RESUMEN
Urinary bladder organogenesis requires coordinated cell growth, specification, and patterning of both mesenchymal and epithelial compartments. Tcf21, a gene that encodes a helix-loop-helix transcription factor, is specifically expressed in the mesenchyme of the bladder during development. Here we show that Tcf21 is required for normal development of the bladder. We found that the bladders of mice lacking Tcf21 were notably hypoplastic and that the Tcf21 mutant mesenchyme showed increased apoptosis. There was also a marked delay in the formation of visceral smooth muscle, accompanied by a defect in myocardin (Myocd) expression. Interestingly, there was also a marked delay in the formation of the basal cell layer of the urothelium, distinguished by diminished expression of Krt5 and Krt14. Our findings suggest that Tcf21 regulates the survival and differentiation of mesenchyme cell-autonomously and the maturation of the adjacent urothelium non-cell-autonomously during bladder development.
Asunto(s)
Factores de Transcripción , Vejiga Urinaria , Animales , Ratones , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Diferenciación Celular/genética , Regulación de la Expresión Génica , Músculo Liso/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Vejiga Urinaria/metabolismoRESUMEN
BACKGROUND: Voiding disorders in humans, particularly in children are associated with increased incidence of behavioral issues as well as past history of childhood abuse. We hypothesized that creating stress in mice, utilizing either a chronic social defeat model (SD) or restraint stress in shallow water model (RSSW) would engender changes in bladder function, morphology, and behavior, thereby enabling us to study the resultant voiding dysfunction. METHODS: For SD stress (14 days), C57BL/6 male mice were exposed daily to a larger aggressive CD-1 male for 10 min, followed by sensory exposure in a barrier cage for 24h. Control mice were similarly housed with no exposure. For RSSW (21 days), C57BL/6 mice were put in a perforated conical tube with feet immersed in water daily for 4h, then returned to single housing cages. Control mice were also in single housing. After the stress period, voiding patterns were obtained on filter paper, followed by behavioral tests. At necropsy, blood was taken for corticosterone analysis, and bladder and body weights measured. Bladder cryosections were stained with hematoxylin and eosin (H&E) for morphological assessment. Sequential sections were immunostained with antibodies to Ki-67 as a proliferation marker, CD31 (endothelial cell marker), and uroplakin-II. ImageJ software was used to measure bladder wall thickness on blinded H&E photomicrographs as well as quantitate CD31 staining. Both Ki-67-positive and -negative nuclei were counted with Imaris software to obtain a proliferation index. RESULTS: Only SD mice had a single large void pattern. Bladder-to-body weight ratios increased in SD mice (p≤0.02) but not in RSSW mice. Plasma corticosterone levels were elevated in all stressed mice. SD mice exhibited lower levels of locomotor activity compared with controls; RSSW mice were hyperactive. In SD mice, bladder wall thickness was increased (p ≤ 0.003) but no change was seen in Ki-67 proliferation index, consistent with hypertrophy. No difference with control mice was seen in vascularity as visualized by CD31 staining. Uniform uroplakin-II staining lined the urothelium of both SD and control mice. CONCLUSIONS: Mice exposed to repeated SD (14 days) respond with altered voiding indicative of urine retention, and exhibit bladder wall changes consistent with hypertrophy while the urothelial barrier is maintained. These changes were not observed with repeated RSSW. SD, in contrast to RSSW, provides a model of psychological stress to further study the interplay of behavior and bladder dysfunction, enabling an improved understanding of voiding dysfunction, and the ability to create innovative and more effective management pathways for children who present with voiding dysfunction.
Asunto(s)
Síntomas del Sistema Urinario Inferior/etiología , Restricción Física/fisiología , Conducta Social , Estrés Psicológico/complicaciones , Vejiga Urinaria/fisiopatología , Análisis de Varianza , Animales , Vasos Sanguíneos/patología , Peso Corporal , Corticosterona , Antígeno Ki-67/metabolismo , Síntomas del Sistema Urinario Inferior/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Actividad Motora/fisiología , Tamaño de los Órganos , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Restricción Física/psicología , Estrés Psicológico/psicología , Natación/psicología , Vejiga Urinaria/patologíaRESUMEN
Little is known of the control of gene expression in the animal hemisphere of the Xenopus embryo. Here we show that expression of FoxI1e, a gene essential for normal ectoderm formation, is expressed regionally within the animal hemisphere, in a highly dynamic fashion. In situ hybridization shows that FoxI1e is expressed in a wave-like fashion that is initiated on the dorsal side of the animal hemisphere, extends across to the ventral side by the mid-gastrula stage, and is then turned off in the dorsal ectoderm, the neural plate, at the neurula stage. It is confined to the inner layers of cells in the animal cap, and is expressed in a mosaic fashion throughout. We show that this dynamic pattern of expression is controlled by both short- and long-range signals. Notch signaling controls both the mosaic, and dorsal/ventral changes in expression, and is controlled, in turn, by Vg1 signaling from the vegetal mass. FoxI1e expression is also regulated by nodal signaling downstream of VegT. Canonical Wnt signaling contributes only to late changes in the FoxI1e expression pattern. These results provide new insights into the roles of vegetally localized mRNAs in controlling zygotic genes expressed in the animal hemisphere by long-range signaling. They also provide novel insights into the role of Notch signaling at the earliest stages of vertebrate development.