RESUMEN
During the process of spermatogenesis, the proliferation of spermatogonia (stem cell descendants) is replaced by their differentiation in growing spermatocytes responsible for the preparation to meiosis, which is accompanied by a cardinal change in transcriptional programs. We have demonstrated that, in drosophila, this process is accompanied by a splash of the expression of ß-subunit of nascent polypeptide-associated complex (NAC) associated by ribosomes. Nascent polypeptide-associated complex is known as a chaperone involved in co-translational protein folding. This is the first case of the detection of tissue-specific co-translational NAC cofactor in multicellular eukaryotes. It is proposed that spermatocyte specific NAC is involved in the modulation of the expression of the proteins that provide the functioning of subsequent stages of spermatogenesis.
Asunto(s)
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica , Chaperonas Moleculares/genética , Espermatocitos/metabolismo , Testículo/metabolismo , Animales , Diferenciación Celular , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/metabolismo , Masculino , Meiosis , Chaperonas Moleculares/metabolismo , Biosíntesis de Proteínas , Subunidades de Proteína/genética , Subunidades de Proteína/metabolismo , Ribosomas/genética , Ribosomas/metabolismo , Espermatocitos/crecimiento & desarrollo , Espermatocitos/ultraestructura , Espermatogénesis/genética , Testículo/crecimiento & desarrolloRESUMEN
A full-length copy of the retrotransposon GATE was identified as an insertion in the tandemly repeated, heterochromatic, Stellate genes, which are expressed in the testis of Drosophila melanogaster. Sequencing of this heterochromatic GATE copy revealed that it is closely related to the BEL retrotransposon, a representative of the recently defined BEL-like group of LTR retrotransposons. This copy contains identical LTRs, indicating that the insertion is a recent event. By contrast, the euchromatic part of the D. melanogaster genome contains only profoundly damaged GATE copies or fragments of the transposon. The preferential localization of GATE sequences in heterochromatin was confirmed for the other species in the melanogaster subgroup. The level of GATE expression is dramatically increased in ovaries, but not in testes, of spn-E(1) homozygous flies. We speculate that spn-E is involved in the silencing of GATE via an RNA interference mechanism.