Regulation Of Protein Translation Research Articles

The Lack of Functional DNMT2 Gene Modulates Gvhd Process Via tRNA m5c Modification

Acute graft versus host disease (GVHD), one of the major complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT), develops in approximately 50% of patients and even leads to death. The primary treatment is the immunosuppressive therapy, but treatment failure is common and often accompanied by infection, recurrence, and organ function damage. It is a tough clinic problem that needs to be solved urgently. RNA modifications, as emerging epigenetic regulators, play important roles in the regulation of protein translation, ribosome biosynthesis, cellular processes and the occurrence of diseases. In this study, we found that the tRNA modification signature of T-cells from liver and spleen organs (7 days post-transplantation) was altered, especially m6A, m3C, and m5C, were significantly up-regulated. Further analysis showed that levels of tRNA m3C and m5C in injected-derived T (45.2) cells were significantly increased compared with that in the de novo T (45.1) cells from spleen and liver. Western bolt confirmed that tRNA methyltransferase DNMT2, responsible for m5C modification, was highly expressed in injected-T (45.2) cells isolated from liver and spleen of GVHD model mice. Deletion of Dnmt2 led to the decrease of m5C in T-cell tRNA of spleen. The transplantation experiment, Dnmt2 knockout mice as donor, showed that lack of Dnmt2 in T cell could alleviate the development of GVHD, and the serum levels of IFNγ, TNFα and other pro-inflammatory cytokines were also significantly reduced. In conclusion, our data indicated that Dnmt2-mediated tRNA m5C modification in injected T (45.2) cells was involved in the occurrence and development of GVHD. However, the molecular mechanism under Dnmt2-mediated tRNA m5C regulates GVHD and its impact on immune response need to be further elucidated.

CSIG-20. PROTEOGENOMICS PROFILING REVEALS ENRICHED PROTEIN TRANSLATION REGULATORS AS NEW THERAPEUTIC TARGETS IN DIPG

Abstract Diffuse intrinsic pontine glioma (DIPG) is a devastating brain tumor arising in the brainstems of children. Current therapies are ineffective resulting in a median survival rate of less than one year and it is the leading cause of brain tumor-related death in children. A novel mutation in histone H3 protein (H3K27M) was recently identified as a genetic initiation event and affects global K27 trimethylation on histone H3 proteins and DNA methylation. The epigenetic changes caused by H3K27M mutation suggest the existence of an H3K27M-specific transcriptome and proteome. We investigated DIPG tissues at the multi-omics level including total proteome, phosphoproteome, methylproteome and metabolome by mass spectrometry. A total of 30 patient tumours were profiled to identify differentially expressed proteins, differentially phosphorylated proteins, and differentially methylated proteins in tumour tissues compared to normal brains. We identified 2995 proteins that are differentially regulated, suggesting changes in key oncogenic pathways including negative regulation of apoptosis, translation, and metabolic pathways such as methionine salvage and TCA cycle in DIPG. The deregulation of these metabolic pathways due to the differentially expressed proteins in DIPG cells was confirmed by metabolomics studies. Protein phosphorylation and protein methylation profiling of DIPG implicated that translation-related proteins were the most highly modified (post-translationally) proteins in DIPG tissues. Furthermore, protein translation measured by CyTOF showed higher translation rates in DIPG and immortalized astrocytes carrying H3K27M than their WT counterparts. We investigated the functional consequence of knockdown of the highest methylated translation regulator EEF1A1 and its methyltransferase METTL13. ShRNA knockdown of both, EEF1A and METTL13 in DIPG cells significantly reduced the cell growth. Multi-omics analysis of DIPG highlighted regulation of protein translation as a potential therapeutic target.

Organotin and organochlorine toxicants activate key translational regulatory proteins in human immune cells.

Environmental contaminant exposures occur due to the widespread use of synthetic chemicals. Tributyltin (TBT), dibutyltin (DBT), and pentachlorophenol (PCP) are each used in a variety of applications, including antifouling paints and stabilizers in certain plastics. Each of these compounds has been found in human blood, as well as other tissues, and they have been shown to stimulate pro-inflammatory cytokine production in human immune cells, Inflammatory cytokines mediate response to injury or infection. However, if their levels are increased in the absence of an appropriate stimulus, chronic inflammation can occur. Chronic inflammation is associated with a number of pathologies including cancer. Stimulation of pro-inflammatory cytokine production by these toxicants is dependent on activation of ERK 1/2 and/or p38 MAPK pathways. MAPK pathways have the capacity to regulate translation by increasing phosphorylation of key translation regulatory proteins. There have been no previous studies examining the effects of TBT, DBT, or PCP on translation. The current study shows that ribosomal protein S6 (S6), eukaryotic initiation factor 4B (eIF4B), and eIF4E are phosphorylated (activated) and/or their total levels are elevated in response to each of these compounds at concentrations found in human blood. Activation/increased levels of translational proteins occurred at concentrations of the compounds that have been shown to elevate pro-inflammatory cytokine production, but where there is no increase in mRNA for those proteins was seen. Compound-stimulated increases in translation appear to be part of the mechanism by which they elevate protein production in immune cells.

OR04-6 Comprehensive Profiling of the MELK Inhibitor OTSSP167's Action and Its Effect on Sensitization to Wee1 Inhibitor AZD1775 in a Spectrum of ACC Models

Abstract Adrenocortical carcinoma (ACC) is an aggressive cancer with a significant risk of recurrence and high mortality rates. ACC has limited response to currently used treatments and there is an unmet clinical need to identify new treatment options. Disease rarity coupled with absence of preclinical models of disease heterogeneity contributed to limited therapeutic progress in ACC. We previously established new in vitro and in vivo ACC models (CUACC1, CUACC2, CUACC9) with variable genomic alterations commonly seen in ACC tumors. Prior work demonstrated that maternal leucine embryonic kinase (MELK) is an oncogenic kinase in ACC, and that it can be targeted with the MELK inhibitor OTSSP167. To further evaluate the anti-tumor efficacy and mode of action of OTSSP167, this study used genetically diverse ACC cell lines (CUACC1, CUACC2, H295R), patient derived xenografts (PDX) (CUACC1 and CUACC9) and a cell line xenograft model (H295R) of ACC. ACC PDXs treated with 10 mg/kg OTSSP167 had significantly reduced MELK expression, tumor growth inhibition of more than 80%, reduced mitosis, and increased tumor tissue necrosis. Transcriptomic and phospho-proteomic analysis at multiple treatment timepoints in in vitro models revealed that OTSSP167 induced wide transcriptomic and proteomic changes involving effectors of signal transduction, cell cycle, protein translation, and epigenetic regulation to exert its anti-tumorigenic effects. Evaluation of OTSSP167's role in protein synthesis via a puromycin based SUnSET (surface sensing of translation) and kinase assay established that OTSSP167 inhibits de-novo protein synthesis, and targets RSK1 and its substrate rpS6 (S235/S236). Varying the degree of MELK silencing in H295R cell lines using a doxycycline inducible shRNA construct, inhibited RSK1 phosphorylation at T573 and S380 indicating a MELK-RSK1 axis in ACC. Additionally, OTSSP167's effect on the DNA damage pathway was validated, which activated the G2/M checkpoint protein Wee1, increased inhibitory phosphorylation of CDK1, causing an accumulation of cyclin B1 and G2/M arrest independent of TP53 status. Combination treatment with the Wee1 inhibitor AZD1775 and OTSSP167 enhanced OTSSP167 mediated cytotoxic effects in in-vitro models with an increase in mitotic entry and caspase mediated apoptosis. In summary, OTSSP167 exerted its anti-tumorigenic effects via inhibition of the protein translation machinery, DNA damage and cell cycle dysregulation causing drug sensitization. Results from these studies are a first demonstration of the anti-cancer effects of OTSSP167 in sensitization to Wee1 inhibition in ACC. These data suggest that OTSSP167 is a potential therapeutic option for patients with ACC and could be combined with Wee1 inhibitors in a clinical trial using a synthetic lethal approach. Presentation: Saturday, June 11, 2022 12:45 p.m. - 1:00 p.m.

Lin28 Regulates Cancer Cell Stemness for Tumour Progression.

Simple SummaryCancer stem cells (CSCs) are a small population of tumour cells bearing stemness characteristics. They have been deemed as a root of cancer development and a promising drug target for anticancer therapy. Herein, we discuss the roles of an RNA-binding protein, Lin28, in regulating cancer cell stemness to drive tumour progression. Lin28 acts on various types of RNAs in cancer cells and regulates these RNA functions to control the expression of oncogenes. In these ways, Lin28 promotes cancer cell survival, growth, and invasion. We also discuss recent efforts in developing Lin28 inhibitors targeting CSCs in tumours.Tumours develop therapy resistance through complex mechanisms, one of which is that cancer stem cell (CSC) populations within the tumours present self-renewable capability and phenotypical plasticity to endure therapy-induced stress conditions and allow tumour progression to the therapy-resistant state. Developing therapeutic strategies to cope with CSCs requires a thorough understanding of the critical drivers and molecular mechanisms underlying the aforementioned processes. One such hub regulator of stemness is Lin28, an RNA-binding protein. Lin28 blocks the synthesis of let-7, a tumour-suppressor microRNA, and acts as a global regulator of cell differentiation and proliferation. Lin28also targets messenger RNAs and regulates protein translation. In this review, we explain the role of the Lin28/let-7 axis in establishing stemness, epithelial-to-mesenchymal transition, and glucose metabolism reprogramming. We also highlight the role of Lin28 in therapy-resistant prostate cancer progression and discuss the emergence of Lin28-targeted therapeutics and screening methods.

Target of Rapamycin Mediated Ornithine Decarboxylase Antizyme Modulate Intracellular Putrescine and Ganoderic Acid Content in Ganoderma lucidum.

ABSTRACTPutrescine (Put) has been shown to play an important regulatory role in cell growth in organisms. As the primary center regulating the homeostasis of polyamine (PA) content, ornithine decarboxylase antizyme (AZ) can regulate PA content through feedback. Nevertheless, the regulatory mechanism of Put is poorly understood in fungi. Here, our analysis showed that GlAZ had a modulate effect on intracellular Put content by interacting with ornithine decarboxylase (ODC) proteins and reducing its intracellular protein levels. In addition, GlAZ upregulated the metabolic pathway of ganoderic acid (GA) biosynthesis in Ganoderma lucidum by modulating the intracellular Put content. However, a target of rapamycin (TOR) was found to promote the accumulation of intracellular Put after the GlTOR inhibitor Rap was added exogenously, and unbiased analyses demonstrated that GlTOR may promote Put production through its inhibitory effect on the level of GlAZ protein in GlTOR-GlAZ-cosilenced strains. The effect of TOR on fungal secondary metabolism was further explored, and the content of GA in the GlTOR-silenced strain after the exogenous addition of the inhibitor Rap was significantly increased compared with that in the untreated wild-type (WT) strain. Silencing of TOR in the GlTOR-silenced strains caused an increase in GA content, which returned to the WT state after replenishing Put. Moreover, the content of GA in GlTOR-GlAZ-cosilenced strains was also not different from that in the WT strain. Consequently, these results strongly indicate that GlTOR affects G. lucidum GA biosynthesis via GlAZ.IMPORTANCE Research on antizyme (AZ) in fungi has focused on the mechanism by which AZ inhibits ornithine decarboxylase (ODC). Moreover, there are existing reports on the regulation of AZ protein translation by TOR. However, little is known about the mechanisms that influence AZ in fungal secondary metabolism. Here, both intracellular Put content and GA biosynthesis in G. lucidum were shown to be regulated through protein interactions between GlAZ and GlODC. Furthermore, exploration of upstream regulators of GlAZ suggested that GlAZ was regulated by the upstream protein GlTOR, which affected intracellular Put levels and ganoderic acid (GA) biosynthesis. The results of our work contribute to the understanding of the upstream regulation of Put and provide new insights into PA regulatory systems and secondary metabolism in fungi.

Comprehensive elaboration of circular RNA in multiple myeloma

Circular RNAs (circRNAs), a novel category of endogenous non-coding RNAs, are usually well conserved across different species with a covalent closed-loop structure. Existing and emerging evidence confirms that circRNAs can function as regulators of alternative splicing, microRNA and RNA-binding protein sponges and translation, as well as gene transcription. In consideration of their multi-faceted functions, circRNAs are critically involved in hematological malignancies including multiple myeloma (MM). In particular, circRNAs have been found to play vital roles in tumor microenvironment and drug resistance, which may grant them potential roles as biomarkers for MM diagnosis and targeted therapy. In this review, we comprehensively elaborate the current state-of-the-art knowledge of circRNAs in MM, and then focus on their potential as biomarkers in diagnosis and therapy of MM.

LB1037 Aberrant regulation of protein translation controlled by eukaryotic initiation factor 4F (eIF4F) in the pathogenesis of hidradenitis suppurativa (HS) and associated cutaneous squamous cell carcinoma (cSCC)

HS is a chronic inflammatory skin disorder and often associated with neoplastic growth of cSSC. Between 1%-3.2% of HS patients develop cSCC, however, the molecular pathogenesis of this disease remains undefined. Here, we demonstrate the pathogenic role for the 5’cap-binding protein complex eIF4F in HS and lesion-associated cSSC. This complex is composed of the scaffold protein eIF4G, the cap-binding protein eIF4E and a DEAD-box helicase eIF4A1. Employing confocal microscopy, we observed elevated expression of eIF4E, eIF4G, and eIF4A1 in HS skin that co-localized in hyperproliferative keratinocytes and associated with enhanced eIF4E translation targets, Cyclin D1 and c-Myc.

Abstract 2562: eIF4E modulators to address breast cancer resistance

Abstract ER+/HER2- advanced or metastatic breast cancers represents a large patient population served by CDK4/6 inhibitors combined with hormonal therapy as standard of care. As acquired resistance emerges, molecular profiling indicates about > 100 different mutations render resistance, creating challenges for treating physicians, patients, and the healthcare system broadly. The aim of our work is to maintain consolidation of this large patient population by developing targeted therapies to a key fundamental mechanism at the convergence of many oncogenic signaling pathways through which resistance arises. The regulation of CAP dependent protein translation is a central element in oncogenesis. One of a family of CAP binding proteins, eIF4E serves to anchor the m7GTP CAP of RNA into several protein complexes and regulates multiple aspects of mRNA processing such as nuclear export and ribosomal translation. Our efforts focused on simultaneously developing potent small molecule modulators of eIF4E and patient hypotheses through which to direct their initial clinical use. By aligning medicinal chemistry tools with patient directed pharmacology, we optimized our inhibitors to identify orally bioavailable, nM modulators of eIF4E. Biochemical assays demonstrated direct binding and allosteric modulation of eIF4E activity by PICRN941, along with Proximity Ligation Assays (PLA) demonstrating reduced eIF4E and 4G association in cells. Western analysis demonstrated that PICRN941 induced simultaneous and significant modulation of a number of key oncogenes that have been postulated to drive intrinsic or acquired resistance in response to standard of care including anti-estrogen treatment, CDK4/6 inhibitors or PI3K inhibitors combined with hormonal therapy, including MYC, CDK2, CDK4, CCND1 and eIF4E itself. Treatment of ER+ breast cancer cell lines including ZR-75-1, T47D, and ZR-75-30 with PICRN941 induced a dose dependent reduction in the levels of hyper-phosphorylated 4E-BP1 commensurate to increases in unphosphorylated 4E-BP1, and dose-dependent reduction in protein expression of Cyclin D1, CDK4, ER alpha, phosphorylated Rb and eIF4E. Reduced protein expression correlated with subsequent cell cycle arrest and apoptosis. We further studied our inhibitors in primary patient derived organoids in collaboration with the Hubrecht Institute, where we observed potent and complete responses in breast cancer organoids that represent patient populations where unmet needs remain high including PTEN and RB null organoid models. Markers of target engagement correlated well with organoid model sensitivity, including Cyclin D1 responses. Our findings suggest that our allosteric eIF4E modulators may provide a unique and efficient therapeutic approach to address multiple resistance mechanisms across cancer patient populations, toward fulfilling the promise of this elusive target. Citation Format: Lisa Sturla, Bassil Dekky, Xuemei Zhang, Katherine S. Bowdish, Chris VanDeusen. eIF4E modulators to address breast cancer resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2562.

The role of circular RNAs in pulmonary hypertension.

Circular RNAs (circRNAs) are endogenous, covalently circularised, non-protein-coding RNAs generated from back-splicing. Most circRNAs are very stable, highly conserved, and expressed in a tissue-, cell- and developmental stage-specific manner. circRNAs play a significant role in various biological processes, such as regulation of gene expression and protein translation via sponging of microRNAs and binding with RNA-binding proteins. circRNAs have become a topic of great interest in research due to their close link with the development of various diseases. Their high stability, conservation and abundance in body fluids make them promising biomarkers for many diseases. A growing body of evidence suggests that aberrant expression of circRNAs and their targets plays a crucial role in pulmonary vascular remodelling and pulmonary arterial hypertension (group 1) as well as other forms (groups 3 and 4) of pulmonary hypertension (PH). Here we discuss the roles and molecular mechanisms of circRNAs in the pathogenesis of pulmonary vascular remodelling and PH. We also highlight the therapeutic and biomarker potential of circRNAs in PH.

PBMC miRNA in diagnosis of rheumatoid arthritis

Background and objective: RA is an autoimmune disorder mediated by autoantibodies. miRNAs have been shown to negatively regulate protein translation via an antisense RNA-RNA interaction. Altered miRNA expression has been well established in autoimmune diseases. In this study, the expression of four microRNA was analysed. Also, correlation between microRNA and immunological markers was examined. Method: RNA was isolated from PBMC obtained from 100 RA patients and age-gender matched healthy controls. Levels of mature miRNA of miR146a, miR155a, miR499 and miR124a were detected using real time PCR. Downstream cytokine was analysed using ELISA from R&D systems. Result: Real time PCR reveals that the expression of miR-146a, miR-155a, miR-499 in PBMC was found to be down regulated in RA patients when compared to the controls by fold change of 0.15, 0.69 and 0.04 respectively whereas, expression of miR124a was found to be low to detect. Expression of TNF- alpha upregulated (p-value=0.09) and IL6 was found to be insignificantly down regulated in patient. miRNA 155a was found to be in significant negative correlation with rheumatoid factor (r= -0.210; p=0.038).

Mechanisms of miR-3189-3p-mediated inhibition of c-MYC translation in triple negative breast cancer

BackgroundTriple negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by the lack of estrogen receptor, progesterone receptor, and HER2. Our lab previously characterized miR-3189-3p as a microRNA with potent anti-cancer activity against glioblastoma. Here, we hypothesized a similar activity in TNBC cells. As miR-3189-3p is predicted to target a variety of RNA binding proteins, we further hypothesized an inhibitory effect of this miRNA on protein synthesis.MethodsMDA-MB-231 and MDA-MB-468 cells were used to investigate the effect of miR-3189-3p on cell proliferation, migration, and invasion. TGCA database was used to analyze the expression of miR-3189-3p, c-MYC, 4EPB1, and eIF4E in breast cancer. Western blotting and RT-qPCR assays were used to assess the expression of selected proteins and RNAs after transfections.ResultsAlthough c-MYC is not a predicted gene target for miR-3189-3p, we discovered that c-MYC protein is downregulated in miRNA-treated TNBC cells. We found that the downregulation of c-MYC by miR-3189-3p occurs in both normal growth conditions and in the absence of serum. The mechanism involved the direct inhibition of eIF4EBP1 by miR-3189-3p. Additionally, we found that miR-3189-3p could negatively affect cap-independent translation mediated by internal ribosome entry sites (IRES) or by m6A. Finally, miR-3189-3p sensitized TNBC cells to doxorubicin.ConclusionOverall, results indicated that miR-3189-3p exerts its anti-tumor activity through targeting translational regulatory proteins leading to an impairment in c-MYC translation, and possibly other oncogenic factors, suggesting that miR-3189-3p, alone or in combination, could be a valuable therapeutic approach against a malignancy with few treatment options.

Daf-16 mediated repression of cytosolic ribosomal protein genes facilitates a hypoxia sensitive to hypoxia resistant transformation in long-lived germline mutants.

In C. elegans, germline ablation leads to long life span and stress resistance. It has been reported that mutations that block oogenesis or an upstream step in germline development confer strong resistance to hypoxia. We demonstrate here that the hypoxia resistance of sterile mutants is dependent on developmental stage and age. In just a 12-hour period, sterile animals transform from hypoxia sensitive L4 larvae into hypoxia resistant adults. Since this transformation occurs in animals with no germline, the physiological programs that determine hypoxia sensitivity in germline mutants occur independently of germline signals and instead rely on signals from somatic tissues. Furthermore, we found two distinct mechanisms of hypoxia resistance in germline deficient animals. First, a DAF-16/FoxO independent mechanism that occurs in all hypoxia resistant sterile adults and, second, a DAF-16/FoxO dependent mechanism that confers an added layer of resistance, or “super-resistance”, to animals with no germline as they age past day 1 of adulthood. RNAseq data showed that genes involved in both cytosolic and mitochondrial protein translation are repressed in sterile adults and further repressed only in germline deficient mutants as they age. Importantly, mutation of daf-16 specifically blocked the repression of cytosolic ribosomal protein genes, but not mitochondrial ribosomal protein genes, implicating DAF-16/FoxO mediated repression of cytosolic ribosomal protein genes as a mechanism of hypoxia super-resistance. Consistent with this hypothesis, the hypoxia super-resistance of aging germline deficient adults was also suppressed by dual mutation of ncl-1 and larp-1, two regulators of protein translation and ribosomal protein abundance. These studies provide novel insight into a profound physiological transformation that takes place in germline mutants during development, showing that some of the unique physiological properties of these long-lived animals are derived from developmentally dependent DAF-16/FoxO mediated repression of genes involved in cytosolic protein translation.

Eukaryotic elongation factor 2 kinase inhibitor, A484954 inhibits perivascular sympathetic nerve stimulation-induced vasoconstriction in isolated renal artery

Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) repressively regulates protein translation through phosphorylating eEF2. We previously showed that expression and activity of eEF2K are increased in isolated mesenteric arteries from spontaneously hypertensive rats (SHR) contributing to development of essential hypertension. Furthermore, we have recently shown that 7-Amino-1-cyclopropyl-3-ethyl-1,2,3,4-tetrahydro-2,4-dioxopyrido[2,3-d]pyrimidine-6-carboxamide (A484954), a selective eEF2K inhibitor, induces endothelium-dependent relaxation in isolated mesenteric arteries from SHR inducing an antihypertensive effect. In order to test the hypothesis that inhibition of eEF2K activity induces vasodilatation by suppressing sympathetic nerve activity, we examined the effects of A484954 on perivascular sympathetic nerve stimulation-induced contraction in isolated renal artery from normotensive and hypertensive rats. Electrodes were placed near the isolated renal arteries that were applied with transmural nerve stimulation (TNS). Then, contraction of the arteries was isometrically measured. A484954 inhibited TNS-induced contraction. The A484954-mediated inhibition of TNS-induced contraction was significantly prevented by NG-nitro-L-arginine methyl ester. In SHR isolated renal artery, TNS-induced contraction was enhanced compared with normotensive Wistar rats. Furthermore, A484954-mediated inhibition of TNS-induced contraction in SHR was enhanced compared with Wistar rats. In conclusion, this study demonstrates for the first time that A484954 inhibits perivascular sympathetic nerve stimulation-induced vasoconstriction at least in part perhaps through nitric oxide (NO) release from NO-operating nerve.

Efficacy of post‐injury anti‐miR‐181a and anti‐miR‐200c intravenous treatment in protection against experimental stroke in aged mice

IntroductionStroke remains the second leading cause of death worldwide and the primary cause of long‐term disability in the US. To date, the only pharmacological treatment for stroke remains tissue plasminogen activator. A major factor for translational failure is likely overwhelming use of young adult rodent models despite the fact that stroke occurs predominantly in aged populations. MicroRNAs (miRs) are non‐coding RNAs that regulate protein translation, and we have previously demonstrated in young adult mice neuroprotection against experimental stroke with anti‐miR‐181a and anti‐miR‐200c. In the present study, to extend translational impact, we tested efficacy of post‐injury intravenous anti‐miR‐181a and anti‐miR‐200c in clinically relevant aged mice.MethodsAll studies were conducted in accordance with National Institutes of Health guidelines for the use of experimental animals, with protocols approved by the Stanford Animal Care and Use Committee. Animal treatment groups were randomized by coin flip, and all analyses were performed by an observer blinded to conditions. Transient focal cerebral ischemia was induced by suture occlusion of the middle cerebral artery (MCAO) for 1h in 20 month‐old male C57BL/6 mice (n=8 per cohort and treatment group). Sham surgery consisted of anesthesia and internal carotid exposure without suture occlusion (n=4 per group). Intravenous infusion: animals were re‐anesthetized and 30 pmol/g anti‐miR‐181a, anti‐miR‐200c or control (MM) in sterile saline (100 μl) was infused over 1 minute into the internal jugular vein at 2h reperfusion. Neurological status was assessed by 4‐point neurologic deficit score at 48h after MCAO. Infarct volume was assessed after sacrifice by anesthesia overdose at 48h after MCAO with triphenyl tetrazolium chloride staining. Infarct volume was calculated as percentage of hemisphere corrected for edema.ResultsMCAO in all groups resulted in significant decreases in neurological score and increased infarct volume relative to sham treated animals. Both anti‐miR‐181a and anti‐miR‐200c treatment resulted in significantly (p<0.05) higher neurological scores and significantly lower infarct volumes relative to MM‐control treated animals. No differences in neurological score or in infarct volume were observed between anti‐miR‐181a and anti‐miR‐200c treatments.ConclusionsBoth anti‐miR‐181a and anti‐miR‐200c are effective non‐invasive post‐stroke interventions to reduce injury in clinically‐relevant aged mice. Future investigations should be extended to testing in aged female cohorts and identifying relevant downstream targets of miR‐181a and miR‐200c.

Liver cancer cells with nuclear MET overexpression release translation regulatory protein‐enriched extracellular vesicles exhibit metastasis promoting activity

MET receptor tyrosine kinase is a cell surface receptor that plays important role in embryonic development and tissue regeneration. Aberrant MET activation has been widely reported in different human cancers, making MET an attractive therapeutic target. The presence of truncated MET within the nucleus (nMET) with potential novel functions poses a great challenge to the current therapeutic strategies against MET surface receptor. Previous work has demonstrated the promoting effect of nMET in aggressive properties of hepatocellular carcinoma (HCC) cells by activating TAK1/NF-κB signalling pathway. Herein, we report the role of nMET in modulating tumour microenvironment and tumour metastasis mediated by extracellular vesicles (EVs). EVs released by nMET overexpressing cells enhanced cell motility and provoked metastasis. Proteomic profiling revealed the enrichment of translational regulatory proteins in EVs derived from nMET overexpressing cells. These proteins include eukaryotic initiation factor (EIF), ribosomal protein small subunit (RPS) and ribosomal protein larger subunit (RPL) gene families. Knockdown of EIF3I, RPS3A and RPL10 diminished the promoting effect of EVs in cell migration invasiveness and metastasis. In conclusion, the findings reveal an unrecognized capacity of nMET to augment HCC through the release of EVs with oncogenic effect. Targeting these translation-related proteins may serve as an alternative treatment for patients with nMET overexpression.

Towards Kinase Inhibitor Therapies for Fragile X Syndrome: Tweaking Twists in the Autism Spectrum Kinase Signaling Network.

Absence of the Fragile X Messenger Ribonucleoprotein 1 (FMRP) causes autism spectrum disorders and intellectual disability, commonly referred to as the Fragile X syndrome. FMRP is a negative regulator of protein translation and is essential for neuronal development and synapse formation. FMRP is a target for several post-translational modifications (PTMs) such as phosphorylation and methylation, which tightly regulate its cellular functions. Studies have indicated the involvement of FMRP in a multitude of cellular pathways, and an absence of FMRP was shown to affect several neurotransmitter receptors, for example, the GABA receptor and intracellular signaling molecules such as Akt, ERK, mTOR, and GSK3. Interestingly, many of these molecules function as protein kinases or phosphatases and thus are potentially amendable by pharmacological treatment. Several treatments acting on these kinase-phosphatase systems have been shown to be successful in preclinical models; however, they have failed to convincingly show any improvements in clinical trials. In this review, we highlight the different protein kinase and phosphatase studies that have been performed in the Fragile X syndrome. In our opinion, some of the paradoxical study conclusions are potentially due to the lack of insight into integrative kinase signaling networks in the disease. Quantitative proteome analyses have been performed in several models for the FXS to determine global molecular processes in FXS. However, only one phosphoproteomics study has been carried out in Fmr1 knock-out mouse embryonic fibroblasts, and it showed dysfunctional protein kinase and phosphatase signaling hubs in the brain. This suggests that the further use of phosphoproteomics approaches in Fragile X syndrome holds promise for identifying novel targets for kinase inhibitor therapies.

Ubiquitin ligases and a processive proteasome facilitate protein clearance during the oocyte-to-embryo transition in Caenorhabditis elegans.

The ubiquitin-mediated degradation of oocyte translational regulatory proteins is a conserved feature of the oocyte-to-embryo transition. In the nematode Caenorhabditis elegans, multiple translational regulatory proteins, including the TRIM-NHL RNA-binding protein LIN-41/Trim71 and the Pumilio-family RNA-binding proteins PUF-3 and PUF-11, are degraded during the oocyte-to-embryo transition. Degradation of each protein requires activation of the M-phase cyclin-dependent kinase CDK-1, is largely complete by the end of the first meiotic division and does not require the anaphase-promoting complex. However, only LIN-41 degradation requires the F-box protein SEL-10/FBW7/Cdc4p, the substrate recognition subunit of an SCF-type E3 ubiquitin ligase. This finding suggests that PUF-3 and PUF-11, which localize to LIN-41-containing ribonucleoprotein particles, are independently degraded through the action of other factors and that the oocyte ribonucleoprotein particles are disassembled in a concerted fashion during the oocyte-to-embryo transition. We develop and test the hypothesis that PUF-3 and PUF-11 are targeted for degradation by the proteasome-associated HECT-type ubiquitin ligase ETC-1/UBE3C/Hul5, which is broadly expressed in C. elegans. We find that several GFP-tagged fusion proteins that are degraded during the oocyte-to-embryo transition, including fusions with PUF-3, PUF-11, LIN-41, IFY-1/Securin, and CYB-1/Cyclin B, are incompletely degraded when ETC-1 function is compromised. However, it is the fused GFP moiety that appears to be the critical determinant of this proteolysis defect. These findings are consistent with a conserved role for ETC-1 in promoting proteasome processivity and suggest that proteasomal processivity is an important element of the oocyte-to-embryo transition during which many key oocyte regulatory proteins are rapidly targeted for degradation.

CircRNA perspective: new strategies for RNA therapy.

Circular RNA (circRNA) is generated via intronic complementary sequence (ICS)-driven, RNA binding protein (RBP)-driven, or lariat-mediated back-splicing (BS) biogenesis models. The physiological and pathological functions of circRNAs occur through miRNA sponging, interacting with circRNA binding proteins (cRBPs), protein translation, or transcriptional regulation. CircRNAs play roles in regulation of cancer development, cardiovascular diseases, neurogenesis and neurological disorders, and metabolic diseases. CircRNA perspective: new strategies for RNA therapy: (Trends in Molecular Medicine , 343–344; 2022)Wu et al.Trends in Molecular MedicineMay 1, 2022In BriefIn the published version of Figure 2, the term 'circRNA' is mispresented as 'ciRNA' due to an editing error. This has been corrected in the revised figure. We apologize for any confusion this caused. Full-Text PDF

PUS7 deficiency in human patients causes profound neurodevelopmental phenotype by dysregulating protein translation.

Protein translation is a highly regulated process involving the interaction of numerous genes on every component of the protein translation machinery. Upregulated protein translation is a hallmark of cancer and is implicated in autism spectrum disorder, but the risks of developing each disease do not appear to be correlated with one another. In this study we identified two siblings from the NIH Undiagnosed Diseases Program with loss of function variants in PUS7, a gene previously implicated in the regulation of total protein translation. These patients exhibited a neurodevelopmental phenotype including autism spectrum disorder in the proband. Both patients also had features of Lesch-Nyhan syndrome, including hyperuricemia and self-injurious behavior, but without pathogenic variants in HPRT1. Patient fibroblasts demonstrated upregulation of protein synthesis, including elevated MYC protein, but did not exhibit increased rates of cell proliferation. Interestingly, the dysregulation of protein translation also resulted in mildly decreased levels of HPRT1 protein suggesting an association between dysregulated protein translation and the LNS-like phenotypic findings. These findings strengthen the correlation between neurodevelopmental disease, particularly autism spectrum disorders, and the rate of protein translation.