RESUMEN
PURPOSE: Although a physiologic relationship between intestinal mucosal integrity and hepatic function has been previously described, the effect of primary liver disease on intestinal mucosal homeostasis has not been previously well documented. In the current study, we studied the effects of chronic liver injury as a primary injury on enterocyte turnover (proliferation and apoptosis) in a mouse model. METHODS: The liver toxin 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-enriched diet was used to induce chronic cholestatic liver injury in mice. Livers and intestine were harvested after 3 weeks of dietary treatment of histologic analysis and a determination of cell proliferation (immunohistochemistry for Ki67), or apoptosis (immunohistochemistry for caspase-3), as well as a determination of Wnt/ß-catenin signaling activity. RESULTS: All DDC-fed animals exhibited histologic evidence of liver damage that was associated with the expansion of atypical ductal proliferation near the periportal areas and increased oxidative stress. In the intestine, DDC-induced liver damage was associated with decreased villus height, decreased enterocyte proliferation, and increased cell apoptosis compared with control animals. There was also evidence for decreased ß-catenin expression by immunostaining in crypt and villus cells of DDC-fed mice compared with control animals. CONCLUSION: Primary liver injury and cholestasis is associated with intestinal mucosal hypoplasia. Decreased cell proliferation and increased cell apoptosis may be responsible for decreased intestinal epithelial cell mass. The observed decrease in cell turnover is accompanied by an alteration in Wnt/ß-catenin signaling.
Asunto(s)
Enfermedad Hepática Crónica Inducida por Sustancias y Drogas/complicaciones , Enfermedades Intestinales/etiología , Mucosa Intestinal/fisiopatología , Animales , Apoptosis , Proliferación Celular , Enfermedad Hepática Crónica Inducida por Sustancias y Drogas/metabolismo , Enfermedad Hepática Crónica Inducida por Sustancias y Drogas/patología , Dicarbetoxidihidrocolidina , Modelos Animales de Enfermedad , Enterocitos/fisiología , Enfermedades Intestinales/metabolismo , Enfermedades Intestinales/patología , Enfermedades Intestinales/fisiopatología , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patología , Ratones , Proteínas Wnt/metabolismo , beta Catenina/metabolismoRESUMEN
The neurodevelopmental disorder Williams-Beuren syndrome is caused by spontaneous approximately 1.5 Mb deletions comprising 25 genes on human chromosome 7q11.23. To functionally dissect the deletion and identify dosage-sensitive genes, we created two half-deletions of the conserved syntenic region on mouse chromosome 5G2. Proximal deletion (PD) mice lack Gtf2i to Limk1, distal deletion (DD) mice lack Limk1 to Fkbp6, and the double heterozygotes (D/P) model the complete human deletion. Gene transcript levels in brain are generally consistent with gene dosage. Increased sociability and acoustic startle response are associated with PD, and cognitive defects with DD. Both PD and D/P males are growth-retarded, while skulls are shortened and brains are smaller in DD and D/P. Lateral ventricle (LV) volumes are reduced, and neuronal cell density in the somatosensory cortex is increased, in PD and D/P. Motor skills are most impaired in D/P. Together, these partial deletion mice replicate crucial aspects of the human disorder and serve to identify genes and gene networks contributing to the neural substrates of complex behaviours and behavioural disorders.
Asunto(s)
Deleción Cromosómica , Conducta Social , Síndrome de Williams/genética , Animales , Encéfalo/anomalías , Encéfalo/patología , Cognición , Condicionamiento Psicológico , Tejido Conectivo/patología , Miedo , Regulación de la Expresión Génica , Ventrículos Cardíacos/patología , Heterocigoto , Humanos , Ratones , Actividad Motora/fisiología , Tamaño de los Órganos , Fenotipo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Cráneo/anomalías , Síndrome de Williams/patología , Síndrome de Williams/fisiopatologíaRESUMEN
Glucocorticoid-induced gene-1 (Gig1) was identified in a yeast one-hybrid screen for factors that interact with the MyoD core enhancer. The Gig1 gene encodes a novel C2H2 zinc finger protein that shares a high degree of sequence similarity with two known DNA binding proteins in humans, Glut4 enhancer factor and papillomavirus binding factor (PBF). The mouse ortholog of PBF was also isolated in the screen. The DNA binding domain of Gig1, which contains TCF-E-tail CR1 and CR2 motifs shown to mediate promoter specificity of TCF-E-tail isoforms, was mapped to a C-terminal domain that is highly conserved in Glut4 enhancer factor and PBF. In mouse embryos, in situ hybridization revealed a restricted pattern of expression of Gig1 that overlaps with MyoD expression. A nuclear-localized lacZ knockin null allele of Gig1 was produced to study Gig1 expression with greater resolution and to assess Gig1 functions. X-gal staining of Gig1(nlacZ) heterozygous embryos revealed Gig1 expression in myotomal myocytes, skeletal muscle precursors in the limb, and in nascent muscle fibers of the body wall, head and neck, and limbs through E14.5 (latest stage examined). Gig1 was also expressed in a subset of Scleraxis-positive tendon precursors/rudiments of the limbs, but not in the earliest tendon precursors of the somite (syndetome) defined by Scleraxis expression. Additional regions of Gig1 expression included the apical ectodermal ridge, neural tube roof plate and floor plate, apparent motor neurons in the ventral neural tube, otic vesicles, notochord, and several other tissues representing all three germ layers. Gig1 expression was particularly well represented in epithelial tissues and in a number of cells/tissues of neural crest origin. Expression of both the endogenous MyoD gene and a reporter gene driven by MyoD regulatory elements was similar in wild-type and homozygous null Gig1(nlacZ) embryos, and mutant mice were viable and fertile, indicating that the functions of Gig1 are redundant with other factors.