Protein-RNA interactions are fundamental to core biological processes, such as mRNA splicing, localization, degradation, and translation. We developed a photoreactive nucleotide-enhanced UV ...crosslinking and oligo(dT) purification approach to identify the mRNA-bound proteome using quantitative proteomics and to display the protein occupancy on mRNA transcripts by next-generation sequencing. Application to a human embryonic kidney cell line identified close to 800 proteins. To our knowledge, nearly one-third were not previously annotated as RNA binding, and about 15% were not predictable by computational methods to interact with RNA. Protein occupancy profiling provides a transcriptome-wide catalog of potential cis-regulatory regions on mammalian mRNAs and showed that large stretches in 3′ UTRs can be contacted by the mRNA-bound proteome, with numerous putative binding sites in regions harboring disease-associated nucleotide polymorphisms. Our observations indicate the presence of a large number of mRNA binders with diverse molecular functions participating in combinatorial posttranscriptional gene-expression networks.
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► System-wide characterization of protein-mRNA interactome ► Identification of 797 proteins interacting with mRNA ► Characterization of binding sites and targets of five mRNA binders by PAR-CLIP ► Protein occupancy profiling globally mapped potential cis-regulatory mRNA regions
RNA helicases are important regulators of gene expression that act by remodeling RNA secondary structures and RNA-protein interactions. Here, we demonstrate that MOV10 has an ATP-dependent 5′ to 3′ ...in vitro RNA unwinding activity and determine the RNA-binding sites of MOV10 and its helicase mutants using PAR-CLIP. We find that MOV10 predominantly binds to 3′ UTRs upstream of regions predicted to form local secondary structures and provide evidence that MOV10 helicase mutants are impaired in their ability to translocate 5′ to 3′ on their mRNA targets. MOV10 interacts with UPF1, the key component of the nonsense-mediated mRNA decay pathway. PAR-CLIP of UPF1 reveals that MOV10 and UPF1 bind to RNA in close proximity. Knockdown of MOV10 resulted in increased mRNA half-lives of MOV10-bound as well as UPF1-regulated transcripts, suggesting that MOV10 functions in UPF1-mediated mRNA degradation as an RNA clearance factor to resolve structures and displace proteins from 3′ UTRs.
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•MOV10 has in vitro 5′ to 3′ directional RNA unwinding activity•MOV10 displays widespread binding to 3′ untranslated regions (3′ UTRs) of mRNAs•PAR-CLIP of helicase-deficient MOV10 indicates impaired translocation along 3′ UTRs•MOV10 interacts with UPF1 and contributes to degradation of UPF1-regulated transcripts
RNA helicases regulate gene expression by remodeling RNA secondary structures and RNA-protein interactions. Gregersen et al. show that the RNA helicase MOV10 binds to 3′ UTRs and translocates 5′ to 3′ on its mRNA targets. MOV10 interacts with UPF1 and functions in UPF1-mediated mRNA degradation as mRNPase clearance factor.
The centrosome is the primary microtubule organizing center of the cells and templates the formation of cilia, thereby operating at a nexus of critical cellular functions. Here, we use ...proximity-dependent biotinylation (BioID) to map the centrosome-cilium interface; with 58 bait proteins we generate a protein topology network comprising >7,000 interactions. Analysis of interaction profiles coupled with high resolution phenotypic profiling implicates a number of protein modules in centriole duplication, ciliogenesis, and centriolar satellite biogenesis and highlights extensive interplay between these processes. By monitoring dynamic changes in the centrosome-cilium protein interaction landscape during ciliogenesis, we also identify satellite proteins that support cilia formation. Systematic profiling of proximity interactions combined with functional analysis thus provides a rich resource for better understanding human centrosome and cilia biology. Similar strategies may be applied to other complex biological structures or pathways.
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•BioID conducted on 58 centriole, satellite, and ciliary transition zone proteins•Centriole-cilium interface map comprises >1,700 unique components, >7,000 interactions•Microscopy and functional screens confirm new centriole-cilium regulatory modules•Dynamic modulation of interaction landscape observed during ciliogenesis program
In vivo proximity-dependent biotinylation (BioID) generates a protein interaction map of the human centrosome-cilium interface, revealing protein modules critical for centrosome and cilium biogenesis and pervasive and dynamic interplay between the two processes.
Mammalian chromosomes fold into arrays of megabase‐sized topologically associating domains (TADs), which are arranged into compartments spanning multiple megabases of genomic DNA. TADs have internal ...substructures that are often cell type specific, but their higher‐order organization remains elusive. Here, we investigate TAD higher‐order interactions with Hi‐C through neuronal differentiation and show that they form a hierarchy of domains‐within‐domains (metaTADs) extending across genomic scales up to the range of entire chromosomes. We find that TAD interactions are well captured by tree‐like, hierarchical structures irrespective of cell type. metaTAD tree structures correlate with genetic, epigenomic and expression features, and structural tree rearrangements during differentiation are linked to transcriptional state changes. Using polymer modelling, we demonstrate that hierarchical folding promotes efficient chromatin packaging without the loss of contact specificity, highlighting a role far beyond the simple need for packing efficiency.
Synopsis
Genome‐wide mapping of chromatin architecture reveals a hierarchical folding of chromatin that involves higher‐order domains interactions across the whole chromosomes, reflects epigenomic features and reorganizes upon differentiation‐induced gene expression changes.
Chromatin architecture is mapped genome‐wide using Hi‐C and a neuronal differentiation model from mESC to post‐mitotic neurons.
Mammalian chromosomes fold hierarchically in a manner that reflects epigenomic features and involves higher‐order domains (metaTADs) up to the chromosome scale.
metaTAD topologies are relatively conserved through differentiation, and their reorganization is related to gene expression changes.
Polymer modelling shows that hierarchical chromatin folding promotes efficient packaging without the loss of contact specificity.
Genome‐wide mapping of chromatin architecture reveals a hierarchical folding of chromatin that involves higher‐order domains interactions across the whole chromosomes, reflects epigenomic features and reorganizes upon differentiation‐induced gene expression changes.
RNA-binding proteins (RBPs) mediate mRNA biogenesis, translation and decay. We recently developed an approach to profile transcriptome-wide RBP contacts on polyadenylated transcripts by ...next-generation sequencing. A comparison of such profiles from different biological conditions has the power to unravel dynamic changes in protein-contacted cis-regulatory mRNA regions without a priori knowledge of the regulatory protein component.
We compared protein occupancy profiles of polyadenylated transcripts in MCF7 and HEK293 cells. Briefly, we developed a bioinformatics workflow to identify differential crosslinking sites in cDNA reads of 4-thiouridine crosslinked polyadenylated RNA samples. We identified 30,000 differential crosslinking sites between MCF7 and HEK293 cells at an estimated false discovery rate of 10%. 73% of all reported differential protein-RNA contact sites cannot be explained by local changes in exon usage as indicated by complementary RNA-seq data. The majority of differentially crosslinked positions are located in 3' UTRs, show distinct secondary-structure characteristics and overlap with binding sites of known RBPs, such as ELAVL1. Importantly, mRNA transcripts with the most significant occupancy changes show elongated mRNA half-lives in MCF7 cells.
We present a global comparison of protein occupancy profiles from different cell types, and provide evidence for altered mRNA metabolism as a result of differential protein-RNA contacts. Additionally, we introduce POPPI, a bioinformatics workflow for the analysis of protein occupancy profiling experiments. Our work demonstrates the value of protein occupancy profiling for assessing cis-regulatory RNA sequence space and its dynamics in growth, development and disease.
The transcriptome, as the pool of all transcribed elements in a given cell, is regulated by the interaction between different molecular levels, involving epigenetic, transcriptional, and ...post-transcriptional mechanisms. However, many previous studies investigated each of these levels individually, and little is known about their interdependency. We present a systems biology study integrating mRNA profiles with DNA-binding events of key cardiac transcription factors (Gata4, Mef2a, Nkx2.5, and Srf), activating histone modifications (H3ac, H4ac, H3K4me2, and H3K4me3), and microRNA profiles obtained in wild-type and RNAi-mediated knockdown. Finally, we confirmed conclusions primarily obtained in cardiomyocyte cell culture in a time-course of cardiac maturation in mouse around birth. We provide insights into the combinatorial regulation by cardiac transcription factors and show that they can partially compensate each other's function. Genes regulated by multiple transcription factors are less likely differentially expressed in RNAi knockdown of one respective factor. In addition to the analysis of the individual transcription factors, we found that histone 3 acetylation correlates with Srf- and Gata4-dependent gene expression and is complementarily reduced in cardiac Srf knockdown. Further, we found that altered microRNA expression in Srf knockdown potentially explains up to 45% of indirect mRNA targets. Considering all three levels of regulation, we present an Srf-centered transcription network providing on a single-gene level insights into the regulatory circuits establishing respective mRNA profiles. In summary, we show the combinatorial contribution of four DNA-binding transcription factors in regulating the cardiac transcriptome and provide evidence that histone modifications and microRNAs modulate their functional consequence. This opens a new perspective to understand heart development and the complexity cardiovascular disorders.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The primary cilium is found in most mammalian cells and plays a functional role in tissue homeostasis and organ development by modulating key signaling pathways. Ciliopathies are a group of ...genetically heterogeneous disorders resulting from defects in cilia development and function. Patients with ciliopathic disorders exhibit a range of phenotypes that include nephronophthisis (NPHP), a progressive tubulointerstitial kidney disease that commonly results in end-stage renal disease (ESRD). In recent years, distal appendages (DAPs), which radially project from the distal end of the mother centriole, have been shown to play a vital role in primary ciliary vesicle docking and the initiation of ciliogenesis. Mutations in the genes encoding these proteins can result in either a complete loss of the primary cilium, abnormal ciliary formation, or defective ciliary signaling. DAPs deficiency in humans or mice commonly results in NPHP. In this review, we outline recent advances in our understanding of the molecular functions of DAPs and how they participate in nephronophthisis development.
Nephronophthisis-related ciliopathies (NPHP-RCs) are a group of inherited diseases that are associated with defects in primary cilium structure and function. To identify genes mutated in NPHP-RC, we ...performed homozygosity mapping and whole-exome sequencing for >100 individuals, some of whom were single affected individuals born to consanguineous parents and some of whom were siblings of indexes who were also affected by NPHP-RC. We then performed high-throughput exon sequencing in a worldwide cohort of 800 additional families affected by NPHP-RC. We identified two ADAMTS9 mutations (c.4575_4576del p.Gln1525Hisfs∗60 and c.194C>G p.Thr65Arg) that appear to cause NPHP-RC. Although ADAMTS9 is known to be a secreted extracellular metalloproteinase, we found that ADAMTS9 localized near the basal bodies of primary cilia in the cytoplasm. Heterologously expressed wild-type ADAMTS9, in contrast to mutant proteins detected in individuals with NPHP-RC, localized to the vicinity of the basal body. Loss of ADAMTS9 resulted in shortened cilia and defective sonic hedgehog signaling. Knockout of Adamts9 in IMCD3 cells, followed by spheroid induction, resulted in defective lumen formation, which was rescued by an overexpression of wild-type, but not of mutant, ADAMTS9. Knockdown of adamts9 in zebrafish recapitulated NPHP-RC phenotypes, including renal cysts and hydrocephalus. These findings suggest that the identified mutations in ADAMTS9 cause NPHP-RC and that ADAMTS9 is required for the formation and function of primary cilia.
Karyomegalic interstitial nephritis (KIN) is a chronic interstitial nephropathy characterized by tubulointerstitial nephritis and formation of enlarged nuclei in the kidneys and other tissues. We ...recently reported that recessive mutations in the gene encoding FANCD2/FANCI-associated nuclease 1 (FAN1) cause KIN in humans. FAN1 is a major component of the Fanconi anemia-related pathway of DNA damage response (DDR) signaling. To study the pathogenesis of KIN, we generated a Fan1 knockout mouse model, with abrogation of Fan1 expression confirmed by quantitative RT-PCR. Challenging Fan1
and wild-type mice with 20 mg/kg cisplatin caused AKI in both genotypes. In contrast, chronic injection of cisplatin at 2 mg/kg induced KIN that led to renal failure within 5 weeks in Fan1
mice but not in wild-type mice. Cell culture studies showed decreased survival and reduced colony formation of Fan1
mouse embryonic fibroblasts and bone marrow mesenchymal stem cells compared with wild-type counterparts in response to treatment with genotoxic agents, suggesting that FAN1 mutations cause chemosensitivity and bone marrow failure. Our data show that Fan1 is involved in the physiologic response of kidney tubular cells to DNA damage, which contributes to the pathogenesis of CKD. Moreover, Fan1
mice provide a new model with which to study the pathomechanisms of CKD.
PIK3C2A is a class II member of the phosphoinositide 3-kinase (PI3K) family that catalyzes the phosphorylation of phosphatidylinositol (PI) into PI(3)P and the phosphorylation of PI(4)P into ...PI(3,4)P2. At the cellular level, PIK3C2A is critical for the formation of cilia and for receptor mediated endocytosis, among other biological functions. We identified homozygous loss-of-function mutations in PIK3C2A in children from three independent consanguineous families with short stature, coarse facial features, cataracts with secondary glaucoma, multiple skeletal abnormalities, neurological manifestations, among other findings. Cellular studies of patient-derived fibroblasts found that they lacked PIK3C2A protein, had impaired cilia formation and function, and demonstrated reduced proliferative capacity. Collectively, the genetic and molecular data implicate mutations in PIK3C2A in a new Mendelian disorder of PI metabolism, thereby shedding light on the critical role of a class II PI3K in growth, vision, skeletal formation and neurological development. In particular, the considerable phenotypic overlap, yet distinct features, between this syndrome and Lowe's syndrome, which is caused by mutations in the PI-5-phosphatase OCRL, highlight the key role of PI metabolizing enzymes in specific developmental processes and demonstrate the unique non-redundant functions of each enzyme. This discovery expands what is known about disorders of PI metabolism and helps unravel the role of PIK3C2A and class II PI3Ks in health and disease.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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