scholarly journals Induction of apoptotic endonuclease EndoG with DNA-damaging agents initiates alternative splicing of telomerase catalytic subunit hTERT and inhibition of telomerase activity hTERT in human CD4+ and CD8+ T-lymphocytes

2017 ◽  
Vol 63 (4) ◽  
pp. 296-305 ◽  
Author(s):  
D.D. Zhdanov ◽  
D.A. Vasina ◽  
V.S. Orlova ◽  
E.V. Orlova ◽  
D.V. Grishin ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
T Lymphocytes ◽  
Splice Variants ◽  
Telomerase Activity ◽  
Catalytic Subunit ◽  
Human Telomerase Reverse Transcriptase ◽  
Dna Damages ◽  
Dna Damaging Agents ◽  
Cd8 T Lymphocytes ◽  
Human Telomerase

Activity of telomerase catalytic subunit hTERT (human Telomerase Reverse Transcriptase) can be regulated by alternative splicing of its mRNA. At present time exact mechanism of hTERT splicing is not fully understood. Apoptotic endonuclease EndoG is known to participate this process. EndoG expression is induced by DNA damages. The aim of this work was to investigate the ability of DNA-damaging agents with different mechanism of action to induce EndoG expression and inhibit telomerase activity due to the activation of hTERT alternative splicing in normal activated human CD4+ and CD8+ T-lymphocytes. All investigated DNA-damaging agents were able to induce EndoG expression. Cisplatin, a therapeutic compound, producing DNA cross-links induced the highest level of DNA damages and EndoG expression. Incubation of CD4+ and CD8+ T-cells with cisplatin caused the changes in proportion of hTERT splice variants and inhibition of telomerase activity.

scholarly journals Apoptotic endonuclease EndoG induces alternative splicing of telomerase catalytic subunit hTERT and death of tumor cells

2016 ◽  
Vol 62 (3) ◽  
pp. 239-250 ◽  
Author(s):  
D.D. Zhdanov ◽  
D.A. Vasina ◽  
V.S. Orlova ◽  
V.Y. Gotovtseva ◽  
M.V. Bibikova ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Cell Fate ◽  
Replicative Senescence ◽  
Splice Variants ◽  
Telomerase Activity ◽  
Catalytic Subunit ◽  
Full Length ◽  
Human Telomerase Reverse Transcriptase ◽  
Mrna Induction ◽  
Human Telomerase

Telomerase activity is known to be regulated by alternative splicing of its catalytic subunit hTERT (human Telomerase Reverse Transcriptase) mRNA. Induction of non-active spliced hTERT leads to inhibition of telomerase activity. However, very little is known about the mechanism of hTERT mRNA alternative splicing. The aim of this study was to determine the role of apoptotic endonuclease EndoG in alternative splicing of hTERT and telomerase activity. Strong correlation was found between expression of EndoG and hTERT splice-variants in 12 colon cancer cell lines. Overexpression of EndoG in СаСо-2 cells downregulated the expression of active full-length hTERT variant and upregulated non-active spliced variant. Reduction of full-length hTERT caused downregulation of telomerase activity, dramatically shortening of telomeres length during cell divisions, converting cells to the replicative senescence state, activation of apoptosis and finally cell death. These data indicated the participation of EndoG in alternative splicing of mRNA of telomerase catalytic subunit, regulation of telomerase activity and cell fate.

scholarly journals Alternative Splicing of Human Telomerase Reverse Transcriptase (hTERT) and Its Implications in Physiological and Pathological Processes

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 526
Author(s):  
Anna A. Plyasova ◽  
Dmitry D. Zhdanov
Keyword(s):  
Alternative Splicing ◽  
Reverse Transcriptase ◽  
Splice Variants ◽  
Biological Activities ◽  
Telomerase Activity ◽  
Telomerase Reverse Transcriptase ◽  
Human Telomerase Reverse Transcriptase ◽  
Independent Manner ◽  
A Cell ◽  
Human Telomerase

Alternative splicing (AS) of human telomerase catalytic subunit (hTERT, human telomerase reverse transcriptase) pre-mRNA strongly regulates telomerase activity. Several proteins can regulate AS in a cell type-specific manner and determine the functions of cells. In addition to being involved in telomerase activity regulation, AS provides cells with different splice variants that may have alternative biological activities. The modulation of telomerase activity through the induction of hTERT AS is involved in the development of different cancer types and embryos, and the differentiation of stem cells. Regulatory T cells may suppress the proliferation of target human and murine T and B lymphocytes and NK cells in a contact-independent manner involving activation of TERT AS. This review focuses on the mechanism of regulation of hTERT pre-mRNA AS and the involvement of splice variants in physiological and pathological processes.

scholarly journals Apoptotic endonuclease EndoG regulates alternative splicing of human telomerase catalytic subunit hTERT

2016 ◽  
Vol 62 (5) ◽  
pp. 544-554 ◽  
Author(s):  
D.D. Zhdanov ◽  
D.A. Vasina ◽  
E.V. Orlova ◽  
V.S. Orlova ◽  
M.V. Pokrovskaya ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Telomerase Activity ◽  
Catalytic Subunit ◽  
Over Expression ◽  
Htert Gene ◽  
Template Strand ◽  
Non Coding Rna ◽  
Dna Strand ◽  
Human Telomerase ◽  
Long Non Coding Rna

Human telomerase catalytic subunit hTERT is subjected to alternative splicing results in loss of its function and leads to decrease of telomerase activity. However, very little is known about the mechanism of hTERT pre-mRNA alternative splicing. Apoptotic endonuclease EndoG is known to participate this process. The aim of this study was to determine the role of EndoG in regulation of hTERT alternative splicing. Increased expression of b-deletion splice variant was determined during EndoG over-expression in CaCo-2 cell line, after EndoG treatment of cell cytoplasm and nuclei and after nuclei incubation with EndoG digested cell RNA. hTERT alternative splicing was induced by 47-mer RNA oligonucleotide in naked nuclei and in cells after transfection. Identified long non-coding RNA, that is the precursor of 47-mer RNA oligonucleotide. Its size is 1754 nucleotides. Based on the results the following mechanism was proposed. hTERT pre-mRNA is transcribed from coding DNA strand while long non-coding RNA is transcribed from template strand of hTERT gene. EndoG digests long non-coding RNA and produces 47-mer RNA oligonucleotide complementary to hTERT pre-mRNA exon 8 and intron 8 junction place. Interaction of 47-mer RNA oligonucleotide and hTERT pre-mRNA causes alternative splicing.

scholarly journals Identification of genes whose mRNAs are subjected to alternative splicing by endonuclease EndoG action in human and murine CD4+ T lymphocytes

2020 ◽  
Vol 3 (2) ◽  
pp. e00128
Author(s):  
D.D. Zhdanov ◽  
N.S. Novachly ◽  
M.V. Pokrovskaya ◽  
S.S. Aleksandrova ◽  
T.A. Kabardokov ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
T Lymphocytes ◽  
Splice Variants ◽  
Total Cell ◽  
Dna Damages ◽  
Mrna Splice ◽  
Healthy Humans ◽  
Number Of Cells

The aim of this work was to identify genes whose mRNAs were subjected to alternative splicing by apoptotic endonuclease EndoG in CD4+ T lymphocytes from healthy humans, mice, and rats. In order to induce EndoG, lymphocytes were transfected with an EndoG-containing plasmid, or a control pGFP plasmid, or were incubated with cisplatin. Efficiency of transfection, number of cells with DNA damages and the level of EndoG expression have been monitored. Total cell mRNA has been sequenced and the changes in proportion of splice variants of genes were analyzed. The changes in the proportion of 28 mRNA splice variants have been identified in human and murine lymphocytes in both transfected with EndoG gene or incubated with cisplatin. Thus, EndoG can be considered as a potent modulator of alternative splicing of mRNA of identified genes.

scholarly journals Functional Regions of Human Telomerase Reverse Transcriptase and Human Telomerase RNA Required for Telomerase Activity and RNA-Protein Interactions

2001 ◽  
Vol 21 (5) ◽  
pp. 1888-1897 ◽  
Author(s):  
François Bachand ◽  
Chantal Autexier
Keyword(s):  
Reverse Transcriptase ◽  
Rna Binding ◽  
Telomerase Activity ◽  
Catalytic Subunit ◽  
Telomerase Rna ◽  
Dna Repeats ◽  
Human Telomerase Reverse Transcriptase ◽  
Template Sequence ◽  
Human Telomerase

ABSTRACT Telomerase is a specialized reverse transcriptase (RT) that is minimally composed of a protein catalytic subunit and an RNA component. The RNA subunit contains a short template sequence that directs the synthesis of DNA repeats at the ends of chromosomes. Human telomerase activity can be reconstituted in vitro by the expression of the human telomerase protein catalytic subunit (hTERT) in the presence of recombinant human telomerase RNA (hTR) in a rabbit reticulocyte lysate (RRL) system. We analyzed telomerase activity and binding of hTR to hTERT in RRL by expressing different hTERT and hTR variants. hTRs containing nucleotide substitutions that are predicted to disrupt base pairing in the P3 helix of the pseudoknot weakly reconstituted human telomerase activity yet retained their ability to bind hTERT. Our results also identified two distinct regions of hTR that can independently bind hTERT in vitro. Furthermore, sequences or structures between nucleotides 208 and 330 of hTR (which include the conserved CR4-CR5 domain) were found to be important for hTERT-hTR interactions and for telomerase activity reconstitution. Human TERT carboxy-terminal amino acid deletions extending to motif E or the deletion of the first 280 amino acids abolished human telomerase activity without affecting the ability of hTERT to associate with hTR, suggesting that the RT and RNA binding functions of hTERT are separable. These results indicate that the reconstitution of human telomerase activity in vitro requires regions of hTERT that (i) are distinct from the conserved RT motifs and (ii) bind nucleotides distal to the hTR template sequence.

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