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Overexpression of eIF-5A2 in mice causes accelerated organismal aging by increasing chromosome instability.

Chen M, Huang JD, Deng HK, Dong S, Deng W, Tsang SL, Huen MS, Chen L, Zan T, Zhu GX, Guan XY - BMC Cancer (2011)

Bottom Line: Recently, we isolated a novel oncogene eIF-5A2 within the 3q26 region.This included decreased growth rate and body weight, shortened life span, kyphosis, osteoporosis, delay of wound healing and ossification.This subsequently allowed for the accumulation of chromosomal instability, such as errors in cell dividing during metaphase and anaphase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical Oncology, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, China.

ABSTRACT

Background: Amplification of 3q26 is one of the most frequent genetic alterations in many human malignancies. Recently, we isolated a novel oncogene eIF-5A2 within the 3q26 region. Functional study has demonstrated the oncogenic role of eIF-5A2 in the initiation and progression of human cancers. In the present study, we aim to investigate the physiological and pathological effect of eIF-5A2 in an eIF-5A2 transgenic mouse model.

Methods: An eIF-5A2 transgenic mouse model was generated using human eIF-5A2 cDNA. The eIF-5A2 transgenic mice were characterized by histological and immunohistochemistry analyses. The aging phenotypes were further characterized by wound healing, bone X-ray imaging and calcification analysis. Mouse embryo fibroblasts (MEF) were isolated to further investigate molecular mechanism of eIF-5A2 in aging.

Results: Instead of resulting in spontaneous tumor formation, overexpression of eIF-5A2 accelerated the aging process in adult transgenic mice. This included decreased growth rate and body weight, shortened life span, kyphosis, osteoporosis, delay of wound healing and ossification. Investigation of the correlation between cellular senescence and aging showed that cellular senescence is not required for the aging phenotypes in eIF-5A2 mice. Interestingly, we found that activation of eIF-5A2 repressed p19 level and therefore destabilized p53 in transgenic mouse embryo fibroblast (MEF) cells. This subsequently allowed for the accumulation of chromosomal instability, such as errors in cell dividing during metaphase and anaphase. Additionally, a significantly increase in number of aneuploidy cells (p < 0.05) resulted from an increase in the incidences of misaligned and lagging chromosomal materials, anaphase bridges, and micronuclei in the transgenic mice.

Conclusion: These observations suggest that eIF-5A2 mouse models could accelerate organismal aging by increasing chromosome instability.

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Characterization of the eIF-5A2 transgenic MEF cells. (A) Senescence associated β-galactosidase staining in transgenic and wild-type MEFs. No difference was observed between these two MEFs. (B) Western blot analysis of lysates from transgenic and wild-type MEFs showed activation of eIF-5A2 repressed p19 level and therefore destabilized p53 and consequently repressed p21 in transgenic MEFs. (C) The replication capacity of both MEFs were measured by seeding 1 × 104 cells into one well of 6-well plate and counted every 3 days. Both wild-type and transgenic MEFs proliferated normally until passage 4 and proliferation capability declined during later passages (p5 and p6). (D, E) The comparison of cell growth curves of transgenic and wild-type MEFs in 10% serum (D) and 1% serum (E). The cell growth rate was significantly higher in transgenic MEFs than in wild-type MEFs (p < 0.05). (F) Increased telomerase activity was detected in eIF-5A2 transgenic mice compared with their wild-type siblings. Protein extracted from HeLa cells was included as positive (+). A 36-bp internal standard was used as a control (IC) in the assay: the bands were weaker in samples with excessively high telomerase activity because amplification of the TRAP products and the IC bands were semicompetitive.
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Figure 6: Characterization of the eIF-5A2 transgenic MEF cells. (A) Senescence associated β-galactosidase staining in transgenic and wild-type MEFs. No difference was observed between these two MEFs. (B) Western blot analysis of lysates from transgenic and wild-type MEFs showed activation of eIF-5A2 repressed p19 level and therefore destabilized p53 and consequently repressed p21 in transgenic MEFs. (C) The replication capacity of both MEFs were measured by seeding 1 × 104 cells into one well of 6-well plate and counted every 3 days. Both wild-type and transgenic MEFs proliferated normally until passage 4 and proliferation capability declined during later passages (p5 and p6). (D, E) The comparison of cell growth curves of transgenic and wild-type MEFs in 10% serum (D) and 1% serum (E). The cell growth rate was significantly higher in transgenic MEFs than in wild-type MEFs (p < 0.05). (F) Increased telomerase activity was detected in eIF-5A2 transgenic mice compared with their wild-type siblings. Protein extracted from HeLa cells was included as positive (+). A 36-bp internal standard was used as a control (IC) in the assay: the bands were weaker in samples with excessively high telomerase activity because amplification of the TRAP products and the IC bands were semicompetitive.

Mentions: Cellular senescence can be triggered by oncogene activation and agents that damage DNA or alter chromatin structure [13,17]. Given our observation of organismal aging in eIF-5A2 mice, we further investigated whether cellular senescence exists under these circumstances. Therefore, MEFs from eIF-5A2 transgenic mice and their wild-type littermates were characterized. eIF-5A2 MEFs were morphologically indistinguishable from the wild-type counterparts at both early and late passages. The activity of senescence associated β-galactosidase (SA-β-gal), a cellular index of senescence, was eximined and no difference was found between eIF-5A2 transgenic and wild-type MEFs (Figure 6A). We also stained the cryostat sections of skin, testis and liver, and did not detect any SA-β-gal positive cells in vivo (not shown).


Overexpression of eIF-5A2 in mice causes accelerated organismal aging by increasing chromosome instability.

Chen M, Huang JD, Deng HK, Dong S, Deng W, Tsang SL, Huen MS, Chen L, Zan T, Zhu GX, Guan XY - BMC Cancer (2011)

Characterization of the eIF-5A2 transgenic MEF cells. (A) Senescence associated β-galactosidase staining in transgenic and wild-type MEFs. No difference was observed between these two MEFs. (B) Western blot analysis of lysates from transgenic and wild-type MEFs showed activation of eIF-5A2 repressed p19 level and therefore destabilized p53 and consequently repressed p21 in transgenic MEFs. (C) The replication capacity of both MEFs were measured by seeding 1 × 104 cells into one well of 6-well plate and counted every 3 days. Both wild-type and transgenic MEFs proliferated normally until passage 4 and proliferation capability declined during later passages (p5 and p6). (D, E) The comparison of cell growth curves of transgenic and wild-type MEFs in 10% serum (D) and 1% serum (E). The cell growth rate was significantly higher in transgenic MEFs than in wild-type MEFs (p < 0.05). (F) Increased telomerase activity was detected in eIF-5A2 transgenic mice compared with their wild-type siblings. Protein extracted from HeLa cells was included as positive (+). A 36-bp internal standard was used as a control (IC) in the assay: the bands were weaker in samples with excessively high telomerase activity because amplification of the TRAP products and the IC bands were semicompetitive.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3118894&req=5

Figure 6: Characterization of the eIF-5A2 transgenic MEF cells. (A) Senescence associated β-galactosidase staining in transgenic and wild-type MEFs. No difference was observed between these two MEFs. (B) Western blot analysis of lysates from transgenic and wild-type MEFs showed activation of eIF-5A2 repressed p19 level and therefore destabilized p53 and consequently repressed p21 in transgenic MEFs. (C) The replication capacity of both MEFs were measured by seeding 1 × 104 cells into one well of 6-well plate and counted every 3 days. Both wild-type and transgenic MEFs proliferated normally until passage 4 and proliferation capability declined during later passages (p5 and p6). (D, E) The comparison of cell growth curves of transgenic and wild-type MEFs in 10% serum (D) and 1% serum (E). The cell growth rate was significantly higher in transgenic MEFs than in wild-type MEFs (p < 0.05). (F) Increased telomerase activity was detected in eIF-5A2 transgenic mice compared with their wild-type siblings. Protein extracted from HeLa cells was included as positive (+). A 36-bp internal standard was used as a control (IC) in the assay: the bands were weaker in samples with excessively high telomerase activity because amplification of the TRAP products and the IC bands were semicompetitive.
Mentions: Cellular senescence can be triggered by oncogene activation and agents that damage DNA or alter chromatin structure [13,17]. Given our observation of organismal aging in eIF-5A2 mice, we further investigated whether cellular senescence exists under these circumstances. Therefore, MEFs from eIF-5A2 transgenic mice and their wild-type littermates were characterized. eIF-5A2 MEFs were morphologically indistinguishable from the wild-type counterparts at both early and late passages. The activity of senescence associated β-galactosidase (SA-β-gal), a cellular index of senescence, was eximined and no difference was found between eIF-5A2 transgenic and wild-type MEFs (Figure 6A). We also stained the cryostat sections of skin, testis and liver, and did not detect any SA-β-gal positive cells in vivo (not shown).

Bottom Line: Recently, we isolated a novel oncogene eIF-5A2 within the 3q26 region.This included decreased growth rate and body weight, shortened life span, kyphosis, osteoporosis, delay of wound healing and ossification.This subsequently allowed for the accumulation of chromosomal instability, such as errors in cell dividing during metaphase and anaphase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical Oncology, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, China.

ABSTRACT

Background: Amplification of 3q26 is one of the most frequent genetic alterations in many human malignancies. Recently, we isolated a novel oncogene eIF-5A2 within the 3q26 region. Functional study has demonstrated the oncogenic role of eIF-5A2 in the initiation and progression of human cancers. In the present study, we aim to investigate the physiological and pathological effect of eIF-5A2 in an eIF-5A2 transgenic mouse model.

Methods: An eIF-5A2 transgenic mouse model was generated using human eIF-5A2 cDNA. The eIF-5A2 transgenic mice were characterized by histological and immunohistochemistry analyses. The aging phenotypes were further characterized by wound healing, bone X-ray imaging and calcification analysis. Mouse embryo fibroblasts (MEF) were isolated to further investigate molecular mechanism of eIF-5A2 in aging.

Results: Instead of resulting in spontaneous tumor formation, overexpression of eIF-5A2 accelerated the aging process in adult transgenic mice. This included decreased growth rate and body weight, shortened life span, kyphosis, osteoporosis, delay of wound healing and ossification. Investigation of the correlation between cellular senescence and aging showed that cellular senescence is not required for the aging phenotypes in eIF-5A2 mice. Interestingly, we found that activation of eIF-5A2 repressed p19 level and therefore destabilized p53 in transgenic mouse embryo fibroblast (MEF) cells. This subsequently allowed for the accumulation of chromosomal instability, such as errors in cell dividing during metaphase and anaphase. Additionally, a significantly increase in number of aneuploidy cells (p < 0.05) resulted from an increase in the incidences of misaligned and lagging chromosomal materials, anaphase bridges, and micronuclei in the transgenic mice.

Conclusion: These observations suggest that eIF-5A2 mouse models could accelerate organismal aging by increasing chromosome instability.

Show MeSH
Related in: MedlinePlus