Adipocyte differentiation is inhibited by melatonin through the regulation of C/EBP beta transcriptional activity

Autor(es)

Cardoso Alonso-Vale, Maria Isabel ^[1] ; Peres, Sidney Barnabe ^[2] ; Vernochet, Cecile ^[2] ; Farmer, Stephen R. ^[2] ; Lima, Fabio Bessa ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 Sao Paulo - Brazil

^[2] Boston Univ, Sch Med, Dept Biochem, Boston, MA 02118 - USA

• Tipo de documento: Artigo Científico
• Fonte: Journal of Pineal Research; v. 47, n. 3, p. 221-227, OCT 2009.
• Citações Web of Science: 50

Resumo

Considering that melatonin has been implicated in body weight control, this work investigated whether this effect involves the regulation of adipogenesis. 3T3-L1 preadipocytes were induced to differentiate in the absence or presence of melatonin (10(-3) m). Swiss-3T3 cells ectopically and conditionally (Tet-off system) over-expressing the 34 kDa C/EBP beta isoform (Swiss-LAP cells) were employed as a tool to assess the mechanisms of action at the molecular level. Protein markers of the adipogenic phenotype were analyzed by Western blot. At 36 hr of differentiation of 3T3-L1 preadipocytes, a reduction of PPAR gamma expression was detected followed by a further reduction, at day 4, of perilipin, aP2 and adiponectin protein expression in melatonin-treated cells. Real-time PCR analysis also showed a decrease of PPAR gamma (60%), C/EBP alpha (75%), adiponectin (30%) and aP2 (40%) mRNA expression. Finally, we transfected Swiss LAP cells with a C/EBP alpha gene promoter/reporter construct in which luciferase expression is enhanced in response to C/EBP beta activity. Culture of such transfected cells in the absence of tetracycline led to a 2.5-fold activation of the C/EBP alpha promoter. However, when treated with melatonin, the level of C/EBP alpha promoter activation by C/EBP beta was reduced by 50% (P = 0.05, n = 6). In addition, this inhibitory effect of melatonin was also reflected in the phenotype of the cells, since their capacity to accumulate lipids droplets was reduced as confirmed by the poor staining with Oil Red O. In conclusion, melatonin at a concentration of 10(-3) m works as a negative regulator of adipogenesis acting in part by inhibiting the activity of a critical adipogenic transcription factor, C/EBP beta. (AU)

• Processo FAPESP: 07/50404-0 - Influência da melatonina na regulação da adipogênese
• Beneficiário: Maria Isabel Cardoso Alonso-Vale
• Modalidade de apoio: Bolsas no Exterior - Pesquisa
• Processo FAPESP: 04/06767-2 - O papel da melatonina no controle do metabolismo energético: interações hormonais, ações centrais e periféricas (pineal, obesidade, diabetes e envelhecimento)
• Beneficiário: José Cipolla Neto
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 04/14696-8 - Regulacao pela melatonina da expressao genica e das funcoes endocrinas e metabolicas de adipocitos isolados de tecido adiposo branco em cultura primaria.
• Beneficiário: Maria Isabel Cardoso Alonso-Vale
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado