Details for: CL1000768

Cell ID: CL1000768

Cell Name: kidney connecting tubule epithelial cell

Description: Any nephron tubule epithelial cell that is part of some renal connecting 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

Image representation

Depiction of kidney connecting tubule epithelial cell
Courtesy of SwissBioPics

Significant Genes List

Genes with the highest and lowest Percentile Rank Scores (PRS) for kidney connecting 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 connecting 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 connecting 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 connecting 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 connecting tubule epithelial cell (CL1000768)

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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 connecting tubule epithelial cell](/details-cell/CL1000768) is a specialized cell type lining the connecting tubule of the nephron, which links the distal convoluted tubule to the collecting duct. **Overall**, the gene significance profile of this cell is overwhelmingly dominated by an exceptionally high and specific expression of mitochondrially-encoded genes, such as [ATP6](/details-gene/4508), [ND2](/details-gene/4536), and [ND1](/details-gene/4535). This molecular signature points to a profound specialization in aerobic respiration and energy production. This high metabolic capacity is essential to power the cell's primary functions in fine-tuning water and electrolyte balance, a role underscored by the co-expression of critical transport proteins like the water channel [AQP2](/details-gene/359) and ion channel subunits such as [SCN2A](/details-gene/6326). ## Key Characteristics and Function Analysis of top marker genes, ranked by expression specificity (CSI Z-score), reveals several core functional clusters that define the [kidney connecting tubule epithelial cell](/details-cell/CL1000768). * **Extraordinary Mitochondrial Activity:** A striking feature of this cell type is the pronounced specificity of numerous genes encoding components of the mitochondrial electron transport chain. The list of top markers includes [ATP6](/details-gene/4508) (ATP synthase), multiple subunits of NADH dehydrogenase ([ND1](/details-gene/4535), [ND2](/details-gene/4536), [ND4](/details-gene/4538), [ND5](/details-gene/4540), [ND3](/details-gene/4537)), and cytochrome c oxidase ([COX1](/details-gene/4512), [COX2](/details-gene/4513), [COX3](/details-gene/4514), [COX5B](/details-gene/1329)), as detailed in foundational work on the human mitochondrial genome ([Link](https://doi.org/10.1038/290457a0)). This collective high specificity suggests that the entire mitochondrial apparatus is a defining characteristic, highlighting the cell's immense capacity for ATP production to fuel active transport. * **Regulated Water and Ion Transport:** The cell's central role in renal homeostasis is confirmed by the high specificity of key transport-related genes. [AQP2](/details-gene/359), the vasopressin-sensitive water channel, is a critical marker whose function is essential for urine concentration ([Link](https://doi.org/10.1126/science.8140421)). Additionally, the high CSI scores for [SCN2A](/details-gene/6326), a voltage-gated sodium channel alpha subunit typically associated with the brain ([Link](https://doi.org/10.1073/pnas.89.17.8220)), and [KCNIP4](/details-gene/80333), a potassium channel interacting protein ([Link](https://doi.org/10.1074/jbc.m200897200)), suggest a specialized and complex machinery for regulating ion flux and transepithelial potential. * **Complex Transcriptional and Post-Transcriptional Regulation:** The cell maintains its specialized state through a unique regulatory landscape. The high specificity of the long non-coding RNA [NEAT1](/details-gene/283131), a core component of nuclear paraspeckles, points to a distinct layer of nuclear organization and gene regulation. Furthermore, significant expression of RNA-binding proteins like [DDX17](/details-gene/10521), [HNRNPC](/details-gene/3183), and [HNRNPA2B1](/details-gene/3181) indicates that post-transcriptional processing, such as alternative splicing, is a key specific feature of this cell type. * **Epithelial Identity and Signaling:** Structural and regulatory proteins confirm the cell's epithelial nature. [KRT8](/details-gene/3856) is a simple epithelial keratin, and [ELF3](/details-gene/1999) is an epithelium-specific Ets transcription factor ([Link](https://doi.org/10.1128/mcb.17.8.4419)). The high specificity of [S100A6](/details-gene/6277), a calcium-binding protein, suggests a role in calcium-dependent signaling, which is integral to regulating transport processes in the kidney. ## Clinical Significance and Contextual Roles **Overall**, the gene expression profile highlights pathways central to renal physiology and disease. The most direct clinical link is through [AQP2](/details-gene/359), where mutations are a known cause of autosomal recessive nephrogenic diabetes insipidus, a condition where the kidneys cannot concentrate urine despite normal vasopressin levels ([Link](https://doi.org/10.1126/science.8140421)). The profound reliance on mitochondrial function suggests that these cells may be particularly vulnerable to mitochondrial dysfunction, a common pathological feature in both acute kidney injury and chronic kidney disease. The high specificity of genes with primary associations outside the kidney presents intriguing possibilities. For instance, [SCN2A](/details-gene/6326) is well-studied for its role in epilepsy and other neurological disorders ([Link](https://doi.org/10.1073/pnas.89.17.8220)). Its highly specific expression in connecting tubule cells suggests a potential, yet unexplored, role in renal pathophysiology or as an off-target site for drugs targeting this channel. Similarly, the specific expression of the lncRNA [NEAT1](/details-gene/283131) could implicate paraspeckle-mediated stress responses in renal pathologies. The strong expression of [B2M](/details-gene/567), a component of MHC class I molecules, may also indicate a role in antigen presentation and interaction with the immune system under specific pathological conditions. ## Potential Mechanisms and Research Directions 1. **Hypothesis:** The highly specific expression of the classically neuronal voltage-gated sodium channel [SCN2A](/details-gene/6326) and the potassium channel modulator [KCNIP4](/details-gene/80333) in [kidney connecting tubule epithelial cells](/details-cell/CL1000768) indicates a non-canonical role in establishing and dynamically regulating the transepithelial electrochemical gradient, which is crucial for efficient, vasopressin-independent ion and water transport. * **Surprising Findings:** The identification of a major brain sodium channel ([SCN2A](/details-gene/6326)) as a top-ranking specificity marker in a non-excitable epithelial cell is highly unexpected. This suggests that its function is decoupled from action potential generation and has been repurposed for fine-tuning baseline membrane potential and vectorial ion transport. * **Testable Questions:** What is the precise subcellular localization of the SCN2A protein in connecting tubule cells? Does targeted pharmacological inhibition or conditional knockout of [SCN2A](/details-gene/6326) in mouse connecting tubules alter basolateral membrane potential and affect the reabsorption rates of sodium, potassium, and calcium? 2. **Hypothesis:** The systemic and uniquely high expression of the entire suite of mitochondrially-encoded electron transport chain genes signifies that [kidney connecting tubule epithelial cells](/details-cell/CL1000768) function as metabolic "power plants" for the distal nephron, with their ATP production and metabolic state directly influencing the function and survival of adjacent, less metabolically active cell types, such as intercalated cells, under both physiological and pathological stress conditions. * **Surprising Findings:** It is not just one or two rate-limiting metabolic enzymes that are highly specific, but rather a large cohort of genes from across multiple mitochondrial complexes ([ND1](/details-gene/4535), [COX1](/details-gene/4512), [ATP6](/details-gene/4508), etc.). This points to a coordinated, systems-level upregulation of the entire mitochondrial genome's transcriptional program as a core identity feature of this cell, a level of metabolic specialization that is exceptional among the cell types analyzed. * **Testable Questions:** Using spatial transcriptomics or single-cell metabolic profiling, is there a measurable gradient of metabolic activity and ATP concentration radiating from connecting tubule cells to adjacent cell types? Does inducing mild mitochondrial stress specifically in these cells (e.g., via targeted expression of a mild uncoupler) trigger a stress response or functional deficit in neighboring intercalated cells?