Catalytic mechanism and substrate specificity of HIF prolyl hydroxylases

Smirnova, Natalia; Hushpulian, Dmitry M.; Speer, Rachel E.; Gaisina, Irina N.; Ratan, Rajiv R.; Gazaryan, I. G.

doi:10.1134/s0006297912100033

Cited by 26 publications

(16 citation statements)

References 67 publications

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“…It must also be emphasized that the consequence of increased levels of HIF-1 in different cell types is highly divergent and dependent on the type of injury. Indeed, it is now becoming clear that the PHDs may also have specific endogenous substrates as well as divergent cell-specific roles (Smirnova et al, 2012). Thus, an additional challenge will be whether development of isoform-specific inhibitors will be more efficacious and safe than a more global approach.…”

Section: Targeted Bbb Cell-specific Treatmentmentioning

confidence: 99%

Cell‐specific blood–brain barrier regulation in health and disease: a focus on hypoxia

Engelhardt

Patkar

Ogunshola

2014

British J Pharmacology

134

121

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The blood-brain barrier (BBB) is a complex vascular structure consisting of microvascular endothelial cells that line the vessel wall, astrocyte end-feet, pericytes, as well as the basal lamina. BBB cells act in concert to maintain the characteristic impermeable and low paracellular flux of the brain vascular network, thus ensuring a homeostatic neuronal environment. Alterations in BBB stability that occur during injury have dire consequences on disease progression and it is clear that BBB cell-specific responses, positive or negative, must make a significant contribution to injury outcome. Reduced oxygenation, or hypoxia, is a characteristic of many brain diseases that significantly increases barrier permeability. Recent data suggest that hypoxia-inducible factor (HIF-1), the master regulator of the hypoxic response, probably mediates many hypoxic effects either directly or indirectly via its target genes. This review discusses current knowledge of physiological cell-specific regulation of barrier function, their responses to hypoxia as well as consequences of hypoxic-and HIF-1-mediated mechanisms on barrier integrity during select brain diseases. In the final sections, the potential of current advances in targeting HIF-1 as a therapeutic strategy will be overviewed. AbbreviationsBBB, blood-brain barrier; HIF-1, hypoxia-inducible factor-1; TJ, tight junction; ECs, endothelial cells; TEER, transendothelial electrical resistanceThe maintenance of CNS homeostasis is performed largely by the blood-brain barrier (BBB), which together with neurons and microglia form an organization referred to as the neurovascular unit (NVU). The BBB is dynamic performing both passive and active features of the brain endothelium essentially acting as a vascular gatekeeper that controls movement of substances from the circulating blood into the brain parenchyma -a role crucial for neuronal, and therefore CNS, homeostasis. Accumulating experimental evidence supports the hypothesis that opening of the BBB triggers a chain of events leading to neuronal dysfunction and damage resulting in neurological disease, and when coupled with previous insults BBB disruption could have serious detrimental consequences for patient outcome. Despite this knowledge, our understanding of physiological barrier function, as well as during disease, is very limited. In addition, the contribution of the perivascular cells that modulate barrier characteristics and their individual responses to injury is poorly characterized. This review will discuss the mechanisms through which hypoxia, a characteristic state of many brain diseases, disrupts barrier function and the importance of BBB cell-specific responses to barrier integrity. Additionally, consequences of hypoxia-mediated barrier modulation during brain disease and future therapeutic use of hypoxia-inducible factor-1 (HIF-1) modulators in the clinics will be reviewed. Physiology BBB organization and cell-specific functionThe BBB is a complex structure consisting of microvascular endothelial cells (ECs) that ...

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Section: Targeted Bbb Cell-specific Treatmentmentioning

confidence: 99%

Cell‐specific blood–brain barrier regulation in health and disease: a focus on hypoxia

Engelhardt

Patkar

Ogunshola

2014

British J Pharmacology

134

121

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“…PHD enzymatic assays employing GST-fusion constructs have been performed in cell lysates from HEK293 cells [120], but not in neuronal cells. In vitro assays of PHD enzyme activity have been developed, but require large amounts of recombinant enzyme and expensive reagents (reviewed by [121]). Therefore it would be highly valuable to be able to biochemically detect not only stabilization but prolyl-hydroxylation and ubiquitination of a HIF-1α reporter in order to identify mechanisms by which HIF-1α is stabilized under given experimental conditions.…”

Section: Cerebral Ischemiamentioning

confidence: 99%

Hypoxia-inducible factor prolyl hydroxylases as targets for neuroprotection by “antioxidant” metal chelators: From ferroptosis to stroke

Speer

Karuppagounder

Basso

et al. 2013

Free Radical Biology and Medicine

117

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Neurologic conditions including stroke, Alzheimer’s disease, Parkinson’s disease and Huntington’s disease are leading causes of death and long-term disability in the United States, and efforts to develop novel therapeutics for these conditions have historically had poor success in translating from bench to bedside. Hypoxia Inducible Factor-1alpha (HIF-1α) mediates a broad, evolutionarily conserved, endogenous adaptive program to hypoxia, and manipulation of components of the HIF pathway are neuroprotective in a number of human neurological diseases and experimental models. In this review, we discuss molecular components of one aspect of hypoxic adpatation in detail, and provide perspective on which targets within this pathway appear to be ripest for preventing and repairing neurodegeneration. Further, we highlight the role of HIF prolyl hydroxylases as emerging targets for the salutary effects of metal chelators on ferroptosis in vitro as well in animal models of neurological diseases.

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“…In well-oxygenated conditions HIFs are bound by the Von Hippel Lindau (VHL) tumor suppressor protein which recruits an ubiquitin ligase that targets these transcription factors for proteasomal degradation [18]. VHL binding is critically dependent on hydroxylation of proline residues in HIF1 (P405 and P564) and HIF2 (P405 and P531) [40]. The oxygen-sensitive α subunits of HIF1 or HIF2 can heterodimerize with the stable HIF1β (ARNT) subunit that together forms a basic helix-loop-helix-PAS (bHLH-PAS) transcriptional regulator that binds to the core sequence RCGTG termed the hypoxia response element (HRE) in promoters of presumed target genes [18], [20], [28], [38].…”

Section: Introductionmentioning

confidence: 99%

Convergence of Hypoxia and TGFβ Pathways on Cell Cycle Regulation in Human Hematopoietic Stem/Progenitor Cells

2014

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Although it has been shown that HIF1 and 2 fulfill essential roles within the hematopoietic system and in the regulation of HSC fate, little is currently known about the specific mechanisms that are involved. We identified transcriptome changes induced by hypoxia, constitutively active HIF1(P402/564) and HIF2(P405/531) in human cord blood CD34+ cells. Thus, we were able to identify common hypoxia-HIF1-HIF2 gene signatures, but we also identified specific target genes that were exclusively regulated by HIF1, HIF2 or hypoxia. Geneset enrichment analysis (GSEA) revealed that, besides known pathways associated with “hypoxia-induced signaling”, also significant enrichment for the Transforming Growth Factor beta (TGFβ) pathway was observed within the hypoxia/HIF1/HIF2 transcriptomes. One of the most significantly upregulated genes in both gene sets was the cyclin dependent kinase inhibitor CDKN1C (p57kip2). Combined hypoxia treatment or HIF overexpression together with TGFβ stimulation resulted in enhanced expression of CDKN1C and enhanced cell cycle arrest within the CD34+/CD38− stem cell compartment. Interestingly, we observed that CD34+ cells cultured under hypoxic conditions secreted high levels of latent TGFβ, suggesting an auto- or paracrine role of TGFβ in the regulation of quiescence of these cells. However, knockdown of SMAD4 could not rescue the hypoxia induced cell cycle arrest, arguing against direct effects of hypoxia-induced secreted TGFβ. Finally, the Gα-coupled receptor GTPase RGS1 was identified as a HIF-dependent hypoxia target that dampens SDF1-induced migration and signal transduction in human CD34+ stem/progenitor cells.

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Catalytic mechanism and substrate specificity of HIF prolyl hydroxylases

Cited by 26 publications

References 67 publications

Cell‐specific blood–brain barrier regulation in health and disease: a focus on hypoxia

Cell‐specific blood–brain barrier regulation in health and disease: a focus on hypoxia

Hypoxia-inducible factor prolyl hydroxylases as targets for neuroprotection by “antioxidant” metal chelators: From ferroptosis to stroke

Convergence of Hypoxia and TGFβ Pathways on Cell Cycle Regulation in Human Hematopoietic Stem/Progenitor Cells

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