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Mapping of cis-Regulatory Sites in the Promoter of Testis-Specific Stellate Genes of Drosophila melanogaster

O. M. Olenkina, K. S. Egorova, A. A. Aravin, N. M. Naumova, V. A. Gvozdev, and L. V. Olenina*

Institute of Molecular Genetics, Russian Academy of Sciences, pl. Kurchatova 2, 123182 Moscow, Russia; fax: (499) 196-0221; E-mail: olenina_ludmila@mail.ru

* To whom correspondence should be addressed.

Received June 22, 2012; Revision received July 3, 2012
Tandem Stellate genes organized into two clusters in heterochromatin and euchromatin of the X-chromosome are part of the Ste–Su(Ste) genetic system required for maintenance of male fertility and reproduction of Drosophila melanogaster. Stellate genes encode a regulatory subunit of protein kinase CK2 and are the main targets of germline-specific piRNA-silencing; their derepression leads to appearance of protein crystals in spermatocytes, meiotic disturbances, and male sterility. A short promoter region of 134 bp appears to be sufficient for testis-specific transcription of Stellate, and it contains three closely located cis-regulatory elements called E-boxes. By using reporter analysis, we confirmed a strong functionality of the E-boxes in the Stellate promoter for in vivo transcription. Using selective mutagenesis, we have shown that the presence of the central E-box 2 is preferable to maintain a high-level testis-specific transcription of the reporter gene under the Stellate promoter. The Stellate promoter provides transcription even in heterochromatin, and corresponding mRNAs are translated with the generation of full-size protein products in case of disturbances in the piRNA-silencing process. We have also shown for the first time that the activity of the Stellate promoter is determined by chromatin context of the X-chromosome in male germinal cells, and it increases at about twofold when relocating in autosomes.
KEY WORDS: promoter, spermatogenesis, Drosophila, Stellate genes, heterochromatin

DOI: 10.1134/S0006297912110077