RESUMEN
Reelin is an extracellular matrix protein that plays a critical role in neuronal migration. Here we show that the mucosa of human colon expresses reelin, its receptors ApoER2 and VLDLR, and its effector protein Dab1. Immunohistochemical analyses reveal that reelin expression is restricted to pericryptal myofibroblasts; Dab1 is detected at myofibroblasts, the apical domain of surface epithelial and crypt cells, and a strong linear staining is observed at the basement membrane; VLDLR and ApoER2 are in the cytoplasm of surface epithelium and myofibroblasts, and VLDLR is also detected in the cytoplasm of the crypt cells. Human colorectal cancer downregulates reelin without change in vimentin or N-cadherin mRNA levels. Decreased Reelin mRNA expression is accompanied by decreased HIC1 mRNA levels, increased mRNA levels of ApoER2 and DNMT1, increased reelin hypermethylation and no change in either Cask or TGF-ß1 mRNAs, suggesting that reelin repression results from a DNMT1-mediated hypermethylation of the reelin gene promoter. Decreased HIC1 expression may repress reelin transcription via increasing ApoER2 transcription. We conclude that the mucosa of human colon expresses the reelin-Dab1 signaling system and that reelin is repressed in colorectal cancer before epithelial-mesenchymal transition has occurred. The significant down-regulation of reelin expression makes this gene a promising biomarker for colorectal cancers. © 2016 Wiley Periodicals, Inc.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/análisis , Moléculas de Adhesión Celular Neuronal/análisis , Colon/patología , Neoplasias Colorrectales/patología , Proteínas de la Matriz Extracelular/análisis , Mucosa Intestinal/patología , Proteínas del Tejido Nervioso/análisis , Recto/patología , Serina Endopeptidasas/análisis , Transducción de Señal , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Anciano , Anciano de 80 o más Años , Cadherinas/análisis , Cadherinas/genética , Cadherinas/metabolismo , Moléculas de Adhesión Celular Neuronal/genética , Moléculas de Adhesión Celular Neuronal/metabolismo , Colon/metabolismo , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/metabolismo , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Mucosa Intestinal/metabolismo , Proteínas Relacionadas con Receptor de LDL/análisis , Proteínas Relacionadas con Receptor de LDL/genética , Proteínas Relacionadas con Receptor de LDL/metabolismo , Masculino , Persona de Mediana Edad , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Receptores de LDL/análisis , Receptores de LDL/genética , Receptores de LDL/metabolismo , Recto/metabolismo , Proteína Reelina , Serina Endopeptidasas/genética , Serina Endopeptidasas/metabolismoRESUMEN
The expression of the phosphoinositides phosphatases Synaptojanins (Synjs) 1 and 2 has been shown in brain and in some peripheral tissues, but their expression in the intestine has not been reported. Herein we show that the small and large intestine express Synj1 and Synj2. Their mRNA levels, measured by RT-PCR, are not affected by development in the small intestine but in the colon they increase with age. Immunostaining assays reveal that both Synjs localize at the apical domain of the epithelial cells and at the lamina propria at sites also expressing the neuron marker calretinin. Synj2 staining at the lamina propria is fainter than that of Synj1. In colonocytes Synjs are at the apical membrane and cytosolic membrane vesicles. Synj2 is also at the mitochondria. Western blots reveal that the intestinal mucosa expresses at least two Synj1 (170- and 139-kDa) and two Synj2 (160- and 148-kDa) isoforms. The observations suggest that Synj1-170, Synj2-160, and Synj2-148 in colonocytes, might participate in processes that take place mainly at the apical domain of the epithelial cells whereas Synj1-139 in those at the enteric nervous system. Experimental colitis augments the mRNA abundance of both Synjs in colon but only Synj2 mRNA levels are increased in colon tumors. In conclusion, as far as we know, this is the first report showing expression, location and isoforms of Synj1 and Synj2 in the small and large intestine and that they might participate in intestinal pathology.
