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Biochem Biophys Res Commun ; 295(5): 1077-84, 2002 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-12135604

RESUMO

Hepatocytes (Heps) and sinusoidal endothelial cells (SECs) perform different roles in normal and pathological liver functions through the differential expression of fibronectin (FN) polypeptides. Nonetheless, the molecular basis underlying cell-type specific FN expression remains unknown. Using liver cell isolation techniques followed by short-term primary culture and transient transfection, here, we compare the transcriptional regulation of the FN promoter in Heps and SEC in conditions that closely resemble in vivo physiology. Transfection experiments allowed us to reveal cell-type specific regulatory elements operating through the proximal regions of the FN promoter. To investigate this further, we examined the occupation patterns of key elements of the FN promoter such as the -170 CRE and -150 CCAAT sites. Transcriptional activity of mutagenised promoter constructs confirmed that in Heps, these two sites behave as a composite element critical for normal promoter activity. In addition, DNA-binding experiments demonstrate that the -170 CRE element displays a clear cell-type specific occupation with binding activities for ATF-2 and ATF-3 being specific to Heps. These results establish the starting point to investigate the molecular basis of changes in transcriptional regulation of the FN gene involved in liver pathology.


Assuntos
Endotélio/fisiologia , Fibronectinas/genética , Hepatócitos/fisiologia , Regiões Promotoras Genéticas/fisiologia , Animais , Fator de Ligação a CCAAT/metabolismo , Elementos Facilitadores Genéticos/fisiologia , Fibronectinas/metabolismo , Regulação da Expressão Gênica , Fígado/citologia , Masculino , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Fatores de Transcrição/metabolismo
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