Abstract:Neuronal PAS domain protein 2 (NPAS2) is a mammalian transcription factor that binds DNA as an obligate dimeric partner of BMAL1 and is implicated in the regulation of circadian rhythm. Here we show that both PAS domains of NPAS2 bind heme as a prosthetic group and that the heme status controls DNA binding in vitro. NPAS2-BMAL1 heterodimers, existing in either the apo (heme-free) or holo (heme-loaded) state, bound DNA avidly under favorably reducing ratios of the reduced and oxidized forms of nicotinamide aden… Show more
“…Mechanistically, we favor the hypothesis that, in mammals, heme oxygenase-derived CO attenuates CLOCK(NPAS2)-BMAL1 DNA binding, probably via coordination by a heme molecule bound to NPAS2 (ref. 6) and probably also to CLOCK 31 , and thereby modulates expression of CLOCK(NPAS2)-BMAL1-target genes. Although this scenario is not the only possible interpretation of our results (as described below), our preferred model is consistent with both past and present observations.…”
Section: Discussionmentioning
confidence: 99%
“…(i) In vitro, micromolar concentrations of CO have been shown to impair DNA binding and BMAL-heterodimer formation of heme-bound NPAS2 but not apo-NPAS2 (ref. 6), and in the brain, these concentrations of CO are generated by heme oxygenases 32 (detailed discussion of CO concentration in Supplementary Note 1). (ii) Mutation of heme-coordinating residues within NPAS2 also impairs heterodimer formation with BMAL1, thus decreasing both specific DNA binding to canonical E boxes and NPAS2-BMAL1 transactivation activity, probably via conformational changes within the PAS-A domain of NPAS2 (ref.…”
Section: Discussionmentioning
confidence: 99%
“…In vitro, CO inhibits binding of NPAS2-BMAL1 to DNA 6 . If such an inhibitory effect also occurs in vivo, transcription of NPAS2-BMAL1-target genes should increase when endogenous CO levels are decreased.…”
Section: Heme Degradation Is Regulated By the Circadian Clockmentioning
“…Mechanistically, we favor the hypothesis that, in mammals, heme oxygenase-derived CO attenuates CLOCK(NPAS2)-BMAL1 DNA binding, probably via coordination by a heme molecule bound to NPAS2 (ref. 6) and probably also to CLOCK 31 , and thereby modulates expression of CLOCK(NPAS2)-BMAL1-target genes. Although this scenario is not the only possible interpretation of our results (as described below), our preferred model is consistent with both past and present observations.…”
Section: Discussionmentioning
confidence: 99%
“…(i) In vitro, micromolar concentrations of CO have been shown to impair DNA binding and BMAL-heterodimer formation of heme-bound NPAS2 but not apo-NPAS2 (ref. 6), and in the brain, these concentrations of CO are generated by heme oxygenases 32 (detailed discussion of CO concentration in Supplementary Note 1). (ii) Mutation of heme-coordinating residues within NPAS2 also impairs heterodimer formation with BMAL1, thus decreasing both specific DNA binding to canonical E boxes and NPAS2-BMAL1 transactivation activity, probably via conformational changes within the PAS-A domain of NPAS2 (ref.…”
Section: Discussionmentioning
confidence: 99%
“…In vitro, CO inhibits binding of NPAS2-BMAL1 to DNA 6 . If such an inhibitory effect also occurs in vivo, transcription of NPAS2-BMAL1-target genes should increase when endogenous CO levels are decreased.…”
Section: Heme Degradation Is Regulated By the Circadian Clockmentioning
“…They are most closely related to the PAS family members CLOCK and NPAS2 that play an important role in regulating eukaryotic circadian rhythms (Dunlap et al, 1999;Dioum et al, 2002). Overlapping the PAS domains was a partial aryl-hydrocarbon receptor nuclear translocator domain (ARNT), aa 3 -187.…”
Here we report that the OX-TES-1 SEREX antigen, which showed immunological reactivity with serum from four out of 10 diffuse large B-cell lymphoma (DLBCL) patients, is encoded by a novel gene, PAS domain containing 1 (PASD1). PASD1_v1 cDNA encodes a 639 amino-acid (aa) protein product, while an alternatively spliced variant (PASD1_v2), lacking intron 14, encodes a 773 aa protein, the first 638 aa of which are common to both proteins. The PASD1-predicted protein contains a PAS domain that, together with a putative leucine zipper and nuclear localisation signal, suggests it encodes a transcription factor. The expression of PASD1_v1 mRNA was confirmed by RT -PCR in seven DLBCL-derived cell lines, while PASD1_v2 mRNA appears to be preferentially expressed in cell lines derived from non-germinal centre DLBCL. Immunophenotyping studies of de novo DLBCL patients' tumours with antibodies to CD10, BCL-6 and MUM1 indicated that two patients mounting an immune response to PASD1 were of a poor prognosis nongerminal centre subtype. Expression of PASD1 mRNA was restricted to normal testis, while frequent expression was observed in solid tumours (25 out of 68), thus fulfilling the criteria for a novel cancer testis antigen. PASD1 has potential for lymphoma vaccine development that may also be widely applicable to other tumour types.
“…Carbon monoxide (CO) inhibits the DNA binding of NPAS2 by favouring inactive BMAL1 homodimerization instead of active NPAS2/BMAL1 heterodimerization (Dioum et al, 2002). Along this line, NPAS2 and REV-ERBα have both been shown to act as heme sensors, where heme binding controls the DNA binding activity of these two core clock components (Kaasik and Lee, 2004;Yin et al, 2007).…”
Section: Metabolic Control Of Circadian Rhythmsmentioning
The cyclic environmental conditions brought about by the 24 h rotation of the earth have allowed the evolution of endogenous circadian clocks that control the temporal alignment of behaviour and physiology, including the uptake and processing of nutrients. Both metabolic and circadian regulatory systems are built upon a complex feedback network connecting centres of the central nervous system and different peripheral tissues. Emerging evidence suggests that circadian clock function is closely linked to metabolic homeostasis and that rhythm disruption can contribute to the development of metabolic disease. At the same time, metabolic processes feed back into the circadian clock, affecting clock gene expression and timing of behaviour. In this review, we summarize the experimental evidence for this bimodal interaction, with a focus on the molecular mechanisms mediating this exchange, and outline the implications for clock-based and metabolic diseases.
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