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

2016 ◽  
Vol 473 (20) ◽  
pp. 3517-3532 ◽  
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.

scholarly journals Telomerase Activity Reconstitutedin Vitrowith Purified Human Telomerase Reverse Transcriptase and Human Telomerase RNA Component

2000 ◽  
Vol 275 (29) ◽  
pp. 22568-22573 ◽  
Author(s):  
Kenkichi Masutomi ◽  
Shuichi Kaneko ◽  
Naoyuki Hayashi ◽  
Tatsuya Yamashita ◽  
Yukihiro Shirota ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Telomerase Activity ◽  
Telomerase Reverse Transcriptase ◽  
Telomerase Rna ◽  
Human Telomerase Reverse Transcriptase ◽  
Human Telomerase

Effect of hTR Antisense Oligodeoxynucleotides on Telomerase Acitvity and Ciplatin -Sensitivity of Primary Acute Leukemia Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4359-4359
Author(s):  
Yang Xiao
Keyword(s):  
Gel Electrophoresis ◽  
Telomerase Activity ◽  
Leukemic Cells ◽  
Morphological Observation ◽  
Antisense Oligodeoxynucleotide ◽  
Human Telomerase Reverse Transcriptase ◽  
Significant Difference ◽  
Initiator Codon ◽  
Human Telomerase

Abstract BACKGROUND: Between the three key components part of human telomerase, human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) have significant correlation with telomerase activity. The previous study has identified that the telomerase activity of K562 and HL-60 cells was special suppresssed significantly by phosphorothoate antisense oligodeoxynucleotide (ASODN) complementary to the initiator codon of hTR. This study was designed to evalutae the effection of hTR ASODN on telomerase activity and apoptosis of primary acute leukemic cells. To research whether hTR ASODN could enhance apoptosis rates of primary leukemic cells to cisplatin. METHODS: Primary leukemic cells were treated with phosphorothoate ASODN complementary to the initiator codon of hTR in vivo. The changing of telomerase activity was assayed by telomeric repeat amplification protocol(TRAP) and polymerase chain reaction enzyme-linked immunoassay(PCR-ELISA). The survival rates of cells was measured by trypan blue exclusion. Apoptosis was assayed by morphological observation (Giemsa and PI), DNA gel electrophoresis and flow cytometry analysis technology. RESULTS: Primary acute leukemic cells expressed high level of telomerase activity which decreased as the cells treated by hTR ASODN. The telomerase activity was suppresssed significantly by 10umol/L ASODN and the effecttion was most significantly at 72h; Apoptotic bodies of primary leukemic cells were observed easily by fluorescence micrscope when cisplatin was added 48h after ASODN treatment for 24h; Agarose gel electrophoresis of genomic DNA from primary leukemic cells treated with ASODN and cisplatin combination for 72h showed typical DNA ladder; neither did DNA from primary leukemic cells treated with sense oligodeoxynucleotide (SODN) plus cisplatin nor cisplatin alone. In addition, apoptosis rates of primary leukemic cells treated with ASODN for 24h and then with cisplatin for 72h were 41.36±9.28%. There were statistically significant difference in the percentage of apoptotic cells between hTR ASODN plus cisplatin and SODN plus cisplatin (14.51±4.78%) or cisplatin alone group (12.61±2.56)% (P<0.01). CONCLUSIONS: ASODN complementary to the region of hTR could significantly inhibit the telomerase activity of primary acute leukemic cells, and increased the cisplatin-induced apoptosis and enhanced cisplatin-sensitivity in vivo, indicating telomerase may be a new target of treatment to leukemia.

Expression Profile and up-Regulation of Telomere-Associated Proteins In Multiple Myeloma

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4050-4050
Author(s):  
Rafael Díaz de la Guardia ◽  
Carolina Elosua ◽  
Purificación Catalina ◽  
Brian A Walker ◽  
David C Johnson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Multiple Myeloma ◽  
Telomere Length ◽  
Conflicts Of Interest ◽  
Telomerase Activity ◽  
Telomere Maintenance ◽  
Post Translational Modification ◽  
Human Telomerase Reverse Transcriptase ◽  
Immortal Cells ◽  
Human Telomerase

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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