Specific mRNA Transcripts Research Articles

Nab-paclitaxel plus S-1 followed by gemcitabine-oxaliplatin as first-line alternating sequential treatment of pancreatic ductal adenocarcinoma.

Alternating sequential administration of drugs may be a promising approach to overcome chemotherapy resistance in advanced pancreatic ductal adenocarcinoma (PDAC). This study was an open-label, single-arm, and prospective trial included patients with untreated advanced PDAC. They received 2 cycles of NS regimen (nab-paclitaxel:125 mg/m2, intravenously injected on days 1 and 8, plus S-1:40-60 mg, orally twice per day for 1-14 days) followed by 2 cycles of GemOx regimen (gemcitabine, intravenously injected on days 1 and 8, and oxaliplatin: 130 mg/m2, intravenously injected on day 1). The primary efficacy endpoint was a progression-free survival rate at 6 months (PFSR-6m). The secondary efficacy endpoints included overall survival (OS), progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and adverse events (AEs). Specific mRNA transcripts were used to explore survival associated genes. Forty-two patients received a minimum of one treatment cycle, and of these, 30 patients completed one alternating treatment consisting of 4 cycles. The PFSR-6m was 71% (95% CI = 58%-87%). The median PFS and OS were 6.53 months (95% CI = 6.03-8.43) and 11.4 months (95% CI = 9.8-14.4), respectively. Common grades 3-4 hematological AEs included neutropenia 30.9%, leukopenia 26.2%, anemia 2.4%, and thrombocytopenia in 11.9%. Patients with OS > 10 months showed high expression of HLA-DQA2 while melanoma-associated antigen genes (MAGE) were notably upregulated in patients with OS < 10 months. The alternating sequential administration of the NS and GemOx regimens may be a novel approach for first-line chemotherapy in patients with advanced PDAC requiring further study (ClinicalTrials.gov Identifier: ChiCTR1900024867).

The mRNA-capping enzyme localizes to stress granules in the cytoplasm and maintains cap homeostasis of target mRNAs.

The model of RNA stability has undergone a transformative shift with the revelation of a cytoplasmic capping activity that means a subset of transcripts are recapped autonomously of their nuclear counterparts. The present study demonstrates nucleo-cytoplasmic shuttling of the mRNA-capping enzyme (CE, also known as RNA guanylyltransferase and 5'-phosphatase; RNGTT), traditionally acknowledged for its nuclear localization and functions, elucidating its contribution to cytoplasmic capping activities. A unique nuclear export sequence in CE mediates XPO1-dependent nuclear export of CE. Notably, during sodium arsenite-induced oxidative stress, cytoplasmic CE (cCE) congregates within stress granules (SGs). Through an integrated approach involving molecular docking and subsequent co-immunoprecipitation, we identify eIF3b, a constituent of SGs, as an interactive associate of CE, implying that it has a potential role in guiding cCE to SGs. We measured the cap status of specific mRNA transcripts from U2OS cells that were non-stressed, stressed and recovered from stress, which indicated that cCE-target transcripts lost their caps during stress but remarkably regained cap stability during the recovery phase. This comprehensive study thus uncovers a novel facet of cytoplasmic CE, which facilitates cellular recovery from stress by maintaining cap homeostasis of target mRNAs.

Abstract 3016: MCPIP1 endoribonuclease protects from liver fibrosis and regulates hepatocellular development

Abstract Introduction: MCPIP1 (Monocyte Chemotactic Protein-1 Induced Protein), also known as Regnase-1, belongs to the CCCH zinc finger protein family, featuring a PilT N-terminus (PIN) domain-like RNase domain. Utilizing its intrinsic endonuclease activity, MCPIP1 functions as a precise modulator of cytokines, exhibiting an anti-inflammatory effect through the targeted degradation of specific mRNA transcripts. While recent studies have highlighted MCPIP1 as a potential tumor suppressor with decreased levels in breast cancer and clear cell renal cell carcinoma, its role in hepatocellular carcinoma (HCC) development remains unexplored. Material and Methods: To investigate the role of MCPIP1 in HCC development, we used tissue-specific knockout mice with the deletion of Mcpip1 in hepatocytes. HCC was induced by administering diethylnitrosamine (DEN) to two-week-old mice. We conducted a comprehensive analysis, including the assessment of EMT and fibrosis markers, proinflammatory cytokines, and immune cell infiltration, using Western blot (WB), mass spectrometry, quantitative PCR (qPCR), and multiple immunohistochemistry (IHC) stainings. To identify differences between the wild-type (wt) and Mcpip1 knockout (KO) mice groups more effectively, hepatocytes were isolated using the perfusion method, and RNA-Seq analysis was performed. Results and Discussion: The tissue-specific knockout of Mcpip1 in the liver has notable molecular consequences. Transcriptomic profiling revealed an upregulation of transcripts integral to tumor development, including Cxcr4, Met, Cxcl12, Hgf, and Src, alongside factors characteristically associated with cancer stem cells, Myc, Klf4, and CD133. The absence of MCPIP1 triggered immune cell activation in the liver, as evidenced by an augmented expression of markers specific to myeloid and lymphoid cell populations, indicative of an intensified immunological response. IHC examination of liver tissue from Mcpip1-deficient mice revealed significant fibrotic alterations, characterized by increased collagen deposition, and enhanced expression of alpha-smooth muscle actin (αSMA). The lack of Mcpip1 influences the increased levels of vimentin, fibronectin, and connective tissue growth factor (cTGF), indicating enhanced tissue remodeling. Conclusions: MCPIP1, recognized for its anti-inflammatory functions, appears to function as a potential tumor suppressor in HCC development. The lack of MCPIP1 results in the upregulation of transcripts linked to tumorigenesis, immune cell activation, and notable fibrotic changes, highlighting its involvement in the complex molecular dynamics of HCC progression. This study was supported by National Science Center grants no. 2017/26/E/NZ5/00691, 2021/41/N/NZ4/04187. Citation Format: Katarzyna Miekus, Oliwia Kwapisz, Paulina Marona, Judyta Gorka, Jerzy Kotlinowski, Ewelina Pospiech, Jolanta Jura. MCPIP1 endoribonuclease protects from liver fibrosis and regulates hepatocellular development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3016.

RNA is a key component of extracellular DNA networks in Pseudomonas aeruginosa biofilms

The extracellular matrix of bacterial biofilms consists of diverse components including polysaccharides, proteins and DNA. Extracellular RNA (eRNA) can also be present, contributing to the structural integrity of biofilms. However, technical difficulties related to the low stability of RNA make it difficult to understand the precise roles of eRNA in biofilms. Here, we show that eRNA associates with extracellular DNA (eDNA) to form matrix fibres in Pseudomonas aeruginosa biofilms, and the eRNA is enriched in certain bacterial RNA transcripts. Degradation of eRNA associated with eDNA led to a loss of eDNA fibres and biofilm viscoelasticity. Compared with planktonic and biofilm cells, the biofilm matrix was enriched in specific mRNA transcripts, including lasB (encoding elastase). The mRNA transcripts colocalised with eDNA fibres in the biofilm matrix, as shown by single molecule inexpensive FISH microscopy (smiFISH). The lasB mRNA was also observed in eDNA fibres in a clinical sputum sample positive for P. aeruginosa. Thus, our results indicate that the interaction of specific mRNAs with eDNA facilitates the formation of viscoelastic networks in the matrix of Pseudomonas aeruginosa biofilms.

MiR-155-5p Elevated by Ochratoxin A Induces Intestinal Fibrosis and Epithelial-to-Mesenchymal Transition through TGF-β Regulated Signaling Pathway In Vitro and In Vivo.

Ochratoxin A (OTA) is a mycotoxin that induces fibrosis and epithelial-to-mesenchymal transitions (EMT) in kidneys and livers. It enters our bodies through food consumption, where it is absorbed in the intestines. However, the impact of OTA on the intestines is yet to be studied. MicroRNA (miRNAs) are small non-coding single-stranded RNAs that block the transcription of specific mRNAs and are, therefore, involved in many biochemical processes. Our findings indicate that OTA can induce EMT and intestinal fibrosis both in vivo and in vitro. This study examines the impact of OTA on intestinal toxicity and the role of miRNAs in this process. Following OTA treatment, miR-155-5p was the most elevated miRNA by next-generation sequencing. Our research showed that OTA increased miR-155-5p levels through transforming growth factor β (TGF-β), leading to the development of intestinal fibrosis and EMT. Additionally, the study identified that the modulation of TGF-β and miR-155-5p by OTA is linked to the inhibition of CCAAT/enhancer-binding protein β (C/EBPβ) and Smad2/3 accumulation in the progression of intestinal fibrosis.

Transcriptomic impacts and potential routes of detoxification in a lampricide-tolerant teleost exposed to TFM and niclosamide

Sea lamprey (Petromyzon marinus) control in the Laurentian Great Lakes of North America often relies on the application of 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide mixtures to kill larval sea lamprey. Selectivity of TFM against lampreys appears to be due to differential detoxification ability in these jawless fishes compared to bony fishes, particularly teleosts. However, the proximate mechanisms of tolerance to the TFM and niclosamide mixture and the mechanisms of niclosamide toxicity on its own are poorly understood, especially among non-target fishes. Here, we used RNA sequencing to identify specific mRNA transcripts and functional processes that responded to niclosamide or a TFM:niclosamide mixture in bluegill (Lepomis macrochirus). Bluegill were exposed to niclosamide or TFM:niclosamide mixture, along with a time-matched control group, and gill and liver tissues were sampled at 6, 12, and 24 h. We summarized the whole-transcriptome patterns through gene ontology (GO) term enrichment and through differential expression of detoxification genes. The niclosamide treatment resulted in an upregulation of several transcripts associated with detoxification (cyp, ugt, sult, gst), which may help explain the relatively high detoxification capacity in bluegill. Conversely, the TFM:niclosamide mixture resulted in an enrichment of processes related to arrested cell cycle and growth, and cell death alongside a diverse detoxification gene response. Detoxification of both lampricides likely involves the use of phase I and II biotransformation genes. Our findings strongly suggest that the unusually high tolerance of bluegill to lampricides is due to these animals having an inherently high capacity and flexible detoxification response to such compounds.

Hepatic proteomic assessment of oral ingestion of titanium dioxide nano fiber (TDNF) in Sprague Dawley rats

Titanium dioxide nanofibers (TDNF) have been widely employed in pigments, sunscreens, paints, ointments, toothpaste and photocatalytic splitting of water. However, their potential toxicity has not been thoroughly examined. The goal of the present study is to examine hepatic effects associated with the ingestion of TDNF. TDNF was fabricated via electrospinning method and characterized. Six to seven weeks old male Sprague Dawley rats ingested (oral gavage) a total of 0 ppm, 40, 60 ppm TDNF for two weeks. After sacrifice, the liver was assessed for cellular effects using proteomic approach. The fibers diameter ranged from 0.18 − 0.29 μm, forming clusters and majority of the fibers were in the rutile phase. Proteomics assessment revealed more that more than 400 hundred proteins in the liver may be affected. These proteins are involved in such processes as catalysis of fatty acids by CoA, homocysteine metabolism, beta oxidation and the condensation of carbamoyl phosphate in the urea cycle among others. Further analysis of the protein associations showed that 325 biological processes, 140 molecular functions and 70 cellular components appear to be affected from the ingestion of TNDF. Quantitative analysis of specific mRNA transcripts indicated CMBL, GSTM1 and SDS were differentially expressed.

The human DEAD-box helicase DDX3X as a regulator of mRNA translation.

The human DEAD-box protein DDX3X is an RNA remodelling enzyme that has been implicated in various aspects of RNA metabolism. In addition, like many DEAD-box proteins, it has non-conventional functions that are independent of its enzymatic activity, e.g., DDX3X acts as an adaptor molecule in innate immune signalling pathways. DDX3X has been linked to several human diseases. For example, somatic mutations in DDX3X were identified in various human cancers, and de novo germline mutations cause a neurodevelopmental condition now termed 'DDX3X syndrome'. DDX3X is also an important host factor in many different viral infections, where it can have pro-or anti-viral effects depending on the specific virus. The regulation of translation initiation for specific mRNA transcripts is likely a central cellular function of DDX3X, yet many questions regarding its exact targets and mechanisms of action remain unanswered. In this review, we explore the current knowledge about DDX3X's physiological RNA targets and summarise its interactions with the translation machinery. A role for DDX3X in translational reprogramming during cellular stress is emerging, where it may be involved in the regulation of stress granule formation and in mediating non-canonical translation initiation. Finally, we also discuss the role of DDX3X-mediated translation regulation during viral infections. Dysregulation of DDX3X's function in mRNA translation likely contributes to its involvement in disease pathophysiology. Thus, a better understanding of its exact mechanisms for regulating translation of specific mRNA targets is important, so that we can potentially develop therapeutic strategies for overcoming the negative effects of its dysregulation.

Expression Analysis of Moritella viscosa-Challenged Atlantic Salmon Identifies Disease-Responding Genes, MicroRNAs and Their Predicted Target Genes and Pathways.

Moritella viscosa is a bacterial pathogen causing winter-ulcer disease in Atlantic salmon. The lesions on affected fish lead to increased mortality, decreased fish welfare, and inferior meat quality in farmed salmon. MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional regulation by guiding the miRNA-induced silencing complex to specific mRNA transcripts (target genes). The goal of this study was to identify miRNAs responding to Moritella viscosa in salmon by investigating miRNA expression in the head-kidney and the muscle/skin from lesion sites caused by the pathogen. Protein coding gene expression was investigated by microarray analysis in the same materials. Seventeen differentially expressed guide-miRNAs (gDE-miRNAs) were identified in the head-kidney, and thirty-nine in lesion sites, while the microarray analysis reproduced the differential expression signature of several thousand genes known as infection-responsive. In silico target prediction and enrichment analysis suggested that the gDE-miRNAs were predicted to target genes involved in immune responses, hemostasis, angiogenesis, stress responses, metabolism, cell growth, and apoptosis. The majority of the conserved gDE-miRNAs (e.g., miR-125, miR-132, miR-146, miR-152, miR-155, miR-223 and miR-2188) are known as infection-responsive in other vertebrates. Collectively, the findings indicate that gDE-miRNAs are important post-transcriptional gene regulators of the host response to bacterial infection.

New, potent, small molecule agonists of tyrosine kinase receptors attenuate dry eye disease.

Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin3 (NT-3) bind to tyrosine kinase (Trk) receptors, TrkA, TrkB, and TrkC, respectively. This study investigated the efficacy of novel molecule agonists of Trk receptors in an in vivo model of dry eye disease (DED). Small molecule TrkC agonist (C1) and a pan-Trk agonist (pan) were synthesized for this. C57BL/6J mice were subjected to desiccating stress (DS) and received bilateral eye drops of C1, pan, or vehicle (2x/day). Dry eye signs, inflammation and expression of corneal barrier function, and conjunctival goblet cell (GC) densities were measured as part of the DED phenotype. Corneal epithelial lysates were collected for either western blot or RNA extraction. Extracted total RNAs were used for NanoString analyses. Immunofluorescent staining was performed on whole-mount corneas using anti-TNFAIP3 and anti-EP4 antibodies. Compared to vehicle, mice subjected to desiccating stress and treated with agonists pan and C1 showed improved corneal barrier function, while C1 also increased GC density. NanoString analyses revealed upregulation of specific mRNA transcripts (Ptger4, Tnfaip3, Il1a and Ptger4, Tlr3, Osal1) in pan- and C1-treated corneas compared to vehicle-treated corneas. Western blots showed that pan and C1 decreased vehicle-induced NFkB nuclear translocation after DS for one day and increased EP4 and TNFAIP3 protein levels after 5 days of DS in corneal epithelium lysates. We conclude that small-molecule agonists of Trk receptors improve DED by decreasing NFkB activation and increasing protein expression of anti-inflammatory molecules TNFAIP3 and EP4. Surprisingly, the most efficacious small molecule agonists were not TrkA selective but TrkC and panTrk, suggesting that wider exploration of TrkB and C and pan Trk agonists are warranted in efforts to treat DED.

Peripheral CD23hi/IgE+ Plasmablasts Secrete IgE and Correlate with Allergic Disease Severity.

Production and secretion of IgE by B cells, plasmablasts, and plasma cells is a central step in the development and maintenance of allergic diseases. IgE can bind to one of its receptors, the low-affinity IgE receptor CD23, which is expressed on activated B cells. As a result, most B cells bind IgE through CD23 on their surface. This makes the identification of IgE producing cells challenging. In this study, we report an approach to clearly identify live IgE+ plasmablasts in peripheral blood for application by both flow cytometry analysis and in vitro assay. These IgE+ plasmablasts readily secrete IgE, upregulate specific mRNA transcripts (BLIMP-1 IRF4, XBP1, CD138, and TACI), and exhibit highly differentiated morphology all consistent with plasmablast differentiation. Most notably, we compared the presence of IgE+ plasmablasts in peripheral blood of allergic and healthy individuals using a horse model of naturally occurring seasonal allergy, Culicoides hypersensitivity. The model allows the comparison of immune cells both during periods of clinical allergy and when in remission and clinically healthy. Allergic horses had significantly higher percentages of IgE+ plasmablasts and IgE secretion while experiencing clinical allergy compared with healthy horses. Allergy severity and IgE secretion were both positively correlated to the frequency of IgE+ plasmablasts in peripheral blood. These results provide strong evidence for the identification and quantification of peripheral IgE-secreting plasmablasts and provide a missing cellular link in the mechanism of IgE secretion and upregulation during allergy.

Preprint Highlight: The novel Rab5 effector FERRY links early endosomes with the translation machinery.

Early endosomes bind certain mRNAs and are thought to facilitate translation thereon, but the mechanism underlying this function is not known. This study identifies a novel Rab 5 effector complex, the five-subunit endosomal Rab5 and the RNA/ribosome ntermediary (FERRY), which localizes to endosomes in neurons. By combining biochemical- and fluorescence-based assays, the authors find that FERRY binds specific mRNA transcripts, mostly those encoding mitochondrial proteins, and is found in proximity to mitochondria. This study proposes that early endosomes function both as platforms for particular mRNA translation and vehicles for mRNA delivery to mitochondria. Considering that mutations in FERRY subunits are associated with neurological disorders, these findings shed new light on the importance of endosomal-mitochondrial cross-talk in neurons and likely other cell types.

Proximity-based labeling reveals DNA damage–induced phosphorylation of fused in sarcoma (FUS) causes distinct changes in the FUS protein interactome

Accumulation of cytoplasmic inclusions containing fused in sarcoma (FUS), an RNA/DNA-binding protein, is a common hallmark of frontotemporal lobar degeneration and amyotrophic lateral sclerosis neuropathology. We have previously shown that DNA damage can trigger the cytoplasmic accumulation of N-terminally phosphorylated FUS. However, the functional consequences of N-terminal FUS phosphorylation are unknown. To gain insight into this question, we utilized proximity-dependent biotin labeling via ascorbate peroxidase 2 aired with mass spectrometry to investigate whether N-terminal phosphorylation alters the FUS protein–protein interaction network (interactome), and subsequently, FUS function. We report the first analysis comparing the interactomes of three FUS variants: homeostatic wildtype FUS (FUS WT), phosphomimetic FUS (FUS PM; a proxy for N-terminally phosphorylated FUS), and the toxic FUS proline 525 to leucine mutant (FUS P525L) that causes juvenile amyotrophic lateral sclerosis. We found that the phosphomimetic FUS interactome is uniquely enriched for a group of cytoplasmic proteins that mediate mRNA metabolism and translation, as well as nuclear proteins involved in the spliceosome and DNA repair functions. Furthermore, we identified and validated the RNA-induced silencing complex RNA helicase MOV10 as a novel interacting partner of FUS. Finally, we provide functional evidence that N-terminally phosphorylated FUS may disrupt homeostatic translation and steady-state levels of specific mRNA transcripts. Taken together, these results highlight phosphorylation as a unique modulator of the interactome and function of FUS.

Vertical transmission of attaching and invasive E. coli from the dam to neonatal mice predisposes to more severe colitis following exposure to a colitic insult later in life.

The gastrointestinal microbiota begins to be acquired at birth and continually matures through early adolescence. Despite the relevance for gut health, few studies have evaluated the impact of pathobiont colonization of neonates on the severity of colitis later in life. LF82 is an adherent invasive E. coli strain associated with ileal Crohn's disease. The aim of this study was to evaluate the severity of dextran sodium sulfate (DSS)-induced colitis in mice following E. coli LF82 colonization. Gnotobiotic mice harboring the altered Schaedler flora (ASF) were used as the model. While E. coli LF82 is neither adherent nor invasive, it was been demonstrated that adult ASF mice colonized with E. coli LF82 develop more severe DSS-induced colitis compared to control ASF mice treated with DSS. Therefore, we hypothesized that E. coli LF82 colonization of neonatal ASF mice would reduce the severity of DSS-induced inflammation compared to adult ASF mice colonized with E. coli LF82. To test this hypothesis, adult ASF mice were colonized with E. coli LF82 and bred to produce offspring (LF82N) that were vertically colonized with LF82. LF82N and adult-colonized (LF82A) mice were given 2.0% DSS in drinking water for seven days to trigger colitis. More severe inflammatory lesions were observed in the LF82N + DSS mice when compared to LF82A + DSS mice, and were characterized as transmural in most of the LF82N + DSS mice. Colitis was accompanied by secretion of proinflammatory cytokines (IFNγ, IL-17) and specific mRNA transcripts within the colonic mucosa. Using 16S rRNA gene amplicon sequencing, LF82 colonization did not induce significant changes in the ASF community; however, minimal changes in spatial redistribution by fluorescent in situ hybridization were observed. These results suggest that the age at which mice were colonized with E. coli LF82 pathobiont differentially impacted severity of subsequent colitic events.

Changes in Expression of Specific mRNA Transcripts after Single- or Re-Irradiation in Mouse Testes

Alkylating agents and irradiation induce testicular damage, which results in prolonged azoospermia. Even very low doses of radiation can significantly impair testis function. However, re-irradiation is an effective strategy for locally targeted treatments and the pain response and has seen important advances in the field of radiation oncology. At present, little is known about the relationship between the harmful effects and accumulated dose of irradiation derived from continuous low-dose radiation exposure. In this study, we examined the levels of mRNA transcripts encoding markers of 13 markers of germ cell differentiation and 28 Sertoli cell-specific products in single- and re-irradiated mice. Our results demonstrated that re-irradiation induced significantly decreased testicular weights with a significant decrease in germ cell differentiation mRNA species (Spo11, Tnp1, Gfra1, Oct4, Sycp3, Ddx4, Boll, Crem, Prm1, and Acrosin). In the 13 Sertoli cell-specific mRNA species decreased upon irradiation, six mRNA species (Claudin-11, Espn, Fshr, GATA1, Inhbb, and Wt1) showed significant differences between single- and re-irradiation. At the same time, different decreases in Sertoli cell-specific mRNA species were found in single-irradiation (Aqp8, Clu, Cst12, and Wnt5a) and re-irradiation (Tjp1, occludin, ZO-1, and ZO-2) mice. These results indicate that long-term aspermatogenesis may differ after single- and re-irradiated treatment.

MiRNA-Based Regulation of Alternative RNA Splicing in Metazoans.

Alternative RNA splicing is an important regulatory process used by genes to increase their diversity. This process is mainly executed by specific classes of RNA binding proteins that act in a dosage-dependent manner to include or exclude selected exons in the final transcripts. While these processes are tightly regulated in cells and tissues, little is known on how the dosage of these factors is achieved and maintained. Several recent studies have suggested that alternative RNA splicing may be in part modulated by microRNAs (miRNAs), which are short, non-coding RNAs (~22 nt in length) that inhibit translation of specific mRNA transcripts. As evidenced in tissues and in diseases, such as cancer and neurological disorders, the dysregulation of miRNA pathways disrupts downstream alternative RNA splicing events by altering the dosage of splicing factors involved in RNA splicing. This attractive model suggests that miRNAs can not only influence the dosage of gene expression at the post-transcriptional level but also indirectly interfere in pre-mRNA splicing at the co-transcriptional level. The purpose of this review is to compile and analyze recent studies on miRNAs modulating alternative RNA splicing factors, and how these events contribute to transcript rearrangements in tissue development and disease.

Hecw controls oogenesis and neuronal homeostasis by promoting the liquid state of ribonucleoprotein particles

Specialised ribonucleoprotein (RNP) granules are a hallmark of polarized cells, like neurons and germ cells. Among their main functions is the spatial and temporal modulation of the activity of specific mRNA transcripts that allow specification of primary embryonic axes. While RNPs composition and role are well established, their regulation is poorly defined. Here, we demonstrate that Hecw, a newly identified Drosophila ubiquitin ligase, is a key modulator of RNPs in oogenesis and neurons. Hecw depletion leads to the formation of enlarged granules that transition from a liquid to a gel-like state. Loss of Hecw activity results in defective oogenesis, premature aging and climbing defects associated with neuronal loss. At the molecular level, reduced ubiquitination of the Fmrp impairs its translational repressor activity, resulting in altered Orb expression in nurse cells and Profilin in neurons.

The role of circulating blood microRNA-374 and microRNA-10 levels in the pathogenesis and therapeutic mechanisms of major depressive disorder

Compelling recent evidence suggests that microRNAs (miRNAs) regulate specific mRNA transcripts at the transcriptomic level and coordinately influence complex regulatory networks, which may play a crucial role in the pathogenesis of major depressive disorder (MDD) and the treatment effects of antidepressants. To evaluate the possible involvement of miRNAs in the pathophysiology and therapeutic response of MDD, we conducted a miRNA expression array analysis of the peripheral blood mononuclear cells (PBMCs) of 5 depressed patients and 5 healthy controls (HCs). Subsequently, we chose 2 miRNAs for validation with real-time PCR (RT-PCR) analysis pre- and post-treatment in another group of 25 MDD patients and 25 HCs. In the array, 5 miRNAs were differentially expressed in medication-naïve MDD patients compared to HCs, of which 2 miRNAs were upregulated and 3 were downregulated. Furthermore, in comparison with HCs, MDD patients showed significantly lower expression levels of miR-374b and miR-10a before treatment. After 8 weeks of antidepressant treatment, both miR-374b and the miR-10a expression levels in MDD patients were significantly elevated only in responders. In conclusion, these results indicate the involvement of miR-374b and miR-10a in the biological mechanisms and therapeutic response of MDD, and provide new insights for exploring miRNAs as potential biomarkers for MDD.

Constitutive immune surveillance of the nasal mucosa by neutrophils

Abstract The nasal mucosa is a versatile tissue where functions such as olfaction and conditioning of air take place. A particularly relevant and less explored function of this tissue relates to its capacity to respond to insult. Air-borne pathogens can use the nasal mucosa as a portal of entry to further disseminate into deeper tissues and little is known about the immune cell populations these pathogens encounter upon infection. We asked what immune cell populations are present in the murine nasal mucosa and unexpectedly found extravascular neutrophils to be a constitutive and prominent population in the steady state. These neutrophils were found in comparable numbers in conventional vs. germ-free mice and can be divided into three well-defined populations based on the expression of specific cell surface markers and mRNA transcript profiles. One of the populations was traced to nasal mucosa-associated pockets of bone marrow and determined to contribute to the nasal mucosa neutrophil extravascular pool. A second population was found to preferentially phagocytose bacteria during infection. In the absence of infection, this population differentiates into a third population, which interacts with other cells of the nasal mucosa in a manner that resembles trogocytosis. Lastly, we found extravascular granulocyte hematopoietic precursors in the nasal mucosa that likely contribute to the extravascular neutrophil pool. Thus, the nasal mucosa encompasses a constitutive population of extravascular neutrophils that show diverse origins and specialization of function. These findings contribute to our understanding of the composition and development of the microenvironment that air-borne pathogens encounter upon infection in the nasal mucosa.

A Novel Method for Single Molecule Visualization of Active Protein Synthesis in Cardiac Myocytes Reveals SERCA2a mRNA Translation is Sarcoplasmic Reticulum Ca2+ Load Dependent

Protein abundance in cardiomyocytes is controlled at both transcription and translation levels. While changes in transcription in cardiac proteins such as the sarcoplasmic reticulum Ca2+ ATPAse (SERCA2a) in response to both physiological and pathological stimuli have been extensively studied, dynamic modulation of translation and the underlying mechanisms have received little attention. We have developed MR-PLISH (mRNA-rRNA Proximity Ligated in Situ Hybridization), a new imaging method for visualization of translation of endogenous specific mRNA transcripts in cardiomyocytes. This method is based on combined use of RNA in situ hybridization and the proximity ligation assay (PLA) technology and allows us to detect single mRNAs interacting with 18S ribosomal RNA (Rn18s). Using this approach, as well as RNAscope® for single molecule detection of mRNA, we examined the effects of depleting intra-SR Ca2+ with thapsigargin (TG) on transcription and translation of the mRNA for SERCA2a (Atp2a2) in cardiomyocytes. Under baseline conditions both total and 18s rRNA-hybridized Atp2a2 displayed a cell-wide distribution. Treatment with thapsigargin caused no significant changes in abundance or distribution of total Atp2a2 mRNA; however, it resulted in a significant increase in 18s rRNA-hybridized Atp2a2, consistent with an increased rate of active protein synthesis. These results suggest that intra-SR Ca2+ modulates localized translation of SERCA2a mRNA in cardiomyocytes. Thus, SERCA2A translation maybe subject to regulation via a local feedback loop to compensate for reduction in intra-SR Ca2+ levels.