Personnel
Kevin Mills
Associate Staff Scientist
The Jackson Laboratory
(207) 288-6820
kevin.mills@jax.org
http://www.jax.org/staff/mills/index.html
Research:
While chromosomal instability has long been recognized as a hallmark of cancer, the molecular mechanisms behind genomic instability, as well as its precise consequences, are very poorly understood. We are using a series of related mouse lymphoma models, each with characteristic cytogenetic features, to investigate the genetic, molecular, and biophysical bases for oncogenic genome instability. Our efforts are focused in three areas:
1) Understanding the genetic mechanisms of lymphoid transformation. Mice simultaneously deficient for the nonhomologous end joining (NHEJ) pathway of DNA break repair, and for the tumor suppressor p53, rapidly and inevitably develop progenitor B cell tumors with complex chromosomal translocations. In addition to translocations, these tumors also incur various segmental copy number abnormalities (deletions or amplification). We have developed a new, high-resolution array for comparative genomic hybridization (CGH) platform, and are combining this with a novel quantitative PCR approach and with gene expression profile analyses, to map chromosome structural abnormalities in these tumors, understand their functional consequences, and elucidate mechanistically important genome sequence elements.
2) Testing the role of nuclear and chromosomal architecture in the formation of translocations. An emerging view of the mammalian nucleus holds that individual interphase chromosomes are not diffuse throughout the nucleus, but rather, occupy discrete chromosome territories. Chromosome territories are then organized, in some tissues and cell types, into characteristic “territory neighborhoods”. While such nuclear superstructure is thought in influence many biological phenomena, from patterns of transcription to the control of genome stability, it is not clear specifically how large-scale nuclear architectural details are translated into biological effects. One theory posits that characteristic chromosome positioning is at least partly responsible for unique, tissue specific patterns of oncogenic chromosome translocations. By this hypothesis, chromosomes that are nearby in territory neighborhoods are more likely to become translocated than chromosomes positioned at a distance. To begin testing this model we have identified chromosome territory neighborhoods in mouse progenitor B cells. Importantly, we have conducted a direct test of the model that territory neighborhoods define translocation patterns by separating translocation recovery from selective outgrowth of individual clones, following induction of genome-wide random chromosome breaks. We have also begun high-resolution imaging of mouse nuclei, using the extraordinary 3D resolving power of 4Pi confocal microscopy, to identify potential nanoscale positioning effects, and to obtain detailed chromosome position and morphology information. To extract statistically significant, quantitative data from such images we are collaborating with Dr. Andre Khalil, who is developing a suite of new, wavelet-based multi-fractal image analysis tools to interrogate high-resolution data for morphological and positional details.
3) Development of new genome instability models. Although NHEJ/p53 deficient mice are strongly prone to pro-B cell tumorigenesis, it is unknown whether other tissues, given sufficient time, would also develop tumors. To test this, we have generated NHEJ/p53 deficient mice that lack the B-cell specific translocation donor region, and should therefore be resistant to pro-B cell transformation. We will use these mice to determine the tumor susceptibility of NHEJ-deficient T-lineage cells and/or non-lymphoid tissues. We are also testing the role of homologous recombination in maintenance of genome stability and lymphoid tumor suppression.
Recent Publications:
Mills KD, Ferguson DO, Alt FW. 2003. The role of DNA breaks in genomic instability and tumorigenesis. Immunol Rev 194:77-95.
Mills KD, Ferguson DO, Essers J, Eckersdorff. M, Kanaar R, Alt FW. 2004. Rad54 and DNA ligase IV cooperate to maintain mammalian chromatid stability. Genes Dev 18:1283-1292.
Couedel C, Mills KD, Barchi M, Shen L, Oishen A, Johnson RD, Nussenzweig A, Essers J, Kannar R, Li GC, Alt FW, Jasin M. 2004. Collaboration of homologous recombination and nonhomologous end-joining factors to the survival and integrity of mice and cells. Genes Dev 18:1293-1304.
Mostoslavsky R, Chua KF, Lombard DB, Pang WW, Fischer MR, Gellon L, Murphy MM, Mills KD, Patel P, Cheng H-L, Bronson R, Frendeway D, Auerbach W, Valenzuela D, Karow M, Mulligan R, Demple B, Yancopoulos GD, Alt FW. 2005. Genomic instability and aging-like phenotype in the absence of mammalian Sirt6. Cell In Press.
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