Assuntos
Receptores ErbB , Nevo , Neoplasias Cutâneas , Criança , Receptores ErbB/genética , Humanos , Masculino , Mutação/genética , Nevo/genética , Neoplasias Cutâneas/genéticaRESUMO
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.
Assuntos
Calcificação Fisiológica/fisiologia , Endotelinas/farmacologia , Osteoblastos/efeitos dos fármacos , Receptores de Endotelina/fisiologia , Animais , Calcificação Fisiológica/efeitos dos fármacos , Cálcio , Linhagem Celular , AMP Cíclico/metabolismo , Primers do DNA , Antagonistas dos Receptores de Endotelina , Endotelina-1/metabolismo , Endotelina-1/farmacologia , Endotelina-2/farmacologia , Endotelina-3/farmacologia , Endotelinas/fisiologia , Humanos , Inositol 1,4,5-Trifosfato/metabolismo , Camundongos , Osteoblastos/citologia , Osteoblastos/fisiologia , Osteocalcina/biossíntese , Osteocalcina/genética , Peptídeos Cíclicos/farmacologia , Receptor de Endotelina A , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição GênicaRESUMO
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.
Assuntos
Calcificação Fisiológica/efeitos dos fármacos , Endotelinas/farmacologia , Osteoblastos/efeitos dos fármacos , Crânio/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Cálcio/metabolismo , Células Cultivadas , Antagonistas dos Receptores de Endotelina , Humanos , Osteoblastos/metabolismo , Ratos , Ratos Wistar , Receptor de Endotelina A , Crânio/citologiaRESUMO
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.