Details for: CL1001568

Cell ID: CL1001568

Cell Name: pulmonary artery endothelial cell

Description: Any endothelial cell of vascular tree that is part of some pulmonary artery.

Synonyms: PAEC cell

Selected Context(s): Overall

Gene Significance Landscape

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Score:
Display
Genes

Contexts:

Cell Significance Index (CSI) is uniquely calculated to reveal cell-specific gene markers. More info here

Significant Genes List

Genes with the highest and lowest Percentile Rank Scores (PRS) for pulmonary artery endothelial cell within the selected context(s).

Gene ID: A unique numerical identifier for this specific gene.
Symbol: Shortened abbreviation or name that represents this gene.
Ensembl Gene ID: A unique identifier assigned by Ensembl for genomic data mapping.
CSI Score: A combined effect size and statistical significance measure for pulmonary artery endothelial cell. Higher scores indicate a stronger, more significant difference in expression.
(Previously described as "Fold Change", but now represents Cliff's Delta × –log10(p).)

Gene ID: A unique numerical identifier for this specific gene.
Symbol: Shortened abbreviation or name that represents this gene.
Ensembl Gene ID: A unique identifier assigned by Ensembl for genomic data mapping.
CSI Score: A combined effect size and statistical significance measure for pulmonary artery endothelial cell. Higher scores indicate a stronger, more significant difference in expression.
Average CSI: csi sum / gene count
Cell network configuration

This network visualizes key genes for pulmonary artery endothelial cell. It primarily includes:
1. Top genes highly significant for this cell (Num. Top Cell Genes - based on the 'Min. CSI' setting).
2. Any additional specific 'Context Genes' you add below.
The final network is a combined view. Choose an Interaction Source (pathways or protein interactions) and optionally compare CSI scores with a Baseline Cell Type.

Maximum number of selected genes.
Select a context for the baseline cell.
Select a context for the target cell.
Target Cell for CSI:  pulmonary artery endothelial cell (CL1001568)

 Legend
Nodes (Genes):
 Query Gene
Node size also reflects Target Cell CSI magnitude.
Node Color (Target Cell CSI in specific network):
 Very High
 High
 Medium
 Low
 Very Low
 N/A or Not Sig.
Edges (Interactions):
 STRING (Protein-Protein)
 ONTOLOGY (Shared Pathway)
 Colors vary by pathway category; default arrow applies.

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## Summary The [pulmonary artery endothelial cell](/details-cell/CL1001568) (PAEC) is a specialized endothelial cell type lining the pulmonary artery. Based on its gene significance profile, this cell type is characterized by a uniquely high expression of genes involved in immune surveillance and antigen presentation. The top markers, [HLA E](/details-gene/3133) and its essential component [B2M](/details-gene/567), suggest a primary role for PAECs as active participants in modulating immune responses within the pulmonary circulation, acting as a critical interface between circulating blood and the lung tissue. This immune-sentinel function is complemented by a strong signature of genes related to cytoskeletal organization and metabolic activity, reflecting the cell's need to maintain structural integrity and function under the distinct hemodynamic conditions of the pulmonary arterial system. ## Key Characteristics and Function The functional identity of the [pulmonary artery endothelial cell](/details-cell/CL1001568) is defined by several key biological processes, as indicated by its most specifically expressed genes in the **Overall** context. * **Immune Modulation and Antigen Presentation:** The most significant defining markers are [HLA E](/details-gene/3133) (CSI: 83.59) and [B2M](/details-gene/567) (CSI: 78.85), core components of the MHC class I antigen-presenting machinery. [HLA E](/details-gene/3133) is a non-classical MHC molecule known to interact with inhibitory receptors on Natural Killer (NK) cells and a subset of T cells ([Link](https://doi.org/10.1002/(sici)1521-4141(199902)29:02<537::aid-immu537>3.0.co;2-6)), suggesting that PAECs play a crucial role in maintaining immune tolerance and regulating lymphocyte activity in the lung vasculature. The high specificity of these markers underscores this immune-modulatory function as a central feature of the cell's identity. * **Cytoskeletal Dynamics and Mechanotransduction:** A prominent cluster of highly specific genes is associated with the cytoskeleton and contractility. This includes multiple myosin regulatory light chains such as [MYL12B](/details-gene/103910), [MYL6](/details-gene/4637), and [MYL12A](/details-gene/10627). These proteins are critical for the formation of stress fibers and the regulation of cell shape and tension ([Link](https://doi.org/10.1247/csf.26.677)). This signature, along with the calcium-binding protein [S100A6](/details-gene/6277), points to a specialized capacity for mechanotransduction, enabling PAECs to sense and respond to the unique hemodynamic forces (shear stress and cyclic stretch) of the pulmonary artery. * **Metabolic Activity:** The specific expression of several mitochondrial genes, including cytochrome c oxidase subunits [COX1](/details-gene/4512) and [COX2](/details-gene/4513), as well as [CYTB](/details-gene/4519), indicates a high and distinct metabolic demand. This is consistent with the essential role of endothelial cells in regulating vascular tone, transport, and barrier function, all of which are energy-intensive processes. * **Iron Homeostasis and Oxidative Stress Regulation:** The presence of ferritin heavy and light chains, [FTH1](/details-gene/2495) and [FTL](/details-gene/2512), as significant markers suggests a key role in managing iron storage and detoxification. Furthermore, the specific expression of [TXNIP](/details-gene/10628), a regulator of thioredoxin and cellular redox state, highlights the importance of managing oxidative stress at the blood-lung barrier. The anti-marker profile further refines the cell's identity. The negative effect size for [YWHAZ](/details-gene/7534) (14-3-3 protein zeta) suggests that pathways regulated by this protein are less active compared to other cell types. The low specificity (`csi_z`) of numerous genes despite high effect sizes (e.g., [SNAI1](/details-gene/6615), [FGF18](/details-gene/8817)) indicates that while these genes are expressed, they are not unique or defining characteristics of PAECs, distinguishing them from cells undergoing active migration or proliferation in this context. ## Clinical Significance and Contextual Roles The gene signature of [pulmonary artery endothelial cells](/details-cell/CL1001568) provides insights into their potential roles in pulmonary health and disease. The profound immune signature, dominated by [HLA E](/details-gene/3133), positions PAECs as central players in diseases characterized by vascular inflammation and immune dysregulation, such as pulmonary arterial hypertension (PAH), vasculitis, and lung transplant rejection. Dysregulation of HLA-E expression on PAECs could potentially lead to inappropriate activation or inhibition of circulating NK and T cells, contributing to endothelial injury and vascular remodeling. The cell's apparent specialization in mechanotransduction, evidenced by myosin light chain expression, is clinically relevant as altered blood flow and pressure are hallmarks of PAH. The specific molecular machinery highlighted here may be involved in the pathological endothelial response to these abnormal mechanical stimuli. Furthermore, the high specificity of genes involved in iron metabolism ([FTH1](/details-gene/2495), [FTL](/details-gene/2512)) and oxidative stress ([TXNIP](/details-gene/10628)) is significant. Endothelial iron accumulation and oxidative damage are increasingly recognized as key contributors to the pathophysiology of PAH. The specific expression of these genes suggests PAECs are primary sites for these pathological processes. Intriguingly, [ITM2B](/details-gene/9445), a gene whose mutations are linked to familial dementia ([Link](https://doi.org/10.1038/21637)), is a top marker. While its function in PAECs is unknown, its high specificity may indicate a novel role in protein processing or amyloidogenesis within the pulmonary vasculature, a finding that warrants further investigation. ## Potential Mechanisms and Research Directions ### Hypothesis 1 Based on the prominent and highly specific expression of [HLA E](/details-gene/3133) and [B2M](/details-gene/567), we hypothesize that pulmonary artery endothelial cells function as critical regulators of local immune tolerance by presenting peptides via HLA-E to inhibitory receptors on NK cells and CD8+ T cells. This mechanism may be essential for preventing autoimmune-mediated damage in the low-pressure, high-flow pulmonary environment. * **Surprising Findings:** The most defining characteristics of these endothelial cells are not canonical vascular markers (e.g., VWF, PECAM1) but rather immune-modulatory molecules. This suggests their immunological role is their most distinct feature when compared to a broad landscape of other cell types. * **Testable Questions:** In a co-culture model, does siRNA-mediated knockdown of [HLA E](/details-gene/3133) in PAECs lead to increased activation and cytokine release from autologous NK cells? ### Hypothesis 2 The co-enrichment of genes for cytoskeletal contractility ([MYL12B](/details-gene/103910), [MYL6](/details-gene/4637)) and calcium signaling ([S100A6](/details-gene/6277), [CALM1](/details-gene/801)) suggests a specialized program for responding to hemodynamic forces. We hypothesize that this mechanosensitive machinery is central to maintaining vascular homeostasis in the pulmonary artery and that its dysregulation is an early event in the pathogenesis of diseases like pulmonary hypertension. * **Surprising Findings:** The high specificity of [ITM2B](/details-gene/9445), a gene primarily studied in the context of neurodegeneration, is unexpected in pulmonary endothelial cells. This could imply a shared pathway of protein aggregation or stress response between neurodegenerative and pulmonary vascular diseases. * **Testable Questions:** Does exposing cultured PAECs to pathological shear stress, mimicking conditions of pulmonary hypertension, alter the phosphorylation status of [MYL12B](/details-gene/103910) and its interaction with the S100 protein [S100A6](/details-gene/6277)?