 28 polymorphic markers were isolated, and 8 of them were shown to be linked to Ten1, and one to Ten2. One of the 8 markers linked to Ten1 demonstrated no recombination in 18 rats with high thymus ratios. RDA with a DNA pool based on a quantitative phenotype (phenotype-directed RDA) can thus be considered an efficient approach for direct isolation of polymorphic markers linked to a quantitative trait.
Assuntos
Marcadores Genéticos , Fenótipo , Polimorfismo Genético , Hiperplasia do Timo/genética , Animais , Southern Blotting , Mapeamento Cromossômico/métodos , Clonagem Molecular , DNA/análise , Eletroforese em Gel de Ágar , Ligação Genética , Genótipo , Endogamia , Escore Lod , Hibridização de Ácido Nucleico , Reação em Cadeia da Polimerase , Ratos , Ratos Endogâmicos BUF , Ratos Endogâmicos F344 , Ratos Endogâmicos Lew , Ratos Endogâmicos WF , Ratos Endogâmicos WKYRESUMO
Genetic analyses indicate that genes within the major histocompatibility complex (MHC) can be involved in susceptibility to autoimmune disease. To investigate the role of the tumour necrosis factor beta (TNFB) gene in myasthenia gravis (MG) susceptibility, we analysed an NcoI polymorphism within the TNFB gene in 63 MG patients and 93 healthy individuals. When patients were subdivided according to thymic pathology, we found differences between MG patients with thymic hyperplasia and thymoma versus controls. In MG patients with thymic hyperplasia we found a positive association with the TNFB*1 allele [Relative risk (RR): 2.6; P < 0.001] and phenotype (RR: 1.8; P < 0.005) and a negative association with the TNFB*2/2 genotype (RR: 0.2; P < 0.001) when compared to the controls. On the other hand, in MG patients with thymoma we found a positive association with the TNFB*2/2 genotype (RR: 5.6; P < 0.01) and a negative association with the TNFB*1 allele (RR: 0.3; P < 0.05) and *1/2 genotype (RR: 0.2; P < 0.01). These data suggest that the two different forms of MG can have different pathogenesis and that the TNFB gene could influence susceptibility to MG.
Assuntos
Linfotoxina-alfa/genética , Miastenia Gravis/genética , Alelos , Feminino , Genótipo , Antígeno HLA-A1/genética , Antígeno HLA-B8/genética , Antígeno HLA-DR3/genética , Teste de Histocompatibilidade , Humanos , Masculino , Fenótipo , Polimorfismo de Fragmento de Restrição , Timoma/genética , Hiperplasia do Timo/genéticaRESUMO
BUF/Mna (B) rat is a mutated strain, having much larger thymus than WKY/ NCrj (W), ACI/NMs (A), and F344 (F) rats throughout their life-span. Rats of the latter 3 strains have normal sized thymuses, being less than 5.3 in the thymus to body weight ratio (mg/g), when they were killed at 6 weeks of age. Genetic segregation of large thymus size in the B strain at 6 weeks of age was studied by crossing B rats with W, A or F rats. All of 3 types of the F1 hybrid rats between the B strain and the other strains showed intermediate thymus ratios between those of both parental strains. In F2 rats between the B and W strains, the distribution of thymus ratios showed about 5 different peaks. These findings might indicate that two polymeric autosomal loci, thymus enlargement-1 (Ten-1) and thymus enlargement-2 (Ten-2), can enlarge the thymus size in B rats. Histometrically, whole thymus and cortex areas of the B rats were 2-5 times larger than the W rats during 6-12 weeks of age, but medulla areas were slightly different between the strains, showing that larger thymuses in B rats were mainly due to the enlarged cortex areas.
Assuntos
Hiperplasia do Timo/genética , Animais , Animais Lactentes , Peso Corporal/fisiologia , Feminino , Masculino , Tamanho do Órgão/fisiologia , Gravidez , Ratos , Ratos Endogâmicos F344 , Ratos Endogâmicos , Ratos Endogâmicos WKY , Timo/crescimento & desenvolvimento , Hiperplasia do Timo/patologiaRESUMO
SUMMARY: Targeted disruption of the murine p27(Kip1) gene caused a gene dose-dependent increase in animal size without other gross morphologic abnormalities. All tissues were enlarged and contained more cells, although endocrine abnormalities were not evident. Thymic hyperplasia was associated with increased T lymphocyte proliferation, and T cells showed enhanced IL-2 responsiveness in vitro. Thus, p27 deficiency may cause a cell-autonomous defect resulting in enhanced proliferation in response to mitogens. In the spleen, the absence of p27 selectively enhanced proliferation of hematopoietic progenitor cells. p27 deletion, like deletion of the Rb gene, uniquely caused neoplastic growth of the pituitary pars intermedia, suggesting that p27 and Rb function in the same regulatory pathway. The absence of p27 also caused an ovulatory defect and female sterility. Maturation of secondary ovarian follicles into corpora lutea, which express high levels of p27, was markedly impaired.