Satellite sequences are an important part of the pericentromeric regions in mammalian genomes; they
play a relevant role in chromosome stability and DNA hypomethylation of these sequences has been
reported in ICF syndrome and in some cancers that are closely associated with chromosomal abnormalities.
Epigenetic modifications of satellite sequences and their consequences have not been extensively
studied in human cells. In the present work, we evaluated satellite 2 methylation patterns in human
lymphocytes exposed to 5-azacytidine (5-azaC) and assessed the relationship between these patterns
and chromosome missegregation. Human lymphocytes were exposed to 10 M 5-azaC for 24, 48, and
72 h. Segregation errors were evaluated in binucleate cells using FISH against pericentromeric regions
of chromosomes 1, 9, and 16. DNA methylation patterns were evaluated by immunodetection, and by
bisulfite plus urea conversion and sequencing. We have identified that 5-azaC induced missegregation of
chromosomes 1 and 16, which have highly methylated satellite 2, after 72 h of exposure. Chromosome
methylation patterns showed a notable decrease in pericentromeric methylation. Bisulfite conversion
and sequencing analysis demonstrated demethylation of satellite 2 associated to 5-azaC exposure, principally
after 72 h of treatment. This change occurred in a non-specific pattern. Our study demonstrates an
association between loss of satellite 2 DNA methylation and chromosome loss in human lymphocytes.