Protein Composition of Catalytically Active Human Telomerase from Immortal Cells

Abstract Abstract 4050 The role of the telomeres in the mechanisms of ageing and carcinogenesis has generated a considerable interest as a novel approach to the treatment of many cancers. Telomeres are nucleoproteins structures that protect the ends of eukaryotic chromosomes, which are particularly vulnerable due to progressive shortening in almost all dividing cells. The telomere length was observed as a critical factor in the initiation and progression of human cancers, and it is associated to chromosomal instability. Most immortal cells possess enzymatic activity of telomerase. This suggests that telomerase activity and telomere length maintenance may be required for unlimited cell proliferation, tumorigenesis, and protection, allowing the evasion of apoptosis in cancer development. The telomerase activity could also be regulated positively or negatively by post-trancriptional and/or post-translational modification of the enzyme without transcriptional up-regulation of human telomerase reverse transcriptase (hTERT) mRNA. In this work, we analyze the expression data of all genes involved in telomerase activity. Patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), multiple myeloma (MM) and plasma cell leukemia (PLC) were studied through gene expression profiling analysis (Human Genome U133 Plus 2.0 arrays, Affymetrix). We identify 21 deregulated genes, implicated directly in telomere length maintenance activity in clonal plasma cells compared with normal cells (20 up-regulated and 1 down-regulated). These genes are MYC, KRAS, HSPA9, RB1 and members of the families: Small nucleolar ribonucleoproteins (H/ACA snoRNPs), A/B subfamily of ubiquitously expressed heterogeneous nuclear ribonucleoproteins (hnRNPs), and 14-3 -3 family. In conclusion, the myeloma cells acquire the telomere maintenance capability without deregulation of the human telomerase RNA gene (hTERC) and hTERT gene expression. It is an alternative lengthening of telomeres mechanism that has effect in the regulation of the BAD activity in apoptosis. The mechanism is based on preventing the partially-denatured proteins from aggregating, telomere maintenance through the correct processing and intranuclear trafficking of hTERC, telomerase reactivation and telomere stabilization, and efficient accumulation of hTERT in the nucleus. Thus, the findings of this study may help to improve telomerase-based therapy for multiple myeloma. Disclosures: No relevant conflicts of interest to declare.

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Protein composition of catalytically active U7-dependent processing complexes assembled on histone pre-mRNA containing biotin and a photo-cleavable linker

Nucleic Acids Research ◽

10.1093/nar/gky133 ◽

2018 ◽

Vol 46 (9) ◽

pp. 4752-4770 ◽

Cited By ~ 6

Author(s):

Aleksandra Skrajna ◽

Xiao-cui Yang ◽

Michał Dadlez ◽

William F Marzluff ◽

Zbigniew Dominski

Keyword(s):

Protein Composition ◽

Catalytically Active

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RNA Conformation in Catalytically Active Human Telomerase

Journal of the American Chemical Society ◽

10.1021/ja909383n ◽

2010 ◽

Vol 132 (9) ◽

pp. 2852-2853 ◽

Cited By ~ 13

Author(s):

Justin A. Yeoman ◽

Angel Orte ◽

Beth Ashbridge ◽

David Klenerman ◽

Shankar Balasubramanian

Keyword(s):

Rna Conformation ◽

Catalytically Active ◽

Human Telomerase

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Specific association of human telomerase activity with immortal cells and cancer

Science ◽

10.1126/science.7605428 ◽

1994 ◽

Vol 266 (5193) ◽

pp. 2011-2015 ◽

Cited By ~ 4670

Author(s):

N. Kim ◽

M. Piatyszek ◽

K. Prowse ◽

C. Harley ◽

M. West ◽

...

Keyword(s):

Telomerase Activity ◽

Immortal Cells ◽

Specific Association ◽

Human Telomerase

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C-Terminal Regions of the Human Telomerase Catalytic Subunit Essential for In Vivo Enzyme Activity

Molecular and Cellular Biology ◽

10.1128/mcb.22.17.6234-6246.2002 ◽

2002 ◽

Vol 22 (17) ◽

pp. 6234-6246 ◽

Cited By ~ 71

Author(s):

Soma S. R. Banik ◽

Chuanhai Guo ◽

Allyson C. Smith ◽

Seth S. Margolis ◽

D. Ashley Richardson ◽

...

Keyword(s):

Enzyme Activity ◽

Human Cancer ◽

Catalytic Subunit ◽

Human Cancer Cells ◽

C Terminus ◽

Catalytically Active ◽

Higher Eukaryotes ◽

Human Telomerase

ABSTRACT Most human cancer cells are thought to acquire the ability to divide beyond the capacity of normal somatic cells through illegitimately activating the gene hTERT, which encodes the catalytic subunit of telomerase. While telomerase reverse transcriptase (TERT) is conserved in most eukaryotes, mounting evidence suggests that the C terminus of the human protein may have functions unique to higher eukaryotes. To search for domains responsible for such functions, we assayed a panel of tandem substitution mutations encompassing this region of human TERT for in vitro and in vivo functionality. We found four clusters of mutations that inactivated the biochemical and biological functions of telomerase, separated by mutations that had little or no effect on enzyme activity. We also identified a region where mutations generate catalytically active but biologically inert proteins. This C-terminal region that dissociates activities of telomerase (C-DAT) does not appear to be involved in nuclear localization or protein multimerization. Instead, it appears that the C-DAT region is involved in a step of in vivo telomere synthesis after the assembly of a catalytically active enzyme. Intriguingly, all of the described regions reside in a portion of TERT that is dispensable for cellular viability in yeast, arguing for a divergent role of the C terminus in higher eukaryotes.

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Hsp90-binding immunophilin FKBP52 modulates telomerase activity by promoting the cytoplasmic retrotransport of hTERT

Biochemical Journal ◽

10.1042/bcj20160344 ◽

2016 ◽

Vol 473 (20) ◽

pp. 3517-3532 ◽

Cited By ~ 12

Author(s):

Yu Young Jeong ◽

Joonyoung Her ◽

Sue-Young Oh ◽

In Kwon Chung

Keyword(s):

Nuclear Translocation ◽

Nuclear Transport ◽

Heat Shock Protein 90 ◽

Telomerase Activity ◽

Human Telomerase Reverse Transcriptase ◽

Peptidyl Prolyl Isomerase ◽

Fk506 Binding Protein ◽

Catalytically Active ◽

Tetratricopeptide Repeat Domain ◽

Human Telomerase

Telomerase is a unique ribonucleoprotein enzyme that is required for continued cell proliferation. To generate catalytically active telomerase, human telomerase reverse transcriptase (hTERT) must translocate to the nucleus and assemble with the RNA component of telomerase. The molecular chaperones heat shock protein 90 (Hsp90) and p23 maintain hTERT in a conformation that enables nuclear translocation. However, the regulatory role of chaperones in nuclear transport of hTERT remains unclear. In this work, we demonstrate that immunophilin FK506-binding protein (FKBP)52 linked the hTERT–Hsp90 complex to the dynein–dynactin motor, thereby promoting the transport of hTERT to the nucleus along microtubules. FKBP52 interacted with the hTERT–Hsp90 complex through binding of the tetratricopeptide repeat domain to Hsp90 and binding of the dynamitin (Dyt) component of the dynein-associated dynactin complex to the peptidyl prolyl isomerase domain. The depletion of FKBP52 inhibited nuclear transport of hTERT, resulting in cytoplasmic accumulation. Cytoplasmic hTERT was rapidly degraded through ubiquitin (Ub)-dependent proteolysis, thereby abrogating telomerase activity. In addition, overexpression of dynamitin, which is known to dissociate the dynein–dynactin motor from its cargoes, reduced telomerase activity. Collectively, these results provide a molecular mechanism by which FKBP52 modulates telomerase activity by promoting dynein–dynactin-dependent nuclear import of hTERT.

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Catalytically active human telomerase mutants with allele-specific biological properties

Experimental Cell Research ◽

10.1016/s0014-4827(03)00217-9 ◽

2003 ◽

Vol 288 (2) ◽

pp. 277-287 ◽

Cited By ~ 33

Author(s):

M Kim

Keyword(s):

Biological Properties ◽

Catalytically Active ◽

Allele Specific ◽

Human Telomerase

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Bovine Platelet Proteins

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653555 ◽

1969 ◽

Vol 21 (03) ◽

pp. 409-418 ◽

Cited By ~ 2

Author(s):

S Łopaciuk ◽

N. O Solum

Keyword(s):

Bovine Serum ◽

Protein Composition ◽

Disc Electrophoresis ◽

Plasma Fibrinogen ◽

Plasma Albumin ◽

Precipitin Line ◽

Bovine Plasma ◽

Platelet Proteins

Summary1. The protein composition of bovine platelet extracts has been investigated by immunoelectrophoresis and polyacrylamide disc electrophoresis. The information obtained is discussed as a basis for study on platelet fibrinogen.2. With antiserum to platelet proteins 11 precipitin lines were observed 3 of which corresponded electrophoretically to plasma albumin, fibrinogen and γ-globulin. These lines were not seen using the same antiserum absorbed with bovine plasma. The 8 additional lines were still present indicating that they represented specific platelet components. Antiserum to plasma produced the 3 above-mentioned lines, but no others.3. With antiserum to purified bovine plasma fibrinogen 3 precipitin lines were observed. The fibrinogen line was the dominant one. The 2 additional lines did not disappear by absorption of the antiserum with bovine serum nor by incubation of the extracts with thrombin. The latter treatment totally removed the fibrinogen line.4. A non-fibrinogen precipitin line, observed only with the antiserum to platelet extract and positioned in the β2-globulin region, disappeared by the incubation of platelet extracts with thrombin.

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