Details for: CL0005009

Cell ID: CL0005009

Cell Name: renal principal cell

Description: A cuboidal epithelial cell of the kidney which regulates sodium and potassium balance. The activity of sodium and potassium channels on the apical membrane of the cell is regulated by aldosterone and vasopressin. In mammals this cell type is located in the renal collecting duct system.

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 renal 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 renal 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 renal 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 renal 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:  renal principal cell (CL0005009)

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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 [renal principal cell](/details-cell/CL0005009) is a specialized cuboidal epithelial cell type located in the kidney's collecting duct system, fundamentally responsible for the final regulation of sodium, potassium, and water balance. This function is underscored by the high expression specificity of genes central to ion and water transport. **Overall**, the most defining markers include [ATP1B1](/details-gene/481), a subunit of the Na+/K+-ATPase essential for establishing electrochemical gradients, and [AQP2](/details-gene/359), the vasopressin-regulated water channel critical for urine concentration. These markers confirm its canonical role in maintaining bodily fluid homeostasis under the control of hormones like aldosterone and vasopressin. ## Key Characteristics and Function The molecular profile of the [renal principal cell](/details-cell/CL0005009) highlights several integrated functional clusters that define its specialized physiological role. * **Ion and Water Transport Machinery:** The cell's primary function is clearly delineated by a suite of highly specific transport-related genes. The Na+/K+-ATPase pump is represented by the beta subunit [ATP1B1](/details-gene/481) and its modulator [FXYD4](/details-gene/53828). Water reabsorption is unequivocally marked by [AQP2](/details-gene/359). The profile is further refined by the presence of ion channels not classically emphasized in this cell, such as the voltage-gated sodium channel [SCN2A](/details-gene/6326) and the potassium channel interacting protein [KCNIP4](/details-gene/80333), suggesting a more complex system of electrochemical regulation than previously understood. * **Epithelial Identity and Hormonal Sensing:** The cell's identity as a polarized epithelial cell is supported by the high specificity of the epithelial transcription factor [ELF3](/details-gene/1999) and the simple epithelial keratin [KRT8](/details-gene/3856). Its role as a key sensor in systemic homeostasis is indicated by receptors like [PTH2R](/details-gene/5746) (parathyroid hormone 2 receptor) and [PTGER1](/details-gene/5731) (prostaglandin E receptor 1), suggesting responsiveness to a broad range of signaling molecules beyond aldosterone and vasopressin. Furthermore, the expression of [PIGR](/details-gene/5284) (polymeric immunoglobulin receptor) implies a function in mucosal-like immune surveillance within the urinary tract. * **Post-Transcriptional Regulation and Stress Response:** A notable feature is the significant enrichment of numerous genes involved in RNA processing, such as [HNRNPA2B1](/details-gene/3181), [RBM39](/details-gene/9584), and [HNRNPU](/details-gene/3192). This suggests that post-transcriptional regulation, including mRNA splicing and stability, is a critical layer of control for rapidly modulating the cell's transport functions. Additionally, the cell appears well-equipped to handle metabolic byproducts and toxins, as evidenced by specific expression of detoxification enzymes like [GSTP1](/details-gene/2950) and antioxidant proteins like [PRDX1](/details-gene/5052). * **Negative Markers:** The low specificity of numerous genes encoding components of the mitochondrial electron transport chain (e.g., [UQCRB](/details-gene/7381), [COX6A1](/details-gene/1337), [ATP5ME](/details-gene/521)) suggests that while metabolically active, the [renal principal cell](/details-cell/CL0005009) is not defined by the exceptionally high oxidative phosphorylation capacity seen in other renal cell types like proximal tubule cells. The low specificity for [HLA E](/details-gene/3133) is consistent with its non-hematopoietic lineage and limited role in professional antigen presentation. ## Clinical Significance and Contextual Roles The gene signature of the [renal principal cell](/details-cell/CL0005009) provides direct links to several human diseases and highlights its importance in renal pathophysiology. The most critical clinical correlation is with water balance disorders. The high specificity of [AQP2](/details-gene/359) is consistent with its central role in vasopressin-mediated water reabsorption, and mutations in this gene are a primary cause of congenital nephrogenic diabetes insipidus, a disorder characterized by the inability to concentrate urine ([Link](https://doi.org/10.1126/science.8140421)). The prominent and specific expression of [SCN2A](/details-gene/6326), a gene primarily known for its association with severe neurodevelopmental disorders and epilepsy when mutated, is a striking finding. Its role in a non-excitable renal epithelial cell is not well understood, but it may contribute to the renal sodium wasting or electrolyte abnormalities occasionally observed in certain channelopathies. This suggests a potential area for investigating renal contributions to systemic phenotypes in these disorders. Furthermore, the cell's expression of protective enzymes like [GSTP1](/details-gene/2950) suggests a role in defending the distal nephron from filtered toxins and drugs, potentially influencing drug-induced nephrotoxicity. The presence of the [PIGR](/details-gene/5284) receptor points to a role in secretory immunity, potentially contributing to the defense against ascending urinary tract infections by transporting IgA into the tubular fluid. ## Potential Mechanisms and Research Directions 1. **Hypothesis:** The high expression specificity of the voltage-gated sodium channel [SCN2A](/details-gene/6326), typically associated with neurons, suggests it plays a non-canonical but critical role in the fine-tuning of sodium reabsorption or cell volume regulation in [renal principal cells](/details-cell/CL0005009), possibly by sensing or contributing to the transepithelial potential. * **Surprising Findings:** The identification of a major epilepsy- and neurodevelopmental disorder-associated ion channel as a top specific marker in a non-excitable epithelial cell is highly unexpected and challenges the canonical view of its function being restricted to the nervous system. * **Testable Question:** Does conditional knockout of [SCN2A](/details-gene/6326) specifically in principal cells of a mouse model affect urinary sodium concentration, membrane potential, or the cell's response to an aldosterone or vasopressin challenge? 2. **Hypothesis:** The significant enrichment for a large cohort of RNA-binding proteins (e.g., [HNRNPA2B1](/details-gene/3181), [RBM39](/details-gene/9584), [HNRNPC](/details-gene/3183)) indicates that post-transcriptional regulation is a central mechanism for principal cells to rapidly and efficiently modulate their ion and water transport machinery in response to fluctuating hormonal signals. * **Surprising Findings:** While transcriptional control by hormones is well-established, this data suggests that a coordinated post-transcriptional regulatory network may be an equally important, and perhaps underappreciated, layer of control that defines the functional plasticity of this cell type. * **Testable Question:** Using RNA-immunoprecipitation followed by sequencing (RIP-seq) for a key HNRNP protein (e.g., [HNRNPU](/details-gene/3192)) in a renal collecting duct cell line, what specific transporter and channel mRNAs (e.g., [AQP2](/details-gene/359), ENaC subunits) are bound, and does their stability or translation change upon hormonal stimulation with vasopressin or aldosterone?