A centromeric RNA-associated protein complex affects germ line development in Drosophila melanogaster

Abstract

AbstractIn many metazoans, centromeres are embedded in large blocks of highly repetitive (peri-) centromeric heterochromatin from which non-coding RNAs emanate that have been assigned diverse functions in different species. However, little is known about their functional details or regulation. The pericentromere of the X chromosome in Drosophila melanogaster contains a multi mega-base array of the 359 bp satellite repeats from the 1.688 family, which is transcribed into a lncRNA (SAT III RNA). We performed a SAT III RNA pulldown assay and identified a SAT III RNA-associated complex of four previously uncharacterized proteins and show that they affect germline development. These factors not only interact with each other and with SAT III RNA but also co-regulate each other. RNAi depletion of any of the factors leads to severe defects in the developing germline and sterility. Moreover, we show that the complex plays a crucial role in SAT III RNA repression, as RNAi depletion of the factors leads to a drastic increase of SAT III RNA levels. Importantly, genetic reduction of SAT III RNA level in the RNAi-depleted flies partially rescued the germ line defects and infertility phenotype. Based on our results we hypothesize that the identified complex functions in the germline to regulate SAT III RNA levels, possibly to offset effects of chromatin remodelling taking place in the developing germline.