RESUMO
The differentiation of mesenchymal stem cells into hypertrophic chondrocytes is an integral and multistep process important in pattern formation, endochondral ossification, and postnatal growth of the skeleton. In recent years, novel genes involved in these processes have been identified, but still only little is known about the large-scale gene expression profile during skeletal development. We initiated an expressed sequence tag (EST) project aiming at the identification of genes and pathways involved in this complex process. Candidate genes are expected to be of value for diagnosis and treatment of monogenic and multigenic heritable disorders of the skeleton. Here, we describe the sequences of 4,748 clones from a human growth plate cartilage cDNA library generated from 20 weeks prenatal-2 years postnatal specimens. In silico analysis of these sequences revealed 1,688 individual transcription units, corresponding to known (1,274) and to novel, yet uncharacterised potential genes (414). The tissue specificity of the library was reflected by its corresponding EST profile representing a total of approximately 10% proteins already shown to be involved in cartilage/bone development or homeostasis. The EST profile also reflects the developmental stage of the tissue with significant differences in the expression of matrix proteins compared to corresponding EST profiles from 8-12 and 12-20 week human fetal cartilage. Calculation of the relative frequency of transcripts in our cDNA library, as compared to their abundance in other EST datasets, revealed a set of approximately 200 genes, including 81 novel, yet uncharacterised genes, showing increased expression. These genes represent candidates for the large number of osteochondrodysplasias for which the causative gene defects have not yet been identified.
Assuntos
Etiquetas de Sequências Expressas , Feto/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento/genética , Lâmina de Crescimento/embriologia , Lâmina de Crescimento/metabolismo , Proteínas da Matriz Extracelular/genética , Humanos , Proteoglicanas/genéticaRESUMO
Both myosin 7A (MYO7A) and calmodulin (CaM) are required for transduction and adaptation processes in inner ear hair cells. We identified a novel heterozygous missense mutation (c.2557C>T; p.R853C) in a family with autosomal dominant non-syndromic hearing loss that changes an evolutionarily invariant residue of the fifth IQ motif (IQ5), a putative calmodulin (CaM) binding domain, of MYO7A. Functional effects of the p.R853C mutation were investigated in a physiological cellular environment by expressing MYO7A IQ5-containing peptides in smooth muscle cells of microarteries, in which overexpression of wildtype IQ5 (with intact calmodulin binding) would be expected to compete with myosin light chain kinase (MLCK) for CaM binding. Indeed, analysis of calmodulin-dependent vasoconstriction suggests constitutive binding of CaM to the wildtype, but not the p.R853C-mutated IQ5 motif at all physiologically relevant Ca2+ concentrations. Thus our data suggest a disturbed CaM/MYO7A binding of the p.R853C mutant, this amino acid change may result in impaired adaptation to environmental stimuli and progressive deterioration of hearing transduction in heterozygotes. A defect in CaM/MYO7A interaction represents a novel pathomechanism for genetic hearing loss. It provides an attractive molecular target for therapeutic interventions aimed to delay or prevent the onset of hearing loss in families with mutations in myosin IQ domains.
Assuntos
Substituição de Aminoácidos , Calmodulina/metabolismo , Perda Auditiva/genética , Mutação de Sentido Incorreto , Miosinas/genética , Mutação Puntual , Adolescente , Idoso , Idoso de 80 Anos ou mais , Motivos de Aminoácidos , Animais , Ligação Competitiva , Cricetinae , Repetições de Dinucleotídeos , Dineínas , Feminino , Genes Dominantes , Heterozigoto , Humanos , Lactente , Recém-Nascido , Íntrons/genética , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Tono Muscular , Músculo Liso Vascular/metabolismo , Miosina VIIa , Quinase de Cadeia Leve de Miosina/metabolismo , Miosinas/metabolismo , Linhagem , Ligação Proteica , Proteínas Recombinantes de Fusão/metabolismo , Transfecção , Vasoconstrição/genética , Vasoconstrição/fisiologiaRESUMO
INTRODUCTION: Lymphogranuloma venereum (LGV) is a sexually transmitted infection (STI) caused by chlamydia trachomatis (CT) genotype L (L1, L2 and L3). Recent outbreaks of LGV in Europe and North America affected mainly men who have sex with men (MSM). Infections with CT serotypes D-K are mostly associated with mild symptoms or may be clinically silent. However, infections with L genotypes are more invasive and induce anogenital ulcer or inguinal lymphadenopathy. MATERIALS AND METHODS: Between 2003 and 2013, anal or genital CT infections were diagnosed in 471 symptomatic patients attending the Infectious Diseases Center Hamburg (ICH). CT DNA was detected by PCR. CT genotyping of positive samples was performed by sequence analyses of omp1 PCR products (samples between 2003 and 2010). Samples between 2012 and 2013 were analyzed by genotype L specific real-time PCR. RESULTS: In total, 221 LGV patients were identified (3 in 2003; 11 in 2004; 26 in 2005; 33 in 2006; 24 in 2007; 16 in 2008; 18 in 2009; 15 in 2010; 17 in 2011; 26 in 2012 and 32 in 2013). One hundred ninety-eight of 221 (89.6%) patients with LGV were HIV-infected; 10 of 221 (4.5%) were HIV-negative, and the HIV-status unknown in 13 (5.9%). The majority of LGV positive patients (204/221; 92%) had anorectal symptoms (bloody proctitis, rectal pain, purulent or mucous discharge, tenesmus, constipation), compared to 17/221 (8%) who presented with genital symptoms as urethritis, genital ulcer or inguinal lymphadenopathy. Of 283 CT-positive patients with anorectal symptoms, genotype L was detected in 205 (72%), while non-L genotypes (D-K) were found in 78 (28%). In contrast, genotype L was found in only 6% of patients with genital symptoms (11/177), whereas 94% (166/177) were infected with non-L genotypes only. CONCLUSIONS: The epidemic of LGV among predominantly HIV+ MSM is ongoing. LGV might be underdiagnosed, especially in patients with anorectal symptoms. Infections with CT serotypes D-K are more often associated with urogenital symptoms or asymptomatic infection, whereas LGV genotypes are found most frequently in patients with rectal/intestinal symptoms. Anorectal CT infections in MSM should be further characterized by genotyping for LGV, as for LGV three weeks of doxycycline treatment are recommended. CT genotypes D-K generally require shorter antibiotic treatment. If CT genotyping is not available, the duration of treatment should be prolonged to three weeks empirically for CT-positive patients with anorectal or intestinal symptoms.
RESUMO
In this study, we characterize the molecular and functional features of a novel protein called SPOC1. SPOC1 RNA expression was previously reported to be highest in highly proliferating tissues and increased in a subset of ovarian carcinoma patients, which statistically correlated with poor prognosis and residual disease. These observations implied that SPOC1 might play a role in cellular proliferation and oncogenesis. Here we show that the endogenous SPOC1 protein is labile, primarily chromatin associated and its expression as well as localization are regulated throughout the cell cycle. SPOC1 is dynamically regulated during mitosis with increased expression levels and biphasic localization to mitotic chromosomes indicating a functional role of SPOC1 in mitotic processes. Consistent with this postulate, SPOC1 siRNA knockdown experiments resulted in defects in mitotic chromosome condensation, alignment and aberrant sister chromatid segregation. Finally, we have been able to show, using micrococcal nuclease (MNase) chromatin-digestion assays that SPOC1 expression levels proportionally influence the degree of chromatin compaction. Collectively, our findings show that SPOC1 modulates chromatin structure and that tight regulation of its expression levels and subcellular localization during mitosis are crucial for proper chromosome condensation and cell division.
Assuntos
Cromatina/metabolismo , Cromossomos Humanos/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Mitose , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo , Animais , Linhagem Celular Tumoral , Células Eucarióticas , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Humanos , Metáfase , Prófase , Complexo de Endopeptidases do Proteassoma/metabolismo , Processamento de Proteína Pós-Traducional , Estrutura Terciária de Proteína , Transporte Proteico , RNA Interferente Pequeno/metabolismo , Frações Subcelulares/metabolismoRESUMO
We report the identification of a novel human gene (SPOC1) which encodes a protein with a PHD-finger domain. The gene is located in chromosomal region 1p36.23, a region implicated in tumor development and progression. RNA in situ hybridization experiments showed strong SPOC1 expression in some rapidly proliferating cell types, such as spermatogonia, but not in nonproliferating mature spermatocytes. In addition, high SPOC1 mRNA expression was observed in several ovarian cancer cell lines. This prompted us to systematically examine SPOC1 expression in ovarian cancer in relation to prognosis. SPOC1 mRNA expression was quantified in tumor tissue of 103 patients with epithelial ovarian cancer. Interestingly, SPOC1 was associated with residual disease, whereby patients with unresectable tumors showed higher levels compared to patients without residual tumor tissue after surgery (p = 0.029). The univariable proportional hazards model showed an association between SPOC1 expression and survival (p = 0.043, relative risk = 1.535). Median survival time was 1,596 days for patients with low SPOC1 expression vs. only 347 days for patients with high expression, using Kaplan-Meier analysis. However, SPOC1 was not associated with survival when multivariable analysis was adjusted for residual disease. This can be explained by the correlation between residual disease and SPOC1 expression. In conclusion, SPOC1 is a novel PHD-finger protein showing strong expression in spermatogonia and ovarian cancer cells. SPOC1 overexpression was associated with unresectable carcinomas and shorter survival in ovarian cancer.