Transcription factor REST negatively influences the protein kinase C-dependent up-regulation of human mu-opioid receptor gene transcription.
Mu-opioid receptor expression increases during neurogenesis, regulates the survival of maturing neurons and is implicated in ischemia-induced neuronal death. The repressor element 1 silencing transcription factor (REST), a regulator of a subset of genes in differentiating and post-mitotic neurons, is involved in its transcriptional repression. Extracellular signaling molecules and mechanisms that control the human mu-opioid receptor (hMOR) gene transcription are not clearly understood. We examined the role of protein kinase C (PKC) on hMOR transcription in a model of neuronal cells and in the context of the potential influence of REST. In native SH-SY5Y neuroblastoma cells, PKC activation with phorbol 12-myristate 13-acetate (PMA, 16 nM, 24h) down-regulated hMOR transcription and concomitantly elevated the REST binding activity to repressor element 1 of the hMOR promoter. In contrast, PMA activated hMOR gene transcription when REST expression was knocked down by an antisense strategy or by retinoic acid-induced cell differentiation. PMA acts through a PKC-dependent pathway requiring downstream MAP kinases and the transcription factor AP-1. In a series of hMOR-luciferase promoter/reporter constructs transfected into SH-SY5Y cells and PC12 cells, PMA up-regulated hMOR transcription in PC12 cells lacking REST, and in SH-SY5Y cells either transfected with constructs deficient in the REST DNA binding element or when REST was down-regulated in retinoic acid-differentiated cells. These findings help explain how hMOR transcription is regulated and may clarify its contribution to epigenetic modifications and reprogramming of differentiated neuronal cells exposed to PKC-activating agents.
Bedini
Andrea
A
Department of Pharmacology, University of Bologna, Bologna, Italy.
Baiula
Monica
M
Carbonari
Gioia
G
Spampinato
Santi
S
D001483:Base Sequence; D045744:Cell Line, Tumor; D017931:DNA Primers; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation; D006801:Humans; D011493:Protein Kinase C / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000235:genetics*; D012097:Repressor Proteins / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology*; D000099229:RE1-Silencing Transcription Factor
D017931:DNA Primers; D011493:Protein Kinase C; D017450:Receptors, Opioid, mu; D012097:Repressor Proteins; D013755:Tetradecanoylphorbol Acetate; D000099229:RE1-Silencing Transcription Factor