ABSTRACT
OBJECTIVE: We sought to identify glycolysis, glycogenolysis, lipolysis, Krebs cycle, respiratory chain, and oxidative phosphorylation enzymes simultaneously regulated by T3 and cAMP. MATERIALS AND METHODS: We performed in silico analysis of 56 promoters to search for cis-cAMP (CREB) and cis-thyroid (TRE) response elements, considering UCP1, SERCA2 and glyceraldehyde 3-phosphate dehydrogenase as reference. Only regulatory regions with prior in vitro validation were selected. RESULTS: 29/56 enzymes presented potential TREs in their regulatory sequence, and some scored over 0.80 (better predictive value 1): citrate synthase, phosphoglucose isomerase, succinate dehydrogenases A/C, UCP3, UCP2, UCP4, UCP5, phosphoglycerate mutase, glyceraldehyde 3-P dehydrogenase, glucokinase, malate dehydrogenase, acyl-CoA transferase (thiolase), cytochrome a3, and lactate dehydrogenase. Moreover, some enzymes have not yet been described in the literature as genomically regulated by T3. CONCLUSION: Our results point to other enzymes which may possibly be regulated by T3 and CREB, and speculate their joint roles in contributing to the optimal thermogenic acclimation.
OBJETIVO: Identificar enzimas das vias da glicólise, glicogenólise, lipólise, ciclo de Krebs, cadeia respiratória e fosforilação oxidativa possivelmente reguladas por T3 e cAMP. MATERIAIS E MÉTODOS: Analisamos 56 genes metabólicos in silico mediante a identificação dos elementos cis de regulação gênica responsivos ao T3 e cAMP (TREs, thyroid response elements e CREs, cAMP response elements), utilizando como referência o promotor da UCP1, SERCA2 e gliceraldeído 3-fosfato desidrogenase. Selecionamos somente os promotores com estudo funcional prévio in vitro. RESULTADOS: 29/56 enzimas apresentaram TREs em suas regiões regulatórias, parte com escore > 0,80 (melhor valor preditivo 1): citrato sintase, fosfoglucose isomerase, succinato desidrogenase A/C, UCP3, UCP2, UCP4, UCP5, fosfoglicerato mutase, gliceraldeído 3-P desidrogenase, glucoquinase, malato desidrogenase, acil-CoA transferase (tiolase), citocromo a3, e lactato desidrogenase; parte desconhecida como regulada por T3. CONCLUSÃO: Os resultados do presente estudo apontam para novos genes regulados por T3 e cAMP e, por conseguinte, sua contribuição na regulação da termogênese.
Subject(s)
Humans , Cyclic AMP/genetics , Oxidative Phosphorylation , Thermogenesis/genetics , Triiodothyronine/genetics , Enzymes/metabolismABSTRACT
OBJECTIVE: Drug-induced differentiation is commonly used as a therapeutic modality for the treatment of neuroblastoma tumors. Increased level of cyclic adenosine 3', 5'-monophosphate (cAMP) mediates terminal differentiation in some neuroblastoma cell lines through activation of several signaling networks, including cAMP response element binding protein (CREB). Objective was to test whether cAMP-induced differentiation in a murine neuroblastoma cell line (NBP2) is partly mediated by CREB. METHODS: Fluorescent microscopy was used to document neuron-like morphological changes imparted by a constitutively active CREB (VP16CREB). Real time PCR (RT-PCR) was performed to verify changes in the expression of cAMP/CREB responsive genes. RESULTS: It was found that transient expression of VP16CREB into NBP2 cells resulted in morphological changes that were characteristics of terminally differentiated neurons. Furthermore, increased expression of cAMP responsive genes was compromised in cells resisting VP16CREB-mediated differentiation. CONCLUSION: A constitutively active CREB induces terminal differentiation in a subset of NBP2 cell population. Altered expression of cAMP responsive genes may account for differentiation resistant phenotype in NBP2 cells.