Expression Of Hypoxia-induced Mitogenic Factor Research Articles

Peptide Blocking Self-Polymerization of Extracellular Calcium-Sensing Receptor Attenuates Hypoxia-Induced Pulmonary Hypertension.

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Hypoxia-Induced Mitogenic Factor: A Multifunctional Protein Involved in Health and Disease.

Hypoxia-induced mitogenic factor (HIMF), also known as resistin-like molecule α (RELMα) or found in inflammatory zone 1 (FIZZ1) is a member of the RELM protein family expressed in mice. It is involved in a plethora of physiological processes, including mitogenesis, angiogenesis, inflammation, and vasoconstriction. HIMF expression can be stimulated under pathological conditions and this plays a critical role in pulmonary, cardiovascular and metabolic disorders. The present review summarizes the molecular characteristics, and the physiological and pathological roles of HIMF in normal and diseased conditions. The potential clinical significance of these findings for human is also discussed.

HIMF deletion ameliorates acute myocardial ischemic injury by promoting macrophage transformation to reparative subtype

Appropriately manipulating macrophage M1/M2 phenotypic transition is a promising therapeutic strategy for tissue repair after myocardial infarction (MI). Here we showed that gene ablation of hypoxia-induced mitogenic factor (HIMF) in mice (Himf−/− and HIMFflox/flox;Lyz2-Cre) attenuated M1 macrophage-dominated inflammatory response and promoted M2 macrophage accumulation in infarcted hearts. This in turn reduced myocardial infarct size and improved cardiac function after MI. Correspondingly, expression of HIMF in macrophages induced expression of pro-inflammatory cytokines; the culturing medium of HIMF-overexpressing macrophages impaired the cardiac fibroblast viability and function. Furthermore, macrophage HIMF was found to up-regulate C/EBP-homologous protein (CHOP) expression, which exaggerated the release of pro-inflammatory cytokines via activating signal transducer of activator of transcription 1 (STAT1) and 3 (STAT3) signaling. Together these data suggested that HIMF promotes M1-type and prohibits M2-type macrophage polarization by activating the CHOP–STAT1/STAT3 signaling pathway to negatively regulate myocardial repair. HIMF might thus constitute a novel target to treat MI.

HIMF (Hypoxia-Induced Mitogenic Factor)-IL (Interleukin)-6 Signaling Mediates Cardiomyocyte-Fibroblast Crosstalk to Promote Cardiac Hypertrophy and Fibrosis.

HIMF (hypoxia-induced mitogenic factor) is a secreted proinflammatory cytokine with a critical role in cardiac hypertrophy development. Loss of HIMF attenuates transverse aortic constriction-induced cardiac hypertrophy and fibrosis, but the underlying mechanisms are unknown. We show that IL (interleukin)-6 production increases following transverse aortic constriction in wild-type mice; this effect is inhibited in HIMF gene knockout ( Himf-/-) mice. IL-6 production also increases in cultured cardiac myocytes overexpressing HIMF and neutralizing IL-6 with an anti-IL-6 antibody prohibits HIMF-induced cardiomyocyte hypertrophy. HIMF expression in cardiac fibroblasts cannot be stimulated by transverse aortic constriction or exposure to prohypertrophic factors, including phenylephrine, Ang II (angiotensin II), TGF (transform growth factor)-β, and hypoxia. However, conditioned medium from cardiomyocytes overexpressing HIMF can increase IL-6 production, and cardiac fibroblast proliferation, migration, and myofibroblast differentiation to a similar level as exposure to exogenous rHIMF (recombinant HIMF). Again, neutralizing IL-6 prevented cardiac fibroblasts activation. Finally, the MAPK (mitogen-activated protein kinase) and CaMKII (Ca2+/calmodulin-dependent protein kinase II)-STAT3 (signal transducers and activators of transcription 3) pathways are activated in HIMF-overexpressing cardiomyocytes and rHIMF-stimulated cardiac fibroblasts; this effect can be inhibited on neutralizing IL-6. These data support that HIMF induces cardiac fibrosis via a cardiomyocyte-to-fibroblast paracrine effect. IL-6 is a downstream signal of HIMF and has a central role in cardiomyocyte hypertrophy and myocardial fibrosis that is mediated by activating the MAPK and CaMKII-STAT3 pathways.

Expression of hypoxia-induced mitogenic factor in mouse bronchopulmonary dysplasia model and its significance

Objective To study the expression of hypoxia-induced mitogenic factor (HIMF) in mouse bronchopulmonary dysplasia ( BPD) model and its significance. Methods Thirty-two Kunming neonatal mice were randomly divided into normoxia exposure group (21% 02,n=16) and hyperoxia exposure group (85% O2,n=16). After exposure for 7, 14, 21 and 28 days, HE staining was applied to observe the morphological changes of lung tissues. The mRNA and protein levels of HIMF were detected by real-time reverse transcription-polymerase chain reaction ( RT-PCR) and Western blotting, respectively. Results In normoxia exposure group, the alveoli was gradually mature and well-distributed, with thin interstitial tissue. However, in hyperoxia exposure group, the increased septa] wall thickness and alveolar fusion were observed, and the radical alveolar count was decreased by 31.1%-65.3%. As compared with normoxia exposure group, the mRNA and protein levels of HIMF were enhanced by 2.435-2.528 times (P<0.05) and 2.45-5.42 times (P<0.05) at the 7th, 14th and 21st day after exposure, but decreased by 52. 81 % (P<0. 05) and 74. 60% at the 28th day after exposure. Conclusion The mouse BPD model was successfully established, and HIMF may participate in the pathogenesis of BPD. Key words: Hypoxia-induced mitogenic factor; Bronchopulmonary dysplasia; Gene expression

Ets-1 participates in and facilitates developmental expression of hypoxia-induced mitogenic factor in mouse lung

Hypoxia-induced mitogenic factor (HIMF) possesses mitogenic, vasoconstrictive, angiogenic, and antiapoptotic effects. While HIMF is known to be expressed in developmental mouse lung, its gene expression regulation during this period is completely unknown. Genomic sequencing of HIMF gene has shown that there is an Ets-1 binding site in its 5'-promoter-region. To test the hypothesis that Ets-1 protein expressed in developing mouse lung may participate in the process of HIMF gene expression regulation via direct involvement or facilitation, we characterized the proximal promoter of HIMF gene (409-bp long fragment that includes the -347-bp promoter region from transcription start site), and investigated HIMF and Ets-1 expression with western blot and immunohistochemistry, electrophoretic mobility shift assay (EMSA) for Ets-1, HIMF promoter luciferase reporter gene assays, and chromatin-immunoprecipitation (CHIP). Western blots revealed that both Ets-1 and HIMF proteins were developmentally expressed in the lung. Immunohistochemical localization revealed Ets-1 signals in the nucleus of HIMF-expressing airway epithelial cells and alveolar type II cells, whereas HIMF was localized in cytoplasm. Presence of Ets-1 protein within E16, E20, and adult lung nuclear extract was demonstrated by EMSA. Co-transfection of Ets-1 expression plasmid with HIMF promoter construct increased luciferase activity in NIH3T3 cells, but mutation or deletion of Ets-1 site eliminated HIMF promoter luciferase activity. CHIP with anti-Ets-1 antibody revealed Ets-1 binding to HIMF promoter region in E20 and P1 but not in E15 lung. We conclude that Ets-1 participates in the process of HIMF gene expression and Ets-1-mediated HIMF expression may play an important role in lung development and maturation.

Hypoxia-Induced Mitogenic Factor Promotes Vascular Adhesion Molecule-1 Expression via the PI-3K/Akt–NF-κB Signaling Pathway

Hypoxia-induced mitogenic factor (HIMF), also known as FIZZ1 (found in inflammatory zone 1), is an important player in lung inflammation. However, the effects of HIMF on cell adhesion molecules involved in lung inflammation remain largely unknown. In the present work, we tested whether HIMF modulates vascular adhesion molecule (VCAM)-1 expression, and dissected the possible signaling pathways that link HIMF to VCAM-1 upregulation. Recombinant HIMF protein, instilled intratracheally into adult mouse lungs, results in a significant increase of VCAM-1 production in vascular endothelial, alveolar type II, and airway epithelial cells. In cultured mouse endothelial SVEC 4-10 and lung epithelial MLE-12 cells, we demonstrated that HIMF induces VCAM-1 expression via the phosphatidylinositol-3 kinase (PI-3K)/Akt-nuclear factor (NF)-kappaB signaling pathway. Knockdown of HIMF expression by small interference RNA attenuated LPS-induced VCAM-1 expression in vitro. We showed that HIMF induced phosphorylation of the IkappaB kinase signalsome and, subsequently, IkappaBalpha, leading to activation of NF-kappaB. Meanwhile, VCAM-1 production was correspondingly upregulated. Blocking NF-kappaB signaling pathway by expression of dominant-negative mutants of IkappaB kinase and IkappaBalpha suppressed HIMF-induced VCAM-1 upregulation. HIMF also strongly induced phosphorylation of Akt. A dominant-negative mutant of PI-3K, Deltap85, as well as PI-3K inhibitor, LY294002, also blocked HIMF-induced NF-kappaB activation and attenuated VCAM-1 production. Furthermore, LY294002 pretreatment abolished HIMF-enhanced mononuclear cells adhesion to endothelial and epithelial cells. Our findings connect HIMF to signaling pathways that regulate inflammation, and thus reveal the critical roles that HIMF plays in lung inflammation.

Hypoxia-Induced Mitogenic Factor Modulates Surfactant Protein B and C Expression in Mouse Lung

Previous studies have demonstrated a robust pulmonary expression of hypoxia-induced mitogenic factor (HIMF) during the perinatal period, when surfactant protein (SP) synthesis begins. We hypothesized that HIMF modulates SP expression and participates in lung development and maturation. The temporal-spatial expression of HIMF, SP-B, and SP-C in developing mouse lungs was examined by immunohistochemical staining, Western blot, and RT-PCR. The expression and localization of SP-B and SP-C were investigated in mouse lungs after intratracheal instillation of HIMF in adult mice. The effects of HIMF on SP-B and SP-C transcription activity, and on mRNA degradation, were investigated in mouse lung epithelial (MLE)-12 and C10 cells using the promoter-luciferase reporter assay and actinomycin D incubation. The activation of Akt, extracellular signal-regulated kinase (ERK)1/2, and p38 mitogen-activated protein kinase was explored by Western blot. Intratracheal instillation of HIMF resulted in significant increases of SP-B and SP-C production, predominantly localized to alveolar type II cells. In MLE-12 and C10 cells, HIMF enhanced SP-B and SP-C mRNA levels in a dose-dependent manner. Meanwhile, HIMF increased transcription activity and prevented actinomycin D-facilitated SP-B and SP-C mRNA degradation in MLE-12 cells. Incubation of cells with LY294002, PD098059, or U0126 abolished HIMF-induced Akt and ERK1/2 phosphorylation and suppressed HIMF-induced SP-B and SP-C production, whereas SB203580 had no effect. These results indicate that HIMF induces SP-B and SP-C production in mouse lungs and alveolar type II-like cell lines via activations of phosphatidylinositol 3-kinase/Akt and ERK1/2 mitogen-activated protein kinase, suggesting that HIMF plays critical roles in lung development and maturation.

Upregulation of Hypoxia-Induced Mitogenic Factor in Compensatory Lung Growth after Pneumonectomy

After pneumonectomy, the remaining lung increases in size. This process is referred to as compensatory lung growth. Various pathways likely play important roles in this growth response. The molecular mechanisms involved in compensatory lung growth, however, remain poorly understood. Hypoxia-induced mitogenic factor (HIMF), also called FIZZ1 or RELM-alpha, possesses mitogenic, vasoconstrictive, angiogenic, and antiapoptotic effects. In this study, we examined the expression of HIMF in mouse lung after pneumonectomy to test the hypothesis that HIMF expression is upregulated during compensatory lung growth. Results showed that HIMF is upregulated from Day 1 after pneumonectomy and peaking at Day 7 in the lung. HIMF upregulation is temporally and spatially related to lung cell proliferation, as demonstrated by expression of proliferating cell nuclear antigen. Immunohistochemical staining and in situ hybridization showed that upregulated HIMF protein and mRNA are mainly distributed in airway epithelium, alveolar type II cells, and endothelial cells of the pulmonary vessels. Intratracheal instillation of recombinant HIMF resulted in widespread cell proliferation, including airway epithelium, alveolar type II cells, and cells in the alveolar septa. These results indicate a new role for HIMF in compensatory lung growth, which is that HIMF may act as a lung-specific growth factor and participate in lung regeneration after pneumonectomy.

Developmental expression of hypoxia-induced mitogenic factor (HIMF) in mouse lung

Developmental expression of hypoxia-induced mitogenic factor (HIMF) in mouse lung

Hypoxia-induced mitogenic factor has antiapoptotic action and is upregulated in the developing lung: coexpression with hypoxia-inducible factor-2alpha.

Hypoxia-induced mitogenic factor (HIMF), also called FIZZ1 or RELMalpha, was a newly found cytokine. Hypoxia caused robust HIMF induction in the lung, and HIMF has potent pulmonary vasoconstrictive, proliferative, and angiogenic properties. To investigate the role of HIMF in lung development, we determined its spatial and temporal expression. From embryonic day (E)16 to postnatal day (P)28, HIMF was strongly expressed in the cytoplasm of bronchial epithelial cells, type II cells, endothelial cells, and primitive mesenchymal cells. Treatment with HIMF resulted in a significant reduction of apoptosis in cultured embryonic lung, thus revealing a previously unknown function of HIMF. Because HIMF gene is upregulated by hypoxia and contains a hypoxia-inducible transcription factor (HIF) binding site, we subsequently investigated whether HIMF was coexpressed with HIF-2alpha or HIF-1alpha. HIF-1alpha expression was temporally distinct from HIMF expression. In contrast, HIF-2alpha was present in endothelial cells, bronchial epithelial cells, and type II cells from E18 to P28. Thus, HIMF and HIF-2alpha were temporally and spatially coexpressed in the developing lung. These results indicate a role for HIMF in lung development, possibly under the control of HIF-2, and suggest that HIMF regulates apoptosis and may participate in lung alveolarization and maturation.