Biology subjects

Ulitsky, I.

Publications and source records attributed to Ulitsky, I..

At least 19 recordsLinked to original sources

bioRxiv2026

Genomic context tunes sequence-encoded RNA processing

Sequence and genomic position jointly determine RNA processing, but at native loci the two are difficult to separate. Here, we uncoupled them by integrating RNA-processing elements into endogenous transcription units at tens of thousands of mapped positions and different elements at shared positions. Genomic position dominated RNA production levels but differentially influenced RNA processing events. A cryptic polyadenylation site, used natively only upon U1 inhibition, was rarely used ectopically. In contrast, introns partially retained at their native loci remained so across thousands of ectopic positions, with a substantial fraction of transcripts reaching the cytoplasm unspliced. SON depletion reduced splicing of two such introns, preferentially near speckles. Chromatin state, GC content, and speckle proximity tuned this behavior without overriding it, and in opposite directions: speckle proximity improved the splicing of one intron and reduced that of another. Specialized introns are therefore portable modules carrying their own processing information.

molecular biology↗

bioRxiv2025

Widespread DNA off-targeting confounds studies of RNA chromatin occupancy

The importance of long noncoding RNA (lncRNA) functions is recognized across biological systems, but their modes of action remain poorly understood. One mechanism proposed to be particularly common is gene expression regulation via recruitment to specific genomic regions. Several high-throughput sequencing methods were developed for studying the genome-wide chromatin occupancy of lncRNAs, including ChIRP-seq, CHART-seq, and RAP-seq. These methods utilize biotin-labeled probes targeting the RNA of interest to isolate and recover the chromatin associated with it. Many of the datasets obtained with these methods contain thousands of binding sites, which appears to be in contradiction with the low abundance of the interrogated lncRNAs. We studied the chromatin interactome of NESPR lncRNA in cells with varying levels of endogenous expression and then performed a meta-analysis using dozens of RNA-chromatin interaction datasets in human and mouse cells. We demonstrate that thousands of regions reported to bind lncRNAs most likely arise from the spurious recovery of DNA elements, where the ends of the recovered DNA fragments exhibit partial complementarity with the probes used for the pulldown. In addition, crucial controls were rarely used in studies profiling RNA-chromatin interactions. Therefore, most chromatin regions reported as bound by trans-acting RNAs in recent studies in mammalian cells appear to be technical artifacts. We provide suggestions for assessing the quality of RNA-chromatin datasets and their improvement.

molecular biology↗

bioRxiv2025

Inducible formation of fusion transcripts upregulates haploinsufficient CHD2 gene expression

Modes of action of long noncoding RNAs (lncRNAs) are poorly understood. CHASERR is a broadly expressed lncRNA located immediately upstream of the promoter of the CHD2 gene. We show that antisense oligonucleotides (ASOs) targeting conserved motifs in CHASERRs last exon induce the formation of a fusion transcript joining CHASERR to CHD2. This fusion transcript is exported to the cytoplasm and translated into full-length CHD2 protein. Deleting the same motifs in mice mimics the ASO effect, increasing CHD2 protein without causing the deleterious effects associated with full CHASERR ablation. The fusion transcripts are also expressed endogenously, induced in activated neurons, and their constitutive induction affects neuronal gene expression and chromatin accessibility. Perinatal introduction of the ASO into Chd2+/- mice up-regulates CHD2 expression and alleviates behavioral phenotypes caused by CHD2 haploinsufficiency, providing a therapeutic route to CHD2 haploinsufficiency. This concept of targeting upstream genes with ASOs to induce transcript fusion can be extended to other gene pairs, and is thus a broadly relevant approach for increasing haploinsufficient gene expression.

molecular biology↗

bioRxiv2025

EPB41L4A-AS1 long noncoding RNA acts in both cis- and trans-acting transcriptional regulation and controls nucleolar biology

Mammalian genomes are pervasively transcribed into long noncoding RNAs (lncRNAs), whose functions and modes of action remain poorly understood. EPB41L4A-AS1 is an evolutionary conserved, broadly and highly expressed lncRNA that produces the H/ACA snoRNA SNORA13 from one of its introns. We studied the consequences of EPB41L4A-AS1 perturbation in breast cancer cells and found that it acts both in cis, to enhance transcription of the proximal EPB41L4A gene and additional genes in its two flanking topologically associated domains, and in trans by broadly regulating gene expression, including expression of snoRNAs, transcription of genes involved in nucleolar biology and the distribution of nucleolar proteins. These effects are phenocopied by the loss of SUB1, an interactor of EPB41L4A-AS1, and are observed following transient perturbations of EPB41L4A-AS1 that do not affect steady-state SNORA13 levels or the rRNA modification it helps install. Exogenous expression of the full-length EPB41L4A-AS1 locus but not SNORA13 expression can rescue the trans-acting transcriptional effects of its perturbation. The EPB41L4A-AS1 gene is thus a versatile locus producing RNA molecules acting on multiple levels for key cellular functions.

molecular biology↗

bioRxiv2025

The positionally conserved long non-coding RNA DANCR is an essential regulator of zebrafish development and a human melanoma oncogene

Long non-coding RNAs (lncRNAs) can regulate gene expression. Some are essential for organismal development and physiology and can contribute to diseases including cancer. Whilst most lncRNAs exhibit little sequence similarity, conservation of lncRNA transcription relative to neighbouring protein-coding genes suggests potential functional significance. Most positionally equivalent lncRNAs are uncharacterized and it remains unclear whether they exert similar roles in distant species. Here, we identified syntenic melanoma-associated lncRNAs predicted to be components of the MITF gene regulatory network in human melanoma, with positionally equivalent transcripts in zebrafish. We prioritized Differentiation Antagonizing Non-Protein Coding RNA (DANCR), a cancer-associated lncRNA critical for maintaining somatic progenitor cells in human models, for functional investigation. Dancr is a multi-exonic, cytoplasmically-enriched lncRNA transcribed from syntenic regions in the human and zebrafish genomes. MITF and c-MYC, key melanoma transcription factors, regulate human DANCR expression and melanoma patients with high DANCR display significantly decreased survival. DANCR is a melanoma oncogene that controls cancer-associated gene expression networks and promotes human melanoma cell proliferation and migration. Zebrafish dancr is dynamically expressed across multiple different cell types in the developing embryo, regulates genes involved in cell death, and is essential for embryonic development. Our work suggests that cancer-critical lncRNAs such as DANCR, expressed from similar regions in vertebrate genomes, may regulate related genes and processes involved in both embryonic development and tumorigenesis across species.

cancer biology↗

bioRxiv2025

Alterations in background ECoG activity and behavioral deficits in a mouse model of CHD2-related developmental delay

Heterozygous loss of function mutations in the CHD2 gene, encoding for chromodomain helicase DNA-binding protein 2, are associated with severe childhood-onset epilepsy, global developmental delay, and autistic features. Here, we characterized the behavioral and epileptic phenotypes of a mouse model harboring a frameshift truncating mutation in the Chd2 gene (Chd2WT/m and Chd2m/m mice). Genetic background dramatically affected the phenotypes. While no phenotypes were observed on the pure C57BL/6J background, crossing these mice onto the 129X1/SvJ genetic background gradually uncovered neurodevelopmental phenotypes. Transcriptomic analysis identified Kcnj11 as a potential genetic modifier. On the 129X1/SvJ background, Chd2m/m mice demonstrated growth retardation, and both Chd2WT/m and Chd2m/m showed motor deficits, including clasping behavior and reduced abilities to balance on a rotating rod. Autistic-like features were also observed, with Chd2m/m showing reduced nest-building abilities and Chd2WT/m demonstrating increased repetitive-like behavior in the marble burying test and altered social behavior. Quantitative analysis of electrocorticographic (ECoG) recordings revealed neuronal changes consisting of a global reduction in the total power of background activity in Chd2WT/m and Chd2m/m mice, as well as increased susceptibility to seizures induced by acute administration of 4-aminopyridine. Overall, this mouse model recapitulates multiple key phenotypes observed in CHD2 patients, providing a valuable platform to study the molecular basis and treatment options for this intractable disease.

neuroscience↗

bioRxiv2025

BAHCC1 promotes gene expression in neuronal cells by antagonizing SIN3A-HDAC1

Chromatin modifications play a key role in regulating gene expression during development and adult physiology. Histone acetylation, particularly H3K27ac, is associated with increased activity of gene regulatory elements such as enhancers and promoters. However, the regulation of the machinery that write, read, and erase this modification remains poorly understood. In particular, the SIN3A-HDAC1 complex possesses histone deacetylase activity, yet it commonly resides at active regulatory regions. Here, we study BAHCC1, a large chromatin-associated protein essential for viability, and recently reported to play a largely repressive role. We show that in neuronal lineage cells, BAHCC1 is mainly associated with regulatory elements marked with H3K27ac. BAHCC1 interacts and co-occupies shared genomic regions with the SIN3A scaffold protein, and its perturbations lead to altered acetylation and expression of proximal genes in a neuronal cell line and primary cortical neurons. The regulated genes are enriched for those functioning in neurogenesis and cell migration, and primary cortical neurons with reduced Bahcc1 expression display impaired neurite outgrowth. We thus propose a model in which BAHCC1 antagonizes SIN3A histone deacetylation and positively regulates the expression of genes that are important for growth and migration-related processes in the neuronal lineage.

molecular biology↗

bioRxiv2024

Comparative single-cell analyses reveal evolutionary repurposing of a conserved gene program in bat wing development

Bats are the only mammals capable of self-powered flight, an evolutionary innovation based on the transformation of forelimbs into wings. The bat wing is characterized by an extreme elongation of the second to fifth digits and a wing membrane called chiropatagium connecting them. Here we investigated the developmental and cellular origin of this structure by comparing bat and mouse limbs using omics tools and single-cell analyses. Despite the substantial morphological differences between the species, we observed an overall conservation of cell populations and gene expression patterns including interdigital apoptosis. Single-cell analyses of micro-dissected embryonic chiropatagium identified a specific fibroblast population, independent of apoptosis-associated interdigital cells, as the origin of this tissue. These distal cells express a conserved gene program including the transcription factors MEIS2 and TBX3, which are commonly known to specify and pattern the early proximal limb. Transgenic ectopic expression of MEIS2 and TBX3 in mouse distal limb cells resulted in the activation of genes expressed during wing development and phenotypic changes related to wing morphology, such as the fusion of digits. Our results elucidate fundamental molecular mechanisms of bat wing development and illustrate how drastic morphological changes can be achieved through repurposing of existing developmental programs during evolution.

evolutionary biology↗

bioRxiv2024

Conserved RNA-binding protein interactions mediate syntologous lncRNA functions

Syntologous long noncoding RNAs (lncRNAs) are loci with conserved genomic positions that often show little or no sequence similarity. Despite diverging primary sequences, lncRNA syntologs from distant species can carry out similar functions. However, determinants underlying conserved functions of syntologous lncRNA transcripts with no sequence similarity remain unknown. Using CASC15 and melanoma formation as a paradigm for fast evolving lncRNAs and their functions, we found that human and zebrafish CASC15 syntologs with no detectable sequence similarity retained their function across 450 million years of evolution. Similar to the casc15-deficient zebrafish, CASC15-mutant human melanoma cells show increased cell migration. Expression of human CASC15 in zebrafish rescues loss of casc15 function by attenuating melanoma formation. This conserved function is supported by a set of RNA-binding proteins, interacting with both zebrafish and human CASC15 transcripts. Together, our findings demonstrate that conserved RNA-protein interactions can define functions of rapidly evolving lncRNA transcripts.

molecular biology↗

bioRxiv2024

Neuromuscular dysfunction in patient-derived FUSR244RR-ALS iPSC model via axonal downregulation of neuromuscular junction proteins

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative condition characterized by the progressive degeneration of motor neurons, ultimately resulting in death due to respiratory failure. A common feature among ALS cases is the early loss of axons, pointing to defects in axonal transport and translation as initial disease indicators. Here, we established a FUSR244RR-ALS hiPSC-derived model that recapitulates the motor neuron survival and muscle contractility defects characteristic of ALS patients. Analysis of the protein and mRNA expression profiles in axonal and somatodendritic compartments of ALS-afflicted and isogenic control motor neurons revealed a selective downregulation of proteins essential for the neuromuscular junction function in FUS-ALS axons. Furthermore, analysis of FUS CLIP and RIP data showed that FUS binds mRNAs encoding these proteins. This work shed light on the pathogenic mechanisms of ALS and emphasized the importance of axonal gene expression analysis in elucidating the mechanisms of neurodegenerative disorders.

cell biology↗

bioRxiv2024

Systematic analysis of the target recognition and repression by the Pumilio proteins

RNA binding proteins orchestrate the post-transcriptional fate of RNA molecules, but the principles of their action remain poorly understood. Pumilio (PUM) proteins bind 3UTRs of mRNAs and lead to mRNA decay. To comprehensively map the determinants of recognition of sequences by PUM proteins in cells and to study the binding outcomes, we developed a massively parallel RNA assay that profiled thousands of PUM binding sites in cells undergoing various perturbations or RNA immunoprecipitation. By studying fragments from the NORAD long noncoding RNA, we find two features that antagonize repression by PUM proteins - G/C rich sequences, particularly those upstream of the PUM recognition element, and binding of FAM120A, which limits the repression elicited by PUM binding sites. We also find that arrays of PUM sites separated by 8-12 bases offer particularly strong repression and use them to develop a particularly sensitive reporter for PUM repression. In contrast, PUM sites separated by shorter linkers, such as some of those found in NORAD, exhibit strong activity interdependence, likely mediated by competition between PUM binding and formation of strong secondary structures. Overall, our findings expand our understanding of the determinants of PUM protein activity in human cells. HighlightsO_LIA massively parallel assay reports on the binding and activity of Pumilio proteins in human cells C_LIO_LIG/C rich sequence context inhibits repression by Pumilio proteins C_LIO_LIFAM120a binds sequences with Pumilio sites and antagonizes repression by Pumilio proteins C_LIO_LIArrays of Pumilio binding sites are most effective at distances of 8-12 nt. C_LIO_LIStrong inter-dependency in the tandem Pumilio binding sites in NORAD. C_LI

molecular biology↗

bioRxiv2023

CENTRE: A gradient boosting algorithm for Cell-type-specific ENhancer-Target pREdiction

MotivationIdentifying target promoters of active enhancers is a crucial step for realizing gene regulation and deciphering phenotypes and diseases. Up to now, several computational methods were developed to predict enhancer gene interactions but they require either many epigenomic and transcriptomic experimental assays to generate cell-type-specific predictions or a single experiment applied to a large cohort of cell types to extract correlations between activities of regulatory elements. Thus, inferring cell-type-specific enhancer gene interactions in unstudied or poorly annotated cell types becomes a laborious and costly task. ResultsHere, we aim to infer cell-type-specific enhancer target interactions, using minimal experimental input. We introduce CENTRE, a machine learning framework that predicts enhancer target interactions in a cell-type-specific manner, using only gene expression and ChIP-seq data for three histone modifications for the cell type of interest. CENTRE exploits the wealth of available datasets and extracts cell-type agnostic statistics to complement the cell-type specific information. CENTRE is thoroughly tested across many datasets and cell types and achieves equivalent or superior performance than existing algorithms that require massive experimental data. AvailabilityCENTREs open source code is available at GitHub via https://github.com/slrvv/CENTRE

bioinformatics↗

bioRxiv2022

Silc1 long noncoding RNA is an immediate-early gene promoting efficient memory formation

Long noncoding RNAs (lncRNAs) are expressed in many brain circuits and neuronal types, but their significance to normal brain functions has remained largely unknown. Here, we study the functions in the central nervous system of Silc1, a lncRNA we previously showed to be important for neuroregeneration in the peripheral nervous system. We found that Silc1 is rapidly and strongly induced upon stimulation in the hippocampus and is required for efficient spatial learning. Silc1 production is important for the induction of Sox11 (its cis-regulated target gene) throughout the CA1-CA3 regions and the proper expression of key Sox11 target genes. Consistent with its newly found role in neuronal plasticity, we find that during aging and in models of Alzheimers disease Silc1 levels decline. Overall, we uncover a novel plasticity pathway, in which Silc1 acts as an immediate-early gene to activate Sox11 to induce a neuronal growth-associated transcriptional program important for memory formation.

molecular biology↗

bioRxiv2022

LIS1 RNA-binding orchestrates the mechanosensitive properties of embryonic stem cells in AGO2-dependent and independent ways

Lissencephaly-1 (LIS1) is associated with neurodevelopmental diseases and is known to regulate the activity of the molecular motor cytoplasmic dynein. Here we show that LIS1 is essential for the viability of mouse embryonic stem cells (mESCs), and it regulates the physical properties of these cells. LIS1 dosage substantially affects gene expression, and we uncovered an unexpected interaction of LIS1 with RNA and RNA-binding proteins, most prominently the Argonaute complex. We demonstrate that LIS1 overexpression partially rescued the expression of extracellular matrix (ECM) and mechanosensitive genes conferring stiffness to Argonaute null mESCs. Collectively, our data transforms the current perspective on the roles of LIS1 in post- transcriptional regulation underlying development and mechanosensitive processes.

cell biology↗

bioRxiv2021

Polyclonal lymphoid expansion drives paraneoplastic autoimmunity in neuroblastoma

Neuroblastoma is a lethal childhood solid tumor of developing peripheral nerves. Two percent of children with neuroblastoma develop Opsoclonus Myoclonus Ataxia Syndrome (OMAS), a paraneoplastic disease characterized by cerebellar and brainstem-directed autoimmunity, but typically with outstanding cancer-related outcomes. We compared tumor transcriptomes and tumor infiltrating T- and B-cell repertoires from 38 OMAS subjects with neuroblastoma to 26 non- OMAS associated neuroblastomas. We found greater B- and T-cell infiltration in OMAS- associated tumors compared to controls, but unexpectedly showed that both were polyclonal expansions. Tertiary lymphoid structures (TLS) were enriched in OMAS-associated tumors. We identified significant enrichment of the MHC Class II allele HLA-DOB*01:01 in OMAS patients. OMAS severity scores were associated with the expression of several candidate autoimmune genes. We propose a model in which polyclonal autoreactive B lymphocytes act as antigen presenting cells and drive TLS formation, thereby crucially supporting both sustained polyclonal T-cell-mediated anti-tumor immunity and paraneoplastic OMAS neuropathology.

cancer biology↗

bioRxiv2021

Structural features within the NORAD long noncoding RNA underlie efficient repression of Pumilio activity

It is increasingly appreciated that long non-coding RNAs (lncRNAs) carry out important functions in mammalian cells, but how these are encoded in their sequences and manifested in their structures remains largely unknown. Some lncRNAs bind to and modulate the availability of RNA binding proteins, but the structural principles that underlie this mode of regulation are underexplored. Here, we focused on the NORAD lncRNA, which binds Pumilio proteins and modulates their ability to repress hundreds of mRNA targets. We probed the RNA structure and long-range RNA-RNA interactions formed by NORAD inside cells, under different stressful conditions. We discovered that NORAD structure is highly modular, and consists of well-defined domains that contribute independently to NORAD function. We discovered that NORAD structure spatially clusters the Pumilio binding sites along NORAD in a manner that contributes to the de-repression of Pumilio target proteins. Following arsenite stress, the majority of NORAD structure undergoes relaxation and forms inter-molecular interactions with RNAs that are targeted to stress granules. NORAD sequence thus dictates elaborated structural domain organization that facilitates its function on multiple levels, and which helps explain the extensive evolutionary sequence conservation of NORAD regions that are not predicted to directly bind Pumilio proteins.

molecular biology↗

bioRxiv2021

Massively parallel identification of zipcodes in primary cortical neurons

Cells adopt highly polarized shapes and form distinct subcellular compartments largely due to the localization of many mRNAs to specific areas, where they are translated into proteins with local functions. This mRNA localization is mediated by specific cis-regulatory elements in mRNAs, commonly called "zipcodes." Their recognition by RNA-binding proteins (RBPs) leads to the integration of the mRNAs into macromolecular complexes and their localization. While there are hundreds of localized mRNAs, only a few zipcodes have been characterized. Here, we describe a novel neuronal zipcode identification protocol (N-zip) that can identify zipcodes across hundreds of 3UTRs. This approach combines a method of separating the principal subcellular compartments of neurons - cell bodies and neurites - with a massively parallel reporter assay. Our analysis identifies the let-7 binding site and (AU)n motif as de novo zipcodes in mouse primary cortical neurons and suggests a strategy for detecting many more.

molecular biology↗

bioRxiv2021

Unique features of transcription termination and initiation at closely spaced tandem human genes

The synthesis of RNA Polymerase II (Pol2) products, which include messenger RNAs or long noncoding RNAs, culminates in transcription termination. How the transcriptional termination of a gene impacts the activity of promoters found immediately downstream of it, and which can be subject to potential transcriptional interference, remains largely unknown. We examined in an unbiased manner features of the intergenic region of pairs of tandem and closely spaced (<2kb) genes found on the same strand. Intergenic regions separating tandem genes are enriched with Guanines and are characterized by binding of several proteins, including AGO1 and AGO2 of the RNA interference pathway. Additionally, we found that Pol2 with a specific modification pattern is particularly enriched in this region, and it is lost upon perturbations affecting splicing or transcriptional elongation. Perturbations of genes involved in Pol2 pausing and R loop biology preferentially affect expression of downstream genes in tandem gene pairs. Overall, we find that features associated with potential Pol2 recycling rather than those associated with avoidance of transcriptional interference are the predominant driving force shaping these regions.

genomics↗