GSE54515
Small RNA analysis for fetal testes of Hsp90-alpha knockout mice
HSP90, found in all kingdoms of life, is a major chaperone protein regulating many client proteins. We demonstrated that HSP90a, one of two paralogs duplicated in vertebrates, plays an important role in the biogenesis of fetal PIWI-interacting RNAs (piRNA), which act against the transposon activities, in mouse male germ cells. The knockout mutation of Hsp90a resulted in a large reduction in the expression of primary and secondary piRNAs and mislocalization of MIWI2, a PIWI homolog. Whereas the mutation in Fkbp6 encoding a co-chaperone reduced piRNAs of 28-32 nucleotides in length, the Hsp90a mutation reduced piRNAs of 24-32 nucleotides, suggesting the presence of both FKBP6-dependent and -independent actions of HSP90a. Although DNA methylation and mRNA levels of L1 retrotransposon were largely unchanged in the Hsp90a mutant testes, the L1-encoded protein was increased, suggesting the presence of post-transcriptional regulation. This study revealed the specialized function of the HSP90a isofom in the piRNA biogenesis and repression of retrotransposons during the development of male germ cells in mammals. Overall design: Total RNA was extracted from WT and Hsp90a KO testes at E16.5 (20 testes for each), and used for making a small RNA library with TruSeq Small RNA Library Preparation Kit (Illumina).  The libraries were sequenced on MiSeq (Illumina) by 50-bp single-end sequencing.