Control of Oxygen Homeostasis by Hypoxia-Inducible Factor 1: Essential Roles in Embryogenesis, Physiology, and Disease Pathogenesis

2001 ◽  
pp. 184-211
Keyword(s):  
Hypoxia Inducible Factor ◽  
Disease Pathogenesis ◽  
Hypoxia Inducible Factor 1 ◽  
Oxygen Homeostasis

Involvement of oxygen-sensing pathways in physiologic and pathologic erythropoiesis

Blood ◽  
2009 ◽  
Vol 114 (10) ◽  
pp. 2015-2019 ◽  
Author(s):  
Gregg L. Semenza
Keyword(s):  
Blood Cells ◽  
Tissue Oxygenation ◽  
Hypoxia Inducible Factor ◽  
Α Subunit ◽  
Vhl Gene ◽  
Von Hippel Lindau ◽  
Hypoxia Inducible Factor 1 ◽  
Oxygen Homeostasis ◽  
Genes Encoding ◽  
Asparaginyl Hydroxylase

Abstract Red blood cells deliver O2 from the lungs to every cell in the human body. Reduced tissue oxygenation triggers increased production of erythropoietin by hypoxia-inducible factor 1 (HIF-1), which is a transcriptional activator composed of an O2-regulated α subunit and a constitutively expressed β subunit. Hydroxylation of HIF-1α or HIF-2α by the asparaginyl hydroxylase FIH-1 blocks coactivator binding and transactivation. Hydroxylation of HIF-1α or HIF-2α by the prolyl hydroxylase PHD2 is required for binding of the von Hippel-Lindau protein (VHL), leading to ubiquitination and proteasomal degradation. Mutations in the genes encoding VHL, PHD2, and HIF-2α have been identified in patients with familial erythrocytosis. Patients with Chuvash polycythemia, who are homozygous for a missense mutation in the VHL gene, have multisystem pathology attributable to dysregulated oxygen homeostasis. Intense efforts are under way to identify small molecule hydroxylase inhibitors that can be administered chronically to selectively induce erythropoiesis without undesirable side effects.

scholarly journals Carboxyl-Terminal Transactivation Activity of Hypoxia-Inducible Factor 1α Is Governed by a von Hippel-Lindau Protein-Independent, Hydroxylation-Regulated Association with p300/CBP

2002 ◽  
Vol 22 (9) ◽  
pp. 2984-2992 ◽  
Author(s):  
Nianli Sang ◽  
Jie Fang ◽  
Vickram Srinivas ◽  
Irene Leshchinsky ◽  
Jaime Caro
Keyword(s):  
Hypoxia Inducible Factor ◽  
Adaptation To Hypoxia ◽  
Physical Interaction ◽  
Prolyl Hydroxylases ◽  
Von Hippel Lindau ◽  
Hypoxia Inducible Factor 1 ◽  
Transactivation Activity ◽  
Oxygen Homeostasis ◽  
Stimulation Of

ABSTRACT Hypoxia-inducible factor 1 complex (HIF-1) plays a pivotal role in oxygen homeostasis and adaptation to hypoxia. Its function is controlled by both the protein stability and the transactivation activity of its alpha subunit, HIF-1α. Hydroxylation of at least two prolyl residues in the oxygen-dependent degradation domain of HIF-1α regulates its interaction with the von Hippel-Lindau protein (VHL) that targets HIF-1α for ubiquitination and proteasomal degradation. Several prolyl hydroxylases have been found to specifically hydroxylate HIF-1α. In this report, we investigated possible roles of VHL and hydroxylases in the regulation of the transactivation activity of the C-terminal activating domain (CAD) of HIF-1α. We demonstrate that regulation of the transactivation activity of HIF-1α CAD also involves hydroxylase activity but does not require functional VHL. In addition, stimulation of the CAD activity by a hydoxylase inhibitor, hypoxia, and desferrioxamine was severely blocked by the adenoviral oncoprotein E1A but not by an E1A mutant defective in targeting p300/CBP. We further demonstrate that a hydroxylase inhibitor, hypoxia, and desferrioxamine promote the functional and physical interaction between HIF-1α CAD and p300/CBP in vivo. Taken together, our data provide evidence that hypoxia-regulated stabilization and transcriptional stimulation of HIF-1α function are regulated through partially overlapping but distinguishable pathways.

scholarly journals Adaptive and Maladaptive Cardiorespiratory Responses to Continuous and Intermittent Hypoxia Mediated by Hypoxia-Inducible Factors 1 and 2

2012 ◽  
Vol 92 (3) ◽  
pp. 967-1003 ◽  
Author(s):  
Nanduri R. Prabhakar ◽  
Gregg L. Semenza
Keyword(s):  
Transcriptional Activation ◽  
Intermittent Hypoxia ◽  
Hypoxia Inducible Factor ◽  
Metabolic Reprogramming ◽  
Hypoxia Inducible Factor 1 ◽  
Oxygen Homeostasis ◽  
Physiological Adaptations ◽  
Prolyl Hydroxylation ◽  
Insight Into ◽  
Subsequent Identification

Hypoxia is a fundamental stimulus that impacts cells, tissues, organs, and physiological systems. The discovery of hypoxia-inducible factor-1 (HIF-1) and subsequent identification of other members of the HIF family of transcriptional activators has provided insight into the molecular underpinnings of oxygen homeostasis. This review focuses on the mechanisms of HIF activation and their roles in physiological and pathophysiological responses to hypoxia, with an emphasis on the cardiorespiratory systems. HIFs are heterodimers comprised of an O2-regulated HIF-1α or HIF-2α subunit and a constitutively expressed HIF-1β subunit. Induction of HIF activity under conditions of reduced O2availability requires stabilization of HIF-1α and HIF-2α due to reduced prolyl hydroxylation, dimerization with HIF-1β, and interaction with coactivators due to decreased asparaginyl hydroxylation. Stimuli other than hypoxia, such as nitric oxide and reactive oxygen species, can also activate HIFs. HIF-1 and HIF-2 are essential for acute O2sensing by the carotid body, and their coordinated transcriptional activation is critical for physiological adaptations to chronic hypoxia including erythropoiesis, vascularization, metabolic reprogramming, and ventilatory acclimatization. In contrast, intermittent hypoxia, which occurs in association with sleep-disordered breathing, results in an imbalance between HIF-1α and HIF-2α that causes oxidative stress, leading to cardiorespiratory pathology.

scholarly journals Induction and nuclear translocation of hypoxia-inducible factor-1 (HIF-1): heterodimerization with ARNT is not necessary for nuclear accumulation of HIF-1alpha

1999 ◽  
Vol 112 (8) ◽  
pp. 1203-1212 ◽  
Author(s):  
D. Chilov ◽  
G. Camenisch ◽  
I. Kvietikova ◽  
U. Ziegler ◽  
M. Gassmann ◽  
...  
Keyword(s):  
Nuclear Translocation ◽  
Hypoxia Inducible Factor ◽  
Embryonic Stem ◽  
Nuclear Accumulation ◽  
Nuclear Compartment ◽  
Hypoxia Inducible Factor 1 ◽  
Aryl Hydrocarbon ◽  
Oxygen Homeostasis ◽  
Nuclear Extracts ◽  
Stable Association

Hypoxia-inducible factor-1 (HIF-1) is a master regulator of mammalian oxygen homeostasis. HIF-1 consists of two subunits, HIF-1alpha and the aryl hydrocarbon receptor nuclear translocator (ARNT). Whereas hypoxia prevents proteasomal degradation of HIF-1alpha, ARNT expression is thought to be oxygen-independent. We and others previously showed that ARNT is indispensable for HIF-1 DNA-binding and transactivation function. Here, we have used ARNT-mutant mouse hepatoma and embryonic stem cells to examine the requirement of ARNT for accumulation and nuclear translocation of HIF-1alpha in hypoxia. As shown by immunofluorescence, HIF-1alpha accumulation in the nucleus of hypoxic cells was independent of the presence of ARNT, suggesting that nuclear translocation is intrinsic to HIF-1alpha. Co-immunoprecipitation of HIF-1alpha together with ARNT could be performed in nuclear extracts but not in cytosolic fractions, implying that formation of the HIF-1 complex occurs in the nucleus. A proteasome inhibitor and a thiol-reducing agent could mimic hypoxia by inducing HIF-1alpha in the nucleus, indicating that escape from proteolytic degradation is sufficient for accumulation and nuclear translocation of HIF-1alpha. During biochemical separation, both HIF-1alpha and ARNT tend to leak from the nuclei in the absence of either subunit, suggesting that heterodimerization is required for stable association within the nuclear compartment. Nuclear stabilization of the heterodimer might also explain the hypoxically increased total cellular ARNT levels observed in some of the cell lines examined.

scholarly journals HIF-1: the knowns and unknowns of hypoxia sensing.

2004 ◽  
Vol 51 (3) ◽  
pp. 563-585 ◽  
Author(s):  
Anna Zagórska ◽  
Józef Dulak
Keyword(s):  
Transcriptional Activity ◽  
Hypoxia Inducible Factor ◽  
Hypoxia Inducible Factor 1 ◽  
Hypoxic Conditions ◽  
Oxygen Homeostasis ◽  
Wide Range ◽  
Systemic Oxygen ◽  
Prolyl Hydroxylation ◽  
Energy Deprivation ◽  
Direct Inhibitors

Hypoxia-inducible factor-1 (HIF-1) is a transcriptional activator that functions as a master regulator of cellular and systemic oxygen homeostasis. It consists of two constitutively produced subunits: HIF-1alpha and HIF-1beta. Under normoxic conditions HIF-1alpha undergoes hydroxylation at specific prolyl residues which leads to an immediate ubiquitination and subsequent proteasomal degradation of the alpha subunit. Additionally, hydroxylation of an asparaginyl residue blocks the transcriptional activity of HIF-1 due to inhibition of its interaction with co-activators. In contrast, under hypoxic conditions, abolition of prolyl hydroxylation results in HIF-1alpha stabilization, whereas the lack of asparaginyl hydroxylation allows the transcriptional activity. Additionally, the transcriptional activity may be modulated by phosphorylation or redox modification of HIF-1. Despite its name, HIF-1 is induced not only in response to reduced oxygen availability but also by other stimulants, such as nitric oxide, various growth factors, or direct inhibitors of prolyl and asparaginyl hydroxylases. Therefore, it seems to be a crucial transcription factor elicited by a wide range of stresses such as impaired oxygenation, inflammation, energy deprivation, or intensive proliferation. However, the mechanisms of normoxic activation, as well as of oxygen sensing, are not yet fully known. Further understanding of the processes that control HIF-1 activity will be crucial for the development of new diagnostic and therapeutic strategies.

Regulation of Oxygen Homeostasis by Hypoxia-Inducible Factor 1

Physiology ◽  
2009 ◽  
Vol 24 (2) ◽  
pp. 97-106 ◽  
Author(s):  
Gregg L. Semenza
Keyword(s):  
Transcription Factor ◽  
Growth Factor ◽  
Intermittent Hypoxia ◽  
Hypoxia Inducible Factor ◽  
Metabolic Reprogramming ◽  
Systemic Hypertension ◽  
Adaptive Responses ◽  
Hypoxia Inducible Factor 1 ◽  
Oxygen Homeostasis ◽  
Genes Encoding

Metazoan organisms are dependent on a continuous supply of O2 for survival. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that regulates oxygen homeostasis and plays key roles in development, physiology, and disease. HIF-1 activity is induced in response to continuous hypoxia, intermittent hypoxia, growth factor stimulation, and Ca2+ signaling. HIF-1 mediates adaptive responses to hypoxia, including erythropoiesis, angiogenesis, and metabolic reprogramming. In each case, HIF-1 regulates the expression of multiple genes encoding key components of the response pathway. HIF-1 also mediates maladaptive responses to chronic continuous and intermittent hypoxia, which underlie the development of pulmonary and systemic hypertension, respectively.

scholarly journals Stage-dependent effects of intermittent hypoxia influence the outcome of hippocampal adult neurogenesis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maggie A. Khuu ◽  
Thara Nallamothu ◽  
Carolina I. Castro-Rivera ◽  
Alejandra Arias-Cavieres ◽  
Caroline C. Szujewski ◽  
...  
Keyword(s):  
Sleep Apnea ◽  
Adult Neurogenesis ◽  
Intermittent Hypoxia ◽  
Hypoxia Inducible Factor ◽  
Memory Deficits ◽  
Brain Health ◽  
Hypoxia Inducible Factor 1 ◽  
Oxygen Homeostasis ◽  
Dependent Cell ◽  
Adult Born Neurons

AbstractOver one billion adults worldwide are estimated to suffer from sleep apnea, a condition with wide-reaching effects on brain health. Sleep apnea causes cognitive decline and is a risk factor for neurodegenerative conditions such as Alzheimer’s disease. Rodents exposed to intermittent hypoxia (IH), a hallmark of sleep apnea, exhibit spatial memory deficits associated with impaired hippocampal neurophysiology and dysregulated adult neurogenesis. We demonstrate that IH creates a pro-oxidant condition that reduces the Tbr2+ neural progenitor pool early in the process, while also suppressing terminal differentiation of adult born neurons during late adult neurogenesis. We further show that IH-dependent cell-autonomous hypoxia inducible factor 1-alpha (HIF1a) signaling is activated in early neuroprogenitors and enhances the generation of adult born neurons upon termination of IH. Our findings indicate that oscillations in oxygen homeostasis, such as those found in sleep apnea, have complex stage-dependent influence over hippocampal adult neurogenesis.

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