Characterization and purification of micronuclei

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"Cancer cells frequently exhibit high levels of aneuploidy and chromosomal instability (CIN) as a consequence of errors in chromosome segregation during mitosis. CIN leads to a number of structural and numerical chromosome abnormalities both within and without the nucleus, the latter of which is exemplified by micronuclei (MN). Micronuclei are miniature bodies containing whole lagging chromosomes or acentric chromosome fragments which were excluded from the main nucleus and encapsulated in their own membrane after a dysfunctional mitosis. MN are traditionally thought to arise only via this mechanism, though a handful of studies have suggested they can also form through interphase nuclear budding and contain smaller sequences such as ecDNA. They may either persist, rupture, or reintegrate into the main nucleus, and their membranes often lack key components for structural stability, such as the nuclear lamin proteins, and for nuclear function, such as nuclear pore complexes. However, there are conflicting views as to the level of dysfunction present within the micronucleus regarding transcription, DNA replication, and DNA repair. While MN initially cause unequal inheritance of genetic material - and even loss of genetic material should they rupture or be inherited by only one daughter cell - they have significant implications for tumor heterogeneity, progression, and metastasis, particularly in context of how ruptured MN interact with the inflammatory immune response through cGAS and STING. We aim to enable more specialized investigation of MN contents by developing a kit-based approach to micronucleus purification, in partnership with Qiagen, to determine the relationship between the type of micronucleus and its characteristics. This project aims to understand the formation, fate, and functionality of micronuclei, first in models of induced MN and chromosomally unstable cell lines, and then in tumor samples to better assess their in vivo relevance to tumor progression and prognosis, and their potential as a biomarker."