Project description:The role of different proteins, Always Early (Aly), Spermatocyte Arrest (Sa), Ubi-p63E (Magn) on the gene expression in spermatocyte differentation was assessed by microarray ABSTRACT: The ubiquitin proteasome system (UPS) regulates many biological pathways by posttranslationally ubiquitinating proteins for degradation. Although maintaining a dynamic balance between free ubiquitin and ubiquitinated proteins is key to UPS function, the mechanisms that regulate ubiquitin homeostasis in different tissues through development are not clear. Here we show that loss of function of Drosophila magellan (magn), the polyubiquitin Ubi-p63E, results in specifically meiotic arrest sterility in males. Expression of ubiquitin from magn/Ubi-p63E contributes predominantly to maintaining the free ubiquitin pool in testes. Function of magn/Ubip63E is required cell autonomously for proper meiotic chromatin condensation, cell cycle progression and spermatid differentiation. magn/Ubi-p63E mutant germ cells develop normally to the spermatocyte stage but arrest at the G2/M transition of meiosis I with lack of protein expression of key meiotic cell cycle regulators Boule and Cyclin B. Loss of function of magn/Ubi-p63E did not strongly affect the spermatocyte transcription program regulated by the tTAF and tMAC genes. Knocking down proteasome function specifically in spermatocytes caused a different meiotic arrest phenotype, suggesting that the magn/Ubi-p63E phenotype may not result from general defects in protein degradation. Our results suggest a conserved role of polyubiquitin genes in male meiosis and a potential mechanism leading to meiosis I maturation arrest. RNA was obtained from whole testes of flies with following mutations: 1) aly[2]/aly[5p], 2) sa[1]/sa[2], 3) magn[12c]/magn[23b] or magn[12c]/magn[12c];pSC2, 4) red[1], e[1] (WT). Each genotype had three biological replicates except magn which had four total biological replicates, two from magn[12c]/[23b] and two from [12c]/[12c]; pSC2

Project description:Drosophila melanogaster males mutant for any meiotic arrest gene have defective spermatogenesis, with cells arresting as primary spermatocytes, and failing to progress to later stages. This phenotype is remarkably similar to meiosis I maturation arrest azoospemia in humans. Drosophila meiotic arrest genes can be categorised as "aly-class" or "can-class". The aly-class (aly, zaa and zab) regulates both meiotic division and male germ line differentiation by controlling transcriptional activation of a large set of target genes in primary spermatocytes. This set includes genes required for cell cycle progression and those required for spermatid differentiation. The can-class control transcription of the same set of differentiation genes, but not cell cycle genes. aly belongs to a protein family conserved from humans to plants. Aly protein locates to chromatin in wild type individuals, and probably controls transcriptional activity of target promoters through interaction with a DNA binding protein. Objectives: So far aly- and can-class target genes have been identified by the small-scale approach of individually testing cDNA clones (total 18). Expression of 7 genes was unaffected by the mutations (group A), transcription of 8 depended on both classes of genes (group B), finally three genes required the aly- but not the can-class for their expression (group C). The aly-class targets (group C) are particularly intriguing, since they include a gene, boule, whose human homologue deleted in azoospermia (DAZ) is essential for male fertility. This project will address the following questions: How many genes in total are regulated by the meiotic arrest genes? What types of proteins do they encode? Are they all testis specific, or are they expressed at other stages of the life cycle? What is their relevance for fertility in other species?<br> <br> Plan: We will prepare samples of wild type, aly, can, zaa and zab testes. Those transcripts expressed in wild type testes will be placed into group A, B or C based on analysis of the competitive hybridisation of wild type samples vs each mutant in turn. Microarrays will also enable us to determine whether there is a group D, consisting of genes whose down-regulation in spermatocytes is dependent on the meiotic arrest genes. We have dissected testes from 0-1 day old males of the relevent genotypes. We estimate to get >20 ug total RNA from 100 flies, so have dissected at least 500 males of each mutant genotype, and 2000 of wild type (red e, the background chromosome for aly and can). In total we have about 5000 flies worth of testes in the freezer. We have been careful to only include testes and seminal vesicles, and have excluded other tissues from the genital tract. All the males are collected from bottles that are emptied daily, to ensure they are all the same age. Because of their age relatively few of the males will have mated. For aly and can we have used well characterised null alleles. For zab we have used the only mutant allele, which we also know is a null. We havn't cloned zaa so have no idea whether the only existing mutant allele is null. The testes were dissected in testis buffer over a period of 30 min. Then they were transfered into a very small drop of testis buffer in an eppendorf and frozen in liquid nitrogen. They have been stored at -80C. Before being sent to Cambridge we will defrost the samples, add trizol, and pool samples to supply 3 or 4 tubes per genotype.

Dataset Information

Drosophila melanogaster

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure