Details for: CL1000838

Cell ID: CL1000838

Cell Name: kidney proximal convoluted tubule epithelial cell

Description: Any epithelial cell of proximal tubule that is part of some proximal convoluted tubule and has part some brush border.

Selected Context(s): Overall

Gene Significance Landscape

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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 kidney proximal convoluted tubule epithelial 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 kidney proximal convoluted tubule epithelial 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 kidney proximal convoluted tubule epithelial 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 kidney proximal convoluted tubule epithelial 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:  kidney proximal convoluted tubule epithelial cell (CL1000838)

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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 [kidney proximal convoluted tubule epithelial cell](/details-cell/CL1000838) is a specialized epithelial cell characterized by a prominent brush border, responsible for the bulk of solute reabsorption in the kidney. Gene significance analysis based on expression specificity (**Overall** context) reveals a multifaceted identity for this cell type. Beyond its canonical role in transport and metabolism, it appears to be a crucial player in mucosal immunity and local inflammatory modulation. The high specificity score for [PIGR](/details-gene/5284), the polymeric immunoglobulin receptor, highlights its function as an active immune barrier, transporting immunoglobulins into the tubule lumen. This is complemented by a unique signature of genes involved in metabolic processing, detoxification, and regulation of local hemodynamics and inflammation, defining it as a highly active metabolic and immunological hub. ## Key Characteristics and Function Analysis of gene expression specificity provides a detailed view of the functional specialization of the [kidney proximal convoluted tubule epithelial cell](/details-cell/CL1000838). * **Immune and Inflammatory Modulation:** The most specific marker identified is [PIGR](/details-gene/5284) (CSI: 9.75), which is essential for transporting dimeric IgA across the epithelium, a cornerstone of mucosal immunity. This suggests these cells form a primary immunological barrier in the nephron. This role is further supported by the specific expression of [C7](/details-gene/730), a component of the membrane attack complex in the complement system, and [A2M](/details-gene/2), a broad-spectrum protease inhibitor that can regulate inflammation. The high specificity of [KNG1](/details-gene/3827) indicates local production of kininogens, precursors to bradykinin, which is involved in vasodilation, inflammation, and coagulation. * **Metabolic and Detoxification Hub:** These cells exhibit a strong metabolic signature. The high specificity of [FABP1](/details-gene/2168) points to a significant role in fatty acid uptake and trafficking, likely for beta-oxidation to meet the cell's high energy demands. Additionally, the specific expression of [GSTA1](/details-gene/2938), a glutathione S-transferase, underscores a key function in detoxification by conjugating and neutralizing xenobiotics and endogenous reactive species filtered from the blood. [PDK4](/details-gene/5166), a kinase that inhibits the pyruvate dehydrogenase complex, suggests precise regulation of glucose metabolism, potentially favoring fatty acid oxidation. * **Solute and Ion Transport:** As expected, genes related to transport are defining features. These include the solute carriers [SLC12A3](/details-gene/6559) and [SLC12A1](/details-gene/6557), which are critical for Na+, K+, and Cl- reabsorption. The expression of [ATP1B1](/details-gene/481), a subunit of the Na+/K+-ATPase, is consistent with its role in providing the primary electrochemical gradient for most transport processes. Furthermore, [TRPM3](/details-gene/80036), a cation channel, suggests a role in calcium and magnesium homeostasis. * **Structural Organization:** The specific expression of [ANK3](/details-gene/288) (Ankyrin-G) is crucial for the cell's function. Ankyrin-G is a scaffolding protein that anchors ion transporters and channels to specific domains of the plasma membrane, which is essential for maintaining the polarized epithelial phenotype required for directional transport. * **Negative Markers:** The genes with the lowest specificity scores (Anti-Markers) are predominantly housekeeping genes involved in ubiquitous cellular processes. This includes numerous mitochondrially-encoded genes essential for oxidative phosphorylation ([COX1](/details-gene/4512), [ND1](/details-gene/4535), [CYTB](/details-gene/4519)), ribosomal components ([RNR1](/details-gene/4549), [RNR2](/details-gene/4550)), and genes involved in the ubiquitin-proteasome system ([UBB](/details-gene/7314), [UBC](/details-gene/7316)). A low specificity score for these genes does not imply low expression; rather, it indicates that their expression is not unique to this cell type and thus they do not serve as distinguishing markers. This pattern correctly differentiates the cell's specialized functions from its fundamental, universally shared cellular machinery. ## Clinical Significance and Contextual Roles The gene profile of the [kidney proximal convoluted tubule epithelial cell](/details-cell/CL1000838) directly implicates it in several renal pathologies. * **Channelopathies:** The specific expression of solute carriers links these cells to inherited kidney diseases. Mutations in [SLC12A1](/details-gene/6557) are known to cause Bartter's syndrome ([Link](https://doi.org/10.1038/ng0696-183)), while mutations in [SLC12A3](/details-gene/6559) are the cause of Gitelman's syndrome ([Link](https://doi.org/10.1038/ng0196-24)). Both are characterized by salt wasting and electrolyte imbalances. * **Acute Kidney Injury (AKI):** The specific expression of [IGFBP7](/details-gene/3490) is highly significant, as it is a well-established urinary biomarker for the early detection of AKI. Its specific expression suggests it may be actively synthesized and secreted by these cells in response to stress or injury. * **Inflammatory and Vascular Kidney Diseases:** The local production of components of the kallikrein-kinin system ([KNG1](/details-gene/3827)) and the complement cascade ([C7](/details-gene/730)) implies that these cells can actively modulate local blood flow and inflammatory responses. Dysregulation of these pathways could contribute to hypertension, diabetic nephropathy, and glomerulonephritis. Similarly, the role of [PIGR](/details-gene/5284) in mucosal immunity suggests that its dysfunction could be a factor in IgA nephropathy or increase susceptibility to ascending urinary tract infections. * **Metabolic and Mineral Disorders:** The expression of [MGP](/details-gene/4256), a potent inhibitor of soft tissue calcification, suggests these cells may play a protective role against nephrocalcinosis. The presence of [HSD11B2](/details-gene/3291), which inactivates cortisol to corticosterone, is critical for preventing illicit activation of the mineralocorticoid receptor, thereby regulating blood pressure. ## Potential Mechanisms and Research Directions 1. **Hypothesis: Kidney proximal tubule cells function as frontline immunological sensors and effectors, actively shaping the luminal environment beyond simple reabsorption.** The highly specific expression of the immunoglobulin transporter [PIGR](/details-gene/5284) alongside a terminal complement component ([C7](/details-gene/730)) suggests an integrated system for both adaptive immune surveillance (via IgA) and innate immune defense (via complement). * **Surprising Findings:** The high specificity of [C7](/details-gene/730) is particularly striking. While complement deposition is common in kidney disease, local synthesis by tubular epithelial cells implies a more proactive and regulated role in initiating or propagating complement-mediated defense or pathology directly at the epithelial surface. * **Testable Questions:** In an in-vitro model of [kidney proximal convoluted tubule epithelial cells](/details-cell/CL1000838), does stimulation with bacterial ligands (e.g., LPS) lead to increased synthesis and apical secretion of C7, and does this secretion enhance the lysis of non-invasive bacteria in the culture medium? 2. **Hypothesis: Proximal tubule cells possess a mechanism to prevent pathological mineralization driven by their high solute transport activity.** The unique co-expression of genes for high-volume ion transport ([SLC12A1](/details-gene/6557), [ATP1B1](/details-gene/481)) and a potent calcification inhibitor ([MGP](/details-gene/4256)) suggests a protective mechanism. These cells create local microenvironments with high concentrations of calcium and phosphate, and [MGP](/details-gene/4256) may be expressed specifically to prevent the formation of mineral deposits (nephrocalcinosis) that could otherwise result. * **Surprising Findings:** The expression of [MGP](/details-gene/4256) is more commonly associated with vascular smooth muscle cells and chondrocytes. Its high specificity in a renal epithelial context is unexpected and points to a previously underappreciated role in maintaining kidney parenchymal integrity. * **Testable Questions:** Does siRNA-mediated knockdown of [MGP](/details-gene/4256) in primary human proximal tubule cell cultures lead to increased calcium phosphate deposition when the cells are cultured in media with high calcium and phosphate concentrations, mimicking conditions of hypercalciuria?