Promotion of cell proliferation by HBXIP via upregulation of human telomerase reverse transcriptase in human mesenchymal stem cells.
OBJECTIVE
We previously found that the hepatitis B X-interacting protein (HBXIP) was able to promote the proliferation of cells. Telomerase activity is known to be critical in cellular senescence and its level is modulated by the regulation of the telomerase catalytic subunit, telomerase reverse transcriptase (TERT), at both the transcriptional and post-transcriptional levels. To investigate the mechanism of promoting proliferation by HBXIP, the effect of HBXIP on human TERT (hTERT) was investigated in human mesenchymal stem cells (hMSC).


METHODS
BMMS-03 cells and hMSC from the bone marrow of a 4-month-old elicited fetus, were transiently transfected with the pcDNA3-hbxip plasmid encoding the HBXIP gene and pSilencer-hbxip plasmid encoding RNA interference (RNAi) targeting HBXIP mRNA, followed by the examination of the hTERT promoter reporter gene by luciferase assay, and the detection of telomerase activity by telomeric repeat amplication protocol, respectively, as well as the expression levels of hTERT, c-Myc, and Bcl-2 by Western blot analysis.


RESULTS
The overexpression of HBXIP led to a significant upregulation of hTERT promoter activity, telomerase activity, and the expression levels of hTERT, c-Myc, and Bcl-2 in BMMS-03 cells. RNAi targeting HBXIP mRNA produced the opposite results completely.


CONCLUSIONS
Our data demonstrated that HBXIP significantly stimulated the transcription and expression of hTERT and increased the activity of telomerase in BMMS-03 cells, which provides a new insight into the mechanism of promoting cell proliferation by HBXIP.
Wang
Feng-ze
FZ
Departments of Biochemistry, Tianjin Key Laboratory of Microbial Functional Genomics, Institute for Molecular Biology, College of Life Sciences, Nankai University, Tianjin, China.
Sha
Li
L
Ye
Li-hong
LH
Zhang
Xiao-dong
XD
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000502:physiology*; D002460:Cell Line; D049109:Cell Proliferation; D019254:Genes, bcl-2 / Q000235:genetics; D016259:Genes, myc / Q000235:genetics; D005822:Genetic Vectors; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D019098:Telomerase / Q000096:biosynthesis* / Q000235:genetics*; D015854:Up-Regulation
D048868:Adaptor Proteins, Signal Transducing; C110719:LAMTOR5 protein, human; D034741:RNA, Small Interfering; D019098:Telomerase