Transcription Machinery Research Articles

Architecture of the spinach plastid-encoded RNA polymerase.

The plastid-encoded RNA polymerase serves as the principal transcription machinery within chloroplasts, transcribing over 80% of all primary plastid transcripts. This polymerase consists of a prokaryotic-like core enzyme known as the plastid-encoded RNA polymerase core, and is supplemented by newly evolved associated proteins known as PAPs. However, the architecture of the plastid-encoded RNA polymerase and the possible functions of PAPs remain unknown. Here, we present the cryo-electron microscopy structure of a 19-subunit plastid-encoded RNA polymerase complex derived from spinach (Spinacia oleracea). The structure shows that the plastid-encoded RNA polymerase core resembles bacterial RNA polymerase. Twelve PAPs and two additional proteins (FLN2 and pTAC18) bind at the periphery of the plastid-encoded RNA polymerase core, forming extensive interactions that may facilitate complex assembly and stability. PAPs may also protect the complex against oxidative damage and has potential functions in transcriptional regulation. This research offers a structural basis for future investigations into the functions and regulatory mechanisms governing the transcription of plastid genes.

Thermo-amplifier circuit in probiotic E. coli for stringently temperature-controlled release of a novel antibiotic.

Peptide drugs have seen rapid advancement in biopharmaceutical development, with over 80 candidates approved globally. Despite their therapeutic potential, the clinical translation of peptide drugs is hampered by challenges in production yields and stability. Engineered bacterial therapeutics is a unique approach being explored to overcome these issues by using bacteria to produce and deliver therapeutic compounds at the body site of use. A key advantage of this technology is the possibility to control drug delivery within the body in real time using genetic switches. However, the performance of such genetic switches suffers when used to control drugs that require post-translational modifications or are toxic to the host. In this study, these challenges were experienced when attempting to establish a thermal switch for the production of a ribosomally synthesized and post-translationally modified peptide antibiotic, darobactin, in probiotic E. coli. These challenges were overcome by developing a thermo-amplifier circuit that combined the thermal switch with a T7 RNA Polymerase. Due to the orthogonality of the Polymerase, this strategy overcame limitations imposed by the host transcriptional machinery. This circuit enabled production of pathogen-inhibitory levels of darobactin at 40°C while maintaining leakiness below the detection limit at 37°C. Furthermore, the thermo-amplifier circuit sustained gene expression beyond the thermal induction duration such that with only 2h of induction, the bacteria were able to produce pathogen-inhibitory levels of darobactin. This performance was maintained even in physiologically relevant simulated conditions of the intestines that include bile salts and low nutrient levels.

Transcription regulation by biomolecular condensates.

Biomolecular condensates regulate transcription by dynamically compartmentalizing the transcription machinery. Classic models of transcription regulation focus on the recruitment and regulation of RNA polymerase II by the formation of complexes at the 1-10 nm length scale, which are driven by structured and stoichiometric interactions. These complexes are further organized into condensates at the 100-1,000 nm length scale, which are driven by dynamic multivalent interactions often involving domain-ligand pairs or intrinsically disordered regions. Regulation through condensate-mediated organization does not supersede the processes occurring at the 1-10 nm scale, but it provides regulatory mechanisms for promoting or preventing these processes in the crowded nuclear environment. Regulation of transcription by transcriptional condensates is involved in cell state transitions during animal and plant development, cell signalling and cellular responses to the environment. These condensate-mediated processes are dysregulated in developmental disorders, cancer and neurodegeneration. In this Review, we discuss the principles underlying the regulation of transcriptional condensates, their roles in physiology and their dysregulation in human diseases.

HnRNPA2B1 deacetylation by SIRT6 restrains local transcription and safeguards genome stability.

Repair of double strand breaks (DSBs) by RNA-binding proteins (RBPs) is vital for ensuring genome integrity. DSB repair is accompanied by local transcriptional repression in the vicinity of transcriptionally active genes, but the mechanism by which RBPs regulate transcriptional regulation is unclear. Here, we demonstrated that RBP hnRNPA2B1 functions as a RNA polymerase-associated factor that stabilizes the transcription complex under physiological conditions. Following a DSB, hnRNPA2B1 is released from damaged chromatin, reducing the efficiency of RNAPII complex assembly, leading to local transcriptional repression. Mechanistically, SIRT6 deacetylates hnRNPA2B1 at K113/173 residues, enforcing its rapid detachment from DSBs. This process disrupts the integrity of the RNAPII complex on active chromatin, which is a pre-requisite for transient but complete repression of local transcription. Functionally, the overexpression of an acetylation mimic stabilizes the transcription complex and facilitates the functioning of the transcription machinery. hnRNPA2B1 acetylation status was negatively correlated with SIRT6 expression, and acetylation mimic enhanced radio-sensitivity in vivo. Our findings demonstrate that hnRNPA2B1 is crucial for transcriptional repression. We have uncovered the missing link between DSB repair and transcriptional regulation in genome stability maintenance, highlighting the potential of hnRNPA2B1 as a therapeutic target.

Redox regulation, protein S-nitrosylation, and synapse loss in Alzheimer's and related dementias.

Redox-mediated posttranslational modification, as exemplified by protein S-nitrosylation, modulates protein activity and function in both health and disease. Here, we review recent findings that show how normal aging, infection/inflammation, trauma, environmental toxins, and diseases associated with protein aggregation can each trigger excessive nitrosative stress, resulting in aberrant protein S-nitrosylation and hence dysfunctional protein networks. These redox reactions contribute to the etiology of multiple neurodegenerative disorders as well as systemic diseases. In the CNS, aberrant S-nitrosylation reactions of single proteins or, in many cases, interconnected networks of proteins lead to dysfunctional pathways affecting endoplasmic reticulum (ER) stress, inflammatory signaling, autophagy/mitophagy, the ubiquitin-proteasome system, transcriptional and enzymatic machinery, and mitochondrial metabolism. Aberrant protein S-nitrosylation and transnitrosylation (transfer of nitric oxide [NO]-related species from one protein to another) trigger protein aggregation, neuronal bioenergetic compromise, and microglial phagocytosis, all of which contribute to the synapse loss that underlies cognitive decline in Alzheimer's disease and related dementias.

MoaB2, a newly identified transcription factor, binds to σA in Mycobacterium smegmatis.

In mycobacteria, σA is the primary sigma factor. This essential protein binds to RNA polymerase (RNAP) and mediates transcription initiation of housekeeping genes. Our knowledge about this factor in mycobacteria is limited. Here, we performed an unbiased search for interacting partners of Mycobacterium smegmatis σA. The search revealed a number of proteins; prominent among them was MoaB2. The σA-MoaB2 interaction was validated and characterized by several approaches, revealing that it likely does not require RNAP and is specific, as alternative σ factors (e.g., closely related σB) do not interact with MoaB2. The structure of MoaB2 was solved by X-ray crystallography. By immunoprecipitation and nuclear magnetic resonance, the unique, unstructured N-terminal domain of σA was identified to play a role in the σA-MoaB2 interaction. Functional experiments then showed that MoaB2 inhibits σA-dependent (but not σB-dependent) transcription and may increase the stability of σA in the cell. We propose that MoaB2, by sequestering σA, has a potential to modulate gene expression. In summary, this study has uncovered a new binding partner of mycobacterial σA, paving the way for future investigation of this phenomenon.IMPORTANCEMycobacteria cause serious human diseases such as tuberculosis and leprosy. The mycobacterial transcription machinery is unique, containing transcription factors such as RbpA, CarD, and the RNA polymerase (RNAP) core-interacting small RNA Ms1. Here, we extend our knowledge of the mycobacterial transcription apparatus by identifying MoaB2 as an interacting partner of σA, the primary sigma factor, and characterize its effects on transcription and σA stability. This information expands our knowledge of interacting partners of subunits of mycobacterial RNAP, providing opportunities for future development of antimycobacterial compounds.

Harnessing the optimization of enzyme catalytic rates in engineering of metabolic phenotypes.

The increasing availability of enzyme turnover number measurements from experiments and of turnover number predictions from deep learning models prompts the use of these enzyme parameters in precise metabolic engineering. Yet, there is no computational approach that allows the prediction of metabolic engineering strategies that rely on the modification of turnover numbers. It is also unclear if modifications of turnover numbers without alterations in the host's transcriptional regulatory machinery suffice to increase the production of chemicals of interest. Here, we present a constraint-based modeling approach, termed Overcoming Kinetic rate Obstacles (OKO), that uses enzyme-constrained metabolic models to predict in silico strategies to increase the production of a given chemical, while ensuring specified cell growth. We demonstrate that the application of OKO to enzyme-constrained metabolic models of Escherichia coli and Saccharomyces cerevisiae results in strategies that can at least double the production of over 40 compounds with little penalty to growth. Interestingly, we show that the overproduction of compounds of interest does not entail only an increase in the values of turnover numbers. Lastly, we demonstrate that a refinement of OKO, allowing also for manipulation of enzyme abundance, facilitates the usage of the available compendia and deep learning models of turnover numbers in the design of precise metabolic engineering strategies. Our results expand the usage of genome-scale metabolic models toward the identification of targets for protein engineering, allowing their direct usage in the generation of innovative metabolic engineering designs for various biotechnological applications.

Multi-Modal Analysis of human Hepatic Stellate Cells identifies novel therapeutic targets for Metabolic Dysfunction-Associated Steatotic Liver Disease

Background and aimsMetabolic dysfunction-associated steatotic liver disease (MASLD) ranges from Metabolic dysfunction-associated steatotic liver (MASL) to Metabolic dysfunction-associated steatohepatitis (MASH) with fibrosis. Activation of Hepatic Stellate Cells (HSCs) into fibrogenic myofibroblasts plays a critical role in the pathogenesis of MASH liver fibrosis. We compared transcriptome and chromatin accessibility of human HSCs from NORMAL, MASL, and MASH livers at single cell resolution. We aimed to identify genes that are upregulated in activated HSCs and to determine which of these genes are key in the pathogenesis of MASH fibrosis. Methods18 human livers were profiled using single-nucleus (sn)RNA-seq and snATAC-seq. High priority targets were identified, then tested in 2D human HSC cultures, 3D human liver spheroids, and HSC-specific gene knockout mice. ResultsMASH-enriched activated (A) HSC subclusters are the major source of extracellular matrix proteins. We identified a set of concurrently upregulated and more accessible core genes (GAS7, SPON1, SERPINE1, LTBP2, KLF9, EFEMP1) that drive activation of (A) HSC subclusters. Expression of these genes was regulated via crosstalk between lineage-specific (JUNB/AP1), cluster-specific (RUNX1/2) and signal-specific (FOXA1/2) transcription factors. The pathological relevance of the selected targets, such as SERPINE1 (PAI-1), was demonstrated using dsiRNA-based HSC-specific gene knockdown or pharmacological inhibition of PAI-1 in 3D human MASH liver spheroids, and HSC-specific Serpine1 knockout mice. ConclusionThis study identified novel gene targets and regulatory mechanisms underlying activation of MASH fibrogenic HSCs and demonstrated that genetic or pharmacological inhibition of select genes suppressed liver fibrosis. Impact and implicationsHere we present snRNA-seq and snATAC-seq analysis of human HSCs from NORMAL, MASL, and MASH livers. We identified additional subclusters that were not detected by previous studies and characterized the mechanism by which HSCs activate in the MASH livers, including the transcriptional machinery that activates HSCs into myofibroblasts. For the first time, we described the pathogenic role of activated HSC-derived PAI-1 (a product of SERPINE1 gene) in the development of MASH liver fibrosis. Targeting of RUNX1/2-SERPINE1 axis may provide a novel strategy for treatment of liver fibrosis in patients.

Blood-derived mitochondrial DNA copy number is associated with Alzheimer disease, Alzheimer-related biomarkers and serum metabolites

BackgroundBlood-derived mitochondrial DNA copy number (mtDNA-CN) is a proxy measurement of mitochondrial function in the peripheral and central systems. Abnormal mtDNA-CN not only indicates impaired mtDNA replication and transcription machinery but also dysregulated biological processes such as energy and lipid metabolism. However, the relationship between mtDNA-CN and Alzheimer disease (AD) is unclear.MethodsWe performed two-sample Mendelian randomization (MR) using publicly available summary statistics from GWAS for mtDNA-CN and AD to investigate the causal relationship between mtDNA-CN and AD. We estimated mtDNA-CN using whole-genome sequence data from blood and brain samples of 13,799 individuals from the Alzheimer’s Disease Sequencing Project. Linear and Cox proportional hazards models adjusting for age, sex, and study phase were used to assess the association of mtDNA-CN with AD. The association of AD biomarkers and serum metabolites with mtDNA-CN in blood was evaluated in Alzheimer’s Disease Neuroimaging Initiative using linear regression. We conducted a causal mediation analysis to test the natural indirect effects of mtDNA-CN change on AD risk through the significantly associated biomarkers and metabolites.ResultsMR analysis suggested a causal relationship between decreased blood-derived mtDNA-CN and increased risk of AD (OR = 0.68; P = 0.013). Survival analysis showed that decreased mtDNA-CN was significantly associated with higher risk of conversion from mild cognitive impairment to AD (HR = 0.80; P = 0.002). We also identified significant associations of mtDNA-CN with brain FDG-PET (β = 0.103; P = 0.022), amyloid-PET (β = 0.117; P = 0.034), CSF amyloid-β (Aβ) 42/40 (β=-0.124; P = 0.017), CSF t-Tau (β = 0.128; P = 0.015), p-Tau (β = 0.140; P = 0.008), and plasma NFL (β=-0.124; P = 0.004) in females. Several lipid species, amino acids, biogenic amines in serum were also significantly associated with mtDNA-CN. Causal mediation analyses showed that about a third of the effect of mtDNA-CN on AD risk was mediated by plasma NFL (P = 0.009), and this effect was more significant in females (P < 0.005).ConclusionsOur study indicates that mtDNA-CN measured in blood is predictive of AD and is associated with AD biomarkers including plasma NFL particularly in females. Further, we illustrate that decreased mtDNA-CN possibly increases AD risk through dysregulation of mitochondrial lipid metabolism and inflammation.

A High-Throughput Screen for Antiproliferative Peptides in Mammalian Cells Identifies Key Transcription Factor Families.

Transcription factors (TFs) are a promising therapeutic target for a multitude of diseases. TFs perform their cellular roles by participating in multiple specific protein-protein interactions. For example, homo- or heterodimerization of some TFs controls DNA binding, while interactions between TFs and components of basal transcriptional machinery or chromatin modifiers can also be critical. While, in theory, small molecules could be used to disrupt specific protein-protein interfaces required for TF function, in practice, it is difficult to identify small molecules with the necessary specificity and efficacy, likely due to the extensive protein-protein interfaces that often underlie TF function. However, in contrast to small molecules, peptides have the potential to provide both the specificity and efficacy required to disrupt such interfaces. Here, we identified ∼15 peptides that inhibit the proliferation of leukemia cells using a high-throughput pooled screen of a library of 80-mer protein regions (peptides) derived from human nuclear-localized proteins. The antiproliferative peptides were enriched for regions known to be involved in specific TF dimerization, including the basic leucine zipper (bZIP) domain family. One of these bZIP domains, JDP2;bZIP_1, from the TF JDP2, was the top antiproliferative peptide, reducing the proliferation of K562 cells by 2-fold. JDP2;bZIP_1 inhibited AP-1 transcriptional activity and phenocopied JDP2 overexpression, suggesting that the peptide affected proliferation through a native JDP2 mechanism. Unexpectedly, given the strong conservation of the bZIP domain, residues outside of the annotated dimerization domain were critical for the peptide's antiproliferative potency. The peptide-mediated antiproliferative effect initiated erythrocyte differentiation in K562 cells and increased G0/G1 cells across multiple cell line models. We also found that many of the antiproliferative peptides identified in this study, including JDP2;bZIP_1, did not require a nuclear localization signal to function, a potential benefit for delivering these peptides in therapeutic applications.

TFIIS is required for reproductive development and thermal adaptation in barley

Key messageBarley reproductive fitness and efficient heat stress adaptation requires the activity of TFIIS, the elongation cofactor of RNAPII.Regulation of transcriptional machinery and its adaptive role under different stress conditions are studied extensively in the dicot model plant Arabidopsis, but our knowledge on monocot species remains elusive. TFIIS is an RNA polymerase II-associated transcription elongation cofactor. Previously, it was shown that TFIIS ensures efficient transcription elongation that is necessary for heat stress survival in A. thaliana. However, the function of TFIIS has not been analysed in monocots. In the present work, we have generated and studied independent tfIIs-crispr-mutant barley lines. We show that TFIIS is needed for reproductive development and heat stress survival in barley. The molecular basis of HS-sensitivity of tfIIs mutants is the retarded expression of heat stress protein transcripts, which leads to late accumulation of HSP chaperones, enhanced proteotoxicity and ultimately to lethality. We also show that TFIIS is transcriptionally regulated in response to heat, supporting a conserved adaptive function of these control elements for plant thermal adaptation. In sum, our results are a step forward for the better understanding of transcriptional machinery regulation in monocot crops.

LINC01116-dependent upregulation of RNA polymerase I transcription drives oncogenic phenotypes in lung adenocarcinoma

BackgroundHyperactive RNA Polymerase I (Pol I) transcription is canonical in cancer, associated with malignant proliferation, poor prognosis, epithelial-mesenchymal transition, and chemotherapy resistance. Despite its significance, the molecular mechanisms underlying Pol I hyperactivity remain unclear. This study aims to elucidate the role of long noncoding RNAs (lncRNAs) in regulating Pol I transcription in lung adenocarcinoma (LUAD).MethodsBioinformatics analyses were applied to identify lncRNAs interacting with Pol I transcriptional machinery. Fluorescence in situ hybridization was employed to examine the nucleolar localization of candidate lncRNA in LUAD cells. RNA immunoprecipitation assay validated the interaction between candidate lncRNA and Pol I components. Chromatin isolation by RNA purification and Chromatin Immunoprecipitation (ChIP) were utilized to confirm the interactions of candidate lncRNA with Pol I transcriptional machinery and the rDNA core promoter. Functional analyses, including lncRNA knock-in and knockdown, inhibition of Pol I transcription, quantitative PCR, cell proliferation, clonogenicity, apoptosis, cell cycle, wound-healing, and invasion assays, were performed to determine the effect of candidate lncRNA on Pol I transcription and associated malignant phenotypes in LUAD cells. ChIP assays and luminometry were used to investigate the transcriptional regulation of the candidate lncRNA.ResultsWe demonstrate that oncogenic LINC01116 scaffolds essential Pol I transcription factors TAF1A and TAF1D, to the ribosomal DNA promoter, and upregulate Pol I transcription. Crucially, LINC01116-driven Pol I transcription activation is essential for its oncogenic activities. Inhibition of Pol I transcription abrogated LINC01116-induced oncogenic phenotypes, including increased proliferation, cell cycle progression, clonogenicity, reduced apoptosis, increased migration and invasion, and drug sensitivity. Conversely, LINC01116 knockdown reversed these effects. Additionally, we show that LINC01116 upregulation in LUAD is driven by the oncogene c-Myc, a known Pol I transcription activator, indicating a functional regulatory feedback loop within the c-Myc-LINC01116-Pol I transcription axis.ConclusionCollectively, our findings reveal, for the first time, that LINC01116 enhances Pol I transcription by scaffolding essential transcription factors to the ribosomal DNA promoter, thereby driving oncogenic activities in LUAD. We propose the c-Myc-LINC01116-Pol I axis as a critical oncogenic pathway and a potential therapeutic target for modulating Pol I transcription in LUAD.Graphical

The zinc-finger transcription factor Sfp1 imprints specific classes of mRNAs and links their synthesis to cytoplasmic decay

To function effectively as an integrated system, the transcriptional and post-transcriptional machineries must communicate through mechanisms that are still poorly understood. Here, we focus on the zinc-finger Sfp1, known to regulate transcription of proliferation-related genes. We show that Sfp1 can regulate transcription either by binding to promoters, like most known transcription activators, or by binding to the transcribed regions (gene bodies), probably via RNA polymerase II (Pol II). We further studied the first mode of Sfp1 activity and found that, following promoter binding, Sfp1 binds to gene bodies and affects Pol II configuration, manifested by dissociation or conformational change of its Rpb4 subunit and increased backtracking. Surprisingly, Sfp1 binds to a subset of mRNAs co-transcriptionally and stabilizes them. The interaction between Sfp1 and its client mRNAs is controlled by their respective promoters and coincides with Sfp1’s dissociation from chromatin. Intriguingly, Sfp1 dissociation from the chromatin correlates with the extent of the backtracked Pol II. We propose that, following promoter recruitment, Sfp1 accompanies Pol II and regulates backtracking. The backtracked Pol II is more compatible with Sfp1’s relocation to the nascent transcripts, whereupon Sfp1 accompanies these mRNAs to the cytoplasm and regulates their stability. Thus, Sfp1’s co-transcriptional binding imprints the mRNA fate, serving as a paradigm for the cross-talk between the synthesis and decay of specific mRNAs, and a paradigm for the dual-role of some zinc-finger proteins. The interplay between Sfp1’s two modes of transcription regulation remains to be examined.

The zinc-finger transcription factor Sfp1 imprints specific classes of mRNAs and links their synthesis to cytoplasmic decay.

To function effectively as an integrated system, the transcriptional and post-transcriptional machineries must communicate through mechanisms that are still poorly understood. Here, we focus on the zinc-finger Sfp1, known to regulate transcription of proliferation-related genes. We show that Sfp1 can regulate transcription either by binding to promoters, like most known transcription activators, or by binding to the transcribed regions (gene bodies), probably via RNA polymerase II (Pol II). We further studied the first mode of Sfp1 activity and found that, following promoter binding, Sfp1 binds to gene bodies and affects Pol II configuration, manifested by dissociation or conformational change of its Rpb4 subunit and increased backtracking. Surprisingly, Sfp1 binds to a subset of mRNAs co-transcriptionally and stabilizes them. The interaction between Sfp1 and its client mRNAs is controlled by their respective promoters and coincides with Sfp1's dissociation from chromatin. Intriguingly, Sfp1 dissociation from the chromatin correlates with the extent of the backtracked Pol II. We propose that, following promoter recruitment, Sfp1 accompanies Pol II and regulates backtracking. The backtracked Pol II is more compatible with Sfp1's relocation to the nascent transcripts, whereupon Sfp1 accompanies these mRNAs to the cytoplasm and regulates their stability. Thus, Sfp1's co-transcriptional binding imprints the mRNA fate, serving as a paradigm for the cross-talk between the synthesis and decay of specific mRNAs, and a paradigm for the dual-role of some zinc-finger proteins. The interplay between Sfp1's two modes of transcription regulation remains to be examined.

ZIC2 and ZIC3 promote SWI/SNF recruitment to safeguard progression towards human primed pluripotency

The primed epiblast acts as a transitional stage between the relatively homogeneous naïve epiblast and the gastrulating embryo. Its formation entails coordinated changes in regulatory circuits driven by transcription factors and epigenetic modifications. Using a multi-omic approach in human embryonic stem cell models across the spectrum of peri-implantation development, we demonstrate that the transcription factors ZIC2 and ZIC3 have overlapping but essential roles in opening primed-specific enhancers. Together, they are essential to facilitate progression to and maintain primed pluripotency. ZIC2/3 accomplish this by recruiting SWI/SNF to chromatin and loss of ZIC2/3 or degradation of SWI/SNF both prevent enhancer activation. Loss of ZIC2/3 also results in transcriptome changes consistent with perturbed Polycomb activity and a shift towards the expression of genes linked to differentiation towards the mesendoderm. Additionally, we find an intriguing dependency on the transcriptional machinery for sustained recruitment of ZIC2/3 over a subset of primed-hESC specific enhancers. Taken together, ZIC2 and ZIC3 regulate highly dynamic lineage-specific enhancers and collectively act as key regulators of human primed pluripotency.

The TRIM28-PARP1-CTNNB1 Complex Is Associated with the Transcriptional Elongation Machinery for Aqp2 Gene Transcription

The TRIM28-PARP1-CTNNB1 Complex Is Associated with the Transcriptional Elongation Machinery for Aqp2 Gene Transcription

Targeting heparanase/heparan sulfate proteoglycans by non‐anticoagulant heparins: Opportunities for innovative therapeutic approaches in sarcomas

AbstractSarcomas are a heterogeneous group of aggressive mesenchymal malignancies. They account for 1% of all tumors in the general population and 15–20% in pediatric age and young adults. Despite differences in histology and pathobiology, the diverse types of sarcomas are traditionally managed with a common multi‐modal approach including surgery, radiotherapy, and aggressive polychemotherapy. Unfortunately, the prognosis for advanced or recurrent disease remains poor. Moreover, the disease rarity and a high cellular, molecular, and genetic/epigenetic heterogeneity make identification of therapeutic targets challenging. Therefore it remains an urgent need to identify effective therapies to improve patients' outcome. Common or peculiar biological motifs including deregulation of growth factor signaling, proangiogenic and promigratory pathways, tumor‐microenviroment interactions, transcriptional and epigenetic machinery, and differentiation program, provide actionable dependencies exploitable for therapeutic intervention. Among these, a deregulated heparan sulfate proteoglycan system due to aberrant expression of key components as well as structural/functional modifications mediated by endosulfatases and the endoβ‐d‐glycosidase heparanase, is emerging as a crucial player in tumor growth and progression and as a valuable therapeutic target across different sarcoma subtypes. In preclinical studies, non‐anticoagulant heparins have been shown to counteract the growth and metastatic dissemination of various sarcoma models according to their heparan sulfate mimetic and anti‐heparanase activities. Heparin derivatives also improved the anti‐sarcoma efficacy of molecularly targeted agents and cytotoxic drugs. In this minireview, we summarize the current knowledge about the interplay between the heparanase/heparan sulfate proteoglycan system and pathways involved in sarcomagenesis and disease progression. We illustrate the current understanding of the mechanisms of action of non‐anticoagulant heparins and the contribution of their anti‐heparanase, anti‐receptor tyrosine kinase, and likely immunomodulatory activities to their anti‐sarcoma effects. Finally, we discuss a few aspects worthy of exploration highlighting how elucidation of mechanisms underpinning antitumor activities of non‐anticoagulant heparin derivatives in the different sarcoma biological contexts may suggest new vulnerabilities and therapeutic approaches.

Phosphorus uptake 1 (Pup1) QTL performs major regulatory functions under phosphorus starvation/deficiency stress in rice (Oryza sativa L.)

Phosphorus (P) is an essential macronutrient required for respiration, photosynthesis/carbohydrate metabolism, redox homeostasis, signaling, and synthesis/function of nucleic acids, cellular membranes, enzymes, etc. To cope with P-deficiency, plants reprogram gene expression for necessary alterations in metabolic/signaling pathways. To attain P homeostasis, plants readjust metabolism through transcriptional, post-transcriptional, and/or post-translational machinery involving biochemical, physiological, genomic, epigenomic, proteomic, and metabolomic functions. However, the underlying molecular mechanisms/pathways/genes for P-deficiency tolerance in crop plants remain elusive. To decipher the mechanisms/pathways adopted by rice under P-starvation/deficiency stress, a pair of contrasting rice [Pusa-44 (high-yielding, P-deficiency sensitive) and its near-isogenic line (NIL)-23, P-deficiency tolerant) for Pup1 QTL] genotype was used for comparative analyses. Omics analyses of shoot and root tissues from 45-day-old plants grown hydroponically in P-sufficient (16 ppm Pi), P-deficient (4 ppm Pi) or P-starved (0 ppm Pi) medium revealed important roles of P transporters, transcription factors (TFs), Transposable elements (TEs), auxin-responsive proteins, cell wall modulation, fatty acid metabolism, and chromatin architecture/epigenetic modifications in making NIL-23 tolerant to stress. The proteins involved in photosynthesis, sucrose-/starch-/energy-metabolism, transcription factors, and phytohormone signaling were observed to be differentially expressed in NIL-23. Since only a few coding genes are located on the QTL, modulations in morpho-physio-biochemical and molecular parameters under P-starvation/deficiency stress were attributed to the regulatory functions of Pup1 through TFs, TEs, epigenetic/chromatin architectural changes, etc. introgressed in Pusa-44 genetic background. Thus, the study provides new insights into molecular/regulatory functions of Pup1 under P-starvation/deficiency stress in rice, which might be useful to improve P-use efficiency in rice for better productivity in P-deficient soils.

Exploring common pathogenic association between Epstein Barr virus infection and long-COVID by integrating RNA-Seq and molecular dynamics simulations.

The term "Long-COVID" (LC) is characterized by the aftereffects of COVID-19 infection. Various studies have suggested that Epstein-Barr virus (EBV) reactivation is among the significant reported causes of LC. However, there is a lack of in-depth research that could largely explore the pathogenic mechanism and pinpoint the key genes in the EBV and LC context. This study mainly aimed to predict the potential disease-associated common genes between EBV reactivation and LC condition using next-generation sequencing (NGS) data and reported naturally occurring biomolecules as inhibitors. We applied the bulk RNA-Seq from LC and EBV-infected peripheral blood mononuclear cells (PBMCs), identified the differentially expressed genes (DEGs) and the Protein-Protein interaction (PPI) network using the STRING database, identified hub genes using the cytoscape plugins CytoHubba and MCODE, and performed enrichment analysis using ClueGO. The interaction analysis of a hub gene was performed against naturally occurring bioflavonoid molecules using molecular docking and the molecular dynamics (MD) simulation method. Out of 357 common genes, 22 genes (CCL2, CCL20, CDCA2, CEP55, CHI3L1, CKAP2L, DEPDC1, DIAPH3, DLGAP5, E2F8, FGF1, NEK2, PBK, TOP2A, CCL3, CXCL8, DEPDC1, IL6, RETN, MMP2, LCN2, and OLR1) were classified as hub genes, and the remaining ones were classified as neighboring genes. Enrichment analysis showed the role of hub genes in various pathways such as immune-signaling pathways, including JAK-STAT signaling, interleukin signaling, protein kinase signaling, and toll-like receptor pathways associated with the symptoms reported in the LC condition. ZNF and MYBL TF-family were predicted as abundant TFs controlling hub genes' transcriptional machinery. Furthermore, OLR1 (PDB: 7XMP) showed stable interactions with the five shortlisted refined naturally occurring bioflavonoids, i.e., apigenin, amentoflavone, ilexgenin A, myricetin, and orientin compounds. The total binding energy pattern was observed, with amentoflavone being the top docked molecule (with a binding affinity of -8.3 kcal/mol) with the lowest total binding energy of -18.48 kcal/mol. In conclusion, our research has predicted the hub genes, their molecular pathways, and the potential inhibitors between EBV and LC potential pathogenic association. The in vivo or in vitro experimental methods could be utilized to functionally validate our findings, which would be helpful to cure LC or to prevent EBV reactivation.

Herpes simplex virus 1 inhibits phosphorylation of RNA polymerase II CTD serine-7.

Transcriptional activity of RNA polymerase II (Pol II) is influenced by post-translational modifications of the C-terminal domain (CTD) of the largest Pol II subunit, RPB1. Herpes simplex virus type 1 (HSV-1) usurps the cellular transcriptional machinery during lytic infection to efficiently express viral mRNA and shut down host gene expression. The viral immediate-early protein ICP22 interferes with serine 2 phosphorylation (pS2) by targeting CDK9 and other CDKs, but the full functional implications of this are not well understood. Using Western blotting, we report that HSV-1 also induces a loss of serine 7 phosphorylation (pS7) of the CTD during lytic infection, requiring expression of the two immediate-early proteins ICP22 and ICP27. ICP27 has also been proposed to target RPB1 for degradation, but we show that pS2/S7 loss precedes the drop in total protein levels. Cells with the RPB1 polyubiquitination site mutation K1268R, preventing proteasomal degradation during transcription-coupled DNA repair, displayed loss of pS2/S7 but retained higher overall RPB1 protein levels later in infection, indicating this pathway is not involved in early CTD dysregulation but may mediate bulk protein loss later. Using α-amanitin-resistant CTD mutants, we observed differential requirements for Ser2 and Ser7 for the production of viral proteins, with Ser2 facilitating viral immediate-early genes and Ser7 appearing dispensable. Despite dysregulation of CTD phosphorylation and different requirements for Ser2/7, all CTD modifications tested could be visualized in viral replication compartments with immunofluorescence. These data expand the known means that HSV employs to create pro-viral transcriptional environments at the expense of host responses.IMPORTANCECells rapidly induce changes in the transcription of RNA in response to stress and pathogens. Herpes simplex virus (HSV) disrupts many processes of host mRNA transcription, and it is necessary to separate the actions of viral proteins from cellular responses. Here, we demonstrate that viral proteins inhibit two key phosphorylation patterns on the C-terminal domain (CTD) of cellular RNA polymerase II and that this is separate from the degradation of polymerases later in infection. Furthermore, we show that viral genes do not require the full "CTD code." Together, these data distinguish multiple steps in the remodeling of RNA polymerase during infection and suggest that shared transcriptional phenotypes during stress responses do not revolve around a core disruption of CTD modifications.