RESUMEN
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.
Asunto(s)
Células Ciliadas Auditivas/fisiología , Audición/fisiología , Proteínas con Dominio LIM/deficiencia , Factores de Transcripción/deficiencia , Actinas/metabolismo , Animales , Cóclea/fisiología , Modelos Animales de Enfermedad , Células Ciliadas Auditivas/ultraestructura , Células Ciliadas Auditivas Internas/fisiología , Células Ciliadas Auditivas Internas/ultraestructura , Audición/genética , Pérdida Auditiva/etiología , Pérdida Auditiva/genética , Pérdida Auditiva/fisiopatología , Proteínas con Dominio LIM/genética , Proteínas con Dominio LIM/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Ratones Noqueados , Microscopía Electrónica de Rastreo , Estereocilios/genética , Estereocilios/fisiología , Estereocilios/ultraestructura , Factores de Transcripción/genética , Factores de Transcripción/fisiologíaRESUMEN
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.
Asunto(s)
Anomalías Múltiples/genética , Pulmón/metabolismo , Mutación , Proteínas Serina-Treonina Quinasas/genética , Anomalías Múltiples/enzimología , Anomalías Múltiples/patología , Animales , Animales Recién Nacidos , Células Cultivadas , Corteza Cerebral/anomalías , Corteza Cerebral/metabolismo , Cilios/metabolismo , Modelos Animales de Enfermedad , Sistema Endocrino/anomalías , Sistema Endocrino/metabolismo , Regulación del Desarrollo de la Expresión Génica , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Humanos , Immunoblotting , Pulmón/embriología , Pulmón/enzimología , Ratones Endogámicos C57BL , Ratones Transgénicos , Anomalías Musculoesqueléticas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , SíndromeRESUMEN
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.
Asunto(s)
Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Transactivadores/genética , Transactivadores/metabolismo , Ácido Aspártico/genética , Ácido Aspártico/metabolismo , Infecciones por Escherichia coli/genética , Infecciones por Escherichia coli/metabolismo , Infecciones por Escherichia coli/microbiología , Perfilación de la Expresión Génica/métodos , Regulación Bacteriana de la Expresión Génica/genética , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Sistemas de Lectura Abierta/genética , Factores de Virulencia/genética , Factores de Virulencia/metabolismoRESUMEN
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.