RESUMO
Fluxes in human copper levels recently garnered attention for roles in cellular signaling, including affecting levels of the signaling molecule cyclic adenosine monophosphate. We herein apply an unbiased temporal evaluation of the signaling and whole genome transcriptional activities modulated by copper level fluctuations to identify potential copper sensor proteins responsible for driving these activities. We find that fluctuations in physiologically relevant copper levels modulate EGFR signal transduction and activation of the transcription factor CREB. Both intracellular and extracellular assays support Cu1+ inhibition of the EGFR phosphatase PTPN2 (and potentially PTPN1)-via ligation to the PTPN2 active site cysteine side chain-as the underlying mechanism. We additionally show i) copper supplementation drives weak transcriptional repression of the copper importer CTR1 and ii) CREB activity is inversely correlated with CTR1 expression. In summary, our study reveals PTPN2 as a physiological copper sensor and defines a regulatory mechanism linking feedback control of copper stimulated EGFR/CREB signaling and CTR1 expression.
Assuntos
Transportador de Cobre 1 , Cobre , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico , Receptores ErbB , Proteína Tirosina Fosfatase não Receptora Tipo 2 , Transdução de Sinais , Receptores ErbB/metabolismo , Receptores ErbB/genética , Cobre/metabolismo , Humanos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Transportador de Cobre 1/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Transcrição Gênica/efeitos dos fármacosRESUMO
Fluxes in human intra- and extracellular copper levels recently garnered attention for roles in cellular signaling, including affecting levels of the signaling molecule cyclic adenosine monophosphate (cAMP). We herein applied an unbiased temporal evaluation of the whole-genome transcriptional activities modulated by fluctuations in copper levels to identify the copper sensor proteins responsible for driving these activities. We found that fluctuations in physiologically-relevant copper levels rapidly modulate EGFR/MAPK/ERK signal transduction and activation of the transcription factor cAMP response element-binding protein (CREB). Both intracellular and extracellular assays support Cu 1+ inhibition of the EGFR-phosphatase PTPN2 (and potentially the homologous PTPN1)-via direct ligation to the PTPN2 active site cysteine side chain-as the underlying mechanism of copper-stimulated EGFR signal transduction activation. Depletion of copper represses this signaling pathway. We additionally show i ) copper supplementation drives transcriptional repression of the copper importer CTR1 and ii ) CREB activity is inversely correlated with CTR1 expression. In summary, our study reveals PTPN2 as a physiological copper sensor and defines a regulatory mechanism linking feedback control of copper-stimulated MAPK/ERK/CREB-signaling and CTR1 expression, thereby uncovering a previously unrecognized link between copper levels and cellular signal transduction.