Polycythemia vera (PV) is a clonal disorder arising from the acquired somatic mutations of the JAK2 gene, including JAK2V617F or several others in exon 12. A 38-year-old female had a stroke at age 32 and found to have elevated hemoglobin, normal leukocytes, normal platelets, and tested negative for JAK2V617F and exon 12 mutations. Next generation sequencing revealed a novel mutation: JAK2R715T in the pseudokinase domain (JH2) at 47.5%. Its presence in her nail DNA confirmed a germline origin. Her mother and her son similarly had erythrocytosis and a JAK2R715T mutation. Computer modeling indicated gain-of-function JAK2 activity. The propositus and her mother had polyclonal myelopoiesis, ruling out another somatic mutation-derived clonal hematopoiesis. Some erythroid progenitors of all three generations grew without erythropoietin, a hallmark of PV. The in vitro reporter assay confirmed increased activity of the JAK2R715T kinase. Similar to PV, the JAK2R715T native cells have increased STAT5 phosphorylation, augmented transcripts of prothrombotic and inflammatory genes, and decreased KLF2 transcripts. The propositus was not controlled by hydroxyurea, and JAK2 inhibitors were not tolerated; however, Ropeginterferon-alfa-2b (Ropeg-IFN-α) induced a remission. Ropeg-IFN-α treatment also reduced JAK2 activity in the propositus, her mother and JAK2V617F PV subjects. We report dominantly inherited erythrocytosis secondary to a novel germline JAK2R715T gain-of-function mutation with many but not all comparable molecular features to JAK2V617F PV. We also document a previously unreported inhibitory mechanism of JAK2 signaling by Ropeg-IFN-α.

• MeSH
• aktivační mutace MeSH
• dospělí MeSH
• interferon alfa terapeutické užití   MeSH
• Janus kinasa 2 * genetika   MeSH
• lidé MeSH
• polycytemie * genetika   farmakoterapie   MeSH
• polycythaemia vera genetika   farmakoterapie   MeSH
• rodokmen MeSH
• zárodečné mutace * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

Obstructive sleep apnea (OSA) causes intermittent hypoxia during sleep. Hypoxia predictably initiates an increase in the blood hemoglobin concentration (Hb); yet in our analysis of 527 patients with OSA, >98% did not have an elevated Hb. To understand why patients with OSA do not develop secondary erythrocytosis due to intermittent hypoxia, we first hypothesized that erythrocytosis occurs in these patients, but is masked by a concomitant increase in plasma volume. However, we excluded that explanation by finding that the red cell mass was normal (measured by radionuclide labeling of erythrocytes and carbon monoxide inhalation). We next studied 45 patients with OSA before and after applying continuous positive airway pressure (CPAP). We found accelerated erythropoiesis in these patients (increased erythropoietin and reticulocytosis), but it was offset by neocytolysis (lysis of erythrocytes newly generated in hypoxia upon return to normoxia). Parameters of neocytolysis included increased reactive oxygen species from expanded reticulocytes' mitochondria. The antioxidant catalase was also downregulated in these cells from hypoxia-stimulated microRNA-21. In addition, inflammation-induced hepcidin limited iron availability for erythropoiesis. After CPAP, some of these intermediaries diminished but Hb did not change. We conclude that in OSA, the absence of significant increase in red cell mass is integral to the pathogenesis, and results from hemolysis via neocytolysis combined with inflammation-mediated suppression of erythropoiesis.

• MeSH
• hepcidiny MeSH
• hypoxie MeSH
• lidé MeSH
• obstrukční spánková apnoe * komplikace   MeSH
• polycytemie * etiologie   MeSH
• reaktivní formy kyslíku MeSH
• zánět MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

• Publikační typ
• abstrakt z konference MeSH

Iron availability for erythropoiesis is controlled by the iron-regulatory hormone hepcidin. Increased erythropoiesis negatively regulates hepcidin synthesis by erythroferrone (ERFE), a hormone produced by erythroid precursors in response to erythropoietin (EPO). The mechanisms coordinating erythropoietic activity with iron homeostasis in erythrocytosis with low EPO are not well defined as exemplified by dominantly inherited (heterozygous) gain-of-function mutation of human EPO receptor (mtHEPOR) with low EPO characterized by postnatal erythrocytosis. We previously created a mouse model of this mtHEPOR that develops fetal erythrocytosis with a transient perinatal amelioration of erythrocytosis and its reappearance at 3-6 weeks of age. Prenatally and perinatally, mtHEPOR heterozygous and homozygous mice (differing in erythrocytosis severity) had increased Erfe transcripts, reduced hepcidin, and iron deficiency. Epo was transiently normal in the prenatal life; then decreased at postnatal day 7, and remained reduced in adulthood. Postnatally, hepcidin increased in mtHEPOR heterozygotes and homozygotes, accompanied by low Erfe induction and iron accumulation. With aging, the old, especially mtHEPOR homozygotes had a decline of erythropoiesis, myeloid expansion, and local bone marrow inflammatory stress. In addition, mtHEPOR erythrocytes had a reduced lifespan. This, together with reduced iron demand for erythropoiesis, due to its age-related attenuation, likely contributes to increased iron deposition in the aged mtHEPOR mice. In conclusion, the erythroid drive-mediated inhibition of hepcidin production in mtHEPOR mice in the prenatal/perinatal period is postnatally abrogated by increasing iron stores promoting hepcidin synthesis. The differences observed in studied characteristics between mtHEPOR heterozygotes and homozygotes suggest dose-dependent alterations of downstream EPOR stimulation.

• MeSH
• aktivační mutace MeSH
• dospělí MeSH
• erythropoetin * genetika   farmakologie   MeSH
• erytropoéza genetika   MeSH
• hepcidiny genetika   metabolismus   MeSH
• hormony MeSH
• lidé MeSH
• myši MeSH
• polycytemie * genetika   MeSH
• receptory erythropoetinu genetika   metabolismus   MeSH
• senioři MeSH
• železo metabolismus   MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• myši MeSH
• senioři MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Myeloproliferative neoplasms (MPN) are genetically very complex and heterogeneous diseases in which the acquisition of a somatic driver mutation triggers three main myeloid cytokine receptors, and phenotypically expresses as polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF). The course of the diseases may be influenced by germline predispositions, modifying mutations, their order of acquisition and environmental factors such as aging and inflammation. Deciphering these contributory elements, their mutual interrelationships, and their contribution to MPN pathogenesis brings important insights into the diseases. Animal models (mainly mouse and zebrafish) have already significantly contributed to understanding the role of several acquired and germline mutations in MPN oncogenic signaling. Novel technologies such as induced pluripotent stem cells (iPSCs) and precise genome editing (using CRISPR/Cas9) contribute to the emerging understanding of MPN pathogenesis and clonal architecture, and form a convenient platform for evaluating drug efficacy. In this overview, the genetic landscape of MPN is briefly described, with an attempt to cover the main discoveries of the last 15 years. Mouse and zebrafish models of the driver mutations are discussed and followed by a review of recent progress in modeling MPN with patient-derived iPSCs and CRISPR/Cas9 gene editing.

• MeSH
• dánio pruhované MeSH
• esenciální trombocytemie genetika   MeSH
• fenotyp MeSH
• indukované pluripotentní kmenové buňky metabolismus   MeSH
• Janus kinasa 2 genetika   MeSH
• kalretikulin genetika   MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• mutace MeSH
• myeloproliferativní poruchy genetika   patofyziologie   MeSH
• myši MeSH
• nádory genetika   MeSH
• polycythaemia vera genetika   MeSH
• primární myelofibróza genetika   MeSH
• receptory thrombopoetinu genetika   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The patients with mantle cell lymphoma (MCL) have translocation t(11;14) associated with cyclin D1 overexpression. We observed that iron (an essential cofactor of dioxygenases including prolyl hydroxylases [PHDs]) depletion by deferoxamine blocked MCL cells' proliferation, increased expression of DNA damage marker γH2AX, induced cell cycle arrest and decreased cyclin D1 level. Treatment of MCL cell lines with dimethyloxalylglycine, which blocks dioxygenases involving PHDs by competing with their substrate 2-oxoglutarate, leads to their decreased proliferation and the decrease of cyclin D1 level. We then postulated that loss of EGLN2/PHD1 in MCL cells may lead to down-regulation of cyclin D1 by blocking the degradation of FOXO3A, a cyclin D1 suppressor. However, the CRISPR/Cas9-based loss-of-function of EGLN2/PHD1 did not affect cyclin D1 expression and the loss of FOXO3A did not restore cyclin D1 levels after iron chelation. These data suggest that expression of cyclin D1 in MCL is not controlled by ENGL2/PHD1-FOXO3A pathway and that chelation- and 2-oxoglutarate competition-mediated down-regulation of cyclin D1 in MCL cells is driven by yet unknown mechanism involving iron- and 2-oxoglutarate-dependent dioxygenases other than PHD1. These data support further exploration of the use of iron chelation and 2-oxoglutarate-dependent dioxygenase inhibitors as a novel therapy of MCL.

• MeSH
• aminokyseliny dikarboxylové farmakologie   MeSH
• chelátory železa farmakologie   MeSH
• cyklin D1 metabolismus   MeSH
• deferoxamin farmakologie   MeSH
• deficit železa MeSH
• dioxygenasy antagonisté a inhibitory   metabolismus   MeSH
• down regulace účinky léků   MeSH
• hydroxylace MeSH
• hypoxie buňky účinky léků   MeSH
• inhibitory enzymů farmakologie   MeSH
• kyseliny ketoglutarové farmakologie   MeSH
• lidé MeSH
• lymfom z plášťových buněk enzymologie   MeSH
• messenger RNA genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• poškození DNA MeSH
• prolyl-4-hydroxylasy HIF metabolismus   MeSH
• protein FOXO3 genetika   metabolismus   MeSH
• železo MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Erythropoietin (EPO) is recognized for neuroprotective and angiogenic effects and has been associated with aging and neovascular age-related macular degeneration (AMD). We hypothesized that systemic EPO facilitates the development of choroidal neovascularization (CNV). Wild type mice expressed murine EPOR (mWtEPOR) in RPE/choroids at baseline and had significantly increased serum EPO after laser treatment. To test the role of EPO signaling, we used human EPOR knock-in mice with the mWtEPOR gene replaced by either the human EPOR gene (hWtEPOR) or a mutated human EPOR gene (hMtEPOR) in a laser-induced choroidal neovascularization (LCNV) model. Loss-of-function hWtEPOR mice have reduced downstream activation, whereas gain-of-function hMtEPOR mice have increased EPOR signaling. Compared to littermate controls (mWtEPOR), hMtEPOR with increased EPOR signaling developed larger CNV lesions. At baseline, hMtEPOR mice had increased numbers of macrophages, greater expression of macrophage markers F4/80 and CD206, and following laser injury, had greater expression of cytokines CCL2, CXCL10, CCL22, IL-6, and IL-10 than mWtEPOR controls. These data support a hypothesis that injury from age- and AMD-related changes in the RPE/choroid leads to choroidal neovascularization through EPOR-mediated cytokine production.

• MeSH
• choroidea krevní zásobení   metabolismus   MeSH
• cytokiny metabolismus   MeSH
• erythropoetin metabolismus   MeSH
• kultivované buňky MeSH
• makrofágy cytologie   fyziologie   MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• neovaskularizace choroidey metabolismus   patologie   MeSH
• receptory erythropoetinu fyziologie   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Tibetans existed in high altitude for ~25 thousand years and have evolutionary selected unique haplotypes assumed to be beneficial to hypoxic adaptation. EGLN1/PHD2 and EPAS1/HIF-2α, both crucial components of hypoxia sensing, are the two best-established loci contributing to high altitude adaptation. The co-adapted Tibetan-specific haplotype encoding for PHD2:p.[D4E/C127S] promotes increased HIF degradation under hypoxic conditions. The Tibetan-specific 200 kb EPAS1 haplotype introgressed from an archaic human population related to Denisovans which underwent evolutionary decay; however, the functional variant(s) responsible for high-altitude adaptation at EPAS1/HIF-2α have not yet been identified. Since HIF modulates the behavior of cancer cells, we hypothesized that these Tibetan selected genomic variants may modify cancer risk predisposition. Here, we ascertained the frequencies of EGLN1D4E/C127S and EGLN1C127S variants and ten EPAS1/HIF-2α variants in lung cancer patients and controls in Nepal, whose population consists of people with Indo-Aryan origin and Tibetan-related Mongoloid origin. We observed a significant association between the selected Tibetan EGLN1/PHD2 haplotype and lung cancer (p=0.0012 for D4E, p=0.0002 for C127S), corresponding to a two-fold increase in lung cancer risk. We also observed a two-fold or greater increased risk for two of the ten EPAS1/HIF-2α variants, although the association was not significant after correcting for multiple comparisons (p=0.12). Although these data cannot address the role of these genetic variants on lung cancer initiation or progression, we conclude that some selected Tibetan variants are strongly associated with a modified risk of lung cancer.

• MeSH
• aklimatizace MeSH
• faktor 1 indukovatelný hypoxií - podjednotka alfa genetika   metabolismus   MeSH
• hypoxie genetika   metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nádory plic genetika   metabolismus   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Tibet MeSH

Tibetans have lived at high altitude for generations and are thought to be genetically adapted to hypoxic environments. Most are protected from hypoxia-induced polycythemia, and a haplotype of EPAS1, encoding hypoxia-inducible factor (HIF-2α), has been associated with lower hemoglobin levels. We earlier reported a Tibetan-specific EGLN1 haplotype encoding PHD2 which abrogates HIF augmentation in hypoxia. We genotyped 347 Tibetan individuals from varying altitudes for both the Tibetan-specific EGLN1 haplotype and 10 candidate SNPs in the EPAS1 haplotype and correlated their association with hemoglobin levels. The effect of the EGLN1 haplotype on hemoglobin exhibited age dependency at low altitude, while at higher altitudes, it showed a trend to lower hemoglobin levels in the presence of the Tibetan-selected EPAS1 rs142764723 C/C allele. The observed gene-environment and gene-gene interactions and the moderate effect of the EGLN1 and EPAS1 haplotypes on hemoglobin indicate that other modifiers exist. It remains to be determined whether a blunting of erythropoiesis or other physiological consequences of HIF downregulation are the primary drivers of these genetic adaptations among Tibetans. KEY MESSAGE: Most Tibetans are protected from polycythemia while living in high altitude. An EGLN1 co-adapted haplotype, EGLN1 c.12C>G, c.380G>C is uniquely Tibetan. The Tibetan EPAS1 haplotype has introgressed from the Denisovan genome. While EGLN1 and EPAS1 genotypes lower Hb, this study indicates additional Hb modifiers.

• MeSH
• aklimatizace genetika   MeSH
• Asijci genetika   MeSH
• dospělí MeSH
• erythropoetin krev   MeSH
• ferritiny krev   MeSH
• haplotypy MeSH
• hemoglobiny analýza   MeSH
• interakce genů a prostředí MeSH
• jednonukleotidový polymorfismus MeSH
• lidé MeSH
• nadmořská výška MeSH
• prolyl-4-hydroxylasy HIF genetika   MeSH
• transkripční faktory bHLH genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Tibet MeSH