Evidence for and consequences of chronic heme deficiency in Belgrade rat reticulocytes

Garrick, Michael D.; Scott, Donna L.; Kulju, David; Romano, Michelle A.; Dolan, Kevin G.; Garrick, Laura M.

doi:10.1016/s0167-4889(99)00006-3

Cited by 24 publications

(20 citation statements)

References 34 publications

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“…Thus, the LBD in the context of the full-length protein retains its heme coordination environment and its high affinity for heme. Furthermore, because these K d values are below the 0.1-0.2 M concentration of the intracellular exchangeable heme pool (78,79), the receptors would be expected to exist predominantly within the cell in the hemebound state. On the other hand, the H568F and H568F/C384A variants, with 1000-fold lower heme affinity than the wild-type protein, would exist as apoproteins within the cell.…”

Section: Discussionmentioning

confidence: 99%

High Affinity Heme Binding to a Heme Regulatory Motif on the Nuclear Receptor Rev-erbβ Leads to Its Degradation and Indirectly Regulates Its Interaction with Nuclear Receptor Corepressor

Carter

Gupta

Ragsdale

2016

Journal of Biological Chemistry

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Rev-erb␣ and Rev-erb␤ are heme-binding nuclear receptors (NR) that repress the transcription of genes involved in regulating metabolism, inflammation, and the circadian clock. Previous gene expression and co-immunoprecipitation studies led to a model in which heme binding to Rev-erb␣ recruits nuclear receptor corepressor 1 (NCoR1) into an active repressor complex. However, in contradiction, biochemical and crystallographic studies have shown that heme decreases the affinity of the ligand-binding domain of Rev-erb NRs for NCoR1 peptides. One explanation for this discrepancy is that the ligand-binding domain and NCoR1 peptides used for in vitro studies cannot replicate the key features of the full-length proteins used in cellular studies. However, the combined in vitro and cellular results described here demonstrate that heme does not directly promote interactions between full-length Rev-erb␤ (FLRev-erb␤) and an NCoR1 construct encompassing all three NR interaction domains. NCoR1 tightly binds both apo-and heme-replete FLRev-erb␤⅐DNA complexes; furthermore, heme, at high concentrations, destabilizes the FLRev-erb␤⅐NCoR1 complex. The interaction between FLRev-erb␤ and NCoR1 as well as Reverb␤ repression at the Bmal1 promoter appear to be modulated by another cellular factor(s), at least one of which is related to the ubiquitin-proteasome pathway. Our studies suggest that heme is involved in regulating the degradation of Rev-erb␤ in a manner consistent with its role in circadian rhythm maintenance. Finally, the very slow rate constant (10 ؊6 s ؊1 ) of heme dissociation from Rev-erb␤ rules out a prior proposal that Reverb␤ acts as an intracellular heme sensor.Nuclear receptors (NRs) 2 are eukaryotic transcription factors that activate or repress gene expression in response to binding small signaling molecules such as steroid hormones, lipophilic vitamins, and fatty acids (1). Genes regulated by NRs are involved in a myriad of cellular processes ranging from metabolic homeostasis to growth and development. The subjects of this article, Rev-erb␣ and Rev-erb␤, are NRs that have overlapping functions and tissue expression patterns (2-9) and are under circadian control (10 -12). Rev-erb NRs repress the transcription of key genes, e.g. Bmal1, CLOCK, and Rev-erb␣ itself, involved in regulating the molecular clock (13)(14)(15). This is accomplished in part through the formation of a heterodimeric Bmal1-CLOCK complex that activates the transcription of clock-controlled genes including Rev-erb␣/␤, completing a critical feedback loop required for circadian rhythm maintenance (6, 7). Rev-erb␣ and Rev-erb␤ also regulate the expression of genes involved in gluconeogenesis, lipid homeostasis, and immune responses, ultimately synchronizing these processes to the diurnal cycle (16 -21).The multiple functions of NRs (DNA, ligand, and coregulator binding) are accomplished through their modular structure (22, 23). The N-terminal A/B domain is hypervariable, is involved in ligand-independent transcriptional regulation, and is subject to ...

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Section: Discussionmentioning

confidence: 99%

High Affinity Heme Binding to a Heme Regulatory Motif on the Nuclear Receptor Rev-erbβ Leads to Its Degradation and Indirectly Regulates Its Interaction with Nuclear Receptor Corepressor

Carter

Gupta

Ragsdale

2016

Journal of Biological Chemistry

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“…Hemolysates were prepared by the method of Garrick et al (36). The lysates were run through a 0.5 × 4 cm column (0.8 mL) of Dowex 1-X8 resin equilibrated in 2 mol/L NaCl and 5 mmol/L NaPO 4 , pH 7.4.…”

Section: Blood Free Heme Detectionmentioning

confidence: 99%

“…The lysates were run through a 0.5 × 4 cm column (0.8 mL) of Dowex 1-X8 resin equilibrated in 2 mol/L NaCl and 5 mmol/L NaPO 4 , pH 7.4. Hemoglobin does not bind to the column under these conditions, but "free" heme does (36). The column was rinsed with 5× the bed volume of 2 mol/L NaCl and 5 mmol/L NaPO 4 , pH 7.4, to assure that all the hemoglobin had passed through, and then with 10× the bed volume of 5 mmol/L NaPO 4 , pH 7.4.…”

Section: Blood Free Heme Detectionmentioning

confidence: 99%

Mammal Cells Double Their Total RNAs against Diabetes, Ischemia Reperfusion and Malaria-Induced Oxidative Stress

Zhang

Cheng

et al. 2010

Mol Med

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Total cellular RNA level is stable usually, although it may increase gradually during growth or decrease gradually under certain stressors. However, we found that mammal cell RNAs could be doubled within 24 h in response to free heme accumulation (ischemia reperfusion and malaria infection) or a high level of glucose treatment (diabetes). Clinical investigations in rats showed that pretreatment with heme (24 h for doubling total RNAs) alleviated oxidative damages caused by diabetes, and pretreatment with glucose (24 h for trebling total RNAs) alleviated oxidative damages caused by ischemia reperfusion or malaria infection. Therefore, this rapid RNA amplification may play an important role in mammal adaptation to diabetes, ischemia reperfusion and malaria infection-derived oxidative stress. This rapid RNA amplification is derived from glucose and heme, but not from their accompanying reactive oxygen species. Hexokinases endure glucose-derived reactive oxygen species accumulation but are not related glucose-derived RNA amplification. In contrast, the TATA box-binding protein (TBP) mediates all glucose-and hemeinduced RNA amplification in mammal cells.

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“…However, it is quite difficult to determine such low "free heme" concentrations in the cell by conventional methods [56]. In a pulse chase experiment with 59 Fe-transferrin, the "free heme" pool in reticulocytes in Belgrade rats was shown to behave as an intermediate for hemoglobin biosynthesis, with a rapid half-life of a little over 2 hours [57]. With the exception of this animal model, no direct demonstration of "free heme" concentration is known.…”

Section: The Toxic Effects Of Free Hemementioning

confidence: 99%

“…The greatest confounding factor in "free heme" determination is the fact that "free heme" is in a rapid dynamic equilibrium between the protein-bound and the unbound state [20,57]. Thus, even using column chromatography that can separate "free heme" from hemoproteins, results obtained may not necessarily reflect the exact concentration of "free heme" in cells.…”

Section: The Toxic Effects Of Free Hemementioning

confidence: 99%

Biological Implications of Heme Metabolism

Sassa

2006

J. Clin. Biochem. Nutr.

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Evidence for and consequences of chronic heme deficiency in Belgrade rat reticulocytes

Cited by 24 publications

References 34 publications

High Affinity Heme Binding to a Heme Regulatory Motif on the Nuclear Receptor Rev-erbβ Leads to Its Degradation and Indirectly Regulates Its Interaction with Nuclear Receptor Corepressor

High Affinity Heme Binding to a Heme Regulatory Motif on the Nuclear Receptor Rev-erbβ Leads to Its Degradation and Indirectly Regulates Its Interaction with Nuclear Receptor Corepressor

Mammal Cells Double Their Total RNAs against Diabetes, Ischemia Reperfusion and Malaria-Induced Oxidative Stress

Biological Implications of Heme Metabolism

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