Kinetochor

The kinetochor (Greek kínesis 'movement' and chōros 'place') is a special, plate- or hemispherical structure of proteins and DNA segments, which is placed on the side of the centromere and serves as a point of attachment for the fibers of the spindle apparatus during nuclear division processes. The upregulation of different Kinetochor genes could be detected in various malignant tumors, including actinic keratoses and squamous cell carcinoma of the skin (KNSTRN gene).

The kinetochor is essential for cell division. During cell division, the kinetochor protein-DNA complex ensures the attachment of spindle fibres to the chromosome.

The kinetochor complex contains 2 regions: an internal region firmly attached to the centromere of the chromosome and an extremely dynamic external region attached to microtubules of the cells. The exogenous part is only active during cell division.

Cell division: In the prometaphase of cell division, the nuclear envelope breaks down. The spindle fibres of the spindle apparatus penetrate from both poles into the region of the now envelopeless caryoplasm. In this process, the kinetochor protein complex located in the centromere region plays a central role by anchoring the microtubules of the spindle fibres to the chromosomes. By means of the now attached spindle fibres, the chromosomes can now be moved, aligned and arranged. In the metaphase the chromosomes are aligned in the equatorial plane, in the anaphase their two chromatids are separated and pulled apart towards the spindle poles. In the telophase, the last phase of cell division, the kinetochorm microtubules are depolymerized, the nuclear envelope is rebuilt and the chromosomes decondens. Afterwards, the genes can be read again, the nucleus has its original working form again.

Mutations in the kinetochore genes of various malignant tumours (including bronchial carcinoma and prostate carcinoma) have been detected with corresponding incorrectly expressed checkpoint proteins (>100 proteins have now been identified in human cells). For actinic keratoses and squamous cell carcinoma of the skin, somatic point mutations in the kinetochore gene "KNSTRN" were detected, which led to an upregulation of the gene.

Antibodies against kinetochore proteins(centromere antibodies) are highly specific for CREST syndrome.

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