INK4 locus of the tumor-resistant rodent, the naked mole rat, expresses a functional p15/p16 hybrid isoform
Edited* by Eviatar Nevo, Institute of Evolution, Haifa, Israel, and approved December 1, 2014 (received for review September 21, 2014)
Significance
The naked mole rat is a longest lived and cancer-resistant rodent. Tumor resistance in the naked mole rat is mediated by signals from the extracellular matrix component hyaluronan triggering the induction of INK4 (inhibitors of cyclin dependent kinase 4) locus expression. The human and mouse INK4 locus encodes three critical tumor-suppressor proteins, p15INK4b, ARF (alternate reading frame), and p16INK4a, which are among the most frequently mutated in cancer. Furthermore, p16INK4a is implicated in aging and senescence. Here, we show that the naked mole rat INK4 locus encodes an additional product, a hybrid between p15INK4b and p16INK4a. The novel product, named pALTINK4a/b, may contribute to tumor resistance and longevity of the naked mole rat. Understanding the regulation of the INK4 locus is critical for cancer and aging research.
Abstract
The naked mole rat (Heterocephalus glaber) is a long-lived and tumor-resistant rodent. Tumor resistance in the naked mole rat is mediated by the extracellular matrix component hyaluronan of very high molecular weight (HMW-HA). HMW-HA triggers hypersensitivity of naked mole rat cells to contact inhibition, which is associated with induction of the INK4 (inhibitors of cyclin dependent kinase 4) locus leading to cell-cycle arrest. The INK4a/b locus is among the most frequently mutated in human cancer. This locus encodes three distinct tumor suppressors: p15INK4b, p16INK4a, and ARF (alternate reading frame). Although p15INK4b has its own ORF, p16INK4a and ARF share common second and third exons with alternative reading frames. Here, we show that, in the naked mole rat, the INK4a/b locus encodes an additional product that consists of p15INK4b exon 1 joined to p16INK4a exons 2 and 3. We have named this isoform pALTINK4a/b (for alternative splicing). We show that pALTINK4a/b is present in both cultured cells and naked mole rat tissues but is absent in human and mouse cells. Additionally, we demonstrate that pALTINK4a/b expression is induced during early contact inhibition and upon a variety of stresses such as UV, gamma irradiation-induced senescence, loss of substrate attachment, and expression of oncogenes. When overexpressed in naked mole rat or human cells, pALTINK4a/b has stronger ability to induce cell-cycle arrest than either p15INK4b or p16INK4a. We hypothesize that the presence of the fourth product, pALTINK4a/b of the INK4a/b locus in the naked mole rat, contributes to the increased resistance to tumorigenesis of this species.
Acknowledgments
This work was supported by grants from the US National Institutes of Health (to Z.D.Z., J.V., V.N.G., V.G., and A.S.), the Life Extension Foundation (to V.G. and A.S.), the Glenn Foundation for Medical Research (to V.G. and J.V.), and the Ellison Medical Foundation (to V.G. and A.S.).
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References
1
YH Edrey, M Hanes, M Pinto, J Mele, R Buffenstein, Successful aging and sustained good health in the naked mole rat: A long-lived mammalian model for biogerontology and biomedical research. ILAR J 52, 41–53 (2011).
2
R Buffenstein, The naked mole-rat: A new long-living model for human aging research. J Gerontol A Biol Sci Med Sci 60, 1369–1377 (2005).
3
MA Delaney, L Nagy, MJ Kinsel, PM Treuting, Spontaneous histologic lesions of the adult naked mole rat (Heterocephalus glaber): A retrospective survey of lesions in a zoo population. Vet Pathol 50, 607–621 (2013).
4
R Buffenstein, Negligible senescence in the longest living rodent, the naked mole-rat: Insights from a successfully aging species. J Comp Physiol B 178, 439–445 (2008).
5
A Seluanov, et al., Hypersensitivity to contact inhibition provides a clue to cancer resistance of naked mole-rat. Proc Natl Acad Sci USA 106, 19352–19357 (2009).
6
X Tian, et al., High-molecular-mass hyaluronan mediates the cancer resistance of the naked mole rat. Nature 499, 346–349 (2013).
7
WY Kim, NE Sharpless, The regulation of INK4/ARF in cancer and aging. Cell 127, 265–275 (2006).
8
M Serrano, et al., Role of the INK4a locus in tumor suppression and cell mortality. Cell 85, 27–37 (1996).
9
CJ Sherr, Ink4-Arf locus in cancer and aging. Wiley Interdiscip Rev Dev Biol 1, 731–741 (2012).
10
M Serrano, GJ Hannon, D Beach, A new regulatory motif in cell-cycle control causing specific inhibition of cyclin D/CDK4. Nature 366, 704–707 (1993).
11
CY Dai, GH Enders, p16 INK4a can initiate an autonomous senescence program. Oncogene 19, 1613–1622 (2000).
12
S Brookes, J Rowe, A Gutierrez Del Arroyo, J Bond, G Peters, Contribution of p16(INK4a) to replicative senescence of human fibroblasts. Exp Cell Res 298, 549–559 (2004).
13
AV Molofsky, et al., Increasing p16INK4a expression decreases forebrain progenitors and neurogenesis during ageing. Nature 443, 448–452 (2006).
14
H Li, et al., The Ink4/Arf locus is a barrier for iPS cell reprogramming. Nature 460, 1136–1139 (2009).
15
R Tacutu, A Budovsky, H Yanai, VE Fraifeld, Molecular links between cellular senescence, longevity and age-related diseases: A systems biology perspective. Aging (Albany, NY Online) 3, 1178–1191 (2011).
16
Y Ovadya, V Krizhanovsky, Senescent cells: SASPected drivers of age-related pathologies. Biogerontology 15, 627–642 (2014).
17
Y Liu, et al., Expression of p16(INK4a) in peripheral blood T-cells is a biomarker of human aging. Aging Cell 8, 439–448 (2009).
18
Y Liu, et al., INK4/ARF transcript expression is associated with chromosome 9p21 variants linked to atherosclerosis. PLoS ONE 4, e5027 (2009).
19
CE Burd, et al., Expression of linear and novel circular forms of an INK4/ARF-associated non-coding RNA correlates with atherosclerosis risk. PLoS Genet 6, e1001233 (2010).
20
CL Kuo, et al., Cdkn2a is an atherosclerosis modifier locus that regulates monocyte/macrophage proliferation. Arterioscler Thromb Vasc Biol 31, 2483–2492 (2011).
21
C Yuan, TL Selby, J Li, IJ Byeon, MD Tsai, Tumor suppressor INK4: Refinement of p16INK4A structure and determination of p15INK4B structure by comparative modeling and NMR data. Protein Sci 9, 1120–1128 (2000).
22
C Yuan, J Li, TL Selby, IJ Byeon, MD Tsai, Tumor suppressor INK4: Comparisons of conformational properties between p16(INK4A) and p18(INK4C). J Mol Biol 294, 201–211 (1999).
23
T Kamijo, et al., Tumor suppression at the mouse INK4a locus mediated by the alternative reading frame product p19ARF. Cell 91, 649–659 (1997).
24
Y Zhang, Y Xiong, WG Yarbrough, ARF promotes MDM2 degradation and stabilizes p53: ARF-INK4a locus deletion impairs both the Rb and p53 tumor suppression pathways. Cell 92, 725–734 (1998).
25
JD Weber, et al., p53-independent functions of the p19(ARF) tumor suppressor. Genes Dev 14, 2358–2365 (2000).
26
R Szklarczyk, J Heringa, SK Pond, A Nekrutenko, Rapid asymmetric evolution of a dual-coding tumor suppressor INK4a/ARF locus contradicts its function. Proc Natl Acad Sci USA 104, 12807–12812 (2007).
27
J Gilley, M Fried, One INK4 gene and no ARF at the Fugu equivalent of the human INK4A/ARF/INK4B tumour suppressor locus. Oncogene 20, 7447–7452 (2001).
28
DE Quelle, F Zindy, RA Ashmun, CJ Sherr, Alternative reading frames of the INK4a tumor suppressor gene encode two unrelated proteins capable of inducing cell cycle arrest. Cell 83, 993–1000 (1995).
29
SH Kim, M Mitchell, H Fujii, S Llanos, G Peters, Absence of p16INK4a and truncation of ARF tumor suppressors in chickens. Proc Natl Acad Sci USA 100, 211–216 (2003).
30
EB Kim, et al., Genome sequencing reveals insights into physiology and longevity of the naked mole rat. Nature 479, 223–227 (2011).
31
S Pavey, S Conroy, T Russell, B Gabrielli, Ultraviolet radiation induces p16CDKN2A expression in human skin. Cancer Res 59, 4185–4189 (1999).
32
P Krimpenfort, KC Quon, WJ Mooi, A Loonstra, A Berns, Loss of p16Ink4a confers susceptibility to metastatic melanoma in mice. Nature 413, 83–86 (2001).
33
G Schneider, RM Schmid, Genetic alterations in pancreatic carcinoma. Mol Cancer 2, 15 (2003).
34
M Esteller, et al., K-ras and p16 aberrations confer poor prognosis in human colorectal cancer. J Clin Oncol 19, 299–304 (2001).
35
A Matheu, et al., Anti-aging activity of the Ink4/Arf locus. Aging Cell 8, 152–161 (2009).
36
A Matheu, et al., Increased gene dosage of Ink4a/Arf results in cancer resistance and normal aging. Genes Dev 18, 2736–2746 (2004).
37
DJ Baker, et al., Clearance of p16Ink4a-positive senescent cells delays ageing-associated disorders. Nature 479, 232–236 (2011).
38
WR Jeck, AP Siebold, NE Sharpless, Review: A meta-analysis of GWAS and age-associated diseases. Aging Cell 11, 727–731 (2012).
39
J Cocquet, A Chong, G Zhang, RA Veitia, Reverse transcriptase template switching and false alternative transcripts. Genomics 88, 127–131 (2006).
40
P Krimpenfort, et al., p15Ink4b is a critical tumour suppressor in the absence of p16Ink4a. Nature 448, 943–946 (2007).
41
F Zindy, DE Quelle, MF Roussel, CJ Sherr, Expression of the p16INK4a tumor suppressor versus other INK4 family members during mouse development and aging. Oncogene 15, 203–211 (1997).
42
J Krishnamurthy, et al., Ink4a/Arf expression is a biomarker of aging. J Clin Invest 114, 1299–1307 (2004).
43
M Thullberg, et al., Distinct versus redundant properties among members of the INK4 family of cyclin-dependent kinase inhibitors. FEBS Lett 470, 161–166 (2000).
44
OV Leontieva, ZN Demidenko, MV Blagosklonny, Contact inhibition and high cell density deactivate the mammalian target of rapamycin pathway, thus suppressing the senescence program. Proc Natl Acad Sci USA 111, 8832–8837 (2014).
45
SD Tyner, et al., p53 mutant mice that display early ageing-associated phenotypes. Nature 415, 45–53 (2002).
46
B Maier, et al., Modulation of mammalian life span by the short isoform of p53. Genes Dev 18, 306–319 (2004).
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Published online: December 30, 2014
Published in issue: January 27, 2015
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Acknowledgments
This work was supported by grants from the US National Institutes of Health (to Z.D.Z., J.V., V.N.G., V.G., and A.S.), the Life Extension Foundation (to V.G. and A.S.), the Glenn Foundation for Medical Research (to V.G. and J.V.), and the Ellison Medical Foundation (to V.G. and A.S.).
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*This Direct Submission article had a prearranged editor.
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The authors declare no conflict of interest.
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INK4 locus of the tumor-resistant rodent, the naked mole rat, expresses a functional p15/p16 hybrid isoform, Proc. Natl. Acad. Sci. U.S.A.
112 (4) 1053-1058,
https://doi.org/10.1073/pnas.1418203112
(2015).
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