CTDSPL Human

What is CTDSPL and what are its main functions in human cells?

CTDSPL (CTD Small Phosphatase Like) is a protein coding gene that preferentially catalyzes the dephosphorylation of 'Ser-5' within the tandem 7 residue repeats in the C-terminal domain (CTD) of the largest RNA polymerase II subunit POLR2A. It plays a crucial role in negatively regulating RNA polymerase II transcription, possibly by controlling the transition from initiation/capping to processive transcript elongation . Additionally, CTDSPL is recruited by REST to neuronal genes containing RE-1 elements, contributing to neuronal gene silencing in non-neuronal cells .

The phosphatase activity of CTDSPL suggests its involvement in protein dephosphorylation pathways, particularly in the negative regulation of the G1/S transition of the mitotic cell cycle and negative regulation of protein phosphorylation . This role in cell cycle regulation is consistent with its tumor suppressive functions observed in multiple cancer types.

What are the common aliases and identifiers for the CTDSPL gene?

CTDSPL is known by multiple aliases in scientific literature and databases, which can be important for comprehensive literature searches:

• HYA22

• RBSP3 (RB Protein Serine Phosphatase From Chromosome 3)

• SCP3 (Small CTD Phosphatase 3)

• C3orf8

• PSR1

• Small C-Terminal Domain Phosphatase 3

• Nuclear LIM Interactor-Interacting Factor 1

Key identifiers for database searches include:

• HGNC: 16890

• NCBI Gene: 10217

• Ensembl: ENSG00000144677

• OMIM®: 608592

• UniProtKB/Swiss-Prot: O15194

How does CTDSPL function in normal cellular processes?

In normal cellular processes, CTDSPL primarily functions as a phosphatase that removes phosphate groups from specific substrates. Its most characterized function is dephosphorylating 'Ser-5' within the CTD of RNA polymerase II, which helps regulate transcriptional processes . This dephosphorylation activity contributes to the negative regulation of RNA polymerase II transcription by potentially controlling the transition from initiation/capping to transcript elongation .

CTDSPL also participates in the negative regulation of the G1/S transition of the mitotic cell cycle, suggesting it plays a role in cell cycle checkpoint control . This function aligns with its observed tumor suppressor properties, as disruption of cell cycle checkpoints is a hallmark of cancer development.

How is CTDSPL expression regulated by microRNAs?

CTDSPL expression is regulated by several microRNAs, which are small non-coding RNAs that bind to complementary sequences in target mRNAs to induce degradation or translational repression. Research has shown that hsa-miR-503-5p directly targets CTDSPL and negatively regulates its expression . This regulatory relationship was confirmed through dual-luciferase reporter assays that verified the binding relationship between hsa-miR-503-5p and CTDSPL .

In lung adenocarcinoma (LUAD), hsa-miR-503-5p exhibits elevated expression levels while CTDSPL shows decreased expression . The overexpression of hsa-miR-503-5p contributes to cisplatin resistance and promotes angiogenesis in LUAD cells by suppressing CTDSPL expression . Experimental knockdown of hsa-miR-503-5p resensitized LUAD cells to cisplatin, inhibited angiogenesis, and reduced the protein expression of angiogenesis-related factors like VEGFR1 and VEGFR2 .

What transcription factors are involved in regulating CTDSPL?

According to ENCODE data analysis, several transcription factors have been predicted to bind to the CTDSPL intron 1-6367bp fragment (chr3:37979882-37986249), suggesting their potential role in regulating CTDSPL expression . These transcription factors include:

• Upstream transcription factor 2 (USF2) (chr3:37,981,985-37,982,248)

• Activating transcription factor 3 (ATF3) (chr3:37,982,058-37,982,290)

• Upstream transcription factor 1 (USF1) (chr3:37,982,074-37,982,317)

• Zinc finger protein 263 (ZNF263) (chr3:37,982,058-37,982,290)

• GATA binding protein 2 (GATA2) (chr3:37,983,211-37,983,617)

• Interferon regulatory factor 1 (IRF1) (chr3:37,986,122-37,986,432)

All of these transcription factors are expressed in cervical cells, suggesting potential regulatory roles in CTDSPL expression in cervical tissue . Three DNase-sensitive sites were also identified overlapping with the binding regions of these transcription factors, further supporting their regulatory function .

What evidence supports CTDSPL's role as a tumor suppressor?

Multiple lines of evidence support CTDSPL's role as a tumor suppressor:

• Functional studies in cervical cancer: Genome-wide CNV (Copy Number Variation) studies identified CTDSPL as a tumor suppressor gene for cervical cancer . To validate this function, researchers ectopically expressed CTDSPL in HeLa cells (which lack CTDSPL) and observed anti-tumor effects .

• Negative regulation of cell cycle progression: CTDSPL is involved in the negative regulation of G1/S transition of the mitotic cell cycle , a function consistent with tumor suppressor activity as uncontrolled cell cycle progression is a hallmark of cancer.

• Decreased expression in cancer: CTDSPL shows decreased expression in various cancer types, including lung adenocarcinoma, suggesting that loss of CTDSPL contributes to cancer progression .

• Effects of restored expression: Experimental restoration of CTDSPL expression in cancer cells typically results in reduced proliferation, migration, and invasion capabilities, supporting its tumor suppressive function .

How does CTDSPL influence chemotherapy resistance in cancer?

CTDSPL plays a significant role in modulating chemotherapy resistance, particularly to cisplatin in lung adenocarcinoma:

• Negative regulation by miR-503-5p: In lung adenocarcinoma, hsa-miR-503-5p exhibits high expression and negatively regulates CTDSPL. This miRNA-mediated suppression of CTDSPL contributes to cisplatin resistance in LUAD cells .

• Re-sensitization through CTDSPL restoration: Knockdown of hsa-miR-503-5p, which results in increased CTDSPL expression, resensitizes LUAD cells to cisplatin. This indicates that restoration of CTDSPL expression can overcome cisplatin resistance .

• Impact on cell survival pathways: CTDSPL likely influences chemotherapy resistance by regulating cell survival pathways. When CTDSPL expression is restored through miR-503-5p inhibition, there is increased apoptosis in cisplatin-treated LUAD cells .

• Potential therapeutic target: The relationship between CTDSPL and chemotherapy resistance suggests that targeting the miR-503-5p/CTDSPL axis could be a novel strategy for overcoming cisplatin resistance in cancer treatment .

What is known about CTDSPL's role in angiogenesis?

Research indicates that CTDSPL influences angiogenesis, particularly in the context of lung adenocarcinoma:

• Negative regulation of angiogenic factors: CTDSPL appears to negatively regulate angiogenesis by suppressing the expression of key angiogenic factors. When CTDSPL expression is increased (through miR-503-5p inhibition), there is a reduction in the protein expression of vascular endothelial growth factor receptors (VEGFR1 and VEGFR2) .

• Inhibition of endothelial cell functions: Enhanced CTDSPL expression (via miR-503-5p knockdown) inhibits the angiogenic ability of human umbilical vein endothelial cells (HUVECs), suggesting that CTDSPL suppresses endothelial cell functions required for new blood vessel formation .

• EMT regulation: CTDSPL also influences epithelial-mesenchymal transition (EMT)-related targets, which can indirectly affect angiogenesis as EMT and angiogenesis are often co-regulated processes in cancer progression .

What techniques are effective for studying CTDSPL expression?

Several techniques have proven effective for studying CTDSPL expression in research settings:

• Quantitative Real-Time PCR (qRT-PCR): This technique has been successfully used to measure CTDSPL mRNA expression levels in both cell lines and tissue samples . Primers targeting specific regions of CTDSPL can be designed for accurate quantification.

• Western Blotting: Western blot analysis is commonly employed to detect CTDSPL protein expression, allowing researchers to assess how interventions affect CTDSPL at the protein level .

• Copy Number Variation (CNV) Analysis: SybrGreen real-time quantitative PCR has been used to validate CNVs in CTDSPL. The ΔΔCt method with normalization against reference genes and samples without corresponding CNVs provides accurate quantification .

• Dual-Luciferase Reporter Assays: These assays are valuable for studying regulatory mechanisms of CTDSPL expression, such as validating the binding relationship between CTDSPL and microRNAs like hsa-miR-503-5p .

How can researchers effectively manipulate CTDSPL expression in experimental models?

Researchers have successfully employed several strategies to manipulate CTDSPL expression:

• Plasmid-based Overexpression: CTDSPL cDNA fragments can be amplified and inserted into expression vectors (e.g., pcDNA3.1/myc-his-A) for transfection into cell lines. This approach has been used to ectopically express CTDSPL in HeLa cells lacking endogenous CTDSPL .

• CRISPR/Cas9 System: CTDSPL knockout models have been generated using CRISPR/Cas9 technology. For instance, Ctdspl knockout mice were created by targeting specific exons (e.g., Exon 2) with CRISPR/Cas9, with founders genotyped by PCR followed by DNA sequencing analysis .

• MicroRNA Modulation: Since CTDSPL is regulated by microRNAs such as hsa-miR-503-5p, researchers can indirectly manipulate CTDSPL expression by targeting these regulatory miRNAs. For example, knockdown of hsa-miR-503-5p results in increased CTDSPL expression .

• Colony Formation Assays: These assays provide a functional readout for CTDSPL manipulation, allowing researchers to assess how changes in CTDSPL expression affect the clonogenic potential of cells .

How does CTDSPL interact with the JAK/STAT and PI3K/AKT pathways?

While the search results primarily focus on CTDSPL2 rather than CTDSPL in relation to JAK/STAT and PI3K/AKT pathways, the mechanisms may provide insights for CTDSPL research:

CTDSPL2, a related phosphatase, interacts with JAK1 and positively regulates its expression. Through this interaction, CTDSPL2 activates the PI3K/AKT signaling pathway, promoting the progression of non-small cell lung cancer . Given the functional similarities between CTDSPL and CTDSPL2 as phosphatases, CTDSPL might also interact with components of these signaling pathways, though potentially with different outcomes given its tumor suppressor role.

For researchers investigating CTDSPL's interaction with these pathways, experimental approaches could include:

• Co-immunoprecipitation to identify physical interactions between CTDSPL and JAK/STAT or PI3K/AKT pathway components

• Western blotting to assess phosphorylation states of pathway members following CTDSPL manipulation

• Functional assays to determine how CTDSPL affects the activity of these signaling pathways

What is the significance of CTDSPL in immune cell infiltration in tumors?

While direct information about CTDSPL and immune cell infiltration is limited in the search results, there is evidence regarding CTDSPL2:

Silencing of CTDSPL2 enhanced CD4+ T cell infiltration into tumors in mouse models of non-small cell lung cancer . This finding suggests that phosphatases in this family may influence the tumor immune microenvironment.

For CTDSPL specifically, researchers might investigate:

• Whether CTDSPL expression correlates with immune cell infiltration in human tumor samples

• How manipulation of CTDSPL in tumor models affects different immune cell populations (T cells, macrophages, etc.)

• The molecular mechanisms by which CTDSPL might influence immune cell recruitment or function in the tumor microenvironment

Given CTDSPL's role as a tumor suppressor, it might have different effects on immune infiltration compared to CTDSPL2, potentially promoting rather than inhibiting anti-tumor immune responses.

How do genomic alterations in CTDSPL contribute to cancer development?

Genomic alterations in CTDSPL have been implicated in cancer development through several mechanisms:

• Copy Number Variations (CNVs): Genome-wide CNV studies have identified CTDSPL alterations associated with cervical cancer risk . These CNVs can affect CTDSPL expression levels, potentially compromising its tumor suppressor function.

• Transcriptional Regulation: The CTDSPL gene contains binding sites for multiple transcription factors within its intron 1-6367bp fragment, including USF2, ATF3, USF1, ZNF263, GATA2, and IRF1 . Alterations in these binding sites could disrupt normal transcriptional regulation of CTDSPL.

• MicroRNA-mediated Silencing: Elevated expression of regulatory microRNAs like hsa-miR-503-5p can downregulate CTDSPL expression, contributing to cancer progression and therapy resistance .

For researchers studying CTDSPL genomic alterations, approaches might include:

• Comprehensive genomic profiling of CTDSPL in different cancer types

• Functional validation of identified variants through CRISPR-based editing

• Correlation of genomic alterations with CTDSPL expression and patient outcomes

How might targeting the miR-503-5p/CTDSPL axis improve cancer therapy?

The miR-503-5p/CTDSPL regulatory axis represents a promising target for cancer therapy development:

• Overcoming Chemoresistance: Inhibiting miR-503-5p to restore CTDSPL expression has been shown to resensitize lung adenocarcinoma cells to cisplatin . This approach could potentially overcome therapy resistance in other cancer types as well.

• Anti-angiogenic Effects: Targeting this axis inhibits angiogenesis by reducing VEGFR1 and VEGFR2 expression , suggesting it could complement existing anti-angiogenic therapies.

• Therapeutic Strategies: Potential approaches include:

  • AntimiR technology to inhibit miR-503-5p

  • Small molecule activators of CTDSPL

  • Combination therapy with existing chemotherapeutic agents

• Biomarker Development: The expression levels of miR-503-5p and CTDSPL could serve as biomarkers to predict therapy response and guide treatment decisions .

For researchers pursuing this direction, emphasis should be placed on developing clinically viable methods to modulate this axis and identifying patient populations most likely to benefit from such interventions.

What are the key challenges in translating CTDSPL research to clinical applications?

Several challenges exist in translating CTDSPL research findings to clinical applications:

• Tissue-Specific Functions: CTDSPL may have different functions in different tissues and cancer types. Understanding these context-dependent roles is essential for developing targeted interventions.

• Delivery Methods: Developing effective delivery methods for CTDSPL-modulating therapies (such as miRNA inhibitors or CTDSPL expression vectors) remains challenging, particularly for achieving tumor-specific effects.

• Compensatory Mechanisms: Cancer cells may develop compensatory mechanisms to overcome CTDSPL restoration, potentially limiting therapeutic efficacy. Identifying and targeting these mechanisms would be crucial.

• Identification of Optimal Patient Populations: Determining which patient subgroups would benefit most from CTDSPL-targeted therapies requires comprehensive biomarker studies and potentially new diagnostic approaches.

Addressing these challenges will require interdisciplinary approaches combining molecular biology, drug delivery technology, and clinical research to move CTDSPL-based interventions toward clinical application.