Oxygen-regulated expression of the RNA-binding proteins RBM3 and CIRP by a HIF-1-independent mechanism

Prognostic Significance of RBM3 Expression in Epithelial Ovarian Cancer: A Tissue Microarray-Based Study

Background/Objectives: RNA-binding motif protein 3 (RBM3) is a cold-shock protein associated with a favorable prognosis in various malignancies. However, its role in epithelial ovarian cancer (OC) remains unclear. This study aimed to evaluate the prognostic significance of RBM3 expression in OC and its association with clinicopathological features. Methods: We retrospectively analyzed 183 cases of OC. Tissue microarrays were constructed using paired 2 mm tumor cores, and RBM3 expression was assessed by immunohistochemistry. Nuclear staining was semi-quantitatively scored based on intensity and proportion, generating a nuclear score (NS). Cases were classified as high (NS > 1) or low (NS ≤ 1) expression. Associations with clinicopathological parameters and survival outcomes were analyzed using chi-square tests, Kaplan-Meier survival curves, and Cox regression models. Results: High RBM3 expression was observed in 51.4% of cases and was significantly associated with favorable histologic subtypes (mucinous, endometrioid, clear cell), early International Federation of Gynecology and Obstetrics (FIGO) stage, and the absence of distant metastasis. Subgroup survival analyses stratified by histologic subtype revealed no significant differences in survival outcomes. RBM3 expression was correlated with prolonged disease-free and overall survival, although it did not retain significance in multivariate analysis. Conclusions: RBM3 expression is strongly associated with favorable pathological features in epithelial ovarian cancer. Although not an independent prognostic marker, RBM3 may serve as a complementary biomarker for risk stratification and prognosis in clinical practice.

CIRBP mRNA level in breast cancer is associated with HIF1α gene expression and microvascular density

OBJECTIVE

Based on the available evidence, the cold-inducible RNA-binding protein (CIRBP) appears to play a role in increasing the stability of hypoxia-inducible factor 1-alpha (HIF1α) mRNA. This research aimed to examine the levels of CIRBP and HIF1α mRNA within breast tumor tissues and explore the relationship between their gene expression and tumor Microvascular density (MVD).

RESULTS

The results revealed a significant upregulation of CIRBP (5.07-fold) and HIF1α (4.5-fold) gene expression in BC samples compared to the surrounding normal tissues (p < 0.001). This upregulation was also associated with various clinicopathologic features. Furthermore, there was a correlation between CIRBP mRNA expression, HIF1α mRNA expression, and MVD. Consequently, this study suggests that CIRBP may have a role in promoting angiogenesis in BC.

Extracellular Cold-Inducible RNA-Binding Protein: Progress from Discovery to Present

Extracellular cold-inducible RNA-binding protein (eCIRP) is a critical damage-associated molecular pattern (DAMP) that drives inflammation and tissue injury in hemorrhagic and septic shock, and has emerged as a promising therapeutic target. Since then, extensive research using preclinical models of diseases and patient materials has explored eCIRP's role in driving inflammatory responses and its potential as a biomarker. The main objective of this comprehensive review is to provide a detailed overview of eCIRP, covering its discovery, role in disease pathophysiology, mechanisms of release and action, potential as a biomarker, and therapeutic strategies targeting eCIRP in preclinical models of inflammatory and ischemic diseases. We examine the molecular, cellular, and immunological mechanisms through which eCIRP contributes to disease progression, and explore both well-established and emerging areas of research. Furthermore, we discuss potential therapeutic strategies targeting eCIRP across a broad spectrum of inflammatory conditions, including shock, ischemia-reperfusion injury, neurodegenerative diseases, and radiation injury.

Therapeutic modulation of protein RBM3 for ischemic stroke treatment

Several preclinical assays and clinical trials have found hypothermia as an efficient protective treatment for stroke. However, systemic hypothermia impairs several physiological functions being difficult to implement in acute critical patients. A deeper understanding of the mechanisms underlying the therapeutic effects of hypothermia could inspire new treatments based on the protective effects of cold. Furthermore, this could contribute to the reduction of the side effects associated with it. One of the metabolic landmarks of hypothermia is the overexpression of a small subset of shock proteins while global protein synthesis is reduced. Among these cold-shock proteins, RBM3 (RNA-binding motif protein 3) seems to play a central protective role. In physiological conditions, which is involved in the regulation of protein synthesis. In several models of cerebral diseases, in vitro and in vivo, RBM3 exhibited the ability to mitigate apoptosis or increase neural proliferation. In stroke models, RBM3 has shown specially promising effects attenuating neural damage and enhancing cell survival. Future prospects should be directed towards the design of efficient strategies to modulate RBM3 levels. This mini-review aims to summarize the progress made in understanding the role of RBM3 in cerebral tissue protection, while encouraging efforts to address research gaps, particularly in its modulation and clinical application.

Intracellular CIRP promotes liver regeneration via STAT3 signaling pathway activation after partial hepatectomy in mice

Cold‑inducible RNA‑binding protein (CIRP) is a cold shock protein implicated in the regulation of multiple biological processes depending on its cellular localization. However, to the best of our knowledge, the role of CIRP in liver regeneration and injury after hepatectomy has not been investigated. The present study was therefore designed to explore whether CIRP is involved in liver regeneration after hepatectomy and its specific role and underlying molecular mechanism. The overall involvement of CIRP in liver regeneration and injury after hepatectomy was evaluated in CIRP‑deficient mice. C23, an antagonist of extracellular CIRP, was used to assess the effect of extracellular CIRP on liver regeneration and injury after hepatectomy. CIRP overexpression and short hairpin RNA plasmids were transfected into HepG2 cells to study the effect of intracellular CIRP on cell proliferation. The effects of extracellular CIRP on cell proliferation and injury were determined via the use of recombinant CIRP protein to stimulate HepG2 cells in vitro. The results indicated that both hepatic and serum CIRP levels significantly increased after partial hepatectomy. Additionally, CIRP deficiency impaired liver regeneration but alleviated liver injury after partial hepatectomy in mice. C23 administration attenuated liver injury and suppressed endoplasmic reticulum (ER) stress and oxidative stress. Loss‑ and gain‑of‑function analyses in HepG2 cells indicated that an increase in intracellular CIRP promoted cell proliferation via signal transducers and activation of transcription 3 (STAT3) signaling pathway activation. Moreover, recombinant CIRP had no effect on cell proliferation or STAT3 phosphorylation but induced ER stress, which was blocked by TAK242, an inhibitor of Toll‑like receptor 4 (TLR4), in HepG2 cells. Taken together, the results of the present study demonstrated that intracellular CIRP promotes liver regeneration by activating the STAT3 pathway, whereas extracellular CIRP induces ER stress possibly via the TLR4 signaling pathway after hepatectomy.

Oxygen-dependent alternative mRNA splicing and a cone-specific motor protein revealed by single-cell RNA sequencing in hypoxic retinas

Restricted oxygen supply in the aging eye may lead to hypoxic conditions in the outer retina and contribute not only to physiological aging but also to nonhereditary degenerative retinal diseases. To understand the hypoxic response of specific retinal cell types, we performed single-cell RNA sequencing of retinas isolated from mice exposed to hypoxia. Significantly upregulated expression of marker genes in hypoxic clusters confirmed a general transcriptional response to hypoxia. By focusing on the hypoxic response in photoreceptors, we identified and confirmed a kinesin motor protein (Kif4) that was specifically and strongly induced in hypoxic cones. In contrast, RNA-binding proteins Rbm3 and Cirbp were differentially expressed across clusters but demonstrated isoform switching in hypoxia. The resulting short variants of these gene transcripts are connected to epitranscriptomic regulation, a notion supported by the differential expression of writers, readers and erasers of m6A RNA methylations in the hypoxic retina. Our data indicate that retinal cells adapt to hypoxic conditions by adjusting their transcriptome at various levels including gene expression, alternative splicing and the epitranscriptome. Adaptational processes may be cell-type specific as exemplified by the cone-specific upregulation of Kif4 or general like alternative splicing of RNA binding proteins.

DNA repair and anti-cancer mechanisms in the long-lived bowhead whale

At over 200 years, the maximum lifespan of the bowhead whale exceeds that of all other mammals. The bowhead is also the second-largest animal on Earth, reaching over 80,000 kg1. Despite its very large number of cells and long lifespan, the bowhead is not highly cancer-prone, an incongruity termed Peto's Paradox2. This phenomenon has been explained by the evolution of additional tumor suppressor genes in other larger animals, supported by research on elephants demonstrating expansion of the p53 gene3-5. Here we show that bowhead whale fibroblasts undergo oncogenic transformation after disruption of fewer tumor suppressors than required for human fibroblasts. However, analysis of DNA repair revealed that bowhead cells repair double strand breaks (DSBs) and mismatches with uniquely high efficiency and accuracy compared to other mammals. The protein CIRBP, implicated in protection from genotoxic stress, was present in very high abundance in the bowhead whale relative to other mammals. We show that CIRBP and its downstream protein RPA2, also present at high levels in bowhead cells, increase the efficiency and fidelity of DNA repair in human cells. These results indicate that rather than possessing additional tumor suppressor genes as barriers to oncogenesis, the bowhead whale relies on more accurate and efficient DNA repair to preserve genome integrity. This strategy which does not eliminate damaged cells but repairs them may be critical for the long and cancer-free lifespan of the bowhead whale.

Unraveling the intricacies of cold-inducible RNA-binding protein: A comprehensive review

Cold-inducible RNA-binding protein (CIRP) is a versatile RNA-binding protein, pivotal in modulating cellular responses to diverse stress stimuli including cold shock, ultraviolet radiation, hypoxia, and infections, with a principal emphasis on cold stress. The temperature range of 32-34 °C is most suitable for CIRP expression. The human CIRP is an 18-21 kDa polypeptide containing 172 amino acids coded by a gene located on chromosome 19p13.3. CIRP has an RNA-recognition motif (RRM) and an arginine-rich motif (RGG), both of which have roles in coordinating numerous cellular activities. CIRP itself also undergoes conformational changes in response to diverse environmental stress. Transcription factors such as hypoxia-inducible factor 1 alpha and nuclear factor-kappa B have been implicated in coordinating CIRP transcription in response to specific stimuli. The potential of CIRP to relocate from the nucleus to the cytoplasm upon exposure to different stimuli enhances its varied functional roles across different cellular compartments. The different functions include decreasing nutritional demand, apoptosis suppression, modulation of translation, and preservation of cytoskeletal integrity at lower temperatures. This review explores the diverse functions and regulatory mechanisms of CIRP, shedding light on its involvement in various cellular processes and its implications for human health and disease.

Time-resolved profiling of RNA binding proteins throughout the mRNA life cycle

mRNAs continually change their protein partners throughout their lifetimes, yet our understanding of mRNA-protein complex (mRNP) remodeling is limited by a lack of temporal data. Here, we present time-resolved mRNA interactome data by performing pulse metabolic labeling with photoactivatable ribonucleoside in human cells, UVA crosslinking, poly(A)+ RNA isolation, and mass spectrometry. This longitudinal approach allowed the quantification of over 700 RNA binding proteins (RBPs) across ten time points. Overall, the sequential order of mRNA binding aligns well with known functions, subcellular locations, and molecular interactions. However, we also observed RBPs with unexpected dynamics: the transcription-export (TREX) complex recruited posttranscriptionally after nuclear export factor 1 (NXF1) binding, challenging the current view of transcription-coupled mRNA export, and stress granule proteins prevalent in aged mRNPs, indicating roles in late stages of the mRNA life cycle. To systematically identify mRBPs with unknown functions, we employed machine learning to compare mRNA binding dynamics with Gene Ontology (GO) annotations. Our data can be explored at chronology.rna.snu.ac.kr.

A NOVEL OLIGONUCLEOTIDE MRNA MIMIC ATTENUATES HEMORRHAGE-INDUCED ACUTE LUNG INJURY

ABSTRACT

Hemorrhagic shock (HS) is accompanied by a pronounced activation of the inflammatory response in which acute lung injury (ALI) is one of the most frequent consequences. Among the pivotal orchestrators of this inflammatory cascade, extracellular cold-inducible RNA-binding protein (eCIRP) emerges as a noteworthy focal point, rendering it as a promising target for the management of inflammation and tissue injury. Recently, we have reported that oligonucleotide poly(A) mRNA mimic termed A 12 selectively binds to the RNA binding region of eCIRP and inhibits eCIRP binding to its receptor TLR4. Furthermore, in vivo administration of eCIRP induces lung injury in healthy mice and that mouse deficient in CIRP showed protection from inflammation-associated lung injury. We hypothesize that A 12 inhibits systemic inflammation and ALI in HS. To test the impacts of A 12 on systemic and lung inflammation, extent of inflammatory cellular infiltration and resultant lung damage were evaluated in a mouse model of HS. Male mice were subjected to controlled hemorrhage with a mean arterial pressure of 30 mm Hg for 90 min and then resuscitated with Ringer's lactate solution containing phosphate-buffered saline (vehicle) or A 12 at a dose of 4 nmol/g body weight (treatment). The infusion volume was twice that of the shed blood. At 4 h after resuscitation, mice were euthanized, and blood and lung tissues were harvested. Blood and tissue markers of inflammation and injury were evaluated. Serum markers of injury (lactate dehydrogenase, alanine transaminase, and blood urea nitrogen) and inflammation (TNF-α, IL-6) were increased after HS and A 12 treatment significantly decreased their levels. A 12 treatment also decreased lung levels of TNF-α, MIP-2, and KC mRNA expressions. Lung histological injury score, neutrophil infiltration (Ly6G staining and myeloperoxidase activity), and lung apoptosis were significantly attenuated after A 12 treatment. Our study suggests that the capacity of A 12 in attenuating HS-induced ALI and may provide novel perspectives in developing efficacious pharmaceutics for improving hemorrhage prognosis.

Regulation of cold-inducible RNA-binding protein (CIRBP) in response to cellular stresses

Cold-inducible RNA-Binding Protein (CIRBP) is a general stress-response factor in vertebrates harboring two domains: an RNA-recognition motif and a regulatory domain rich in RG/RGG motifs. CIRBP has been described to bind mRNAs upon various stress conditions (cold, infections, UV, hypoxia …) and regulate their stability and translation. The proteins encoded by its targets are involved in key stress-responsive cellular pathways including apoptosis, inflammation, cell proliferation or translation, thus allowing their coordination. Due to its role in regulating central cellular functions, the expression of CIRBP is tightly controlled. We review here current understanding of the multiple mechanistic layers affecting CIRBP expression and function. Beyond transcriptional regulation by cold-responsive elements and the use of alternative promoters and transcription start sites, CIRBP undergoes various alternative splicing (AS) events which, depending on conditions, modulate the stability of CIRBP transcripts and/or impact the sequence of the encoded polypeptide. Typically, whilst CIRBP expression is induced in the context of hypothermia or viral infection, AS events preferentially address alternative isoforms towards mRNA degradation pathways in response to heat stress or to bacterial-secreted pore forming toxins. Post-translational modifications of CIRBP, mostly in its RGG domain, also condition CIRBP subcellular localization and access to its targets, thereby promoting or inhibiting their expression. For instance, phosphorylation and methylation events gate CIRBP nuclear to cytoplasmic translocation and control its recruitment to stress granules. Considering the therapeutic potential of modulating the expression and function of this central player in stress responses, a fine understanding of CIRBP regulation mechanisms deserves further attention.

Promising results of a clinical feasibility study: CIRBP as a potential biomarker in pediatric cardiac surgery

Objective

Cold-inducible RNA binding Protein (CIRBP) has been shown to be a potent inflammatory mediator and could serve as a novel biomarker for inflammation. Systemic inflammatory response syndrome (SIRS) and capillary leak syndrome (CLS) are frequent complications after pediatric cardiac surgery increasing morbidity, therefore early diagnosis and therapy is crucial. As CIRBP serum levels have not been analyzed in a pediatric population, we conducted a clinical feasibility establishing a customized magnetic bead panel analyzing CIRBP in pediatric patients undergoing cardiac surgery.

Methods

A prospective hypothesis generating observational clinical study was conducted at the German Heart Center Berlin during a period of 9 months starting in May 2020 (DRKS00020885, https://drks.de/search/de/trial/DRKS00020885). Serum samples were obtained before the cardiac operation, upon arrival at the pediatric intensive care unit, 6 and 24 h after the operation in patients up to 18 years of age with congenital heart disease (CHD). Customized multiplex magnetic bead-based immunoassay panels were developed to analyze CIRBP, Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Monocyte chemotactic protein 1 (MCP-1), Syndecan-1 (SDC-1), Thrombomodulin (TM), Vascular endothelial growth factor (VEGF-A), Angiopoietin-2 (Ang-2), and Fibroblast growth factor 23 (FGF-23) in 25 µl serum using the Luminex MagPix® system.

Results

19 patients representing a broad range of CHD (10 male patients, median age 2 years, 9 female patients, median age 3 years) were included in the feasibility study. CIRBP was detectable in the whole patient cohort. Relative to individual baseline values, CIRBP concentrations increased 6 h after operation and returned to baseline levels over time. IL-6, IL-8, IL-10, and MCP-1 concentrations were significantly increased after operation and except for MCP-1 concentrations stayed upregulated over time. SDC-1, TM, Ang-2, as well as FGF-23 concentrations were also significantly increased, whereas VEGF-A concentration was significantly decreased after surgery.

Discussion

Using customized magnetic bead panels, we were able to detect CIRBP in a minimal serum volume (25 µl) in all enrolled patients. To our knowledge this is the first clinical study to assess CIRBP serum concentrations in a pediatric population.

Rbm3 deficiency leads to transcriptome-wide splicing alterations

Rbm3 (RNA-binding motif protein 3) is a stress responsive gene, which maintains cellular homeostasis and promotes survival upon various harmful cellular stimuli. Rbm3 protein shows conserved structural and molecular similarities to heterogeneous nuclear ribonucleoproteins (hnRNPs), which regulate all steps of the mRNA metabolism. Growing evidence is pointing towards a broader role of Rbm3 in various steps of gene expression. Here, we demonstrate that Rbm3 deficiency is linked to transcriptome-wide pre-mRNA splicing alterations, which can be reversed through Rbm3 co-expression from a cDNA. Using an MS2 tethering assay, we show that Rbm3 regulates splice site selection similar to other hnRNP proteins when recruited between two competing 5  ' splice sites. Furthermore, we show that the N-terminal part of Rbm3 encompassing the RNA recognition motif (RRM), is sufficient to elicit changes in splice site selection. On the basis of these findings, we propose a novel, undescribed function of Rbm3 in RNA splicing that contributes to the preservation of transcriptome integrity.

CIRP attenuates acute kidney injury after hypothermic cardiovascular surgery by inhibiting PHD3/HIF-1α-mediated ROS-TGF-β1/p38 MAPK activation and mitochondrial apoptotic pathways

BACKGROUND

The ischemia-reperfusion (IR) environment during deep hypothermic circulatory arrest (DHCA) cardiovascular surgery is a major cause of acute kidney injury (AKI), which lacks preventive measure and treatment. It was reported that cold inducible RNA-binding protein (CIRP) can be induced under hypoxic and hypothermic stress and may have a protective effect on multiple organs. The purpose of this study was to investigate whether CIRP could exert renoprotective effect during hypothermic IR and the potential mechanisms.

METHODS

Utilizing RNA-sequencing, we compared the differences in gene expression between Cirp knockout rats and wild-type rats after DHCA and screened the possible mechanisms. Then, we established the hypothermic oxygen-glucose deprivation (OGD) model using HK-2 cells transfected with siRNA to verify the downstream pathways and explore potential pharmacological approach. The effects of CIRP and enarodustat (JTZ-951) on renal IR injury (IRI) were investigated in vivo and in vitro using multiple levels of pathological and molecular biological experiments.

RESULTS

We discovered that Cirp knockout significantly upregulated rat Phd3 expression, which is the key regulator of HIF-1α, thereby inhibiting HIF-1α after DHCA. In addition, deletion of Cirp in rat model promoted apoptosis and aggravated renal injury by reactive oxygen species (ROS) accumulation and significant activation of the TGF-β1/p38 MAPK inflammatory pathway. Then, based on the HK-2 cell model of hypothermic OGD, we found that CIRP silencing significantly stimulated the expression of the TGF-β1/p38 MAPK inflammatory pathway by activating the PHD3/HIF-1α axis, and induced more severe apoptosis through the mitochondrial cytochrome c-Apaf-1-caspase 9 and FADD-caspase 8 death receptor pathways compared with untransfected cells. However, silencing PHD3 remarkably activated the expression of HIF-1α and alleviated the apoptosis of HK-2 cells in hypothermic OGD. On this basis, by pretreating HK-2 and rats with enarodustat, a novel HIF-1α stabilizer, we found that enarodustat significantly mitigated renal cellular apoptosis under hypothermic IR and reversed the aggravated IRI induced by CIRP defect, both in vitro and in vivo.

CONCLUSION

Our findings indicated that CIRP may confer renoprotection against hypothermic IRI by suppressing PHD3/HIF-1α-mediated apoptosis. PHD3 inhibitors and HIF-1α stabilizers may have clinical value in renal IRI.

RNA-binding proteins in degenerative joint diseases: A systematic review

RNA-binding proteins (RBPs), which are conserved proteins comprising multiple intermediate sequences, can interact with proteins, messenger RNA (mRNA) of coding genes, and non-coding RNAs to perform different biological functions, such as the regulation of mRNA stability, selective polyadenylation, and the management of non-coding microRNA (miRNA) synthesis to affect downstream targets. This article will highlight the functions of RBPs, in degenerative joint diseases (intervertebral disc degeneration [IVDD] and osteoarthritis [OA]). It will reviews the latest advancements on the regulatory mechanism of RBPs in degenerative joint diseases, in order to understand the pathophysiology, early diagnosis and treatment of OA and IVDD from a new perspective.

RBM3 is associated with acute lung injury in septic mice and patients via the NF-κB/NLRP3 pathway

Sepsis refers to host response disorders caused by infection, leading to life-threatening organ dysfunction. RNA-binding motif protein 3 (RBM3) is an important cold-shock protein that is upregulated in response to mild hypothermia or hypoxia. In this study, we aimed to investigate whether RBM3 is involved in sepsis-associated acute lung injury (ALI). Intraperitoneal injection of LPS (10 mg/kg) was performed in wild type (WT) and RBM3 knockout (KO, RBM3-/-) mice to establish an in vivo sepsis model. An NLRP3 inflammasome inhibitor, MCC950 (50 mg/kg), was injected intraperitoneally 30 min before LPS treatment. Serum, lung tissues, and BALF were collected 24 h later for further analysis. In addition, we also collected serum from sepsis patients and healthy volunteers to detect their RBM3 expression. The results showed that the expression of RBM3 in the lung tissues of LPS-induced sepsis mice and the serum of patients with sepsis was significantly increased and positively correlated with disease severity. In addition, RBM3 knockout (KO) mice had a low survival rate, and RBM3 KO mice had more severe lung damage, inflammation, lung cell apoptosis, and oxidative stress than WT mice. LPS treatment significantly increased the levels of nucleotide binding and oligomerization domain-like receptor family 3 (NLRP3) inflammasomes and mononuclear cell nuclear factor-κB (NF-κB) in the lung tissues of RBM3 KO mice. However, these levels were only slightly elevated in WT mice. Interestingly, MCC950 improved LPS-induced acute lung injury in WT and RBM3 KO mice but inhibited the expression of NLRP3, caspase-1, and IL-1β. In conclusion, RBM3 was overexpressed in sepsis patients and LPS-induced mice. RBM3 gene deficiency aggravated sepsis-associated ALI through the NF-κB/NLRP3 pathway.

Nucleolin Regulates Pulmonary Artery Smooth Muscle Cell Proliferation under Hypoxia by Modulating miRNA Expression

Hypoxia induces the abnormal proliferation of vascular smooth muscle cells (VSMCs), resulting in the pathogenesis of various vascular diseases. RNA-binding proteins (RBPs) are involved in a wide range of biological processes, including cell proliferation and responses to hypoxia. In this study, we observed that the RBP nucleolin (NCL) was downregulated by histone deacetylation in response to hypoxia. We evaluated its regulatory effects on miRNA expression under hypoxic conditions in pulmonary artery smooth muscle cells (PASMCs). miRNAs associated with NCL were assessed using RNA immunoprecipitation in PASMCs and small RNA sequencing. The expression of a set of miRNAs was increased by NCL but reduced by hypoxia-induced downregulation of NCL. The downregulation of miR-24-3p and miR-409-3p promoted PASMC proliferation under hypoxic conditions. These results clearly demonstrate the significance of NCL-miRNA interactions in the regulation of hypoxia-induced PASMC proliferation and provide insight into the therapeutic value of RBPs for vascular diseases.

Short-term transcriptomic changes in the mouse neural tube induced by an acute alcohol exposure

Alcohol exposure during the formation and closure of the neural tube, or neurulation (embryonic day [E] 8-10 in mice; ∼4th week of human pregnancy), perturbs development of midline brain structures and significantly disrupts gene expression in the rostroventral neural tube (RVNT). Previously, alcohol exposure during neurulation was found to alter gene pathways related to cell proliferation, p53 signaling, ribosome biogenesis, immune signaling, organogenesis, and cell migration 6 or 24 h after administration. Our current study expands upon this work by investigating short-term gene expression changes in the RVNT following a single binge-like alcohol exposure during neurulation. Female C57BL/6J mice were administered a single dose of 2.9 g/kg alcohol or vehicle on E9.0 to target mid-neurulation. The RVNTs of stage-matched embryos were collected 2 or 4 h after exposure and processed for RNA-seq. Functional profiling was performed with g:Profiler, as well as with the CiliaCarta and DisGeNet databases. Two hours following E9.0 alcohol exposure, 650 genes in the RVNT were differentially expressed. Functional enrichment analysis revealed that pathways related to cellular metabolism, gene expression, cell cycle, organogenesis, and Hedgehog signaling were down-regulated, and pathways related to cellular stress response, p53 signaling, and hypoxia were up-regulated by alcohol. Four hours after alcohol exposure, 225 genes were differentially expressed. Biological processes related to metabolism, RNA binding, ribosome biogenesis, and methylation were down-regulated, while protein localization and binding, autophagy, and intracellular signaling pathways were up-regulated. Two hours after alcohol exposure, the differentially expressed genes were associated with disease terms related to eye and craniofacial development and anoxia. These data provide further information regarding the biological functions targeted by alcohol exposure during neurulation in regions of the neural tube that give rise to alcohol-sensitive midline brain structures. Disruption of these gene pathways contributes to the craniofacial and brain malformations associated with prenatal alcohol exposure.

A hypothermia mimetic molecule (zr17-2) reduces ganglion cell death and electroretinogram distortion in a rat model of intraorbital optic nerve crush (IONC)

Introduction: Ocular and periocular traumatisms may result in loss of vision. Our previous work showed that therapeutic hypothermia prevents retinal damage caused by traumatic neuropathy. We also generated and characterized small molecules that elicit the beneficial effects of hypothermia at normal body temperature. Here we investigate whether one of these mimetic molecules, zr17-2, is able to preserve the function of eyes exposed to trauma. Methods: Intraorbital optic nerve crush (IONC) or sham manipulation was applied to Sprague-Dawley rats. One hour after surgery, 5.0 µl of 330 nmol/L zr17-2 or PBS, as vehicle, were injected in the vitreum of treated animals. Electroretinograms were performed 21 days after surgery and a- and b-wave amplitude, as well as oscillatory potentials (OP), were calculated. Some animals were sacrificed 6 days after surgery for TUNEL analysis. All animal experiments were approved by the local ethics board. Results: Our previous studies showed that zr17-2 does not cross the blood-ocular barrier, thus preventing systemic treatment. Here we show that intravitreal injection of zr17-2 results in a very significant prevention of retinal damage, providing preclinical support for its pharmacological use in ocular conditions. As previously reported, IONC resulted in a drastic reduction in the amplitude of the b-wave (p < 0.0001) and OPs (p < 0.05), a large decrease in the number of RGCs (p < 0.0001), and a large increase in the number of apoptotic cells in the GCL and the INL (p < 0.0001). Interestingly, injection of zr17-2 largely prevented all these parameters, in a very similar pattern to that elicited by therapeutic hypothermia. The small molecule was also able to reduce oxidative stress-induced retinal cell death in vitro. Discussion: In summary, we have shown that intravitreal injection of the hypothermia mimetic, zr17-2, significantly reduces the morphological and electrophysiological consequences of ocular traumatism and may represent a new treatment option for this cause of visual loss.

Chronic Kidney Disease Induces Proarrhythmic Remodeling

BACKGROUND

Patients with chronic kidney disease (CKD) are at increased risk of developing cardiac arrhythmogenesis and sudden cardiac death; however, the basis for this association is incompletely known.

METHODS

Here, using murine models of CKD, we examined interactions between kidney disease progression and structural, electrophysiological, and molecular cardiac remodeling.

RESULTS

C57BL/6 mice with adenine supplemented in their diet developed progressive CKD. Electrocardiographically, CKD mice developed significant QT prolongation and episodes of bradycardia. Optical mapping of isolated-perfused hearts using voltage-sensitive dyes revealed significant prolongation of action potential duration with no change in epicardial conduction velocity. Patch-clamp studies of isolated ventricular cardiomyocytes revealed changes in sodium and potassium currents consistent with action potential duration prolongation. Global transcriptional profiling identified dysregulated expression of cellular stress response proteins RBM3 (RNA-binding motif protein 3) and CIRP (cold-inducible RNA-binding protein) that may underlay the ion channel remodeling. Unexpectedly, we found that female sex is a protective factor in the progression of CKD and its cardiac sequelae.

CONCLUSIONS

Our data provide novel insights into the association between CKD and pathologic proarrhythmic cardiac remodeling. Cardiac cellular stress response pathways represent potential targets for pharmacologic intervention for CKD-induced heart rhythm disorders.

RNA binding motif protein 3 (RBM3) promotes protein kinase B (AKT) activation to enhance glucose metabolism and reduce apoptosis in skeletal muscle of mice under acute cold exposure

The main danger of cold stress to animals in cold regions is systemic metabolic changes and protein synthesis inhibition. RBM3, an exceptional cold shock protein, is rapidly upregulated in response to hypothermia to resist the adverse effects of cold stress. However, the mechanism of the protective effect and the rapid upregulation of RBM3 remains unclear. O-GlcNAcylation, an atypical O-glycosylation, is precisely regulated only by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) and participates in the signal transduction of multiple cellular stress responses as a "stress and nutrition receptor." Therefore, our study aimed to explore the mechanism of RBM3 regulating glucose metabolism and promoting survival in skeletal muscle under acute cold exposure. Meanwhile, our study verifies whether O-GlcNAcylation mediated by OGT rapidly upregulates RBM3. The blood and skeletal muscle of mice were collected at the end of cold exposure treatment for 0, 2, and 4 h. Changes in levels of RBM3, AKT, glycolysis apoptosis, and OGT were measured. The results show that acute cold exposure upregulated RBM3, OGT, and AKT phosphorylation and increased energy consumption, which enhanced glycolysis and prevent apoptosis. In the 32 °C mild hypothermia model in vitro, overexpression of RBM3 enhanced AKT phosphorylation. Meanwhile, inactivation of AKT by wortmannin resulted in increased apoptosis and decreased glucose metabolism in skeletal muscle under acute cold exposure. In addition, OGT-mediated O-GlcNAcylation of p65 was confirmed in mouse myoblast cell line (C2C12) cells at mild hypothermia. O-GlcNAcylation level affected p65 activity and nuclear translocation. Compared with wild type (WT) mice, RBM3 and p65 phosphorylation were decreased in specific skeletal muscle Ogt (KO) mice, whereas AKT phosphorylation, glycolysis, and apoptosis were increased. Taken together, O-GlcNAcylation of p65 upregulates RBM3 to promote AKT phosphorylation, enhance glucose metabolism, and reduce apoptosis in skeletal muscle of mice under acute cold exposure.

Angiostatic freeze or angiogenic move? Acute cold stress prevents angiokine secretion from murine myotubes but primes primary endothelial cells for greater migratory capacity

The skeletal muscle tissue can adapt to exercise and environmental stressors with a remarkable plasticity. Prolonged cold stress exposure has been associated to increased skeletal muscle capillarization. Angioadaptation refers to the coordinated molecular and cellular processes that influence the remodeling of skeletal muscle microvasculature. Two cell types are central to angioadaptation: the myocytes, representing an important source of angiokines; and the skeletal muscle endothelial cell (SMECs), targets of these angiokines and main constituents of muscle capillaries. The influence of cold stress on skeletal muscle angioadaptation remains largely unknown, particularly with respect to myocyte-specific angiokines secretion or endothelial cell angioadaptive responses. Here, we use an in vitro model to investigate the impact of cold stress (28°C versus 37°C) on C2C12 myotubes and SMECs. Our main objectives were to evaluate: 1) the direct impact of cold stress on C2C12 cellular expression of angiokines and their release in the extracellular environment; 2) the indirect impact of cold stress on SMECs migration via these C2C12-derived angiokines; and 3) the direct effect of cold stress on SMECs angioadaptive responses, including migration, proliferation, and the activation of the vascular endothelial growth factor receptor-2 (VEGFR2). Cold stress reduced the secretion of angiokines in C2C12 myotubes culture media irrespective their pro-angiogenic or angiostatic nature. In SMECs, cold stress abrogated cell proliferation and reduced the activation of VEGFR2 despite a greater expression of this receptor. Finally, SMECs pre-conditioned to cold stress displayed an enhanced migratory response when migration was stimulated in rewarming conditions. Altogether our results suggest that cold stress may be overall angiostatic. However, cold stress accompanied by rewarming may be seen as a pro-angiogenic stressor for SMECs. This observation questions the potential for using pre-cooling in sport-performance or therapeutic exercise prescription to enhance skeletal muscle angioadaptive responses to exercise.

Serum concentration of extracellular cold-inducible RNA-binding protein is associated with respiratory failure in COVID-19

Uncontrolled release of damage-associated molecular patterns (DAMPs) is suggested to be a major trigger for the dysregulated host immune response that leads to severe COVID-19. Cold-inducible RNA-binding protein (CIRP), is a newly identified DAMP that aggravates inflammation and tissue injury, and induces respiratory failure in sepsis. Whether CIRP contributes to the pathogenesis of respiratory failure in COVID-19 has not yet been explored.

Aim

To investigate if the concentration of extracellular CIRP (eCIRP) in serum associates with respiratory failure and lung involvement by chest computed tomography (CT) in COVID-19.

Methods

Herein we report a prospective observational study of patients with COVID-19 included at two University Hospitals in Sweden between April 2020 and May 2021. Serum from hospitalized patients in Örebro (N=97) were used to assess the association between eCIRP and the level of respiratory support and its correlation with pulmonary involvement on chest CT and inflammatory biomarkers. A cohort of hospitalized and non-hospitalized patients from Umeå (N=78) was used as an external validation cohort. The severity of disease was defined according to the highest degree of respiratory support; mild disease (no oxygen), non-severe hypoxemia (conventional oxygen or high-flow nasal oxygen, HFNO <50% FiO2), and severe hypoxemia (HFNO ≥50% FiO2, mechanical ventilation). Unadjusted and adjusted linear regression was used to evaluate peak eCIRP day 0-4 in respect to severity, age, sex, Charlson comorbidity score, symptom duration, and BMI.

Results

Peak eCIRP concentrations were higher in patients with severe hypoxemia and were independently associated with the degree of respiratory support in both cohorts (Örebro; p=0.01, Umeå; p<0.01). The degree of pulmonary involvement measured by CT correlated with eCIRP, rs=0.30, p<0.01 (n=97).

Conclusion

High serum levels of eCIRP are associated with acute respiratory failure in COVID-19. Experimental studies are needed to determine if treatments targeting eCIRP reduces the risk of acute respiratory failure in COVID-19.

Hypoxia-ischemia-mediated effects on neurodevelopmentally regulated cold-shock proteins in neonatal mice under strict temperature control

BACKGROUND

Neonates have high levels of cold-shock proteins (CSPs) in the normothermic brain for a limited period following birth. Hypoxic-ischemic (HI) insults in term infants produce neonatal encephalopathy (NE), and it remains unclear whether HI-induced pathology alters baseline CSP expression in the normothermic brain.

METHODS

Here we established a version of the Rice-Vannucci model in PND 10 mice that incorporates rigorous temperature control.

RESULTS

Common carotid artery (CCA)-ligation plus 25 min hypoxia (8% O2) in pups with targeted normothermia resulted in classic histopathological changes including increased hippocampal degeneration, astrogliosis, microgliosis, white matter changes, and cell signaling perturbations. Serial assessment of cortical, thalamic, and hippocampal RNA-binding motif 3 (RBM3), cold-inducible RNA binding protein (CIRBP), and reticulon-3 (RTN3) revealed a rapid age-dependent decrease in levels in sham and injured pups. CSPs were minimally affected by HI and the age point of lowest expression (PND 18) coincided with the timing at which heat-generating mechanisms mature in mice.

CONCLUSIONS

The findings suggest the need to determine whether optimized therapeutic hypothermia (depth and duration) can prevent the age-related decline in neuroprotective CSPs like RBM3 in the brain, and improve outcomes during critical phases of secondary injury and recovery after NE.

IMPACT

The rapid decrease in endogenous neuroprotective cold-shock proteins (CSPs) in the normothermic cortex, thalamus, and hippocampus from postnatal day (PND) 11-18, coincides with the timing of thermogenesis maturation in neonatal mice. Hypoxia-ischemia (HI) has a minor impact on the normal age-dependent decline in brain CSP levels in neonates maintained normothermic post-injury. HI robustly disrupts the expected correlation in RNA-binding motif 3 (RBM3) and reticulon-3 (RTN3). The potent neuroprotectant RBM3 is not increased 1-4 days after HI in a mouse model of neonatal encephalopathy (NE) in the term newborn and in which rigorous temperature control prevents the manifestation of endogenous post-insult hypothermia.

Pre-clinical and clinical studies on the role of RBM3 in muscle-invasive bladder cancer: longitudinal expression, transcriptome-level effects and modulation of chemosensitivity

Background

The response to neoadjuvant cisplatin-based chemotherapy (NAC) in muscle-invasive bladder cancer (MIBC) is impaired in up to 50% of patients due to chemoresistance, with no predictive biomarkers in clinical use. The proto-oncogene RNA-binding motif protein 3 (RBM3) has emerged as a putative modulator of chemotherapy response in several solid tumours but has a hitherto unrecognized role in MIBC.

Methods

RBM3 protein expression level in tumour cells was assessed via immunohistochemistry in paired transurethral resection of the bladder (TURB) specimens, cystectomy specimens and lymph node metastases from a consecutive cohort of 145 patients, 65 of whom were treated with NAC. Kaplan-Meier and Cox regression analyses were applied to estimate the impact of RBM3 expression on time to recurrence (TTR), cancer-specific survival (CSS), and overall survival (OS) in strata according to NAC treatment. The effect of siRNA-mediated silencing of RBM3 on chemosensitivity was examined in RT4 and T24 human bladder carcinoma cells in vitro. Cellular functions of RBM3 were assessed using RNA-sequencing and gene ontology analysis, followed by investigation of cell cycle distribution using flow cytometry.

Results

RBM3 protein expression was significantly higher in TURB compared to cystectomy specimens but showed consistency between primary tumours and lymph node metastases. Patients with high-tumour specific RBM3 expression treated with NAC had a significantly reduced risk of recurrence and a prolonged CSS and OS compared to NAC-untreated patients. In high-grade T24 carcinoma cells, which expressed higher RBM3 mRNA levels compared to RT4 cells, RBM3 silencing conferred a decreased sensitivity to cisplatin and gemcitabine. Transcriptomic analysis revealed potential involvement of RBM3 in facilitating cell cycle progression, in particular G₁/S-phase transition, and initiation of DNA replication. Furthermore, siRBM3-transfected T24 cells displayed an accumulation of cells residing in the G₁-phase as well as altered levels of recognised regulators of G₁-phase progression, including Cyclin D1/CDK4 and CDK2.

Conclusions

The presented data highlight the potential value of RBM3 as a predictive biomarker of chemotherapy response in MIBC, which could, if prospectively validated, improve treatment stratification of patients with this aggressive disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-09168-7.

Hypoxia causes mitochondrial dysfunction and brain memory disorder in a manner mediated by the reduction of Cirbp

Environmental hypoxic hazard has increasingly become a global public health issue, with impelling evidences supporting the relation between hypoxia and cognitive disorders. As a potent stressor, hypoxia causes mitochondrial dysfunction with insufficient energy production, thus the formation of brain memory disorder. Yet, the underlying molecular mechanism/s against hypoxia induced injury have yet to be identified. Here, we report that cold inducible RNA binding protein (Cirbp) attenuates hypoxia induced insufficient energy production and oxidative stress. Further analyses show that Cirbp sustains protein levels of respiratory chain complexes II (SDHB) and IV (MT-CO1), and directly binds the 3'UTR of Atp5g3 to control mitochondrial homeostasis and ATP biogenesis upon hypoxic stress. Altogether, our data establish Cirbp as a critical protective factor against hypoxic health hazard and provide novel insights into its latent regulation network.

Exosome-Mediated eCIRP Release From Macrophages to Induce Inflammation in Sepsis

Extracellular cold-inducible RNA-binding protein (eCIRP) is an important damage-associated molecular pattern (DAMP). Despite our understanding of the potentially harmful effects of eCIRP in sepsis, how eCIRP is released from cells remains elusive. Exosomes are endosome-derived extracellular vesicles, which carry proteins, lipids, and nucleic acids to facilitate intercellular communication and several extracellular functions. We hypothesized that eCIRP is released via exosomes to induce inflammation in sepsis. Exosomes isolated from the supernatants of LPS-treated macrophage culture and serum of endotoxemia and polymicrobial sepsis mice showed high purity, as revealed by their unique median sizes ranging between 70 and 126 nm in diameter. eCIRP levels of the exosomes were significantly increased after LPS treatment in the supernatants of macrophage culture, mouse serum, and cecal ligation and puncture (CLP)-induced sepsis mouse serum. Protease protection assay demonstrated the majority of eCIRP was present on the surface of exosomes. Treatment of WT macrophages and mice with exosomes isolated from LPS-treated WT mice serum increased TNFα and IL-6 production. However, treatment with CIRP-/- mice serum exosomes significantly decreased these levels compared with WT exosome-treated conditions. CIRP-/- mice serum exosomes significantly decreased neutrophil migration in vitro compared with WT exosomes. Treatment of mice with serum exosomes isolated from CIRP-/- mice significantly reduced neutrophil infiltration into the peritoneal cavity. Our data suggest that eCIRP can be released via exosomes to induce cytokine production and neutrophil migration. Thus, exosomal eCIRP could be a potential target to inhibit inflammation.

Structural and dynamic studies of the human RNA binding protein RBM3 reveals the molecular basis of its oligomerization and RNA recognition

Human RNA-binding motif 3 protein (RBM3) is a cold-shock protein which functions in various aspects of global protein synthesis, cell proliferation and apoptosis by interacting with the components of basal translational machinery. RBM3 plays important roles in tumour progression and cancer metastasis, and also has been shown to be involved in neuroprotection and endoplasmic reticulum stress response. Here, we have solved the solution NMR structure of the N-terminal 84 residue RNA recognition motif (RRM) of RBM3. The remaining residues are rich in RGG and YGG motifs and are disordered. The RRM domain adopts a βαββαβ topology, which is found in many RNA-binding proteins. NMR-monitored titration experiments and molecular dynamic simulations show that the beta-sheet and two loops form the RNA-binding interface. Hydrogen bond, pi-pi and pi-cation are the key interactions between the RNA and the RRM domain. NMR, size exclusion chromatography and chemical cross-linking experiments show that RBM3 forms oligomers in solution, which is favoured by decrease in temperature, thus, potentially linking it to its function as a cold-shock protein. Temperature-dependent NMR studies revealed that oligomerization of the RRM domain occurs via nonspecific interactions. Overall, this study provides the detailed structural analysis of RRM domain of RBM3, its interaction with RNA and the molecular basis of its temperature-dependent oligomerization.

Cold-Inducible RNA-Binding Protein but Not Its Antisense lncRNA Is a Direct Negative Regulator of Angiogenesis In Vitro and In Vivo via Regulation of the 14q32 angiomiRs-microRNA-329-3p and microRNA-495-3p

Inhibition of the 14q32 microRNAs, miR-329-3p and miR-495-3p, improves post-ischemic neovascularization. Cold-inducible RNA-binding protein (CIRBP) facilitates maturation of these microRNAs. We hypothesized that CIRBP deficiency improves post-ischemic angiogenesis via downregulation of 14q32 microRNA expression. We investigated these regulatory mechanisms both in vitro and in vivo. We induced hindlimb ischemia in Cirp^−/− and C57Bl/6-J mice, monitored blood flow recovery with laser Doppler perfusion imaging, and assessed neovascularization via immunohistochemistry. Post-ischemic angiogenesis was enhanced in Cirp^−/− mice by 34.3% with no effects on arteriogenesis. In vivo at day 7, miR-329-3p and miR-495-3p expression were downregulated in Cirp^−/− mice by 40.6% and 36.2%. In HUVECs, CIRBP expression was upregulated under hypothermia, while miR-329-3p and miR-495-3p expression remained unaffected. siRNA-mediated CIRBP knockdown led to the downregulation of CIRBP-splice-variant-1 (CIRBP-SV1), CIRBP antisense long noncoding RNA (lncRNA-CIRBP-AS1), and miR-495-3p with no effects on the expression of CIRBP-SV2-4 or miR-329-3p. siRNA-mediated CIRBP knockdown improved HUVEC migration and tube formation. SiRNA-mediated lncRNA-CIRBP-AS1 knockdown had similar long-term effects. After short incubation times, however, only CIRBP knockdown affected angiogenesis, indicating that the effects of lncRNA-CIRBP-AS1 knockdown were secondary to CIRBP-SV1 downregulation. CIRBP is a negative regulator of angiogenesis in vitro and in vivo and acts, at least in part, through the regulation of miR-329-3p and miR-495-3p.

Damage-Associated Molecular Patterns As Double-Edged Swords in Sepsis

Significance: Sepsis is defined as a life-threatening organ dysfunction caused by dysregulated host response to infection. This leads to an uncontrolled inflammatory response at the onset of infection, followed by immunosuppression. The development of a specific treatment modality for sepsis is still challenging, reflecting our inadequate understanding of its pathophysiology. Understanding the mechanism and transition of the early hyperinflammation to late stage of immunosuppression in sepsis is critical for developing sepsis therapeutics. Recent Advances: Damage-associated molecular patterns (DAMPs) are intracellular molecules and released upon tissue injury and cell death in sepsis. DAMPs are recognized by pattern recognition receptors to initiate inflammatory cascades. DAMPs not only elicit an inflammatory response but also they subsequently induce immunosuppression, both are equally important for exacerbating sepsis. Recent advances on a new DAMP, extracellular cold-inducible RNA-binding protein for fueling inflammation and immunosuppression in sepsis, have added a new avenue into the dual functions of DAMPs in sepsis. Critical Issues: The molecular modification of DAMPs and their binding to pattern recognition receptors transit dynamically by the cellular environment in pathophysiologic conditions. Correlation between the dynamic changes of the impacts of DAMPs and the clinical outcomes in sepsis still lacks adequate understanding. Here, we focus on the impacts of DAMPs that cause inflammation as well as induce immunosuppression in sepsis. We further discuss the therapeutic potential by targeting DAMPs to attenuate inflammation and immunosuppression for mitigating sepsis. Future Directions: Uncovering pathways of the transition from inflammation to immunosuppression of DAMPs is a potential therapeutic avenue for mitigating sepsis.

Normothermic machine perfusion attenuates hepatic ischaemia-reperfusion injury by inhibiting CIRP-mediated oxidative stress and mitochondrial fission

Extracellular cold-inducible RNA-binding protein (CIRP) is a proinflammatory mediator that aggravates ischaemia-reperfusion injury (IRI). Normothermic machine perfusion (NMP) could effectively alleviate the IRI of the liver, but the underlying mechanism remains to be explored. We show that human DCD livers secreted a large amount of CIRP during static cold storage (CS), which is released into the circulation after reperfusion. The expression of CIRP was related to postoperative IL-6 levels and liver function. In a rat model, the CIRP expression was upregulated during warm ischaemia and cold storage. Then, rat DCD livers were preserved using CS, hypothermic oxygenated machine perfusion (HOPE) and NMP. C23, a CIRP inhibitor, was administrated in the HOPE group. Compared with CS, NMP significantly inhibited CIRP expression and decreased oxidative stress by downregulating NADPH oxidase and upregulating UCP2. NMP markedly inhibited the mitochondrial fission-related proteins Drp-1 and Fis-1. Further, NMP increased the mitochondrial biogenesis-related protein, TFAM. NMP significantly reduced inflammatory reactions and apoptosis after reperfusion, and NMP-preserved liver tissue had higher bile secretion and ICG metabolism compared to the CS group. Moreover, C23 administration attenuated IRI in the HOPE group. Additionally, HL-7702 cells were stimulated with rhCIRP and C23. High rhCIRP levels increased oxidative stress and apoptosis. In summary, NMP attenuates the IRI of DCD liver by inhibiting CIRP-mediated oxidative stress and mitochondrial fission.

Cooling and Sterile Inflammation in an Oxygen-Glucose-Deprivation/Reperfusion Injury Model in BV-2 Microglia

Objective

Cold-inducible RNA-binding protein (CIRBP) has been shown to be involved not only in cooling-induced cellular protection but also as a mediator of sterile inflammation, a critical mechanism of the innate immune response in ischemia/reperfusion (I/R) injury. The role of microglia and its activation in cerebral I/R injury warrants further investigation as both detrimental and regenerative properties have been described. Therefore, we investigated the effects of cooling, specifically viability, activation, and release of damage associated molecular patterns (DAMPs) on oxygen glucose deprivation/reperfusion- (OGD/R-) induced injury in murine BV-2 microglial cells.

Methods

Murine BV-2 microglial cells were exposed to 2 to 6 h OGD (0.2% O₂ in glucose- and serum-free medium) followed by up to 19 h of reperfusion, simulated by restoration of oxygen (21% O₂) and nutrients. Cells were maintained at either normothermia (37°C) or cooled to 33.5°C, 1 h after experimental start. Cultured supernatants were harvested after exposure to OGD for analysis of DAMP secretions, including high-mobility group box 1 (HMGB1), heat shock protein 70 (HSP70), and CIRBP, and cytotoxicity was assessed by lactate dehydrogenase releases after exposure to OGD and reperfusion. Intracellular cold-shock proteins CIRBP and RNA-binding motif 3 (RBM3) as well as caspases 9, 8, and 3 were also analyzed via Western blot analysis. Furthermore, inducible nitric oxide synthase (iNOS), ionized calcium-binding adaptor molecule 1 (Iba1), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), interleukin-1α (IL-1α), monocyte chemotactic protein 1 (MCP-1), transforming growth factor β (TGFβ), CIRBP, and RBM3 gene expressions were assessed via reverse transcription polymerase chain reaction, and TNF-α, IL-6, and IL-1β releases into the cultured supernatants were assessed via enzyme-linked immunosorbent assays (ELISA).

Results

Prolonged exposure to OGD resulted in increased BV-2 necrotic cell death, which was attenuated by cooling. Cooling also significantly induced cold-shock proteins CIRBP and RBM3 gene expressions, with CIRBP expression more rapidly regulated than RBM3 and translatable to significantly increased protein expression. DAMPs including HMGB-1, HSP70, and CIRBP could be detected in cultured supernatants after 6 h of OGD with CIRBP release being significantly attenuated by cooling. Exposure to OGD suppressed cytokine gene expressions of IL-1β, TNF-α, MCP-1, and TGFβ independently of temperature management, whereas cooling led to a significant increase in IL-1α gene expression after 6 h of OGD. In the reperfusion phase, TNF-α and MCP-1 gene expressions were increased, and cooling was associated with significantly lower TGFβ gene expression. Interestingly, cooled Normoxia groups had significant upregulations of microglial activation marker, Iba1, IL-1β, and TNF-α gene expressions.

Conclusion

BV-2 microglial cells undergo necrotic cell death resulting in DAMP release due to OGD/R-induced injury. Cooling conveyed neuroprotection in OGD/R-injury as observable in increased cell viability as well as induced gene expressions of cold shock proteins. As cooling alone resulted in both upregulation of microglial activation, expression of proinflammatory cytokines, and cold shock protein transcript and protein expression, temperature management might have ambiguous effects in sterile inflammation. However, cooling resulted in a significant decrease of extracellular CIRBP, which has recently been characterized as a novel DAMP and a potent initiator and mediator of inflammation.

Cold-inducible RNA-binding protein migrates from the nucleus to the cytoplasm under cold stress in normal human bronchial epithelial cells via TRPM8-mediated mechanism

Background

Cold-inducible RNA-binding protein (CIRP or hnRNP A18) is a multifunctional stress-responsive protein. Our previous study demonstrated that cold stress increased CIRP expression and migrated from the nucleus to the cytoplasm in airway epithelial cells. However, the mechanism through which CIRP migrates from the nucleus to the cytoplasm upon cold stress remains unknown.

Methods

The expression of CIRP in the bronchial epithelium was examined using immunofluorescence, real-time polymerase chain reaction (RT-PCR), and Western blotting. The expression of inflammatory factors interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) were detected by ELISA and RT-PCR. Transient receptor potential melastatin 8 (TRPM8) receptor function was characterized by Ca²⁺ imaging.

Results

Cold stress upregulated the expression of CIRP, inflammatory factors and promoted the translocation of CIRP from the nucleus to the cytoplasm in normal human bronchial epithelial (NHBE) cells. Cold stress activated the TRPM8/(Ca²⁺)/PKCα/glycogen synthase kinase 3β (GSK3β) signaling cascade, and that inhibition of this signaling pathway attenuated the migration of CIRP from the nucleus to cytoplasm but did not decrease its overexpression induced by cold stress. Knocked down CIRP expression or blocked CIRP migration between the nucleus and cytoplasm significantly decreased inflammatory factor expression.

Conclusions

These results indicate that cold stress leads to the migration of CIRP from the nucleus to the cytoplasm with alteration of expression, which are involved in the expression of inflammatory factors (IL-1β, IL-6, IL-8 and TNF-α) induced by cold air, through TRPM8/Ca²⁺/PKCα/GSK3β signaling cascade.

Diet-altered body temperature rhythms are associated with altered rhythms of clock gene expression in peripheral tissues in vivo

Temperature rhythms can act as potent signals for the modulation of the amplitude and phase of clock gene expression in peripheral organs in vitro, but the relevance of the circadian rhythm of core body temperature (T_c) as a modulating signal in vivo has not yet been investigated. Using calorie restriction and cafeteria feeding, we induced a larger and a dampened T_c amplitude, respectively, in male Wistar rats, and investigated the circadian expression profile of the core clock genes Bmal1, Per2, Cry1, and Rev-erbα, the heat-responsive genes heat shock protein 90 (Hsp90) and cold-inducible RNA binding protein (Cirbp), and Pgc1α, Pparα/γ/δ, Glut1/4, and Chop10 in the liver, skeletal muscle, white adipose tissue (WAT), and adrenal glands. Diet-altered T_c rhythms differentially affected the profiles of clock genes, Hsp90, and Cirbp expression in peripheral tissues. Greater T_c amplitudes elicited by calorie restriction were associated with large amplitudes of Hsp90 and Cirbp expression in the liver and WAT, in which larger amplitudes of clock gene expression were also observed. The amplitudes of metabolic gene expression were greater in the WAT, but not in the liver, in calorie-restricted rats. Conversely, diet-altered T_c rhythms were not translated to distinct changes in the amplitude of Hsp90, Cirbp, or clock or metabolic genes in the skeletal muscle or adrenal glands. While it was not possible to disentangle the effects of diet and temperature in this model, taken together with previous in vitro studies, our study presents novel data consistent with the notion that the circadian T_c rhythm can modulate the amplitude of circadian gene expression in vivo. The different responses of Hsp90 and Cirbp in peripheral tissues may be linked to the tissue-specific responses of peripheral clocks to diet and/or body temperature rhythms, but the association with the amplitude of metabolic gene expression is limited to the WAT.

PRR11 unveiled as a top candidate biomarker within the RBM3-regulated transcriptome in pancreatic cancer

The outlook for patients with pancreatic cancer remains dismal. Treatment options are limited and chemotherapy remains standard of care, leading to only modest survival benefits. Hence, there is a great need to further explore the mechanistic basis for the intrinsic therapeutic resistance of this disease, and to identify novel predictive biomarkers. RNA‐binding motif protein 3 (RBM3) has emerged as a promising biomarker of disease severity and chemotherapy response in several types of cancer, including pancreatic cancer. The aim of this study was to unearth RBM3‐regulated genes and proteins in pancreatic cancer cells in vitro, and to examine their expression and prognostic significance in human tumours. Next‐generation RNA sequencing was applied to compare transcriptomes of MIAPaCa‐2 cells with and without RBM3 knockdown. The prognostic value of differentially expressed genes (DEGs) was examined in The Cancer Genome Atlas (TCGA). Top deregulated genes were selected for further studies in vitro and for immunohistochemical analysis of corresponding protein expression in tumours from a clinically well‐annotated consecutive cohort of 46 patients with resected pancreatic cancer. In total, 19 DEGs (p < 0.01) were revealed, among which some with functions in cell cycle and cell division stood out; PDS5A (PDS cohesin associated factor A) as the top downregulated gene, CCND3 (cyclin D3) as the top upregulated gene, and PRR11 (proline rich 11) as being highly prognostic in TCGA. Silencing of RBM3 in MiaPaCa‐2 cells led to congruent alterations of PDS5A, cyclin D3, and PRR11 levels. High protein expression of PRR11 was associated with adverse clinicopathological features and shorter overall survival. Neither PDS5A nor cyclin D3 protein expression was prognostic. This study unveils several RBM3‐regulated genes with potential clinical relevance in pancreatic cancer, among which PRR11 shows the most consistent association with disease severity, at both transcriptome and protein levels.

Cold-Induced RNA-Binding Protein Promotes Glucose Metabolism and Reduces Apoptosis by Increasing AKT Phosphorylation in Mouse Skeletal Muscle Under Acute Cold Exposure

The main danger of cold stress to animals in cold regions is systemic metabolic changes and protein synthesis inhibition. Cold-induced RNA-binding protein is a cold shock protein that is rapidly up-regulated under cold stimulation in contrast to the inhibition of most proteins and participates in multiple cellular physiological activities by regulating targets. Therefore, this study was carried out to investigate the possible mechanism of CIRP-mediated glucose metabolism regulation and survival promotion in skeletal muscle after acute cold exposure. Skeletal muscle and serum from mice were obtained after 0, 2, 4 and 8 h of acute hypothermia exposure. Subsequently, the changes of CIRP, metabolism and apoptosis were examined. Acute cold exposure increased energy consumption, enhanced glycolysis, increased apoptosis, and up-regulated CIRP and phosphorylation of AKT. In addition, CIRP overexpression in C2C12 mouse myoblasts at each time point under 37°C and 32°C mild hypothermia increased AKT phosphorylation, enhanced glucose metabolism, and reduced apoptosis. CIRP knockdown by siRNA interference significantly reduced the AKT phosphorylation of C2C12 cells. Wortmannin inhibited the AKT phosphorylation of skeletal muscle after acute cold exposure, thereby inhibiting glucose metabolism and aggravating apoptosis. Taken together, acute cold exposure up-regulates CIRP in mouse skeletal muscle, which regulates glucose metabolism and maintains energy balance in skeletal muscle cells through the AKT signaling pathway, thus slowing down the apoptosis of skeletal muscle cells.

Clinical Significance of Cold-Inducible RNA-Binding Protein in Idiopathic Pulmonary Fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is associated with a poor prognosis with variable clinical course. Early identification of patients at high risk for disease progression and death would lead to early therapeutic intervention and thereby improvement of outcomes. Cold-inducible RNA-binding protein (CIRBP) is produced in response to cellular stresses, which is implicated in multiple biological processes, including cell survival and proliferation.

RESEARCH QUESTION

Is CIRBP a useful biomarker for predicting the outcomes of patients with IPF?

STUDY DESIGN AND METHODS

This study included 95 and 93 patients with IPF from two independent hospitals (derivation and validation cohorts, respectively). The associations of serum CIRBP level on IPF diagnosis with disease progression within 1 year after diagnosis (ie, ≥10% relative decline in percent predicted FVC or death) and all-cause mortality were retrospectively analyzed. Discrimination performances for predicting these outcomes were evaluated using the c-index.

RESULTS

Serum and lung tissue CIRBP levels were higher in patients with IPF than in control subjects. In the derivation cohort, the CIRBP^high subgroup had significantly higher 1-year disease progression rates and lower cumulative survival rates than the CIRBP^low subgroup, and the results were replicated in the validation cohort. In multivariate analyses, high serum CIRBP level was independently associated with higher 1-year disease progression and all-cause mortality rates in both cohorts. Combining the Gender-Age-Physiology (GAP) and serum CIRBP models improved the c-indexes for predicting 1-year disease progression and all-cause mortality compared with that of each model alone. The c-indexes of serum CIRBP were particularly high in patients with GAP stage I.

INTERPRETATION

This study successfully validated that serum CIRBP level was an independent predictor of 1-year disease progression and all-cause mortality in IPF. CIRBP is a promising biomarker that can help identify high-risk patients with IPF, especially in the early stage.

CIRP Secretion during Cardiopulmonary Bypass Is Associated with Increased Risk of Postoperative Acute Kidney Injury

BACKGROUND

 Systemic inflammation contributes to cardiac surgery-associated acute kidney injury (AKI). Cardiomyocytes and other organs experience hypothermia and hypoxia during cardiopulmonary bypass (CPB), which induces the secretion of cold-inducible RNA-binding protein (CIRP). Extracellular CIRP may induce a proinflammatory response.

MATERIALS AND METHODS

 The serum CIRP levels in 76 patients before and after cardiac surgery were determined to analyze the correlation between CIRP levels and CPB time. The risk factors for AKI after cardiac surgery and the in-hospital outcomes were also analyzed.

RESULTS

 The difference in the levels of CIRP (ΔCIRP) after and before surgery in patients who experienced cardioplegic arrest (CA) was 26-fold higher than those who did not, and 2.7-fold of those who experienced CPB without CA. The ΔCIRP levels were positively correlated with CPB time (r = 0.574, p < 0.001) and cross-clamp time (r = 0.54, p < 0.001). Multivariable analysis indicated that ΔCIRP (odds ratio: 1.003; 95% confidence interval: 1.000-1.006; p = 0.027) was an independent risk factor for postoperative AKI. Patients who underwent aortic dissection surgery had higher levels of CIRP and higher incidence of AKI than other patients. The incidence of AKI and duration of mechanical ventilation in patients whose serum CIRP levels more than 405 pg/mL were significantly higher than those less than 405 pg/mL (65.8 vs. 42.1%, p = 0.038; 23.1 ± 18.2 vs. 13.8 ± 9.2 hours, p = 0.007).

CONCLUSION

 A large amount of CIRP was released during cardiac surgery. The secreted CIRP was associated with the increased risk of AKI after cardiac surgery.

The Expression of the Cold Shock Protein RNA Binding Motif Protein 3 is Transcriptionally Responsive to Organ Temperature in Mice

BACKGROUND

Mild hypothermia, i.e. maintenance of organ temperature by up to 8°C lower than body temperature, is a critical strategy for exerting some functions of the cells and organs normally, and is an useful therapy for recovering properly from some diseases, including myocardial infarction, cardiac arrest, brain injury, and ischemic stroke. Nevertheless, there were no focusses so far on organ temperature and potential responses of gene expression to organ temperature in organs of homeothermic animals that survive under normal conditions.

OBJECTIVE

The present study aimed to assess organ temperature in homeothermic animals and evaluate the effect of their organ temperature on the expression of the cold shock protein RNA binding motif protein 3 (RBM3), and to gain insights into the organ temperature-mediated regulation of RBM3 gene transcription via Nuclear factor β-light-chain-enhancer of activated B cells (NF-κB) p65, which had been identified as a transcription factor that is activated by undergoing the Ser276 phosphorylation and promotes the RBM3 gene expression during mild hypothermia.

METHODS

We measured the temperature of several organs, where RBM3 expression was examined, in female and male mice. Next, in male mice, we tested NF-κB p65 expression and its Ser276 phosphorylation in organs that have their lower temperature than body temperature and compared them with those in organs that have their temperature near body temperature.

RESULTS

Organ temperature was around 32°C in the brain and reproductive organs, which is lower than the body temperature, and around 37°C in the heart, liver, and kidney, which is comparable to the body temperature. The expression of RBM3 was detected greatly in the brain and reproductive organs with their organ temperature of around 32°C, and poorly in the heart, liver, and kidney with their organ temperature of around 37°C. In accordance with the changes in the RBM3 expression, the NF-κB p65 Ser276 phosphorylation was detected more greatly in the testis and brain with their organ temperature of around 32°C, than in the heart, liver, and kidney with their organ temperature of around 37°C, although the NF-κB p65 expression was unchanged among all the organs tested.

DISCUSSION

Our data suggested that organ temperature lower than body temperature causes the expression of RBM3 in the brain and reproductive organs of mice, and that lower organ temperature causes the NF-κB p65 activation through the Ser276 phosphorylation, resulting in an increase in the RBM3 gene transcription, in the brain and reproductive organs of mice.

CONCLUSION

The study may present the possibility that organ temperature-induced alterations in gene expression are organ specific in homeotherms and the possibility that organ temperature-induced alterations in gene expression are transcriptionally regulated in some organs of homeotherms.

CIRBP promotes ferroptosis by interacting with ELAVL1 and activating ferritinophagy during renal ischaemia-reperfusion injury

Renal ischaemia-reperfusion (IR) is a major cause of acute kidney injury (AKI). Cold-inducible RNA-binding protein (CIRBP) may contribute to AKI because its deficiency protects against renal IR injury in a mechanism believed to involve ferroptosis. We aimed to investigate whether ferroptosis is associated with CIRBP-mediated renal damage. The differential expression of CIRBP was examined in tubular epithelial (HK2) cells during hypoxia-reoxygenation (HR) or in response to erastin, an inducer of ferroptosis. CIRBP expression was increased in response to HR or erastin in HK2 cells but the silencing of CIRBP inhibited HR and erastin-induced ferroptosis together with ferritinophagy. We discovered an interaction between CIRBP and ELAVL1 using STRING software, which was verified through co-immunoprecipitation and fluorescence colocalization assays. We found that ELAVL1 is a critical regulator in the activation of ferritinophagy and the promotion of ferroptosis. HR or erastin also induced the expression of ELAVL1. An autophagy inhibitor (hydroxychloroquine) or si-ELAVL1 transfection reversed CIRBP-enhanced ferritinophagy activation and ferroptosis in HK2 cells under HR. Injection of anti-CIRBP antibody into a mouse model of IR inhibited ferroptosis and decreased renal IR injury in vivo. In summary, our results provide evidence that ferritinophagy-mediated ferroptosis could be responsible for CIRBP-enhanced renal IR injury.

The influence of hypoxia on the prostate cancer proteome

Prostate cancer accounts for around 15% of male deaths in Western Europe and is the second leading cause of cancer death in men after lung cancer. Mounting evidence suggests that prostate cancer deposits exist within a hypoxic environment and this contributes to radio-resistance thus hampering one of the major therapies for this cancer. Recent reports have shown that nitric oxide (NO) donating non-steroidal anti-inflammatory drugs (NSAIDs) reduced tumour hypoxia as well as maintaining a radio-sensitising/therapeutic effect on prostate cancer cells. The aim of this study was to evaluate the impact of hypoxia on the proteome of the prostate and to establish whether NO-NSAID treatment reverted the protein profiles back to their normoxic status. To this end an established hormone insensitive prostate cancer cell line, PC-3, was cultured under hypoxic and normoxic conditions before and following exposure to NO-NSAID in combination with selected other common prostate cancer treatment types. The extracted proteins were analysed by ion mobility-assisted data independent acquisition mass spectrometry (MS), combined with multivariate statistical analyses, to measure hypoxia-induced alterations in the proteome of these cells. The analyses demonstrated that under hypoxic conditions there were well-defined, significantly regulated/differentially expressed proteins primarily involved with structural and binding processes including, for example, TUBB4A, CIRP and PLOD1. Additionally, the exposure of hypoxic cells to NSAID and NO-NSAID agents, resulted in some of these proteins being differentially expressed; for example, both PCNA and HNRNPA1L were down-regulated, corresponding with disruption in the nucleocytoplasmic shuttling process.

ATP regulates RNA-driven cold inducible RNA binding protein phase separation

Intrinsically disordered proteins and proteins containing intrinsically disordered regions are highly abundant in the proteome of eukaryotes and are extensively involved in essential biological functions. More recently, their role in the organization of biomolecular condensates has become evident and along with their misregulation in several neurologic disorders. Currently, most studies involving these proteins are carried out in vitro and using purified proteins. Given that in cells, condensate‐forming proteins are exposed to high, millimolar concentrations of cellular metabolites, we aimed to reveal the interactions of cellular metabolites and a representative condensate‐forming protein. Here, using the arginine–glycine/arginine–glycine–glycine (RG/RGG)‐rich cold inducible RNA binding protein (CIRBP) as paradigm, we studied binding of the cellular metabolome to CIRBP. We found that most of the highly abundant cellular metabolites, except nucleotides, do not directly bind to CIRBP. ATP, ADP, and AMP as well as NAD⁺, NADH, NADP⁺, and NADPH directly interact with CIRBP, involving both the folded RNA‐recognition motif and the disordered RG/RGG region. ATP binding inhibited RNA‐driven phase separation of CIRBP. Thus, it might be beneficial to include cellular metabolites in in vitro liquid–liquid phase separation studies of RG/RGG and other condensate‐forming proteins in order to better mimic the cellular environment in the future.

RBM3 Increases Cell Survival but Disrupts Tight Junction of Microvascular Endothelial Cells in Acute Lung Injury

BACKGROUND

RNA-binding motif protein 3 (RBM3) is an important cold shock protein, which also responds to hypothermia or hypoxia. RBM3 is involved into multiple physiologic processes, such as promoting cell survival. However, its expression and function in acute lung injury (ALI) have not been reported.

METHODS

A mouse ALI model was established by lipopolysaccharides (LPS) treatment. The RBM3 and cold inducible RNA-binding protein mRNA levels were examined by RT-qPCR, and MMP9 mRNA stability was determined by actinomycin D assay. RBM3 and MMP9 mRNA was tested by RNA immunoprecipitation (RIP assay). RBM3 overexpression or silent stable cell lines were established using recombinant lentivirus and subsequently used for cell survival and tight junction measurements.

RESULTS

In this study, we found that RBM3, rather than cold inducible RNA-binding protein, was upregulated in lung tissue of ALI mice. RBM3 was increased in human pulmonary microvascular endothelial cells (HPMVECs) in response to LPS treatment, which is modulated by the NF-κB signaling pathway. Furthermore, RBM3 could reduce cell apoptosis induced by LPS, probably through suppressing p53 expression. Because increased permeability of HPMVECs leads to pulmonary edema in ALI, we subsequently examined the effect of RBM3 on cell tight junctions. Unexpectedly, RBM3 decreased the expression of tight junction protein zonula occludens-1 and increased cell permeability, and RBM3 overexpression increased MMP9 mRNA stability. Furthermore, RIP assay confirmed the interaction between RBM3 and MMP9 mRNA, possibly explaining the contribution of RBM3 to increase cell permeability.

CONCLUSIONS

RBM3 seems to act as a "double-edged sword" in ALI, that RBM3 alleviates cell apoptosis but increases HPMVEC permeability in ALI.

Absence of Cold-Inducible RNA-Binding Protein (CIRP) Promotes Angiogenesis and Regeneration of Ischemic Tissue by Inducing M2-Like Macrophage Polarization

Cold-inducible RNA-binding protein (CIRP) is an intracellular RNA-chaperone and extracellular promoter of inflammation, which is increasingly expressed and released under conditions of hypoxia and cold stress. The functional relevance of CIRP for angiogenesis and regeneration of ischemic muscle tissue has never been investigated and is the topic of the present study. We investigated the role of CIRP employing CIRP deficient mice along with a hindlimb model of ischemia-induced angiogenesis. 1 and 7 days after femoral artery ligation or sham operation, gastrocnemius muscles of CIRP-deficient and wildtype mice were isolated and processed for (immuno-) histological analyses. CIRP deficient mice showed decreased ischemic tissue damage as evidenced by Hematoxylin and Eosin staining, whereas angiogenesis was enhanced as demonstrated by increased capillary/muscle fiber ratio and number of proliferating endothelial (CD31⁺/BrdU⁺) cells on day 7 after surgery. Moreover, CIRP deficiency resulted in a reduction of total leukocyte count (CD45⁺), neutrophils (myeloperoxidase, MPO⁺), neutrophil extracellular traps (NETs) (MPO⁺/CitH3⁺), and inflammatory M1-like polarized macrophages (CD68⁺/MRC1^-), whereas the number of tissue regenerating M2-like polarized macrophages (CD68⁺/MRC1^-) was increased in ischemic tissue samples. In summary, we show that the absence of CIRP ameliorates angiogenesis and regeneration of ischemic muscle tissue, most likely by influencing macrophage polarization in direction to regenerative M2-like macrophages.

Small molecules inhibitors of the heterogeneous ribonuclear protein A18 (hnRNP A18): a regulator of protein translation and an immune checkpoint

We have identified chemical probes that simultaneously inhibit cancer cell progression and an immune checkpoint. Using the computational Site Identification by Ligand Competitive Saturation (SILCS) technology, structural biology and cell-based assays, we identify small molecules that directly and selectively bind to the RNA Recognition Motif (RRM) of hnRNP A18, a regulator of protein translation in cancer cells. hnRNP A18 recognizes a specific RNA signature motif in the 3′UTR of transcripts associated with cancer cell progression (Trx, VEGF, RPA) and, as shown here, a tumor immune checkpoint (CTLA-4). Post-transcriptional regulation of immune checkpoints is a potential therapeutic strategy that remains to be exploited. The probes target hnRNP A18 RRM in vitro and in cells as evaluated by cellular target engagement. As single agents, the probes specifically disrupt hnRNP A18–RNA interactions, downregulate Trx and CTLA-4 protein levels and inhibit proliferation of several cancer cell lines without affecting the viability of normal epithelial cells. These first-in-class chemical probes will greatly facilitate the elucidation of the underexplored biological function of RNA Binding Proteins (RBPs) in cancer cells, including their effects on proliferation and immune checkpoint activation.

Luteolin Suppresses Sepsis-Induced Cold-Inducible RNA-Binding Protein Production and Lung Injury in Neonatal Mice

Neonatal sepsis is a life-threatening inflammatory condition. Extracellular cold-inducible RNA-binding protein (CIRP), a proinflammatory mediator, plays a critical role in the pathogenesis of sepsis-induced lung injury in neonates. Luteolin, a polyphenolic flavonoid, has potent anti-inflammatory properties. However, the effects of luteolin on CIRP production and neonatal sepsis-induced lung injury remained unknown. We therefore hypothesize that treatment with luteolin suppresses CIRP production and attenuates lung injury in neonatal sepsis. To study this, sepsis was induced in C57BL/6J mouse pups (5-7 days) by intraperitoneal cecal slurry injection (CSI). One hour after CSI, luteolin (10 mg/kg body weight) or vehicle (normal saline) was administered through intraperitoneal injection. CIRP mRNA and protein were determined and lung injury was assessed at 10 h after CSI. Our results showed that administration of luteolin decreased CIRP mRNA and protein, improved lung architecture, reduced lung edema, and apoptosis after CSI. To examine the direct effect of luteolin on CIRP production, peritoneal macrophages were isolated from neonatal mice and stimulated with 100 ng/mL LPS with or without the presence of luteolin. The result indicates that luteolin directly inhibited LPS-induced CIRP production in neonatal macrophages. In addition, luteolin also downregulated hypoxia-inducible factor-1α (HIF-1α) and NOD-like receptor 3 (NLRP3) expression in septic neonates and in LPS-stimulated neonatal macrophages. In conclusion, administration of luteolin suppresses CIRP production and attenuates lung injury in neonatal sepsis. The beneficial effect of luteolin may be related to downregulation of HIF-1α and NLRP3 expression in neonatal macrophages. Luteolin may be developed as an adjunctive therapy for neonatal sepsis.

Clinical significance of RBM3 expression in surgically treated colorectal lung metastases and paired primary tumors

BACKGROUND

The lungs are the second most common site of metastases in colorectal cancer (CRC). The aim of this study was to investigate prognostic factors, including RNA-binding motif protein 3 (RBM3) expression, in patients with CRC treated with pulmonary metastasectomy (PM).

METHODS

The cohort included all patients treated with PM at Skåne University Hospital, Lund, Sweden, from 2000 to 2014. Clinicopathological, treatment, and survival data were collected. Immunohistochemical staining of RBM3 was evaluated on tissue microarrays with samples from all lung metastases and a subset of paired primary tumors. Kaplan-Meier analysis and Cox proportional hazards modeling were applied to examine the associations of investigative factors with overall survival (OS) and recurrence-free survival.

RESULTS

In total, 216 patients with a primary tumor in the rectum (57%), left colon (34%), or right colon (9%) underwent PM. The 5-year OS rate was 56%. Age > 60 years, more than one metastasis, size of metastasis > 3 cm, disease-free interval < 24 months, low RBM3 score in the lung metastasis, and no adjuvant chemotherapy following PM were prognostic factors for shorter OS.

CONCLUSIONS

Several prognostic factors, including RBM3 expression, may be of aid in selecting CRC patients with lung metastases for PM as well as adjuvant therapy.

The Prognostic Value of DNA Methylation, Post-Translational Modifications and Correlated with Immune Infiltrates in Gynecologic Cancers

Background

To depict the prognostic landscape of gynecological cancers from the perspective of DNA methylation, alternative splicing (AS) and polyadenylation (APA) events and investigate their correlation with immune infiltrates.

Methods

Methylation and RNA-seq data and corresponding clinical information regarding gynecologic cancers were used to explore the relationships between changes in DNA methylation, AS and APA events and gynecologic cancer prognosis. QRT-PCR and multiple bioinformatics tools were employed to construct a gene interaction network and explore immune infiltrates.

Results

Only the mRNA levels of CIRBP and INPP5K were simultaneously significantly decreased in gynecologic cancers and negatively associated with overall survival, which verified by qrt-PCR. We also identified that CIRBP or INPP5K DNA methylation, AS and APA events are prognostic indicators of gynecologic cancers. The activation of T cells might be the main signaling pathway by which these genes modulate cancer progression. CIRBP/INPP5K expression is positively associated with immune infiltration and is a major risk factor of survival, especially among uterine corpus endometrial carcinoma (UCEC) patients.

Conclusion

According to these findings, the DNA methylation, AS and APA events of CIRBP and INPP5K may serve as important prognostic biomarkers and targets in gynecological cancers by modulating T cell infiltration.

CIRP Sensitizes Cancer Cell Responses to Ionizing Radiation

Cold inducible RNA binding protein (CIRP), also named A18 hnRNP or CIRBP, is a cold-shock RNA-binding protein which can be induced upon various cellular stresses. Its expression level is induced in various cancer tissues relative to adjacent normal tissues; this is believed to play a critical role in cancer development and progression. In this study, we investigated the role of CIRP in cells exposed to ionizing radiation. Our data show that CIRP reduction causes cell colony formation and cell viability reduction after irradiation. In addition, CIRP knockdown cells demonstrated a higher DNA damage rate but less cell cycle arrest after irradiation. As a result, the induced DNA damage with less DNA repair processes led to an increased cell apoptosis rate in CIRP knockdown cells postirradiation. These findings suggest that CIRP is a critical protein in irradiated cells and can be used as a potential target for sensitizing cancer cells to radiation therapy.