Project description:The genome of male germ cells is actively transcribed during spermatogenesis to produce phase-specific protein coding mRNAs and a considerable amount of different non-coding RNAs. Ribonucleoprotein (RNP) granule-mediated RNA regulation provides a powerful means to secure the quality and correct expression of the requisite transcripts. Haploid spermatids are characterized by a unique, unusually large cytoplasmic granule, the chromatoid body (CB), that emerges during the switch between the meiotic and post-meiotic phases of spermatogenesis. To better understand the role of the CB in male germ cell differentiation, we isolated CBs from mouse testes and revealed its full RNA and protein composition. We showed that the CB is mainly composed of RNA-binding proteins and other proteins involved RNA regulation. The CB was loaded with RNA, including pachytene piRNAs, a diverse set of mRNAs and a number of uncharacterized long non-coding transcripts. The CB was demonstrated to accumulate nascent RNA during all the steps of round spermatid differentiation. Our results revealed the CB as a large germ cell -specific RNP platform that is involved in the control of the highly complex transcriptome of haploid male germ cells. Small RNA profiling of purified chromatoid body, each steps of chromatoid body purification, and sortred round spermatid cells
Project description:The genome of male germ cells is actively transcribed during spermatogenesis to produce phase-specific protein coding mRNAs and a considerable amount of different non-coding RNAs. Ribonucleoprotein (RNP) granule-mediated RNA regulation provides a powerful means to secure the quality and correct expression of the requisite transcripts. Haploid spermatids are characterized by a unique, unusually large cytoplasmic granule, the chromatoid body (CB), that emerges during the switch between the meiotic and post-meiotic phases of spermatogenesis. To better understand the role of the CB in male germ cell differentiation, we isolated CBs from mouse testes and revealed its full RNA and protein composition. We showed that the CB is mainly composed of RNA-binding proteins and other proteins involved RNA regulation. The CB was loaded with RNA, including pachytene piRNAs, a diverse set of mRNAs and a number of uncharacterized long non-coding transcripts. The CB was demonstrated to accumulate nascent RNA during all the steps of round spermatid differentiation. Our results revealed the CB as a large germ cell-specific RNP platform that is involved in the control of the highly complex transcriptome of haploid male germ cells. Transcriptome profling of purified chromatoid body, each steps of chromatoid body purification, and sortred round spermatid cells
Project description:In mammals, piRNA populations are dynamic throughout male germ cell development. Embryonic piRNAs consist of both primary and secondary species and are mainly directed toward transposons. In meiotic cells, however, the piRNA population is transposon-poor and restricted to primary piRNAs derived from pachytene piRNA clusters. The mechanism controlling which piRNAs are present at each developmental stage is poorly understood. Here we show that RNF17 shapes adult meiotic piRNA content by suppressing the production of secondary piRNAs. In the absence of RNF17, ping-pong (secondary amplification) occurs inappropriately in meiotic cells – aberrantly targeting protein-coding genes and lncRNAs. Our data indicate that RNF17 comprises one component of a “refereeing” mechanism that prevents deleterious activity of the meiotic piRNA pathway by ensuring the selective loading of PIWI proteins with products of meiotic piRNA clusters. Refer to individual Series
Project description:In mammals, piRNA populations are dynamic throughout male germ cell development. Embryonic piRNAs consist of both primary and secondary species and are mainly directed toward transposons. In meiotic cells, however, the piRNA population is transposon-poor and restricted to primary piRNAs derived from pachytene piRNA clusters. The mechanism controlling which piRNAs are present at each developmental stage is poorly understood. Here we show that RNF17 shapes adult meiotic piRNA content by suppressing the production of secondary piRNAs. In the absence of RNF17, ping-pong (secondary amplification) occurs inappropriately in meiotic cells – aberrantly targeting protein-coding genes and lncRNAs. Our data indicate that RNF17 comprises one component of a “refereeing” mechanism that prevents deleterious activity of the meiotic piRNA pathway by ensuring the selective loading of PIWI proteins with products of meiotic piRNA clusters. Examination of small RNA profile in heterozygous and homozygous RNF17 adult testes, pachytene or round spermatid sorted cells
Project description:In mammals, piRNA populations are dynamic throughout male germ cell development. Embryonic piRNAs consist of both primary and secondary species and are mainly directed toward transposons. In meiotic cells, however, the piRNA population is transposon-poor and restricted to primary piRNAs derived from pachytene piRNA clusters1-6. The mechanism controlling which piRNAs are present at each developmental stage is poorly understood. Here we show that RNF17 shapes adult meiotic piRNA content by suppressing the production of secondary piRNAs. In the absence of RNF17, ping-pong (secondary amplification) occurs inappropriately in meiotic cells – aberrantly targeting protein-coding genes and lncRNAs. Our data indicate that RNF17 comprises one component of a “refereeing” mechanism that prevents deleterious activity of the meiotic piRNA pathway by ensuring the selective loading of PIWI proteins with products of meiotic piRNA clusters. Examination of small RNAs isolated from MIWI and MILI IPs of heterozygous and homozygous RNF17 adult testes
Project description:Nonsense-mediated mRNA decay (NMD) controls the quality of eukaryotic gene expression and also degrades physiologic mRNAs. How NMD targets are identified is incompletely understood. A central NMD factor is the ATP-dependent RNA helicase UPF1. Neither the distance in space between the termination codon and the poly(A) tail nor the binding of steady-state, largely hypophosphorylated UPF1 is a discriminating marker of cellular NMD targets, unlike for PTC-containing reporter mRNAs when compared to their PTC-free counterparts. Here, we map phosphorylated UPF1 (p-UPF1) binding sites using transcriptome-wide footprinting or DNA oligonucleotide-directed mRNA cleavage to report that p-UPF1 provides the first reliable cellular NMD-target marker. p-UPF1 is enriched on NMD target 3'UTRs along with SMG5 and SMG7 but not SMG1 or SMG6. Immunoprecipitations of UPF1 variants deficient in various aspects of the NMD process in parallel with FRET experiments reveal that ATPase/helicase-deficient UPF1 manifests high levels of RNA binding and disregulated hyperphosphorylation, whereas wild-type UPF1 releases from nonspecific RNA interactions in an ATP hydrolysis-dependent mechanism until an NMD target is identified. 3'UTR-associated UPF1 undergoes regulated phosphorylation on NMD targets, providing a binding platform for mRNA degradative activities. p-UPF1 binding to NMD target 3'UTRs is stabilized by SMG5 and SMG7. Our results help to explain why steady-state UPF1 binding is not a marker for cellular NMD substrates and how this binding is transformed to induce mRNA decay. RIP-seq experiments for p-UPF1, control IPs using rabbit IgG and additional control sample without IP were performed in duplicates
Project description:We developed a protein microarray to identify autoantigens in Systemic Lupus Erythematosus (SLE). Baculovirus-Sf9 cell expression system was used to create a protein microarray with 1543 full-length human proteins expressed with a biotin carboxyl carrier protein (BCCP) folding tag. We assayed sera from UK and USA SLE individuals (total n=277), age/ancestry matched control cohorts (n=280) and a confounding disease cohort (n=92).
Project description:During mammalian spermatogenesis the mouse VASA homolog (MVH), a germ cell-specific DEAD-box type RNA binding protein, localizes in a germline-specific RNA granule termed the chromatoid body (CB). Genetic analyses have revealed that MVH is essential to progress through spermatogenesis, although the molecular mechanisms of its function remain elusive. We found that the acetyltransferase HAT1 and its cofactor, p46, are specifically co-localized with MVH in the CB and acetylate MVH at Lys-405, leading to inactivation of its RNA binding activity. Notably, the acetylation is developmentally regulated, paralleling the temporally regulated co-localization of HAT1 and p46 in the CB. We have identified 858 mRNAs as MVH targets, a large proportion of which correspond to previously identified translationally arrested genes. Importantly, eIF4B mRNA, a target of MVH, is selectively released from MVH-RNP when MVH is acetylated, paralleling an increase in eIF4B protein. These findings reveal a novel signaling pathway that links acetylation to RNA processing in the control of spermatogenesis. IMVH target mRNA was purified from MVH immuno precipitated complex, followed by RNA purification and identified by DNA chip. In this study, we identified more than 800 MVH target mRNA in testis.
Project description:MicroRNAs are instructions used by the genetic programs of a cell to fine-regulate protein expression levels. In order to gain insight into the full spectrum of miRNA regulation in a particular cellular context, we have exploited the idea that doubling the quantity of the endogenous miRNAs by transfection would enhance downregulation of the normally targeted transcripts. To this end, we isolated the small RNA fraction from cells in culture and transfected it into an identical culture in an amount corresponding to that of the endogenous miRNAs. A comparative gene expression analysis between transfected and mock-transfected cells revealed a large number of modestly downregulated genes. In silico analysis using TargetScan 5 revealed that a very high number of the expressed genes are predicted targets of the endogenous miRNAs, which we identified by deep-sequencing the small RNA fraction. Network analysis of the downregulated genes showed that miRNAs are involved in the simultaneous regulation of many pathways by targeting key molecules that interact with multiple pathways, suggesting a role of miRNAs in the synchronization of the activities of different pathways. Interestingly, we found a very high percentage of the genes regulated by miRNAs to be related to genetic disorders. This suggests that miRNAs might play a key role in maintaining homeostasis in processes that result in disease states when disregulated. Such a crucial role for miRNA regulation further underlines its importance for cell and organism survival. These results also confirm the important experimental value of our methodology as a high throughput tool for the identification of genes endogenously regulated by miRNAs. We isolated the small RNA fraction (20-200 bp) from one culture of normal human fibroblasts and performed quantitative deep sequencing on the Illumina/Solexa platform. We obtained a total of 19E06 sequences, which were blasted against mRNA, RFAM and repbase. The result revealed that the content of this fraction was shared (in % copy numbers) by rRNA: 1.03%, tRNA: 2.3649%, snRNA: 0.0611%, snoRNA: 1.3803%, mRNA: 1.8183%, ncRNA mapped to Rfam: 6.0411%, sequences mapped to repbase: 3.4146%, and the remaining 83% were pre-miRNA and miRNA. A total of 702 human miRNAs were detected. This number was reduced to 324 after filtering out all miRNAs with a copy number of less than 3.
Project description:Axillary bud outgrowth determines plant shoot architecture and is under control of endogenous hormones and a fine-tuned gene expression network. Some genes associated with shoot development are known targets of small RNAs (sRNAs). Although it is well known that sRNAs act broadly in plant development, our understanding about their roles in vegetative bud outgrowth remains limited. Moreover, the expression profiles of microRNAs (miRNAs) and their targets in axillary buds are unknown. In this study, we employed next-generation sequencing, gene expression analysis and metabolite profiling to identify sRNAs and quantify distinct hormones, respectively, in vegetative axillary buds of the tropical biofuel crop sugarcane (Saccharum spp.). Differential accumulation of abscisic acid (ABA), gibberellins (GA), and cytokinins indicates a dynamic balance of these hormones during sugarcane bud outgrowth. A number of repeat-associated siRNAs generated from distinct transposable elements and genes were highly expressed in both inactive and developing buds. RT-qPCR results revealed that specific miRNAs were differentially expressed in developing buds and some correlate negatively with the expression of their targets. Expression patterns of miR159 and its experimentally confirmed target GAMYB suggest they play roles in regulating ABA and GA-signaling pathways during bud outgrowth. Our work reveals, for the first time, differences in composition and expression profiles of small RNAs and targets between inactive and developing buds that, together with the endogenous balance of specific hormones, may be important to regulate axillary bud outgrowth in plants. Examination of small RNA populations in vegetative axillary buds of the tropical biofuel crop sugarcane (Saccharum spp.)