Asunto(s)
Receptores ErbB , Nevo , Neoplasias Cutáneas , Niño , Receptores ErbB/genética , Humanos , Masculino , Mutación/genética , Nevo/genética , Neoplasias Cutáneas/genéticaRESUMEN
We isolated a member of the facilitative glucose transporter (GLUT) gene family (GLUT11; SLC2A11 as a HGMW-approved symbol) based on the analysis of a human genomic BAC clone KB1125A3 located on band q11.2 of human chromosome 22. The gene GLUT11/SLC2A11 consists of 12 exons spanning over 29 kb in size and is located between two genes, SMARCB1 and MIF. The deduced amino acid sequence indicated the topological features of transmembrane helices and sequence motifs which are common to the GLUT protein family. The cDNA cloning revealed the presence of three types of variation in its transcripts. The first variation is caused by the existence of three distinct first exons (SLC2A11-a, -b, and -c). PCR analysis of multi-tissue-derived cDNA panels indicated the differential expression of these transcript variants. The second variation is caused by skipping over one exon (exon 6). The third variation is caused by the premature transcription termination at a site between exon 8 and exon 9. Both exon skipping and premature termination caused frameshift, resulting in the production of truncated GLUT11/SLC2A11 transcripts. These results suggested that transcription of GLUT11/SCL2A11 gene is controlled in a complex manner.
Asunto(s)
Proteínas de Transporte de Monosacáridos/genética , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Secuencia de Bases , Mapeo Cromosómico , Cromosomas Artificiales Bacterianos/genética , Cromosomas Humanos Par 22/genética , Clonación Molecular , ADN Complementario/genética , Exones , Expresión Génica , Variación Genética , Proteínas Facilitadoras del Transporte de la Glucosa , Humanos , Intrones , Datos de Secuencia Molecular , Proteínas de Transporte de Monosacáridos/química , Familia de Multigenes , Homología de Secuencia de Aminoácido , Transcripción GenéticaRESUMEN
We examined the effects of various endothelins on the mineralization of mouse clonal preosteoblastic MC3T3-E1 cells. MC3T3-E1 cells expressed mRNAs for endothelin (ET)-1 and the A-type receptor for ET (ETA). A pharmacological study also demonstrated the predominant expression of the ETA receptor. Northern blotting analysis revealed that ETs decreased the expression of mRNA for osteocalcin, which is a marker protein for the maturation of osteoblastic cells. ET-1 also decreased in the deposition of calcium by MC3T3-E1 cells in a dose-dependent manner and it had an inhibitory effect even at 10(-11) M. The rank order of potency of ETs was ET-1 = ET-2 > ET-3. Brief treatment with 10(-7) M ET-1 on days 6-8 alone suppressed mineralization. ET-1 enhanced the rate of production of inositol 1,4, 5-trisphosphate (IP3) in MC3T3-E1 cells, but it had no effect on the rate of production of cAMP. Taken together, our data indicate that ET-1 might inhibit the mineralization of osteoblastic cells via an interaction with the ETA receptor, with generation of IP3 as the intracellular signal.
Asunto(s)
Calcificación Fisiológica/fisiología , Endotelinas/farmacología , Osteoblastos/efectos de los fármacos , Receptores de Endotelina/fisiología , Animales , Calcificación Fisiológica/efectos de los fármacos , Calcio , Línea Celular , AMP Cíclico/metabolismo , Cartilla de ADN , Antagonistas de los Receptores de Endotelina , Endotelina-1/metabolismo , Endotelina-1/farmacología , Endotelina-2/farmacología , Endotelina-3/farmacología , Endotelinas/fisiología , Humanos , Inositol 1,4,5-Trifosfato/metabolismo , Ratones , Osteoblastos/citología , Osteoblastos/fisiología , Osteocalcina/biosíntesis , Osteocalcina/genética , Péptidos Cíclicos/farmacología , Receptor de Endotelina A , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transcripción GenéticaRESUMEN
We examined the effects of members of the endothelin (ET) family on mineralization of rat calvarial osteoblast-like cells. The accumulation of calcium in cells and cell layers was attenuated by ETs with the rank order of potency ET-1 = ET-2 > ET-3. We stained the mineralized nodules by von Kossa staining and measured the number and area of mineralized nodules. The inhibitory effects of ET-1 and ET-2 on the formation of mineralized nodules were stronger than those of ET-3. Our data suggest that ET-1 may inhibit the mineralization process of osteoblastic cells through the ETA receptor.