Cytogenetic changes in primary, immortalized and malignant mammalian cells

Area of Science:

• Cell Biology
• Genetics
• Cancer Research

Background:

• Kinetochore proteins are essential for accurate chromosome segregation during cell division.
• Aneuploidy, an abnormal chromosome number, is a hallmark of cancer and developmental disorders.
• The mechanisms leading to aneuploidy are complex and not fully understood.

Purpose of the Study:

• To investigate the presence of kinetochore proteins and micronuclei in various mammalian cells.
• To explore the potential role of kinetochore-deficient chromosomes (K-chromosomes) in aneuploidy generation.
• To determine if the lack of kinetochores is due to the absence of centromeric DNA.

Main Methods:

• Analysis of primary, immortalized, and malignant mammalian cells.
• Detection of kinetochore proteins using antikinetochore antibodies.
• Micronuclei frequency assessment.
• In situ hybridization with minor satellite and alpha satellite DNA sequences.

Main Results:

• Some chromosomes (K-chromosomes) lacked detectable kinetochore proteins.
• A correlation was observed between K-chromosome frequency, micronuclei, and chromosome number variability.
• Some K-chromosomes hybridized with centromeric DNA sequences, indicating DNA presence without kinetochores.
• Dislocated K-chromosomes were found in micronuclei, which are prone to chromosome loss.

Conclusions:

• Kinetochore deficiency in chromosomes represents a potential novel mechanism for aneuploidy.
• The presence of centromeric DNA in K-chromosomes suggests kinetochore dysfunction rather than DNA absence.
• Micronuclei formation and subsequent chromosome loss involving K-chromosomes contribute to aneuploidy generation.