The Effect of TBP-Related Factor 2 on Chromocenter Formation and Chromosome Segregation in Drosophila Melanogaster

Abstract

Chromosome nondisjunction in meiosis causes the gene disbalance and a number of anomalies in development and fertility. Otherwise, genetically programmed sex-ratio meiotic drive occurs in a number of species. One of the forms of eukaryotic genome organization is a chromocenter evolutionally involved in the regulation of chromosome behavior in dividing cells among insects, plants, mammals, mollusks, and even yeast. In Drosophila, TBP related factor 2 (Trf2) belongs to a conservative Tbp (TATA box-binding protein) gene family and encodes a basic transcription factor. Recent data demonstrates that a decrease in TRF2 expression can result in the abnormalities of chromatin condensation; however, no details of this process have been studied. We demonstrated that a decrease in the TRF2 expression damaged proper chromocenter structure and abolished chromatin condensation and it was a reason for the chromosome nondisjunction. We found that compact chromocenter and correct homologue pairing were abolished in flies with a lower Trf2 expression in germline and in somatic cells. We conclude that TRF2 can not only be involved in transcription activation, but also may perform structural function in pericentromeric heterochromatin organization. The possibility of TRF2 to regulate the evolutionary genetically programmed sex-ratio meiotic drive is discussed.

TBP-Related Factor 2 as a Trigger for Robertsonian Translocations and Speciation

“…Previously, it was shown that segregation errors observed in Trf2 mutant meiosis could be a consequence of split chromocenters and improper chromatin condensation not only in Drosophila , but also in mice [ 34 , 35 ]. Moreover, immunostaining of Drosophila polytene chromosomes revealed that Trf2 resides in pericentromeric regions [ 38 ]. However, despite such attractive localization it is unlikely that general transcription factor Trf2 directly participates in pericentromeric heterochromatin organization.…”