Details for: CL4030018

Cell ID: CL4030018

Cell Name: kidney connecting tubule principal cell

Description: A renal principal cell located in the 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

Significant Genes List

Genes with the highest and lowest Percentile Rank Scores (PRS) for kidney connecting tubule 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 connecting tubule 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 connecting tubule 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 connecting tubule 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 connecting tubule principal cell (CL4030018)

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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 principal cell](/details-cell/CL4030018) is a specialized renal epithelial cell whose identity is overwhelmingly defined by an exceptionally high level of mitochondrial bioenergetic activity. **Overall**, the gene significance profile, characterized by extremely high cell significance index (CSI) scores for mitochondrially-encoded components of the electron transport chain, points to a cell with a massive capacity for aerobic respiration. This metabolic state is intrinsically linked to its primary function in the fine-tuning of ion and water reabsorption, driven by a suite of highly specific ion transporters and regulatory proteins. The cell's molecular signature suggests it is a critical nexus for energy-intensive homeostatic processes under precise hormonal control. ## Key Characteristics and Function Analysis of top marker genes reveals a highly specialized cellular machinery organized around two core functional themes: energy production and active transport. * **Mitochondrial Bioenergetics:** The most defining characteristic of this cell type is its profound reliance on aerobic respiration. This is evidenced by the top-ranking markers, which are almost exclusively core subunits of the mitochondrial respiratory chain encoded by the mitochondrial genome. These include components of Complex IV (cytochrome c oxidase), such as [COX2](/details-gene/4513) (CSI: 13.93) and [COX1](/details-gene/4512) (CSI: 13.79), Complex III ([CYTB](/details-gene/4519), CSI: 12.96), Complex I (NADH dehydrogenase), including [ND1](/details-gene/4535), [ND3](/details-gene/4537), [ND5](/details-gene/4540), [ND4](/details-gene/4538), [ND2](/details-gene/4536), and [ND4L](/details-gene/4539), and Complex V (ATP synthase), represented by [ATP6](/details-gene/4508). The high specificity of these genes, indicated by their high `csi_z` scores and maximum effect sizes (+1.0000), suggests that this intense metabolic signature is a unique and fundamental aspect of this cell's identity. * **Ion Transport and Regulation:** The immense ATP-generating capacity is harnessed to power sophisticated ion transport systems. Key markers in this category include [WNK1](/details-gene/65125) (CSI: 12.26), a kinase critical for regulating sodium ion transport and blood pressure, and [ATP1B1](/details-gene/481) (CSI: 11.31), the beta subunit of the Na+/K+ ATPase, the primary active transporter in most animal cells. Further specialization in ion handling is indicated by the high significance of [CALB1](/details-gene/793), a calcium-binding protein involved in calcium reabsorption, [CA12](/details-gene/771), a carbonic anhydrase for pH regulation, and [SLC8A1](/details-gene/6546), a sodium/calcium exchanger. The cell's function is also tightly regulated by systemic hormones, highlighted by the high specificity of [HSD11B2](/details-gene/3291), an enzyme that inactivates cortisol, thereby conferring aldosterone specificity to the mineralocorticoid receptor. The profile of anti-markers, or least significant genes, is also informative. The low specificity scores for broadly expressed housekeeping genes involved in processes like RNA splicing ([SF3B1](/details-gene/23451)) and glycolysis ([PKM](/details-gene/5315)) reinforces that the cell's unique identity is rooted in its specialized functions rather than ubiquitous cellular processes. The presence of some nuclear-encoded mitochondrial proteins like [NDUFS5](/details-gene/4725) as anti-markers is noteworthy, and may suggest a specific stoichiometry of respiratory chain complexes that prioritizes mitochondrially-encoded subunits. ## Clinical Significance and Contextual Roles The gene expression profile of the [kidney connecting tubule principal cell](/details-cell/CL4030018) directly implicates it in several key areas of human health and disease, particularly those related to blood pressure regulation and electrolyte balance. The high significance of [WNK1](/details-gene/65125) is clinically relevant, as mutations in this gene are associated with Familial Hyperkalemic Hypertension, or Gordon's syndrome. This underscores the cell's pivotal role in sodium and potassium homeostasis and its direct link to the pathophysiology of hypertension ([Link](https://pubmed.ncbi.nlm.nih.gov/11571656/)). Similarly, the specific expression of [HSD11B2](/details-gene/3291) is critical; its deficiency leads to the syndrome of apparent mineralocorticoid excess, where cortisol illicitly activates the mineralocorticoid receptor, causing severe hypertension and hypokalemia ([Link](https://doi.org/10.1016/0303-7207(94)90176-7)). Furthermore, the cell's extreme dependence on mitochondrial function suggests a pronounced vulnerability to mitochondrial dysfunction and ischemic injury. Conditions that impair oxidative phosphorylation could disproportionately affect the function of these cells, leading to disruptions in renal function, electrolyte imbalances, and impaired blood pressure control. The unique metabolic signature of these cells may therefore represent a point of susceptibility in various forms of acute and chronic kidney disease. ## Potential Mechanisms and Research Directions 1. **Hypothesis: Kidney connecting tubule principal cells maintain a unique stoichiometry of the electron transport chain (ETC) that is optimized for sustained, high-level active transport.** The data reveal a striking pattern where all top-scoring bioenergetic genes are encoded by the mitochondrial genome, while some nuclear-encoded ETC components, such as [NDUFS5](/details-gene/4725) (a Complex I subunit), have low specificity scores. This suggests that the composition of respiratory supercomplexes in these cells may be distinct from other cell types, possibly favoring a configuration that maximizes ATP output to meet the relentless demands of ion pumping. * **Surprising Findings:** It is unexpected that core subunits of the same mitochondrial complex (Complex I) would appear at opposite ends of the significance spectrum ([ND1](/details-gene/4535) is a top marker, while [NDUFS5](/details-gene/4725) is an anti-marker). This implies that a simple up-regulation of all mitochondrial components is not occurring; instead, a highly specific and regulated assembly process may define the cell's metabolic capacity. * **Testable Questions:** What is the precise molar ratio of mitochondrially-encoded to nuclear-encoded subunits within Complex I and other respiratory complexes in isolated [kidney connecting tubule principal cells](/details-cell/CL4030018) compared to other metabolically active cells like cardiomyocytes? Do techniques like complexome profiling or high-resolution respirometry reveal functional differences in the ETC of these cells that can be attributed to this unique subunit composition? 2. **Hypothesis: The WNK1 kinase acts as a central metabolic rheostat, directly coupling ion transport activity to mitochondrial ATP production.** The co-occurrence of [WNK1](/details-gene/65125), a key regulator of ion channels and transporters, as a top-specificity marker alongside the mitochondrial powerhouse machinery suggests a more integrated role than simple upstream regulation. It is plausible that [WNK1](/details-gene/65125) signaling pathways not only modulate transporter activity at the apical and basolateral membranes but also send direct signals to the mitochondria to modulate ATP synthesis in anticipation of or in response to changes in transport load. * **Surprising Findings:** The significance score of [WNK1](/details-gene/65125) (CSI: 12.26) is remarkably high, placing it in the same tier as core components of the ETC. This suggests its role in defining the cell's identity is as fundamental as the machinery for energy production itself, hinting at a tightly integrated feedback loop. * **Testable Questions:** Does pharmacological inhibition or siRNA-mediated knockdown of [WNK1](/details-gene/65125) in a primary culture model of these cells lead to a rapid decrease in mitochondrial oxygen consumption rate, even when cellular ion gradients are experimentally clamped? Furthermore, does WNK1 phosphorylate any known mitochondrial proteins involved in regulating ETC activity or substrate transport?