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Valosin-containing protein (VCP) is a hexameric ATPase associated with diverse cellular activities. Genetic mutations in VCP are associated with several forms of muscular and neuronal degeneration, including amyotrophic lateral sclerosis (ALS). Moreover, VCP mediates UV-induced proteolysis of RNA polymerase II (RNAPII), but little is known about the effects of VCP mutations on the transcriptional machinery. Here, we used silica particle-assisted chromatin enrichment and mass spectrometry to study proteins co-localized with RNAPII in precursor neurons differentiated from VCP-mutant or control induced pluripotent stem cells. Remarkably, we observed diminished RNAPII binding of proteins involved in transcription elongation and mRNA splicing in mutant cells. One of these is SART3, a recycling factor of the splicing machinery, whose knockdown leads to perturbed intron retention in several ALS-associated genes. Additional reduced proteins are RBM45, EIF5A and RNF220, mutations in which are associated with various neurodegenerative disorders and are linked to TDP-43 aggregation. Conversely, we observed increased RNAPII binding of heat shock proteins such as HSPB1. Together, these findings shed light on how transcription and splicing machinery are impaired by VCP mutations, which might contribute to aberrant alternative splicing and proteinopathy in neurodegeneration.

FOXL2 is a transcription factor essential for female fertility, expressed in somatic cells of the ovary, notably granulosa cells. In the mouse,Foxl2deletion leads to partial sex reversal postnatally, with mutants developing dysgenic ovaries devoid of oocytes. However, deletion of the gene in 8-week-old females leads to granulosa to Sertoli cell transdifferentiation and gonadal sex reversal. We hypothesise that different outcomes ofFoxl2deletion in embryonic versus adult ovary may derive from a different role played by FOXL2 across ovarian development. Therefore, in this study, we take a multi-omics approach to characterise the dynamics of gene expression and chromatin accessibility changes in purified murine granulosa cells across key developmental stages (E14.5, 1 and 8 weeks). We coupled these analyses with genome wide identification of FOXL2 target genes and on-chromatin interacting partners by ChIP-SICAP to reconstruct the gene regulatory networks underpinned by this essential transcription factor. In the embryonic ovary, FOXL2 interacts with factors important for early stages of gonadal development, such as GATA4 and WT1, whilst postnatally it interacts with factors regulating primordial follicle activation, such as NR5A2, and with factors regulating steroidogenesis including AR and ESR2. Integration of chromatin landscape dynamics with gene expression changes and FOXL2 binding sites analysis revealed that its critical role in ovarian cell fate maintenance goes beyond repression of the Sertoli-specific geneSox9. Our chromatome analysis revealed also that FOXL2 interacts with several proteins involved in chromatin remodelling, DNA repair, splicing and gene repression. In summary, in this study we identified target genes dynamically regulated by FOXL2 across ovarian development including known and newly identified FOXL2 targets with a role in embryonic ovarian development and folliculogenesis, as well as cofactors that point towards additional roles played by FOXL2 besides transcriptional regulation. This work constitutes a comprehensive resource for exploration of the molecular mechanisms of ovarian development and causes of female infertility.

RNA-binding proteins (RBPs) play diverse roles in regulating co-transcriptional RNA-processing and chromatin functions, but our knowledge of the repertoire of chromatin-associated RBPs (caRBPs) and their interactions with chromatin remains limited. Here, we developed SPACE (Silica Particle Assisted Chromatin Enrichment) to isolate global and regional chromatin components with high specificity and sensitivity, and SPACEmap to identify the chromatin-contact regions in proteins. Applied to mouse embryonic stem cells, SPACE identified 1459 chromatin-associated proteins, ∼48% of which are annotated as RBPs, indicating their dual roles in chromatin and RNA-binding. Additionally, SPACEmap stringently verified chromatin-binding of 403 RBPs and identified their chromatin-contact regions. Notably, SPACEmap showed that about 40% of the caRBPs bind chromatin by intrinsically disordered regions (IDRs). Studying SPACE and total proteome dynamics from mES cells grown in 2iL and serum medium indicates significant correlation (R = 0.62). One of the most dynamic caRBPs is Dazl, which we find co-localized with PRC2 at transcription start sites of genes that are distinct from Dazl mRNA binding. Dazl and other PRC2-colocalised caRBPs are rich in intrinsically disordered regions (IDRs), which could contribute to the formation and regulation of phase-separated PRC condensates. Together, our approach provides an unprecedented insight into IDR-mediated interactions and caRBPs with moonlighting functions in native chromatin., Graphical Abstract Graphical AbstractSPACE, SPACEmap and ChIP-SPACE are highly sensitive and stringent approaches for identification of chromatin-associated proteins and their chromatin-contact regions.

Integrator is a multi-subunit complex that directly interacts with the C-terminal domain (CTD) of RNA polymerase II (RNAPII). Through its RNA endonuclease activity, Integrator is required for 3′-end processing of both non-coding and coding transcripts. Here we demonstrate that depleting Integrator subunit 11 (INTS11), the main catalytic subunit of the Integrator complex, leads to a global elongation defect as a result of decreased polymerase processivity. We observe this defect in the region approximately 12 to 35 kb downstream of the transcription start site (TSS), where RNAPII normally transitions to its maximum processivity. We also identify an important role for INTS11, possibly in association with RNAPII CTD phospho-Tyr1, in repressing antisense transcription upstream of active promoters, as well as repressing transcription of genic regions near AsiSI-induced double-strand breaks.Altogether, this study points toward a novel function of Integrator in promoting termination of incompetent RNAPII molecules while facilitating the transition to fully processive polymerase in order to enable efficient elongation.

Altered glycoprotein expression is an undisputed corollary of cancer development. Understanding these alterations is paramount but hampered by limitations underlying cellular model systems. For instance, the intricate interactions between tumour and host cannot be adequately recapitulated in monoculture of tumour-derived cell lines. More complex co-culture models usually rely on sorting procedures for proteome analyses and rarely capture the details of protein glycosylation. Here, we report a strategy termed Bio-Orthogonal Cell line-specific Tagging of Glycoproteins (BOCTAG). Cells are equipped by transfection with an artificial biosynthetic pathway that transforms bioorthogonally tagged sugars into the corresponding nucleotide-sugars. Only transfected cells incorporate bioorthogonal tags into glycoproteins in the presence of non-transfected cells. We employ BOCTAG as an imaging technique and to annotate cell-specific glycosylation sites in mass spectrometry-glycoproteomics. We demonstrate application in co-culture and mouse models, allowing for profiling of the glycoproteome as an important modulator of cellular function.

Transcription factors (TFs) control cell fates by precisely orchestrating gene expression. However, how individual TFs promote transcriptional diversity remains unclear. Here, we use the Hox TF Ultrabithorax (Ubx) as a model to explore how a single TF specifies multiple cell types. Using proximity-dependent Biotin IDentification in Drosophila, we identify Ubx interactomes in three embryonic tissues. We find that Ubx interacts with largely non-overlapping sets of proteins with few having tissue-specific RNA expression. Instead most interactors are active in many cell types, controlling gene expression from chromatin regulation to the initiation of translation. Genetic interaction assays in vivo confirm that they act strictly lineage- and process-specific. Thus, functional specificity of Ubx seems to play out at several regulatory levels and to result from the controlled restriction of the interaction potential by the cellular environment. Thereby, it challenges long-standing assumptions such as differential RNA expression as determinant for protein complexes., Many transcription factors regulate gene expression in a lineage- and process-specific manner, despite being expressed in several cell types. Here, the authors show that the Hox transcription factor Ubx has lineage-specific interactomes, which contribute to its cell context-dependent functions.

Summary Gonadal sexual fate in mammals is determined during embryonic development and must be actively maintained in adulthood. Therefore, gonadal sex-specific transcription factors are required to prevent transdifferentiation of gonadal somatic cells to the other sexual fate. Mouse genetic experiments have shown that oestrogen receptor signalling and the transcription factor FOXL2 protect ovarian granulosa cells from transdifferentiation into Sertoli cells, their testicular counterpart. However, the mechanism underlying this protective mechanism is unknown. Here, we show that one post-translational modification (i.e. SUMOylation catalysed by TRIM28) is sufficient to prevent female-to-male sex reversal of the mouse ovary after birth. We found that upon loss of TRIM28 SUMO-E3 ligase activity, ovarian granulosa cells transdifferentiate to Sertoli cells through an intermediate cell type different from gonadal embryonic progenitors. TRIM28 binds to chromatin close to the critical transcription factor FOXL2 to maintain the female pathway through SUMOylation of specific chromatin regions. Therefore, FOXL2 signalling might maintain the adult ovary cell fate via TRIM28-dependent SUMOylation. Improper SUMOylation of chromatin regions in granulosa cells might lead to female reproductive disorders and infertility, the incidence of which is currently increasing.

Functionalization of the genome is carried out by proteins that bind to DNA to regulate gene expression. Since this process is highly dynamic, context-dependent, and rarely performed by single proteins alone, we here describe ChIP-SICAP to identify proteins that co-localize with a protein of interest on the genome. Benefiting from its nature as a dual purification approach via ChIP and DNA biotinylation, ChIP-SICAP distinguishes genuine chromatin-binders and is uniquely placed to identify novel players in genome regulation.

Functionalization of the genome is carried out by proteins that bind to DNA to regulate gene expression. Since this process is highly dynamic, context-dependent, and rarely performed by single proteins alone, we here describe ChIP-SICAP to identify proteins that co-localize with a protein of interest on the genome. Benefiting from its nature as a dual purification approach via ChIP and DNA biotinylation, ChIP-SICAP distinguishes genuine chromatin-binders and is uniquely placed to identify novel players in genome regulation.

Summary Regulatory T cells are important regulators of the immune system and have versatile functions for the homeostasis and repair of tissues. They express the forkhead box transcription factor Foxp3 as a lineage-defining protein. Negative regulators of Foxp3 expression are not well understood. Here, we generated double-stranded DNA probes complementary to the Foxp3 promoter sequence and performed a pull-down with nuclear protein in vitro, followed by elution of bound proteins and quantitative mass spectrometry. Of the Foxp3-promoter-binding transcription factors identified with this approach, one was T cell factor 1 (TCF1). Using viral over-expression, we identified TCF1 as a repressor of Foxp3 expression. In TCF1-deficient animals, increased levels of Foxp3intermediateCD25negative T cells were identified. CRISPR-Cas9 knockout studies in primary human and mouse conventional CD4 T (Tconv) cells revealed that TCF1 protects Tconv cells from inadvertent Foxp3 expression. Our data implicate a role of TCF1 in suppressing Foxp3 expression in activated T cells., Graphical Abstract, Highlights • Quantitative proteomics identifies proteins bound to the Foxp3 gene promoter • Promoter-binding proteins are suppressing Foxp3 expression • TCF1-deficient animals have more Foxp3-expressing CTLA4−CD25−CD4+ T cells • TCF1 suppresses Foxp3 expression in activated non-Treg cells, Molecular Biology; Molecular Mechanism of Gene Regulation; Immunology; Proteomics

Chromatin immunoprecipitation combined with mass spectrometry (ChIP-MS) suffers from unexpected proteins that bind to chromatin during the cell lysis and immunoprecipitation (IP). The so-called hitchhikers of chromatin are hardly washed away by gentle washing steps applied to a normal IP protocol. We employed DNA end-labeling by Terminal Transferase (TdT) to purify proteins specifically bound to chromatin. Using this double purification strategy, chromatin fragments are released from IP beads, and re-captured by streptavidin beads. Thus, we can apply stringent conditions to remove the hitchhikers of chromatin, and to identify authentic proteins co-localized with the protein of interest. We call this protocol Selective Isolation of Chromatin-Associated Proteins (SICAP). So far, ChIP-SICAP was successfully applied to different cell lines such mouse ES cells, mouse fibroblast cells, HEK 293T, HeLa, U2OS as well as mouse and human tissues. Here, we share the most updated version of our protocol. If you have any questions please feel free to email us.

Streptavidin‐mediated enrichment is a powerful strategy to identify biotinylated biomolecules and their interaction partners; however, intense streptavidin‐derived peptides impede protein identification by mass spectrometry. Here, we present an approach to chemically modify streptavidin, thus rendering it resistant to proteolysis by trypsin and LysC. This modification results in over 100‐fold reduction of streptavidin contamination and in better coverage of proteins interacting with various biotinylated bait molecules (DNA, protein, and lipid) in an overall simplified workflow., Many proteomic studies rely on streptavidin‐based purifications. To avoid streptavidin contamination, this study presents a straightforward protocol to prevent its proteolytic digestion. Protein identification rates are improved in various applications.

Simple Summary Chemotherapy is a commonly applied anticancer treatment, however therapy-induced senescent growth arrest has been associated with aggressive disease recurrence. The p21 protein, encoded by CDKN1A, plays a vital role in the induction of senescence. Its transcriptional control by p53 is well-established. However, in many cancers where TP53 is mutated, p21 expression must be triggered by p53-independent mechanisms. We here used a chromatin-directed proteomic approach and identified ZNF84 as a regulator of CDKN1A gene expression in various p53-deficient cell lines. Knock-down of ZNF84, an as-yet un-characterized protein, inhibited p21 gene and protein expression in response to doxorubicin and facilitated senescence bypass. Intriguingly, ZNF84 depletion diminished genotoxic burden evoked by doxorubicin. Clinical data association studies indicated the relevance of ZNF84 expression for patient survival. Collectively, we identified ZNF84 as a critical regulator of senescence-proliferation outcome of chemotherapy, opening possibilities for its targeting in novel anti-cancer therapies of p53-mutated tumours. Abstract The p21WAF1/Cip1 protein, encoded by CDKN1A, plays a vital role in senescence, and its transcriptional control by the tumour suppressor p53 is well-established. However, p21 can also be regulated in a p53-independent manner, by mechanisms that still remain less understood. We aimed to expand the knowledge about p53-independent senescence by looking for novel players involved in CDKN1A regulation. We used a chromatin-directed proteomic approach and identified ZNF84 as a novel regulator of p21 in various p53-deficient cell lines treated with cytostatic dose of doxorubicin. Knock-down of ZNF84, an as-yet un-characterized protein, inhibited p21 gene and protein expression in response to doxorubicin, it attenuated senescence and was associated with enhanced proliferation, indicating that ZNF84-deficiency can favor senescence bypass. ZNF84 deficiency was also associated with transcriptomic changes in genes governing various cancer-relevant processes e.g., mitosis. In cells with ZNF84 knock-down we discovered significantly lower level of H2AX Ser139 phosphorylation (γH2AX), which is triggered by DNA double strand breaks. Intriguingly, we observed a reverse correlation between the level of ZNF84 expression and survival rate of colon cancer patients. In conclusion, ZNF84, whose function was previously not recognized, was identified here as a critical p53-independent regulator of senescence, opening possibilities for its targeting in novel therapies of p53-null cancers.

Summary Maintenance of pluripotency is regulated by a network of transcription factors coordinated by Oct4, Sox2, and Nanog (OSN), yet a systematic investigation of the composition and dynamics of the OSN protein network specifically on chromatin is still missing. Here we have developed a method combining ChIP with selective isolation of chromatin-associated proteins (SICAP) followed by mass spectrometry to identify chromatin-bound partners of a protein of interest. ChIP-SICAP in mouse embryonic stem cells (ESCs) identified over 400 proteins associating with OSN, including several whose interaction depends on the pluripotent state. Trim24, a previously unrecognized protein in the network, converges with OSN on multiple enhancers and suppresses the expression of developmental genes while activating cell cycle genes. Consistently, Trim24 significantly improved efficiency of cellular reprogramming, demonstrating its direct functionality in establishing pluripotency. Collectively, ChIP-SICAP provides a powerful tool to decode chromatin protein composition, further enhanced by its integrative capacity to perform ChIP-seq., Graphical Abstract, Highlights • ChIP-SICAP isolates and identifies proteins that colocalize on chromatin • Chromatin composition around Oct4, Sox2, and Nanog depends on the pluripotent state • Trim24 is part of the pluripotency network and promotes reprogramming • ChIP-SICAP allows recovery of DNA for sequencing with ChIP-seq quality, Rafiee et al. introduce ChIP-SICAP as a novel method to identify chromatin-bound proteins that colocalize with a bait protein on DNA. Applied to Oct4, Sox2, and Nanog in ESCs, they identify Trim24 as a novel protein that is functionally involved in the pluripotency network by promoting cellular reprogramming.

The molecular genotyping of individuals and reconstruction of kinship through short and highly polymorphic DNA markers, so called short tandem repeats (STR), has become one of the important and efficient methods in anthropology studies and forensic science. Although many populations have been analyzed, no study has yet been carried out on Sadat populations who are putative descendents of Prophet Mohammad (peace be upon him). Polymorphisms of 6 Y-STR loci (DYS19, DYS385a/b, DYS389II, DYS390, DYS392, and DYS393) have been studied in an unrelated population of Sadat males. The aim of this study was to find possible similarities within Sadat males, resided in Iran. Among Sadat, DYS385b was proved to be the most polymorphic (GD = 0.8588), and DYS392 showed the lowest polymorphism (GD = 0.3527). In 50 samples, 45 different haplotypes were found, of which 39 haplotypes were unique. In the study, three samples had multi-allelic patterns. Haplotype diversity, in regard to these 7 markers was 0.9942.

Long noncoding RNAs (lncRNAs) have emerged as new regulators of stem cell pluripotency and tumorigenesis. The SOX2 gene, a master regulator of pluripotency, is embedded within the third intron of a lncRNA known as SOX2 overlapping transcript (SOX2OT). SOX2OT has been suspected to participate in regulation of SOX2 expression and/or other related processes; nevertheless, its potential involvement in tumor initiation and/or progression is unclear. Here, we have evaluated a possible correlation between expression patterns of SOX2OT and those of master regulators of pluripotency, SOX2 and OCT4, in esophageal squamous cell carcinoma (ESCC) tissue samples. We have also examined its potential function in the human embryonic carcinoma stem cell line, NTERA2 (NT2), which highly expresses SOX2OT, SOX2, and OCT4. Our data revealed a significant coupregulation of SOX2OT along with SOX2 and OCT4 in tumor samples, compared to the non-tumor tissues obtained from the margin of same tumors. We also identified two novel splice variants of SOX2OT (SOX2OT-S1 and SOX2OT-S2) which coupregulated with SOX2 and OCT4 in ESCCs. Suppressing SOX2OT variants caused a profound alteration in cell cycle distribution, including a 5.9 and 6.9 time increase in sub-G1 phase of cell cycle for SOX2OT-S1 and SOX2OT-S2, respectively. The expression of all variants was significantly diminished, upon the induction of neural differentiation in NT2 cells, suggesting their potential functional links to the undifferentiated state of the cells. Our data suggest a part for SOX2OT spliced variants in tumor initiation and/or progression as well as regulating pluripotent state of stem cells. Stem Cells 2014;32:126–134

Generation of induced pluripotent stem cells (iPSCs) is a process whose mechanistic underpinnings are only beginning to emerge. Here, we applied in-depth quantitative proteomics to monitor proteome changes during the course of reprogramming of fibroblasts to iPSCs. We uncover a 2-step resetting of the proteome during the first and last three days of reprogramming, with multiple functionally related proteins changing in expression in a highly coordinated fashion. This comprised several biological processes with a previously unknown role in reprogramming, including changes in the stoichiometry of electron transport-chain complexes, repressed vesicle-mediated transport during the intermediate stage and an EMT-like process in the late phase. In addition, we demonstrate that the nucleoporin Nup210 is essential for reprogramming by permitting rapid cellular proliferation and subsequent progression through MET. Along with the identification of proteins expressed in a stage-specific manner, this study provides a rich resource towards an enhanced mechanistic understanding of cellular reprogramming.

PURPOSE: To investigate and compare the expression of OCT4B1 between tumor and non-tumor bladder tissues. MATERIALS AND METHODS: We investigated the expression of OCT4B1 in 30 tumor and non-tumor surgical specimens of the bladder, using the TaqMan real-time polymerase chain reaction approach and by carefully designing primers and probes specific for the amplification of the variant. RESULTS: Most tumor and non-tumor samples of the bladder showed OCT4B1 expression, but its expression level was significantly higher in the tumors (P < .002). Moreover, the up-regulation of OCT4B1 was more significant in high-grade tumors compared to the low-grade ones (P < .05). We have also employed the RNA interference strategy to evaluate the functional role of OCT4B1 in a bladder cancer cell line, 5637. Suppression of OCT4B1 caused some changes in cell cycle distribution, and significantly elevated the rate of apoptosis in the cells. CONCLUSION: Our findings suggest that OCT4B1 plays a potential role in tumor initiation and/or progression of the bladder cancer. Additionally, OCT4B1 can be regarded as a new tumor marker for detection, classification, and treatment of the bladder cancer. However, more experimental studies are needed to replicate our findings.

Strain XII, a moderately halophilic bacterium, expressed a peptide in response to saline media. This peptide was designated as salt-inducible factor (Sif-A). The purpose of this study is to describe Sif-A, which might be involved in the osmoresistance mechanism of strain XII. The complete sequence of sif-A was determined using PCR. sif-A codes for a polypeptide of 20.518 kDa. The polypeptide has a putative signal peptide of 27 amino acids (2.667 kDa) preceding the mature protein (17.869 kDa). Motif analysis of the deduced amino acid sequence indicated that there is a p-loop NTPase domain on the C-terminal of the peptide, which might correlate with its function. The sequence of the 16S rRNA gene was analyzed phylogenetically to classify strain XII. This organism was found to have the closest association with Virgibacillus halodenitrificans, which was proven by its phenotypic characteristics.

Deregulation of the EVI1 proto-oncogene by the GATA2 distal hematopoietic enhancer (G2DHE) is a key event in high-risk acute myeloid leukemia carrying 3q21q26 aberrations (3q-AML). Upon chromosomal rearrangement, G2DHE acquires characteristics of a super-enhancer and causes overexpression of EVI1 at 3q26.2. However, the transcription factor (TF) complex of G2DHE remains poorly characterized. The aim of this study was to unravel key components of G2DHE-bound TFs involved in the deregulation of EVI1. We have identified several CEBPA and RUNX1 binding sites to be enriched and critical for G2DHE function in 3q-AML cells. Using ChIP-SICAP (ChIP followed by selective isolation of chromatin-associated proteins), a panel of chromatin interactors of RUNX1 and CEBPA were detected in 3q-AML, including PARP1 and IKZF1. PARP1 inhibition (PARPi) caused a reduction of EVI1 expression and a decrease in EVI1–G2DHE interaction frequency, highlighting the involvement of PARP1 in oncogenic super-enhancer formation. Furthermore, 3q-AML cells were highly sensitive to PARPi and displayed morphological changes with higher rates of differentiation and apoptosis as well as depletion of CD34 + cells. In summary, integrative analysis of the 3q-AML super-enhancer complex identified CEBPA and RUNX1 associated proteins and nominated PARP1 as a potential new therapeutic target in EVI1 + 3q-AML.