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Principal Investigator: Ruslan Rafikov
Organization: INDIANA UNIVERSITY INDIANAPOLIS
Fiscal Year: 2024
Award: $742,328
Funding agency: National Heart Lung and Blood Institute
Hemolysis is one of the critical pathogenic mechanisms of pulmonary hypertension (PH),
predisposing individuals with hemolytic conditions to PH. Notably, 10-30% of sickle cell disease patients
and up to 80% of thalassemia patients develop PH, starkly contrasting to a mere 0.001% prevalence
in the general population. Moreover, our recent findings indicate significant correlations between
elevated sub-clinical hemolysis in Group 1 PAH patients and PAH severity. However, the critical
mechanism of heme actions leading to PH progression still needs to be understood. By elucidating the
impact of heme on the pulmonary vasculature, we aim to shed light on the contribution of heme-
mediated mechanisms to the pathogenesis of Group 1 PAH.
Our previous studies demonstrated that the free heme directly triggers intracellular signaling in
endothelial cells by activating the MKK3/p38 pathway. However, the precise mechanism by which free
heme activates this signaling axis remains to be determined. Our search for heme-sensor factors
identified a Heme-Activating Protein (HAP1) responsible for sensing the heme and initiating heme
target genes in Yeast. The homolog of HAP1 in humans is the INAVA, known to be responsible for
triggering an immune response in macrophages and disrupting the barrier in epithelial cells.
However, there is a gap in knowledge on the molecular mechanism of INAVA action in
endothelial cells and its involvement in hemolytic complications and PH pathogenesis. Based on our
compelling preliminary data, we introduce INAVA as a novel intracellular heme-sensor protein activating
MKK3/p38-mediated signaling by engaging 14-3-3 kinase. Notably, both INAVA and 14-3-3 are
overexpressed in the lung tissues of PAH patients and have increased interaction, implying a disease-
related signaling role. We aim to examine the hypothesis that free heme, by binding to INAVA, induces
14-3-3 activation in the cytosol. This increases endothelial proliferation, barrier dysfunction, and
cytokines, leading to PH pathogenesis.
Our research effort, focused on investigating endothelial cell heterogeneity using a single-cell
approach, allowed us to discern the distinct pulmonary endothelial cell populations, each possessing
unique gene signatures and functional arrays. We found five novel populations of general capillary ECs,
named gCapA-E, in addition to well-known pulmonary arterial, venous, lymphatic endothelium, and
aerocytes. Based on our preliminary data, we hypothesize that heme possesses a differential effect
on each of these endothelial cell populations, compromising the maintenance of adequate endothelial
barrier by gCapA, impairing angiogenic properties of gCapC, and altering proliferation of gCapB.
Terms: <Affect><Binding><Blood capillaries><CSAID-Binding Protein 1><CSAID-Binding Protein 2><CSBP2><Cell Body><Cell Communication and Signaling><Cell Growth in Number><Cell Isolation><Cell Multiplication><Cell Proliferation><Cell Segregation><Cell Separation><Cell Separation Technology><Cell Signaling><Cells><Cellular Proliferation><Cessation of life><Cytokine-Suppressive Antiinflammatory Drug-Binding Protein 1><Cytokine-Suppressive Antiinflammatory Drug-Binding protein 2><Cytosol><Data><Death><Disease><Disorder><Dysfunction><Endothelial Cells><Endothelium><Epithelial Cells><Ferroprotoporphyrin><Functional disorder><GeneHomolog><General Population><General Public><Genes><Hb SS disease><HbSS disease><Heart><Heme><Hemoglobin S Disease><Hemoglobin sickle cell disease><Hemoglobin sickle cell disorder><Hemolysis><Heterogeneity><Homolog><Homologous Gene><Homologue><Human><Immune response><Immunological response><Impairment><Individual><Inflammation><Intracellular Communication and Signaling><Kinases><Knowledge><Lung><Lung Parenchyma><Lung Respiratory System><Lung Tissue><Lymphatic Endothelium><MAPK14><MAPK14 Mitogen-Activated Protein Kinase><MAPK14 gene><Macrophage><Maintenance><Mediating><Mitogen-Activated Protein Kinase 14><Mitotic><Modeling><Modern Man><Molecular><Molecular Interaction><Mxi2><Mφ><Names><Pathogenesis><Pathogenicity><Pathologic><Pathology><Pathway interactions><Patients><Peptides><Phosphotransferase Gene><Phosphotransferases><Physiopathology><Population><Pre-Clinical Model><Preclinical Models><Predisposition><Prevalence><Production><Proliferating><Property><Proteins><Protoheme><Pulmonary Hypertension><Research><Role><SAPK2A><Severities><Sickle Cell Anemia><Signal Transduction><Signal Transduction Systems><Signaling><Stress-Activated Protein Kinase 2A><Structure of parenchyma of lung><Susceptibility><Testing><Thalassemia><Therapeutic><Transphosphorylases><Vascular remodeling><Venous><Work><Yeasts><angiogenesis><biological signal transduction><capillary><cell sorting><cytokine><determine efficacy><efficacy analysis><efficacy assessment><efficacy determination><efficacy evaluation><efficacy examination><erythrolysis><evaluate efficacy><examine efficacy><ferroheme><gene signatures><genetic signature><heme a><host response><immune system response><immunoresponse><inhibitor><lung vascular remodeling><name><named><naming><novel><overexpress><overexpression><p38><p38 MAP Kinase><p38 MAPK Gene><p38 Mitogen Activated Protein Kinase><p38 Protein Kinase><p38 SAPK><p38-Alpha><p38Alpha><pathophysiology><pathway><pulmonary><pulmonary arterial hypertension><pulmonary artery hypertension><pulmonary vascular cell proliferation><pulmonary vascular remodeling><response><right heart failure><right sided heart failure><right ventricle failure><right ventricular failure><right ventricular heart failure><sensor><sickle cell disease><sickle cell disorder><sickle disease><sicklemia><social role><targeted drug therapy><targeted drug treatments><targeted therapeutic><targeted therapeutic agents><targeted therapy><targeted treatment>