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Satellite DNAs and gene expression

Satellite DNAs are highly repetitive sequences located in heterochromatic regions of eukaryotic chromosomes. They are usually characterized by rapid evolution of sequence and copy number what leads to their preservation among a limited number of closely related species. Despite such a high turnover satellite DNAs represent main centromere building element strongly associated with a number of proteins and involved in the formation of unique centromeric chromatin. In addition, their transcripts in the form of siRNAs participate in the epigenetic process of chromatin modulation and heterochromatin establishment. Our recent data obtained by studying satellite DNAs of the coleopteran genus Palorus indicate that evolution of satellite sequence is not only driven by stochastic processes as previously proposed, but is influenced by selective constraints. These conclusions are based on extreme interspecific conservation and wide distribution of Palorus satellite sequences among species separated for long evolutionary periods. It has been proposed that in addition to participating in centromere formation these sequences could act as cis regulatory elements of gene expression. Their transcriptional activity is detected and seems to be developmentally regulated. We suggest that transcripts of Palorus satellite DNAs, because of their abundance, ability to form double-stranded RNA and complex expression pattern might play a role in the developmental regulation of gene expression.

satellite DNA; transcription; gene regulation

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