Prp22 and Spliceosome Components Regulate Chromatin Dynamics in Germ-Line Polyploid Cells

Abstract

During Drosophila oogenesis, the endopolyploid nuclei of germ-line nurse cells undergo a dramatic shift in morphology as oogenesis progresses; the easily-visible chromosomes are initially polytenic during the early stages of oogenesis before they transiently condense into a distinct ‘5-blob’ configuration, with subsequent dispersal into a diffuse state. Mutations in many genes, with diverse cellular functions, can affect the ability of nurse cells to fully decondense their chromatin, resulting in a ‘5-blob arrest’ phenotype that is maintained throughout the later stages of oogenesis. However, the mechanisms and significance of nurse-cell (NC) chromatin dispersal remain poorly understood. Here, we report that a screen for modifiers of the 5-blob phenotype in the germ line isolated the spliceosomal gene peanuts, the Drosophila Prp22. We demonstrate that reduction of spliceosomal activity through loss of peanuts promotes decondensation defects in NC nuclei during mid-oogenesis. We also show that the Prp38 spliceosomal protein accumulates in the nucleoplasm of nurse cells with impaired peanuts function, suggesting that spliceosomal recycling is impaired. Finally, we reveal that loss of additional spliceosomal proteins impairs the full decondensation of NC chromatin during later stages of oogenesis, suggesting that individual spliceosomal subcomplexes modulate expression of the distinct subset of genes that are required for correct morphology in endopolyploid nurse cells.

High-throughput sequencing of small RNAs revealed the diversified cold-responsive pathways during cold stress in the wild banana (Musa itinerans)

“…However, there were only 5 targets in L0 vs L13, the 5 targets disappeared and the other 5 targets (prp22, hnRNPs, prp43, SF3b, Lsm) remained, indicated that the 5 targets were involved in the chilling and 0 °C treated responses. The 5 targets were responsible for mRNA splicing and alternative splicing, such as prp22 and splicesome components regulate chromatin dynamics [ 100 ]; the ATPase activity of prp43 was required for early steps of pre-rRNA processing and normal accumulation of mature rRNAs [ 101 ]; SF3B1 as a principal player in the spliceosome and as a target of inhibitor compounds in pre-mRNA splicing complex [ 102 ]; hnRNPs are complexes of RNA and protein present in the cell nucleus during gene transcription and subsequent post-transcriptional modification of the newly synthesized RNA (pre-mRNA), and the proteins involved in the hnRNP complexes were collectively known as heterogeneous rib nucleoproteins, which was regulated by phosphorylation catalyzed by protein kinase A and was responsible for suppressing RNA splicing at a particular exon by blocking access of the spliceosome to the polypyrimidine tract [ 103 ]. Lsm plays a large number of various roles in mRNA processing and regulation, and depending on which lsm proteins and RNA molecule were involved, this ribonucleic protein complex facilitated a wide variety of RNA processing including degradation, editing, splicing, and regulation [ 104 ].…”

Mutations in the insulator protein Suppressor of Hairy wing induce genome instability

“…The prolonged development of defective egg chambers is eliminated by mid-oogenesis arrest resulting in egg chamber degeneration around stages 9 to 10 ( Baxley et al, 2011;Harrison et al, 1993;Klug et al, 1968). This defective chromatin dispersal is a common trait among a large number of unrelated mutants, such as genes encoding the splicesosome component prp22 (Klusza et al, 2013), the piwi-interacting RNAs (piRNAs) related protein, and rhino (Klattenhoff et al, 2009;Volpe et al, 2001), which complicates the identification of the mechanisms associated with Su(Hw) activity in the genome of egg chamber cells.…”

HemK2 functions for sufficient protein synthesis and RNA stability through eRF1 methylation duringDrosophilaoogenesis

“…However, almost all ovarioles of hemk2 -GLKD harbored nurse cell nuclei containing chromosomes remained in a blob-like configuration even beyond stage 6 (Figure 2B, Figure S2A; 99%). In order to investigate the possible causes that may results in this chromosomal defect, we examined the expression level of the genes which were known to function for chromosomal dispersion (Goodrich et al, 2004; Klusza et al, 2013). Among those genes, qRT-PCR analysis revealed that the mRNA level of otu was most drastically reduced upon hemk2 -GLKD (Figure 2C), suggesting a potential correlation between otu expression and the observed defect.…”

“…S2A; 99%). To investigate the possible causes of this chromosomal defect, we examined the expression levels of genes known to be involved in chromosomal dispersion (Goodrich et al, 2004; Klusza et al, 2013). qRT-PCR analysis showed that the mRNA level of otu was significantly reduced in hemK2 -GLKD ovaries (Fig.…”