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An Epstein-Barr virus-encoded microRNA targets PUMA to promote host cell survival.

Choy EY, Siu KL, Kok KH, Lung RW, Tsang CM, To KF, Kwong DL, Tsao SW, Jin DY - J. Exp. Med. (2008)

Bottom Line: In addition, PUMA was found to be significantly underexpressed in approximately 60% of human NPC tissues.Although expression of miR-BART5 rendered NPC and EBV-GC cells less sensitive to proapoptotic agents, apoptosis can be triggered by depleting miR-BART5 or inducing the expression of PUMA.Collectively, our findings suggest that EBV encodes an miRNA to facilitate the establishment of latent infection by promoting host cell survival.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong.

ABSTRACT
Epstein-Barr virus (EBV) is a herpesvirus associated with nasopharyngeal carcinoma (NPC), gastric carcinoma (GC), and other malignancies. EBV is the first human virus found to express microRNAs (miRNAs), the functions of which remain largely unknown. We report on the regulation of a cellular protein named p53 up-regulated modulator of apoptosis (PUMA) by an EBV miRNA known as miR-BART5, which is abundantly expressed in NPC and EBV-GC cells. Modulation of PUMA expression by miR-BART5 and anti-miR-BART5 oligonucleotide was demonstrated in EBV-positive cells. In addition, PUMA was found to be significantly underexpressed in approximately 60% of human NPC tissues. Although expression of miR-BART5 rendered NPC and EBV-GC cells less sensitive to proapoptotic agents, apoptosis can be triggered by depleting miR-BART5 or inducing the expression of PUMA. Collectively, our findings suggest that EBV encodes an miRNA to facilitate the establishment of latent infection by promoting host cell survival.

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Related in: MedlinePlus

Endogenous PUMA protein expression in EBV+ NPC cell line and human primary NPC tissue samples. (A) Western blot analysis of PUMA-α and PUMA-β proteins in miR-BART5–expressing HK1/EBV cells versus EBV− HK1 cells. (B) Western blot analysis of PUMA-β protein expression in 12 pairs of primary NPC tissue samples and noncancerous nasopharyngeal tissue samples. N, noncancerous nasopharyngeal tissue; T, tumorous NPC tissue.
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fig3: Endogenous PUMA protein expression in EBV+ NPC cell line and human primary NPC tissue samples. (A) Western blot analysis of PUMA-α and PUMA-β proteins in miR-BART5–expressing HK1/EBV cells versus EBV− HK1 cells. (B) Western blot analysis of PUMA-β protein expression in 12 pairs of primary NPC tissue samples and noncancerous nasopharyngeal tissue samples. N, noncancerous nasopharyngeal tissue; T, tumorous NPC tissue.

Mentions: As demonstrated in the previous section, abundant miR-BART5 expression was observed in EBV-infected epithelial cells and tissues. If miR-BART5 functions to counteract PUMA, a significant decrease of PUMA expression should occur in EBV+ NPC cells expressing miR-BART5. To address this issue, we compared the expression levels of PUMA in HK1 and HK1/EBV cells. These two NPC cell lines were chosen because HK1/EBV was derived from HK1 and it represents the EBV+ counterpart of HK1 (24, 25). The expression of PUMA-α and PUMA-β in HK1/EBV cells was diminished 2–2.5-fold when compared with the level in HK1 cells (Fig. 3 A). Consistent with this, specific and statistically significant (P < 0.0027 by Student's t test) inhibition of luciferase expression from plasmid pGL3-PUMA.UTR was observed in HK1/EBV cells but not in HK1 cells (Fig. S2, available at http://www.jem.org/cgi/content/full/jem.20072581/DC1). These results are in accordance with viral modulation of PUMA expression plausibly through miR-BART5.


An Epstein-Barr virus-encoded microRNA targets PUMA to promote host cell survival.

Choy EY, Siu KL, Kok KH, Lung RW, Tsang CM, To KF, Kwong DL, Tsao SW, Jin DY - J. Exp. Med. (2008)

Endogenous PUMA protein expression in EBV+ NPC cell line and human primary NPC tissue samples. (A) Western blot analysis of PUMA-α and PUMA-β proteins in miR-BART5–expressing HK1/EBV cells versus EBV− HK1 cells. (B) Western blot analysis of PUMA-β protein expression in 12 pairs of primary NPC tissue samples and noncancerous nasopharyngeal tissue samples. N, noncancerous nasopharyngeal tissue; T, tumorous NPC tissue.
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2571930&req=5

fig3: Endogenous PUMA protein expression in EBV+ NPC cell line and human primary NPC tissue samples. (A) Western blot analysis of PUMA-α and PUMA-β proteins in miR-BART5–expressing HK1/EBV cells versus EBV− HK1 cells. (B) Western blot analysis of PUMA-β protein expression in 12 pairs of primary NPC tissue samples and noncancerous nasopharyngeal tissue samples. N, noncancerous nasopharyngeal tissue; T, tumorous NPC tissue.
Mentions: As demonstrated in the previous section, abundant miR-BART5 expression was observed in EBV-infected epithelial cells and tissues. If miR-BART5 functions to counteract PUMA, a significant decrease of PUMA expression should occur in EBV+ NPC cells expressing miR-BART5. To address this issue, we compared the expression levels of PUMA in HK1 and HK1/EBV cells. These two NPC cell lines were chosen because HK1/EBV was derived from HK1 and it represents the EBV+ counterpart of HK1 (24, 25). The expression of PUMA-α and PUMA-β in HK1/EBV cells was diminished 2–2.5-fold when compared with the level in HK1 cells (Fig. 3 A). Consistent with this, specific and statistically significant (P < 0.0027 by Student's t test) inhibition of luciferase expression from plasmid pGL3-PUMA.UTR was observed in HK1/EBV cells but not in HK1 cells (Fig. S2, available at http://www.jem.org/cgi/content/full/jem.20072581/DC1). These results are in accordance with viral modulation of PUMA expression plausibly through miR-BART5.

Bottom Line: In addition, PUMA was found to be significantly underexpressed in approximately 60% of human NPC tissues.Although expression of miR-BART5 rendered NPC and EBV-GC cells less sensitive to proapoptotic agents, apoptosis can be triggered by depleting miR-BART5 or inducing the expression of PUMA.Collectively, our findings suggest that EBV encodes an miRNA to facilitate the establishment of latent infection by promoting host cell survival.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong.

ABSTRACT
Epstein-Barr virus (EBV) is a herpesvirus associated with nasopharyngeal carcinoma (NPC), gastric carcinoma (GC), and other malignancies. EBV is the first human virus found to express microRNAs (miRNAs), the functions of which remain largely unknown. We report on the regulation of a cellular protein named p53 up-regulated modulator of apoptosis (PUMA) by an EBV miRNA known as miR-BART5, which is abundantly expressed in NPC and EBV-GC cells. Modulation of PUMA expression by miR-BART5 and anti-miR-BART5 oligonucleotide was demonstrated in EBV-positive cells. In addition, PUMA was found to be significantly underexpressed in approximately 60% of human NPC tissues. Although expression of miR-BART5 rendered NPC and EBV-GC cells less sensitive to proapoptotic agents, apoptosis can be triggered by depleting miR-BART5 or inducing the expression of PUMA. Collectively, our findings suggest that EBV encodes an miRNA to facilitate the establishment of latent infection by promoting host cell survival.

Show MeSH
Related in: MedlinePlus