Details for: CL0000910

Cell ID: CL0000910

Cell Name: cytotoxic T cell

Description: A mature T cell that differentiated and acquired cytotoxic function with the phenotype perforin-positive and granzyme-B positive.

Synonyms: cytotoxic T lymphocyte, cytotoxic T-cell, cytotoxic T-lymphocyte

Selected Context(s): Overall

Gene Significance Landscape

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Score:
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Genes

Contexts:

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 cytotoxic T 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 cytotoxic T 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 cytotoxic T 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 cytotoxic T 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:  cytotoxic T cell (CL0000910)

 Legend
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 [cytotoxic T cell](/details-cell/CL0000910), also known as a cytotoxic T-lymphocyte (CTL), is a mature T-lymphocyte defined by its capacity to kill target cells through the release of cytotoxic molecules like perforin and granzyme B. Analysis of its gene expression profile reveals that its identity is distinguished by a highly specific transcriptional signature. **Overall**, this signature is dominated by numerous long non-coding RNAs and antisense transcripts, such as [ZBTB20 AS4](/details-gene/100874131) and [LINC02679](/details-gene/105378385), which exhibit exceptionally high expression specificity (CSI Z-score > 15.0). This suggests that post-transcriptional regulation and a unique nuclear architecture are paramount in defining the functional state of this cell type, beyond the canonical protein-coding effector molecules. ## Key Characteristics and Function The transcriptional identity of the [cytotoxic T cell](/details-cell/CL0000910) is shaped by several key functional clusters of genes with high expression specificity. * **Regulatory Non-coding RNA Network:** A striking feature is the prominence of non-coding RNAs as top markers. Genes such as [ZBTB20 AS4](/details-gene/100874131), [LOC105374114](/details-gene/105374114), [LINC02679](/details-gene/105378385), and [LINC02569](/details-gene/111082993) show the highest specificity scores. This pattern suggests that the cytotoxic program is finely tuned by a complex layer of regulatory RNAs that may control the expression, stability, and translation of key effector proteins. * **Immune Recognition and Signaling:** The specific expression of [B2M](/details-gene/567) (Beta-2-microglobulin), a critical component of MHC class I molecules, underscores the cell's fundamental role in interacting with antigen-presenting cells and target cells. The presence of [TPT1](/details-gene/7178), a translationally controlled tumor protein involved in calcium binding, may indicate a readiness for rapid protein synthesis and signaling upon T-cell receptor engagement. * **Unexpected Tissue-Associated Markers:** Several top markers are not traditionally associated with immune function. The prion-like protein [PRND](/details-gene/23627) (Doppel), growth factor [GDF3](/details-gene/9573), and [STRC](/details-gene/161497) (Stereocilin), a protein primarily known for its role in inner ear hair bundles ([Link](https://pubmed.ncbi.nlm.nih.gov/11687802/)), are all highly specific. This may point to specialized subsets of [cytotoxic T cells](/details-cell/CL0000910) with roles in tissue-specific surveillance or pathology. * **Metabolic and Housekeeping Profile:** The anti-marker list provides insight into what this cell is not defined by. Many genes with low or negative specificity scores are involved in core cellular processes, including oxidative phosphorylation (e.g., [COX5B](/details-gene/1329), [COX6C](/details-gene/1345), [NDUFA4](/details-gene/4697)), protein degradation ([UBB](/details-gene/7314), [PSMB1](/details-gene/5689)), and general RNA processing ([HNRNPDL](/details-gene/9987)). This suggests that while these functions are active, their expression levels are not uniquely elevated compared to other cell types, perhaps hinting at a specialized metabolic state, such as a reliance on glycolysis over oxidative phosphorylation, to fuel its effector functions. The strong negative CSI for a specific T-cell receptor alpha variable gene, [TRAV39](/details-gene/28642), is particularly notable and may reflect clonal selection processes or the exclusion of this V-gene from the cytotoxic repertoire analyzed. ## Clinical Significance and Contextual Roles The gene significance profile provides several avenues for understanding the clinical relevance of [cytotoxic T cells](/details-cell/CL0000910). Lacking comparative data across different health states, the **Overall** context highlights fundamental aspects that could be pertinent in disease. The unusual prominence of [PRND](/details-gene/23627) as a specific marker is noteworthy. While its function in T-cells is unknown, studies in prion protein-deficient mice have associated its upregulation in the CNS with ataxia and neurodegeneration ([Link](https://pubmed.ncbi.nlm.nih.gov/10525406/)). This raises the possibility that [cytotoxic T cells](/details-cell/CL0000910) expressing [PRND](/details-gene/23627) could be involved in the pathology of certain neurological disorders, either as drivers of inflammation or as a response to it. Similarly, the high specificity of [STRC](/details-gene/161497), a gene whose mutation is linked to non-syndromic deafness ([Link](https://pubmed.ncbi.nlm.nih.gov/17098888/)), is unexpected. This could imply a previously unappreciated role for these lymphocytes in the inner ear, potentially in autoimmune disorders affecting hearing or in response to viral infections in that immunologically distinct site. The expression of such tissue-specific genes may mark unique subsets of tissue-resident or tissue-homing [cytotoxic T cells](/details-cell/CL0000910). ## Potential Mechanisms and Research Directions 1. **Hypothesis:** The functional identity and activation state of [cytotoxic T cells](/details-cell/CL0000910) are predominantly orchestrated by a specific suite of non-coding RNAs, which act as master regulators of the cytotoxic machinery, rather than by the transcription levels of the effector protein genes themselves. * **Surprising Findings:** The most specific molecular markers for this classically defined cell type are not the canonical cytotoxic proteins (e.g., granzymes, perforin) but a diverse group of uncharacterized long non-coding and antisense RNAs like [ZBTB20 AS4](/details-gene/100874131) and [LINC02679](/details-gene/105378385). This challenges the conventional protein-centric view of cell-type definition. * **Testable Questions:** Does targeted degradation of the most specific lncRNAs (e.g., using ASO or CRISPR-Cas13) in activated human T-cells lead to a diminished capacity to kill target cells or alter the expression profile of key cytotoxic effector molecules like *GZMB* and *PRF1*? 2. **Hypothesis:** [Cytotoxic T cells](/details-cell/CL0000910) possess a specialized bioenergetic profile characterized by a relative suppression of certain oxidative phosphorylation (OXPHOS) components, favoring metabolic pathways like aerobic glycolysis to support rapid, high-energy effector functions. * **Surprising Findings:** For a cell type requiring immense energy for proliferation and killing, multiple core subunits of the mitochondrial electron transport chain (e.g., [COX5B](/details-gene/1329), [COX6C](/details-gene/1345), [SOD1](/details-gene/6647)) exhibit negative specificity scores. This suggests a unique metabolic adaptation rather than a simple global upregulation of energy production. * **Testable Questions:** Do single-cell metabolic assays (e.g., scRNA-seq combined with measurements of glycolytic and OXPHOS rates) confirm a lower reliance on OXPHOS in [cytotoxic T cells](/details-cell/CL0000910) compared to other lymphocyte populations? Furthermore, is their cytotoxic function *in vitro* more sensitive to inhibitors of glycolysis than to inhibitors of mitochondrial respiration?