Micronuclei

Micronuclei are small, membrane-bound structures containing chromosome fragments or whole chromosomes that failed to segregate properly during mitosis, forming discrete nuclear-like bodies separated from the primary nucleus. Because their surrounding envelope assembles imperfectly and is prone to rupture, micronuclei readily expose their chromatinized DNA to the cytosol, where it can be recognized by the DNA sensor cGAS and trigger innate immune signaling. Micronuclei formation is closely associated with chromosomal instability and is a recurring feature of cancer cells undergoing mitotic errors.