Scleroderma crest autoantibodies as fluorescent and Immuno-Electron Microscopic probes: Keys to a chromosomal black box

Abstract

The mammalian kinetochore is a highly differentiated structure found at the centromere (primary constriction) of chromosomes that serves as an attachment site for spindle microtubules. Ultrastructurally, the kinetochore typically appears as a tri-layered plate or disc situated at the sides of the centromere (Fig.1). Recent evidence demonstrates that kinetochores have the ability to capture and stabilize microtubules that grow from the spindle poles. Moreover, the motor(s) for chromosome movement appear to be located in or near the kinetochore which actively participates in the generation of forces necessary for chromosome movement in mitosis and meiosis. To understand how the precise ballet-like movements of chromosomes on the mitotic spindle occur, attention has focused on the “black box” of the chromosome; the centromere-kinetochore complex.The fortuitous discovery that serum from individuals with the CREST variant of scleroderma contain autoantibodies that bind to components of the centromere-kinetochore complex has led to major advancements in the understanding of this chromosomal black box. Indirect immunofluorescence has demonstrated the presence of paired fluorescent structures (Fig.2) at the centromeres of both mammalian and plant chromosomes.