Details for: CL1001431

Cell ID: CL1001431

Cell Name: kidney collecting duct principal cell

Description: Any renal principal cell that is part of some collecting duct of renal tubule.

Selected Context(s): Overall

Gene Significance Landscape

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Genes

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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 collecting duct principal 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 collecting duct principal 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 collecting duct principal 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 collecting duct principal 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 collecting duct principal cell (CL1001431)

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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 collecting duct principal cell](/details-cell/CL1001431) is a specialized epithelial cell type lining the renal collecting ducts. Based on its gene significance profile, this cell is characterized by a dual role in maintaining systemic homeostasis and providing local mucosal immunity. Its identity is defined by the highly specific expression of genes essential for regulated water and ion transport, such as [AQP2](/details-gene/359), alongside a robust suite of genes involved in epithelial barrier integrity and innate immune defense. The significant presence of neuron-associated scaffolding and signaling molecules suggests complex organizational principles for its polarized transport machinery, mirroring those found in neuronal synapses. ## Key Characteristics and Function Analysis of the **Overall** gene significance landscape reveals several core functional clusters that define the [kidney collecting duct principal cell](/details-cell/CL1001431). * **Regulated Water and Ion Transport:** As expected, this cell's primary function in water and electrolyte balance is underscored by the high expression specificity ([csi_z](/glossary/csi_z)) of key transport proteins. Most notably, [AQP2](/details-gene/359) (Aquaporin-2), the vasopressin-regulated water channel, is a defining marker. This is complemented by high specificity for ion transport and regulation-associated genes, including the Na/K-ATPase subunit [ATP1B1](/details-gene/481), the voltage-gated sodium channel [SCN2A](/details-gene/6326), and the potassium channel interacting protein [KCNIP4](/details-gene/80333). This molecular signature is consistent with the cell's central role in concentrating urine and fine-tuning sodium and potassium excretion. * **Epithelial Barrier Integrity and Adhesion:** The cell exhibits a strong molecular signature for maintaining a tight epithelial barrier. High specificity is observed for structural proteins like [KRT8](/details-gene/3856) (Keratin 8) and the tight junction component [CLDN7](/details-gene/1366). Furthermore, the cell adhesion molecules [EPCAM](/details-gene/4072) and [NLGN1](/details-gene/22871), along with scaffolding proteins such as [MAGI2](/details-gene/9863) and [DLG2](/details-gene/1740) that organize junctional complexes, are highly specific markers. This highlights the importance of structural integrity for vectorial transport and preventing leakage across the tubule. * **Mucosal and Innate Immunity:** A prominent characteristic is the expression of genes involved in mucosal defense. The high specificity of [PIGR](/details-gene/5284), the polymeric immunoglobulin receptor responsible for transcytosing IgA, suggests an active role in immune surveillance of the urinary space. This is strongly supported by the specific expression of protease inhibitors [SLPI](/details-gene/6590) and [SPINK1](/details-gene/6690), which likely protect the epithelial surface from microbial and inflammatory damage. * **Transcriptional Regulation:** The cell's specialized state appears to be maintained by a distinct set of transcription factors. [ELF3](/details-gene/1999), an Ets-family transcription factor known to be epithelium-specific ([Link](https://pubmed.ncbi.nlm.nih.gov/9234700/)), and [NPAS3](/details-gene/64067) show high expression specificity, indicating their role in driving the unique transcriptional program of this cell. * **Anti-Markers:** The least significant genes for this cell type are dominated by components of mitochondrial electron transport ([COX1](/details-gene/4512), [COX2](/details-gene/4513), [COX3](/details-gene/4514), [CYTB](/details-gene/4519), [ND1](/details-gene/4535), [ND2](/details-gene/4536), [ND3](/details-gene/4537)). The strong negative `csi_z` for these genes does not imply a lack of metabolic activity, but rather indicates that these ubiquitous "housekeeping" functions are not specific identifiers for this cell type compared to others. This emphasizes that the cell's identity is derived from its specialized functions rather than its basal metabolic state. ## Clinical Significance and Contextual Roles The gene expression profile of the [kidney collecting duct principal cell](/details-cell/CL1001431) provides insight into its potential roles in several disease states. * **Disorders of Water Balance:** The most direct clinical link is through [AQP2](/details-gene/359). Mutations in this gene are a primary cause of autosomal nephrogenic diabetes insipidus, a condition characterized by the kidney's inability to concentrate urine in response to vasopressin ([Link](https://doi.org/10.1126/science.8140421), [Link](https://pubmed.ncbi.nlm.nih.gov/7524315/)). * **Renal Carcinoma:** The high specificity of epithelial markers such as [EPCAM](/details-gene/4072), a known tumor antigen, and [KRT8](/details-gene/3856) suggests these could be valuable for diagnosing or classifying renal cancers derived from the collecting duct, such as collecting duct carcinoma. * **Urinary Tract Infections and Inflammation:** The prominent expression of immune-related genes like [PIGR](/details-gene/5284), [SLPI](/details-gene/6590), and [B2M](/details-gene/567) positions this cell as a critical component of the kidney's defense against ascending pathogens. Dysregulation of this localized immune barrier could contribute to susceptibility to or severity of pyelonephritis. * **Potential for Off-Target Effects and Pleiotropy:** Several top markers are primarily studied in other organ systems, most notably the central nervous system. These include [NLGN1](/details-gene/22871) (neuroligin), [DLG2](/details-gene/1740) (discs large homolog 2), and [NPAS3](/details-gene/64067). While their function here is likely related to organizing cell polarity and signaling, their high specificity raises the possibility of unappreciated renal phenotypes in diseases primarily considered neurological, or renal side-effects from drugs targeting these molecules. For instance, disruption of [NPAS3](/details-gene/64067) has been linked to schizophrenia ([Link](https://doi.org/10.1136/jmg.40.5.325)), highlighting its systemic importance. ## Potential Mechanisms and Research Directions 1. **Hypothesis:** The highly specific expression of neuron-associated scaffolding and adhesion molecules, including [NLGN1](/details-gene/22871), [DLG2](/details-gene/1740), and [MAGI2](/details-gene/9863), in [kidney collecting duct principal cells](/details-cell/CL1001431) is functionally convergent with their role in the synapse. These proteins may form a critical "transport-organizing complex" at both apical and basolateral membranes, essential for the precise localization and clustering of channels and transporters like [AQP2](/details-gene/359) and [ATP1B1](/details-gene/481) to enable efficient vectorial transport. * **Surprising Findings:** The identification of [NLGN1](/details-gene/22871), a molecule central to trans-synaptic adhesion, as a top specific marker in a non-neuronal epithelial cell is unexpected. It suggests that molecular mechanisms for establishing highly organized, polarized domains may be conserved between neurons and these specialized renal cells. * **Testable Question:** Does conditional knockout of [NLGN1](/details-gene/22871) in murine collecting duct principal cells lead to mislocalization of [AQP2](/details-gene/359) from the apical membrane and a subsequent impairment in urine concentrating ability under water-deprived conditions? 2. **Hypothesis:** Beyond passive barrier function, [kidney collecting duct principal cells](/details-cell/CL1001431) act as active immunological sentinels of the upper urinary tract. The high constitutive and specific expression of a suite of defense molecules, including [PIGR](/details-gene/5284), [SLPI](/details-gene/6590), and [SPINK1](/details-gene/6690), provides a multi-faceted, standing defense system that is crucial for preventing and controlling ascending bacterial infections. * **Surprising Findings:** The expression specificity of key immune defense genes ([PIGR](/details-gene/5284), [SLPI](/details-gene/6590)) rivals that of canonical transport proteins. This suggests that mucosal immunity is not an ancillary or inducible function but a core, defining feature of this cell type's identity. * **Testable Question:** Using a co-culture system with uropathogenic *E. coli* (UPEC), do [kidney collecting duct principal cells](/details-cell/CL1001431) respond by increasing the secretion of [SLPI](/details-gene/6590) into the apical medium, and does this secreted [SLPI](/details-gene/6590) exhibit direct bactericidal or bacteriostatic activity against UPEC?