RESUMO
Sensory hair cells, the mechanoreceptors of the auditory and vestibular systems, harbor two specialized elaborations of the apical surface, the hair bundle and the cuticular plate. In contrast to the extensively studied mechanosensory hair bundle, the cuticular plate is not as well understood. It is believed to provide a rigid foundation for stereocilia motion, but specifics about its function, especially the significance of its integrity for long-term maintenance of hair cell mechanotransduction, are not known. We discovered that a hair cell protein called LIM only protein 7 (LMO7) is specifically localized in the cuticular plate and the cell junction. Lmo7 KO mice suffer multiple cuticular plate deficiencies, including reduced filamentous actin density and abnormal stereociliar rootlets. In addition to the cuticular plate defects, older Lmo7 KO mice develop abnormalities in inner hair cell stereocilia. Together, these defects affect cochlear tuning and sensitivity and give rise to late-onset progressive hearing loss.
Assuntos
Células Ciliadas Auditivas/fisiologia , Audição/fisiologia , Proteínas com Domínio LIM/deficiência , Fatores de Transcrição/deficiência , Actinas/metabolismo , Animais , Cóclea/fisiologia , Modelos Animais de Doenças , Células Ciliadas Auditivas/ultraestrutura , Células Ciliadas Auditivas Internas/fisiologia , Células Ciliadas Auditivas Internas/ultraestrutura , Audição/genética , Perda Auditiva/etiologia , Perda Auditiva/genética , Perda Auditiva/fisiopatologia , Proteínas com Domínio LIM/genética , Proteínas com Domínio LIM/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Knockout , Microscopia Eletrônica de Varredura , Estereocílios/genética , Estereocílios/fisiologia , Estereocílios/ultraestrutura , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologiaRESUMO
Human endocrine-cerebro-osteodysplasia (ECO) syndrome, caused by the loss-of-function mutation R272Q in the intestinal cell kinase (ICK) gene, is a neonatal-lethal developmental disorder. To elucidate the molecular basis of ECO syndrome, we constructed an Ick R272Q knock-in mouse model that recapitulates ECO pathological phenotypes. Newborns bearing Ick R272Q homozygous mutations die at birth due to respiratory distress. Ick mutant lungs exhibit not only impaired branching morphogenesis associated with reduced mesenchymal proliferation but also significant airspace deficiency in primitive alveoli concomitant with abnormal interstitial mesenchymal differentiation. ICK dysfunction induces elongated primary cilia and perturbs ciliary Hedgehog signaling and autophagy during lung sacculation. Our study identifies an essential role for ICK in lung development and advances the mechanistic understanding of ECO syndrome.
Assuntos
Anormalidades Múltiplas/genética , Pulmão/metabolismo , Mutação , Proteínas Serina-Treonina Quinases/genética , Anormalidades Múltiplas/enzimologia , Anormalidades Múltiplas/patologia , Animais , Animais Recém-Nascidos , Células Cultivadas , Córtex Cerebral/anormalidades , Córtex Cerebral/metabolismo , Cílios/metabolismo , Modelos Animais de Doenças , Sistema Endócrino/anormalidades , Sistema Endócrino/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Humanos , Immunoblotting , Pulmão/embriologia , Pulmão/enzimologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Anormalidades Musculoesqueléticas/genética , Proteínas Serina-Treonina Quinases/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , SíndromeRESUMO
AggR is a transcriptional regulator of enteroaggregative Escherichia coli (EAEC) and has been proposed as the defining factor for typical EAEC strains. Expression of multiple putative virulence factors, including the aggregative adherence fimbriae (AAF), dispersin, the dispersin translocator Aat, and the Aai type VI secretion system, have been found to be regulated by AggR. Here, we confirm the existence of at least 44 AggR-regulated genes using DNA microarray and real-time quantitative reverse transcription-PCR (qRT-PCR); these genes include chromosomal and plasmid-borne loci and 19 previously unsuspected genes. Two previously uncharacterized virulence plasmid-encoded open reading frames (ORFs) (designated ORF3 and ORF4) exhibit significant identity with isoprenoid biosynthesis genes of Bacteria and Archaea. The predicted ORF4 product is closely related to isopentenyl isomerase (IDI) enzymes, whereas the predicted product of the adjacent ORF3 exhibits an aspartate-rich region that is common among trans-isoprenyl phosphate synthases. We show that mutations in these ORFs confer changes in bacterial surface properties. AggR coordinately controls expression of a large number of EAEC genes.
Assuntos
Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Transativadores/genética , Transativadores/metabolismo , Ácido Aspártico/genética , Ácido Aspártico/metabolismo , Infecções por Escherichia coli/genética , Infecções por Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Perfilação da Expressão Gênica/métodos , Regulação Bacteriana da Expressão Gênica/genética , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Fases de Leitura Aberta/genética , Fatores de Virulência/genética , Fatores de Virulência/metabolismoRESUMO
Use of antibiotic-impregnated spacers is common in the two-stage approach to treatment of periprosthetic joint infection despite the lack of information regarding in vivo performance of these implants. Antibiotic elution levels likely often fall below the minimal inhibitory concentration need to inhibit bacterial growth, raising concern that the spacers themselves may provide a potential attachment site for biofilm formation. Advanced microscopy was used in this study to evaluate the surface characteristics of antibiotic-eluting spacers collected at the time of prosthesis reimplantation from 6 patients undergoing two-stage treatment for an infected total joint arthroplasty. Scanning electron microscopy and confocal scanning microscopy of the removed spacers revealed modest fibrous matrix formation and inflammatory cells with no biofilm or bacteria detected. This study supports the continued use of antibiotic spacers in the treatment of periprosthetic joint infection.
