The RNA-binding protein RBM3 is involved in hypothermia induced neuroprotection

Mild and deep hypothermia differentially affect cerebral neuroinflammatory and cold shock response following cardiopulmonary bypass in rat

INTRODUCTION

Targeted temperature management (TTM) is considered to be a neuroprotective strategy during cardiopulmonary bypass (CPB) assisted procedures, possibly through the activation of cold shock proteins. We therefore investigated the effects of mild compared with deep hypothermia on the neuroinflammatory response and cold shock protein expression after CPB in rats.

METHODS

Wistar rats were subjected to 1 hr of mild (33 °C) or deep (18 °C) hypothermia during CPB or sham procedure. PET scan analyses using TSPO ligand [11C]PBR28 were performed on day 1 (short-term) or day 3 and 7 post-procedure (long-term) to assess neuroinflammation. Hippocampal and cortical samples were obtained at day 1 in the short-term group and at day 7 in the long-term group. mRNA expression of M1 and M2 microglia associated cytokines was analysed with RT-PCR. Cold shock protein RNA-binding motive 3 (RBM3) and tyrosine receptor kinase B (TrkB) receptor protein expression were determined with Western Blot and quantified.

RESULTS

In both groups target temperature was reached within an hour. Standard uptake values (SUV) of [11C]PBR28 in CPB rats at 1 day and 3 days were similar to that of sham animals. At 7 days after CPB the SUV was significantly higher in amygdala and hippocampal regions of the CPB 18 °C group as compared to the CPB 33 °C group. No differences were observed in the expression of M1 and M2 microglia-related cytokines between TTM 18 °C and 33 °C. RBM3 protein levels in cortex and hippocampus were significantly higher in CPB 33 °C compared to CPB 18 °C and sham 33 °C, at day 1 and day 7, respectively.

CONCLUSIONS

TTM at 18 °C increased the neuroinflammatory response in amygdala and hippocampus compared to TTM at 33 °C in rats undergoing a CPB procedure. Additionally, TTM at 33 °C induced increased expression of TrkB and RBM3 in cortex and hippocampus of rats on CPB compared to TTM at 18 °C. Together, these data indicate that neuroinflammation is alleviated by TTM at 33 °C, possibly by recruiting protective mechanisms through cold shock protein induction.

RBM3 Promotes Anti-inflammatory Responses in Microglia and Serves as a Neuroprotective Target of Ischemic Stroke

Ischemic stroke is a major cause of death and disability in adults. Hypothermic treatment is successful in treating neonatal cerebral ischemia, but its application is restricted in adult patients due to complex management strategies and severe adverse effects. Two homologous RNA-binding proteins, RBM3 and CIRP, are the only known cold-inducible proteins in vertebrates, and their expression levels are robustly elevated by mild to moderate hypothermia. In previous studies, we and others have demonstrated that both RBM3 and CIRP mediate the neuroprotective and neurogenic effects of hypothermia in cell and animal models. However, CIRP can also be detrimental to neurons by triggering neuroinflammatory responses, complicating its post-stroke functions. In this study, we compared the properties of the two cold-inducible RNA-binding proteins after ischemic stroke. Our results indicated that RBM3 expression was stimulated in the ischemic brain of stroke patients, while CIRP expression was not. In an experimental model, RBM3 can ameliorate ischemic-like insult by promoting neuronal survival and eliciting anti-inflammatory responses in activated microglia, while the impact of CIRP was intriguing. Collectively, our data supported the notion that RBM3 may be a more promising therapeutic target than CIRP for treating ischemic stroke. We further demonstrated that zr17-2, a small molecule initially identified to target CIRP, can specifically target RBM3 but not CIRP in microglia. zr17-2 demonstrated anti-inflammatory and neuroprotective effects after ischemic stroke both in vitro and in vivo, suggesting its potential therapeutic value.

A hypothermia mimetic molecule (zr17-2) reduces ganglion cell death, gliosis, and electroretinogram distortion in male rats subjected to perinatal asphyxia

Introduction: Perinatal asphyxia (PA) represents a major problem in perinatology and may cause visual losses, including blindness. We, and others, have shown that hypothermia prevents retinal symptoms associated to PA. In the present work, we evaluate whether a hypothermia mimetic small molecule, zr17-2, has similar effects in the context of PA. Methods: Four experimental groups were studied in male rats: Naturally born rats as controls (CTL), naturally born rats injected s.c. with 50 µL of 330 nmols/L zr17-2 (ZR), animals that were exposed to PA for 20 min at 37°C (PA), and rats that were exposed to PA and injected with zr17-2 (PA-ZR). Forty-five days after treatment, animals were subjected to electroretinography. In addition, morphological techniques (TUNEL, H&E, multiple immunofluorescence) were applied to the retinas. Results: A reduction in the amplitude of the a- and b-wave and oscillatory potentials (OP) of the electroretinogram (ERG) was detected in PA animals. Treatment with zr17-2 resulted in a significant amelioration of these parameters (p < 0.01). In PA animals, a large number of apoptotic cells was found in the GCL. This number was significantly reduced by treatment with the small molecule (p < 0.0001). In a similar way, the thickness of the inner retina and the intensity of GFAP immunoreactivity (gliosis) increased in PA retinas (p < 0.0001). These parameters were corrected by the administration of zr17-2 (p < 0.0001). Furthermore, injection of the small molecule in the absence of PA did not modify the ERG nor the morphological parameters studied, suggesting a lack of toxicity. Discussion: In conclusion, our results indicate that a single s.c. injection of zr17-2 in asphyctic neonates may provide a novel and efficacious method to prevent the visual sequelae of PA.

Study on the protective effect of RNA-binding motif protein 3 in mild hypothermia oxygen-glucose deprivation/reoxygenation cell model

Mild hypothermia is proven neuroprotective in clinical practice. While hypothermia leads to the decrease of global protein synthesis rate, it upregulates a small subset of protein including RNA-binding motif protein 3 (RBM3). In this study, we treated mouse neuroblastoma cells (N2a) with mild hypothermia before oxygen-glucose deprivation/reoxygenation (OGD/R) and discovered the decrease of apoptosis rate, down-regulation of apoptosis-associated protein and enhancement of cell viability. Overexpression of RBM3 via plasmid exerted similar effect while silencing RBM3 by siRNAs partially reversed the protective effect exerted by mild hypothermia pretreatment. The protein level of Reticulon 3(RTN3), a downstream gene of RBM3, also increased after mild hypothermia pretreatment. Silencing RTN3 weakened the protective effect of mild hypothermia pretreatment or RBM3 overexpression. Also, the protein level of autophagy gene LC3B increased after OGD/R or RBM3 overexpression while silencing RTN3 decreased this trend. Furthermore, immunofluorescence observed enhanced fluorescence signal of LC3B and RTN3 as well as a large number of overlaps after RBM3 overexpressing. In conclusion, RBM3 plays a cellular protective role by regulating apoptosis and viability via its downstream gene RTN3 in the hypothermia OGD/R cell model and autophagy may participate in it.

Hypothermia increases cold-inducible protein expression and improves cerebellar-dependent learning after hypoxia ischemia in the neonatal rat

BACKGROUND

Hypoxic ischemic encephalopathy remains a significant cause of developmental disability.1,2 The standard of care for term infants is hypothermia, which has multifactorial effects.3-5 Therapeutic hypothermia upregulates the cold-inducible protein RNA binding motif 3 (RBM3) that is highly expressed in developing and proliferative regions of the brain.6,7 The neuroprotective effects of RBM3 in adults are mediated by its ability to promote the translation of mRNAs such as reticulon 3 (RTN3).8 METHODS: Hypoxia ischemia or control procedure was conducted in Sprague Dawley rat pups on postnatal day 10 (PND10). Pups were immediately assigned to normothermia or hypothermia at the end of the hypoxia. In adulthood, cerebellum-dependent learning was tested using the conditioned eyeblink reflex. The volume of the cerebellum and the magnitude of cerebral injury were measured. A second study quantified RBM3 and RTN3 protein levels in the cerebellum and hippocampus collected during hypothermia.

RESULTS

Hypothermia reduced cerebral tissue loss and protected cerebellar volume. Hypothermia also improved learning of the conditioned eyeblink response. RBM3 and RTN3 protein expression were increased in the cerebellum and hippocampus of rat pups subjected to hypothermia on PND10.

CONCLUSIONS

Hypothermia was neuroprotective in male and female pups and reversed subtle changes in the cerebellum after hypoxic ischemic.

IMPACT

Hypoxic ischemic produced tissue loss and a learning deficit in the cerebellum. Hypothermia reversed both the tissue loss and learning deficit. Hypothermia increased cold-responsive protein expression in the cerebellum and hippocampus. Our results confirm cerebellar volume loss contralateral to the carotid artery ligation and injured cerebral hemisphere, suggesting crossed-cerebellar diaschisis in this model. Understanding the endogenous response to hypothermia might improve adjuvant interventions and expand the clinical utility of this intervention.

SMYD5 is a novel epigenetic gatekeeper of the mild hypothermia response

Organisms have homeostatic mechanisms to respond to cold temperature to ensure survival including the activation of the mammalian neuroprotective mild hypothermia response (MHR) at 32°C. We show activation of the MHR at euthermia by an FDA-approved medication Entacapone, proof-of-principle that the MHR can be medically manipulated. Utilizing a forward CRISPR-Cas9 mutagenesis screen, we identify the histone lysine methyltransferase SMYD5 as an epigenetic gatekeeper of the MHR. SMYD5 represses the key MHR gene SP1 at euthermia but not at 32°C. This repression is mirrored by temperature-dependent levels of H3K36me3 at the SP1-locus and globally indicating that the mammalian MHR is regulated at the level of histone modifications. We identified 45 additional SMYD5-temperature dependent genes suggesting a broader MHR-related role for SMYD5. Our study provides an example of how the epigenetic machinery integrates environmental cues into the genetic circuitry of mammalian cells and suggests novel therapeutic avenues for neuroprotection after catastrophic events.

ASO targeting RBM3 temperature-controlled poison exon splicing prevents neurodegeneration in vivo

Neurodegenerative diseases are increasingly prevalent in the aging population, yet no disease-modifying treatments are currently available. Increasing the expression of the cold-shock protein RBM3 through therapeutic hypothermia is remarkably neuroprotective. However, systemic cooling poses a health risk, strongly limiting its clinical application. Selective upregulation of RBM3 at normothermia thus holds immense therapeutic potential. Here we identify a poison exon within the RBM3 gene that is solely responsible for its cold-induced expression. Genetic removal or antisense oligonucleotide (ASO)-mediated manipulation of this exon yields high RBM3 levels independent of cooling. Notably, a single administration of ASO to exclude the poison exon, using FDA-approved chemistry, results in long-lasting increased RBM3 expression in mouse brains. In prion-diseased mice, this treatment leads to remarkable neuroprotection, with prevention of neuronal loss and spongiosis despite high levels of disease-associated prion protein. Our promising results in mice support the possibility that RBM3-inducing ASOs might also deliver neuroprotection in humans in conditions ranging from acute brain injury to Alzheimer's disease.

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.

RBM3 interacts with Raptor to regulate autophagy and protect cardiomyocytes from ischemia-reperfusion-induced injury

Acute myocardial infarction (AMI) is a common disease with high morbidity and mortality worldwide. However, postinfarction pathogenesis remains unclear, and it is particularly important to identify new therapeutic targets. The RNA-binding motif protein RBM3 (also known as cold-inducible protein) is known to promote translation and is associated with tumor proliferation and neuroprotection. However, little is known about the biological effects of RBM3 on myocardial infarction. In the present study, we found that RBM3 expression was significantly upregulated in ischemia-reperfusion (I/R) condition and downregulation of RBM3 inhibited autophagy and promoted apoptosis in cardiomyocytes. We confirmed that RBM3 interacts with Raptor to regulate the autophagy pathway. Taken together, these findings illustrate the protective effects of RBM3 against I/R-induced myocardial apoptosis through the autophagy pathway.

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.

11S Proteasome Activator REGγ Promotes Aortic Dissection by Inhibiting RBM3 (RNA Binding Motif Protein 3) Pathway

BACKGROUND

Aortic dissection (AD) is a life-threatening cardiovascular disorder with high mortality and lacking underlying mechanisms or effective treatments. REGγ, the 11S proteasome activator known to promote the degradation of cellular proteins in a ubiquitin- and ATP-independent manner, emerges as a new regulator in the cardiovascular system.

METHODS

Using β-aminopropionitrile (BAPN)-subjected REGγ knockout AD mice and Ang II (angiotensin II)-treated REGγ deficiency vascular smooth muscle cells (VSMCs) to explore the effect of REGγ in AD progression.

RESULTS

REGγ was upregulated in mouse aorta of β-aminopropionitrile-induced AD model in vivo and Ang II-treated VSMCs in vitro. REGγ deficiency ameliorated AD progression in β-aminopropionitrile-induced mice by protecting against the switch in VSMCs from contractile to synthetic phenotype through suppressing RBM3 (RNA-binding motif protein 3) decay. Mechanically, REGγ interacted with and degraded the RNA-binding protein RBM3 directly, leading to decreased mRNA stability, lowered expression and transcriptional activity of transcription factor SRF (serum response factor), subsequently reduced transcription of VSMCs-specific contractile genes, α-SMA (alpha-smooth muscle actin) and SM22α (smooth muscle 22 alpha), caused the switch in VSMCs from contractile to synthetic phenotype and associated AD progression. Ablation of endogenous SRF or RBM3, or overexpressing exogenous RBM3 in VSMCs significantly blocked or reestablished the REGγ-dependent action on VSMCs phenotypic switch of Ang II stimulation in vitro. Furthermore, exogenously introducing RBM3 improved the switch in VSMCs from contractile to synthetic phenotype and associated AD features caused by REGγ in vivo.

CONCLUSIONS

Our results demonstrated that REGγ promoted the switch in VSMCs from contractile to synthetic phenotype and AD progression by inhibiting RBM3-SRF pathway, indicated that modulating REGγ-proteasome activity may be a potential therapeutic approach for AD-associated cardiovascular dysfunction.

Selective intraarterial hypothermia combined with mechanical thrombectomy for acute cerebral infarction based on microcatheter technology: A single-center, randomized, single-blind controlled study

Objective

To investigate the safety and efficacy of selective intraarterial hypothermia combined with mechanical thrombectomy in the treatment of acute cerebral infarction based on microcatheter technology.

Methods

A total of 142 patients with anterior circulation large vessel occlusion were randomly assigned to the hypothermic treatment group (test group) and the conventional treatment group (control group). National Institutes of Health Stroke Scale (NIHSS) scores, postoperative infarct volume, the 90-day good prognosis rate (modified Rankin Scale (mRS) score ≤ 2 points), and the mortality rate of the two groups were compared and analyzed. Blood specimens were collected from patients before and after treatment. Serum levels of superoxide dismutase (SOD), malondialdehyde (MDA), interleukin-6 (IL-6), IL-10, and RNA-binding motif protein 3 (RBM3) were measured.

Results

The 7-day postoperative cerebral infarct volume [(63.7 ± 22.1) ml vs. (88.5 ± 20.8) ml] and NIHSS scores at postoperative Days 1, 7, and 14 [(6.8 ± 3.8) points vs. (8.2 ± 3.5) points; (2.6 ± 1.6) points vs. (4.0 ± 1.8) points; (2.0 ± 1.2) points vs. (3.5 ± 2.1) points] in the test group were significantly lower than those in the control group. The good prognosis rate at 90 days postoperatively (54.9 vs. 35.2%, P = 0.018) was significantly higher in the test group than in the control group. The 90-day mortality rate was not statistically significant (7.0 vs. 8.5%, P = 0.754). Immediately after surgery and 1 day after surgery, SOD, IL-10, and RBM3 levels in the test group were relatively higher than those in the control group, and the differences were statistically significant. Immediately after surgery and 1 day after surgery, MDA and IL-6 levels in the test group were relatively reduced compared with those in the control group, and the differences were statistically significant (P < 0.05). In the test group, RBM3 was positively correlated with SOD and IL-10.

Conclusion

Mechanical thrombectomy combined with intraarterial cold saline perfusion is a safe and effective measure for the treatment of acute cerebral infarction. Postoperative NIHSS scores and infarct volumes were significantly improved with this strategy compared with simple mechanical thrombectomy, and the 90-day good prognosis rate was improved. The mechanism by which this treatment exerts its cerebral protective effect may be by inhibiting the transformation of the ischaemic penumbra of the infarct core area, scavenging some oxygen free radicals, reducing inflammatory injury to cells after acute infarction and ischaemia-reperfusion, and promoting RBM3 production in cells.

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.

Therapeutic hypothermia for stroke: Unique challenges at the bedside

Therapeutic hypothermia has shown promise as a means to improving neurological outcomes at several neurological conditions. At the clinical level, it has been shown to improve outcomes in comatose survivors of cardiac arrest and in neonatal hypoxic ischemic encephalopathy, but has yet to be convincingly demonstrated in stroke. While numerous preclinical studies have shown benefit in stroke models, translating this to the clinical level has proven challenging. Major obstacles include cooling patients with typical stroke who are awake and breathing spontaneously but often have significant comorbidities. Solutions around these problems include selective brain cooling and cooling to lesser depths or avoiding hyperthermia. This review will cover the mechanisms of protection by therapeutic hypothermia, as well as recent progress made in selective brain cooling and the neuroprotective effects of only slightly lowering brain temperature. Therapeutic hypothermia for stroke has been shown to be feasible, but has yet to be definitively proven effective. There is clearly much work to be undertaken in this area.

Hypothermia Alleviates Reductive Stress, a Root Cause of Ischemia Reperfusion Injury

Ischemia reperfusion injury is common in transplantation. Previous studies have shown that cooling can protect against hypoxic injury. To date, the protective effects of hypothermia have been largely associated with metabolic suppression. Since kidney transplantation is one of the most common organ transplant surgeries, we used human-derived renal proximal tubular cells (HKC8 cell line) as a model of normal renal cells. We performed a temperature titration curve from 37 °C to 22 °C and evaluated cellular respiration and molecular mechanisms that can counteract the build-up of reducing equivalents in hypoxic conditions. We show that the protective effects of hypothermia are likely to stem both from metabolic suppression (inhibitory component) and augmentation of stress tolerance (activating component), with the highest overlap between activating and suppressing mechanisms emerging in the window of mild hypothermia (32 °C). Hypothermia decreased hypoxia-induced rise in the extracellular lactate:pyruvate ratio, increased ATP/ADP ratio and mitochondrial content, normalized lipid content, and improved the recovery of respiration after anoxia. Importantly, it was observed that in contrast to mild hypothermia, moderate and deep hypothermia interfere with HIF1 (hypoxia inducible factor 1)-dependent HRE (hypoxia response element) induction in hypoxia. This work also demonstrates that hypothermia alleviates reductive stress, a conceptually novel and largely overlooked phenomenon at the root of ischemia reperfusion injury.

RBM3 is an outstanding cold shock protein with multiple physiological functions beyond hypothermia

RNA-binding motif protein 3 (RBM3), an outstanding cold shock protein, is rapidly upregulated to ensure homeostasis and survival in a cold environment, which is an important physiological mechanism in response to cold stress. Meanwhile, RBM3 has multiple physiological functions and participates in the regulation of various cellular physiological processes, such as antiapoptosis, circadian rhythm, cell cycle, reproduction, and tumogenesis. The structure, conservation, and tissue distribution of RBM3 in human are demonstrated in this review. Herein, the multiple physiological functions of RBM3 were summarized based on recent research advances. Meanwhile, the cytoprotective mechanism of RBM3 during stress under various adverse conditions and its regulation of transcription were discussed. In addition, the neuroprotection of RBM3 and its oncogenic role and controversy in various cancers were investigated in our review.

Time-resolved proteome and transcriptome of paraquat-induced pulmonary fibrosis

BACKGROUNDS

Pulmonary fibrosis (PF) is a pathological state presenting at the progressive stage of heterogeneous interstitial lung disease (ILD). The current understanding of the molecular mechanisms involved is incomplete. This clinical toxicology study focused on the pulmonary fibrosis induced by paraquat (PQ), a widely-used herbicide. Using proteo-transcriptome analysis, we identified differentially expressed proteins (DEPs) derived from the initial development of fibrosis to the dissolved stage and provided further functional analysis.

METHODS

We established a mouse model of progressive lung fibrosis via intratracheal instillation of paraquat. To acquire a comprehensive and unbiased understanding of the onset of pulmonary fibrosis, we performed time-series proteomics profiling (iTRAQ) and RNA sequencing (RNA-Seq) on lung samples from paraquat-treated mice and saline control. The biological functions and pathways involved were evaluated through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway analysis. Correlation tests were conducted on comparable groups 7 days and 28 days post-exposure. Differentially expressed proteins and genes following the same trend on the protein and mRNA levels were selected for validation. The functions of the selected molecules were identified in vitro. The protein level was overexpressed by transfecting gene-containing plasmid or suppressed by transfecting specific siRNA in A549 cells. The levels of endothlial-mesenchymal transition (EMT) markers, including E-cadherin, vimentin, FN1, and α-SMA, were determined via western blot to evaluate the fibrotic process.

RESULTS

We quantified 1358 DEPs on day 7 and 426 DEPs on day 28 post exposure (Fold change >1.2; Q value < 0.05). The top 5 pathways - drug metabolism-cytochrome P450, metabolism of xenobiotics by cytochrome P450, complement and coagulation cascades, chemical carcinogenesis, protein digestion and absorption - were involved on both day 7 and day 28. Several pathways, including tight junction, focal adhesion, platelet activation, and ECM-receptor interaction, were more enriched on day 28 than on day 7. Integrative analysis of the proteome and transcriptome revealed a moderate correlation of quantitative protein abundance ratios with RNA abundance ratios (Spearman R = 0.3950 and 0.2477 on days 7 and 28, respectively), indicating that post-transcriptional regulation plays an important role in lung injury and repair. Western blot identified that the protein expressions of FN1, S100A4, and RBM3 were significantly upregulated while that of CYP1A1, FMO3, and PGDH were significantly downregulated on day 7. All proteins generally recovered to baseline on day 28. qPCR showed the mRNA levels of Fn1, S100a4, Rbm3, Cyp1a1, Fmo3, and Hpgd changed following the same trend as the levels of their respective proteins. Further, in vitro experiments showed that RBM3 was upregulated while PGDH was downregulated in an EMT model established in human lung epithelial A549 cells. RBM3 overexpression and PGDH knockout could both induce EMT in A549 cells. RBM3 knockout or PGDH overexpression had no reverse effect on EMT in A549 cells.

CONCLUSIONS

Our proteo-transcriptomic study determined the proteins responsible for fibrogenesis and uncovers their dynamic regulation from lung injury to repair, providing new insights for the development of biomarkers for diagnosis and treatment of fibrotic diseases.

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.

Mild Therapeutic Hypothermia and Putative Mechanisms of Hair Cell Survival in the Cochlea

Significance: Sensorineural hearing loss has significant implications for quality of life and risk for comorbidities such as cognitive decline. Noise and ototoxic drugs represent two common risk factors for acquired hearing loss that are potentially preventable. Recent Advances: Numerous otoprotection strategies have been postulated over the past four decades with primary targets of upstream redox pathways. More recently, the application of mild therapeutic hypothermia (TH) has shown promise for otoprotection for multiple forms of acquired hearing loss. Critical Issues: Systemic antioxidant therapy may have limited application for certain ototoxic drugs with a therapeutic effect on redox pathways and diminished efficacy of the primary drug's therapeutic function (e.g., cisplatin for tumors). Future Directions: Mild TH likely targets multiple mechanisms, contributing to otoprotection, including slowed metabolics, reduced oxidative stress, and involvement of cold shock proteins. Further work is needed to identify the mechanisms of mild TH at play for various forms of acquired hearing loss.

Emerging Trends in the Use of Therapeutic Hypothermia as a Method for Neuroprotection in Brain Damage (Review)

The review analyzes current clinical studies on the use of therapeutic hypothermia as a neuroprotective method for treatment of brain damage. This method yields good outcomes in patients with acute brain injuries and chronic critical conditions. There has been shown the interest of researchers in studying the preventive potential of therapeutic hypothermia in secondary neuronal damage. There has been described participation of new molecules producing positive effect on tissues and cells of the central nervous system - proteins and hormones of cold stress - in the mechanisms of neuroprotection in the brain. The prospects of using targeted temperature management in treatment of brain damage are considered.

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.

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.

Mild therapeutic hypothermia improves neurological outcomes in a rat model of cardiac arrest

Cardiac arrest (CA) is the leading cause of death in humans. Research has shown that mild therapeutic hypothermia (MTH) can reduce neurological sequelae and mortality after CA. Nevertheless, the mechanism remains unclear. This study aimed to determine whether MTH promotes neurogenesis, attenuates neuronal damage, and inhibits apoptosis of neurons in rats after CA. Sprague-Dawley rats were divided into the normothermia and mild hypothermia groups. The rats in the normothermia and hypothermia groups were exposed to 2 h of normothermia (36-37℃) and hypothermia (32-33℃), respectively, immediately after resuscitation from 5 min of asphyxial CA. Corresponding control groups not subjected to CA were included. On days 1-6, 5-bromodeoxyuridine (BrdU) 100 mg/kg/day was administered intraperitoneally. The animals were euthanized 1 week after CA. Compared with the normothermia group, the hypothermia group showed a significant increase in the number of doublecortin (DCX) immune-positive cells in the subgranular zone of the hippocampus 1 week after CA. Neurogenesis was assessed using double immunofluorescent labeling of BrdU with neuronal-specific nuclear protein (NeuN)/DCX. There was no marked change in the number of newborn mature (BrdU+-NeuN+) neurons, though there was a significant increase in the number of newborn immature (BrdU+-DCX+) neurons in the hypothermia than in the normothermia group 1 week after CA. Neuronal injury and apoptosis in the CA1 region of the hippocampus, assessed using NeuN immunofluorescence and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays, were significantly reduced in the hypothermia group 1 week after CA. Moreover, mild hypothermia increased the expression of cold-shock protein RNA-binding motif protein 3 (RBM3) in the early stage (24 h/48 h) after CA. These results suggested that mild hypothermia promotes generation of neuronal cells, reduces neuronal injury, and inhibits apoptosis of neurons, which may be related to RBM3 expression.

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.

Hypothermic Shock Applied After Perinatal Asphyxia Prevents Retinal Damage in Rats

Perinatal asphyxia (PA) can cause retinopathy and different degrees of visual loss, including total blindness. In a rat model of PA, we have previously shown a protective effect of hypothermia on the retina when applied simultaneously with the hypoxic insult. In the present work, we evaluated the possible protective effect of hypothermia on the retina of PA rats when applied immediately after delivery. Four experimental groups were studied: Rats born naturally as controls (CTL), animals that were exposed to PA for 20 min at 37°C (PA), animals exposed to PA for 20 min at 15°C (HYP), and animals that were exposed to PA for 20 min at 37°C and, immediately after birth, kept for 15 min at 8°C (HYP-PA). To evaluate the integrity of the visual pathway, animals were subjected to electroretinography at 45 days of age. Molecular (real time PCR) and histological (immunohistochemistry, immunofluorescence, TUNEL assay) techniques were applied to the eyes of all experimental groups collected at 6, 12, 24, and 48 h, and 6 days after birth. PA resulted in a significant reduction in the amplitude of the a- and b-wave and oscillatory potentials (OP) of the electroretinogram. All animals treated with hypothermia had a significant correction of the a-wave and OP, but the b-wave was fully corrected in the HYP group but only partially in the HYP-PA group. The number of TUNEL-positive cells increased sharply in the ganglion cell layer of the PA animals and this increase was significantly prevented by both hypothermia treatments. Expression of the cold-shock proteins, cold-inducible RNA binding protein (CIRP) and RNA binding motif protein 3 (RBM3), was undetectable in retinas of the CTL and PA groups, but they were highly expressed in ganglion neurons and cells of the inner nuclear layer of the HYP and HYP-PA groups. In conclusion, our results suggest that a post-partum hypothermic shock could represent a useful and affordable method to prevent asphyxia-related vision disabling sequelae.

TrkB signaling regulates the cold-shock protein RBM3-mediated neuroprotection

Increasing levels of the cold-shock protein, RNA-binding motif 3 (RBM3), either through cooling or by ectopic over-expression, prevents synapse and neuronal loss in mouse models of neurodegeneration. To exploit this process therapeutically requires an understanding of mechanisms controlling cold-induced RBM3 expression. Here, we show that cooling increases RBM3 through activation of TrkB via PLCγ1 and pCREB signaling. RBM3, in turn, has a hitherto unrecognized negative feedback on TrkB-induced ERK activation through induction of its specific phosphatase, DUSP6. Thus, RBM3 mediates structural plasticity through a distinct, non-canonical activation of TrkB signaling, which is abolished in RBM3-null neurons. Both genetic reduction and pharmacological antagonism of TrkB and its downstream mediators abrogate cooling-induced RBM3 induction and prevent structural plasticity, whereas TrkB inhibition similarly prevents RBM3 induction and the neuroprotective effects of cooling in prion-diseased mice. Conversely, TrkB agonism induces RBM3 without cooling, preventing synapse loss and neurodegeneration. TrkB signaling is, therefore, necessary for the induction of RBM3 and related neuroprotective effects and provides a target by which RBM3-mediated synapse-regenerative therapies in neurodegenerative disorders can be used therapeutically without the need for inducing hypothermia.

Research Progress of the Application of Hypothermia in the Eye

Hypothermia is widely used in the medical field to protect organs or tissues from damage. Different research fields have different explanations of the protection mechanism of hypothermia. Hypothermia is also widely used in the field of ophthalmology, for example, in the eye bank, the preservation of corneal tissue and the preservation of the eyeball. Low temperature can also be applied to some ophthalmic diseases, such as allergic conjunctivitis, retinal ischemia, and retinal hypoxia. It is used to relieve eye symptoms or reduce tissue damage. Hypothermic techniques have important applications in ophthalmic surgery, such as corneal refractive surgery, vitrectomy surgery, and ciliary body cryotherapy for end-stage glaucoma. Hypothermia can reduce the inflammation of the cornea and protect the retinal tissue. The eyeball is a complex organ, including collagen tissue of the eyeball wall and retinal nerve tissue and retinal blood vessels. The mechanism of low temperature protecting eye tissue is complicated. It is important to understand the mechanism of hypothermia and its applications in ophthalmology. This review introduces the mechanism of hypothermia and its application in the eye banks, eye diseases (allergic conjunctivitis, retinal ischemia, and hypoxia), and eye surgeries (corneal transplant surgery, corneal refractive surgery, and vitrectomy).

Expression regulation of cold-inducible protein RBM3 by FAK/Src signaling for neuroprotection against rotenone under mild hypothermia

Mild hypothermia is a well-established technique for alleviating neurological injuries in clinical surgery. RNA-binding protein motif 3 (RBM3) has been identified as a crucial factor in mediating hypothermic neuroprotection, providing its induction as a promising strategy for mimicking therapeutic hypothermia. However, little is known about molecular control of RBM3 and signaling pathways affected by hypothermia. In the present study, human SH-SY5Y neuroblastoma cells were used as a neural cell model. Screening of signaling pathways showed that cold exposure led to inactivation of ERK and AMPK pathways, and activation of FAK and PLCγ pathways, with activities of p38, JNK and AKT pathways moderately changed. Next, various small molecule inhibitors specific to these signaling pathways were applied. Interestingly, only FAK-specific inhibitor exhibited a significant inhibitory effect on hypothermia-induced RBM3 gene transcription and protein expression. Likewise, FAK silencing using siRNA technique significantly abrogated the induction of RBM3 by hypothermia. Moreover, FAK inhibition accounted for an inactivation of Src, a known kinase downstream of FAK. Next, either the silencing of Src by siRNA or its inactivation by a chemical inhibitor, strongly blocked the induction of RBM3 by cooling. Notably, in HEK293 and PC12 cells, FAK/Src activation was also shown to be indispensable for hypothermia-stimulated RBM3 expression. Lastly, the CCK8 and Western blot assays showed that both FAK/Src inacitivation and their knockdown substantially abrogate the neuroprotective effects of mild hypothermia against rotenone in SH-SY5Y cells. These data suggest that FAK/Src signaling axis regulates the transcription of Rbm3 gene and mediates neuroprotective effects of mild hypothermia.

The Effects of Targeted Temperature Management on Oxygen-Glucose Deprivation/Reperfusion-Induced Injury and DAMP Release in Murine Primary Cardiomyocytes

Introduction. Ischemia/Reperfusion (I/R) is a primary cause of myocardial injury after acute myocardial infarction resulting in the release of damage-associated molecular patterns (DAMPs), which can induce a sterile inflammatory response in the myocardial penumbra. Targeted temperature management (TTM) after I/R has been established for neuroprotection, but the cardioprotective effect remains to be elucidated. Therefore, we investigated the effect of TTM on cell viability, immune response, and DAMP release during oxygen-glucose deprivation/reperfusion (OGD/R) in murine primary cardiomyocytes. Methods. Primary cardiomyocytes from P1-3 mice were exposed to 2, 4, or 6 hours OGD (0.2% oxygen in medium without glucose and serum) followed by 6, 12, or 24 hours simulated reperfusion (21% oxygen in complete medium). TTM at 33.5°C was initiated intra-OGD, and a control group was maintained at 37°C normoxia. Necrosis was assessed by lactate dehydrogenase (LDH) release and apoptosis by caspase-3 activation. OGD-induced DAMP secretions were assessed by Western blotting. Inducible nitric oxide synthase (iNOS), cytokines, and antiapoptotic RBM3 and CIRBP gene expressions were measured by quantitative polymerase chain reaction. Results. Increasing duration of OGD resulted in a transition from apoptotic programmed cell death to necrosis, as observed by decreasing caspase-3 cleavage and increasing LDH release. DAMP release and iNOS expression correlated with increasing necrosis and were effectively attenuated by TTM initiated during OGD. Moreover, TTM induced expression of antiapoptotic RBM3 and CIRBP. Conclusion. TTM protects the myocardium by attenuating cardiomyocyte necrosis induced by OGD and caspase-3 activation, possibly via induction of antiapoptotic RBM3 and CIRBP expressions, during reperfusion. OGD induces increased Hsp70 and CIRBP releases, but HMGB-1 is the dominant mediator of inflammation secreted by cardiomyocytes after prolonged exposure. TTM has the potential to attenuate DAMP release.

Eukaryotic response to hypothermia in relation to integrated stress responses

Eukaryotic cells respond to hypothermic stress through a series of regulatory mechanisms that preserve energy resources and prolong cell survival. These mechanisms include alterations in gene expression, attenuated global protein synthesis and changes in the lipid composition of the phospholipid bilayer. Cellular responses to hyperthermia, hypoxia, nutrient deprivation and oxidative stress have been comprehensively investigated, but studies of the cellular response to cold stress are more limited. Responses to cold stress are however of great importance both in the wild, where exposure to low and fluctuating environmental temperatures is common, and in medical and biotechnology settings where cells and tissues are frequently exposed to hypothermic stress and cryopreservation. This means that it is vitally important to understand how cells are impacted by low temperatures and by the decreases and subsequent increases in temperature associated with cold stress. Here, we review the ways in which eukaryotic cells respond to hypothermic stress and how these compare to the well-described and highly integrated stress response systems that govern the cellular response to other types of stress.

RNA Binding Protein Motif 3 Inhibits Oxygen-Glucose Deprivation/Reoxygenation-Induced Apoptosis Through Promoting Stress Granules Formation in PC12 Cells and Rat Primary Cortical Neurons

As a sensitive cold-shock protein, RNA binding protein motif 3 (RBM3) exhibits a neuroprotective function in the condition of brain injury. However, how RBM3 is involved in acute ischemic stroke by affecting stress granules (SGs) remains unclear. Here, we established an oxygen-glucose deprivation/reperfusion (OGD/R) model in rat primary cortical neurons and PC12 cells to explore the potential mechanism between RBM3 and SG formation in acute ischemic/reperfusion (I/R) condition. The immunofluorescence results showed that the SG formation significantly decreased in rat primary cortical neurons and PC12 cells during the reperfusion period after 6 h of OGD stimulation. The western blot results, flow cytometry analysis, and cell viability assessment showed that the RBM3 expression and ratio of cell viability significantly decreased, while the rate of apoptosis increased in PC12 cells during the reperfusion period after 6 h of OGD stimulation. Co-immunoprecipitation (Co-IP) and immunofluorescence indicated that RBM3 and GTPase-activating protein-binding protein 1 (G3BP1) colocalized cytoplasm of PC12 cells after 6 h of OGD stimulation when the SGs formation reached the highest level. Besides, overexpression and knockdown of the RBM3 were achieved via plasmid transfection and CRISPR-Cas9 technology, respectively. The results of overexpression and knockdown of RBM3 gene illustrated the pivotal role of RBM3 in affecting SG formation and apoptosis level in OGD-treated PC12 cells. In conclusion, RBM3 could combine with G3BP1 resulted in increasing stress granules generation in rat primary cortical neurons and PC12 cells after 6 h of oxygen-glucose deprivation (OGD) injury, which ultimately reduced the apoptosis in OGD-induced cells. Our study may enable a new promising target for alleviating ischemia-reperfusion injury in cells.

The overexpression of RBM3 alleviates TBI-induced behaviour impairment and AD-like tauopathy in mice

The therapeutic hypothermia is an effective tool for TBI‐associated brain impairment, but its side effects limit in clinical routine use. Hypothermia up‐regulates RNA‐binding motif protein 3 (RBM3), which is verified to protect synaptic plasticity. Here, we found that cognitive and LTP deficits, loss of spines, AD‐like tau pathologies are displayed one month after TBI in mice. In contrast, the deficits of LTP and cognitive, loss of spines and tau abnormal phosphorylation at several sites are obviously reversed in TBI mice combined with hypothermia pre‐treatment (HT). But, the neuroprotective role of HT disappears in TBI mouse models under condition of blocking RBM3 expression with RBM3 shRNA. In other hand, overexpressing RBM3 by AAV‐RBM3 plasmid can mimic HT‐like neuroprotection against TBI‐induced chronic brain injuries, such as improving LTP and cognitive, loss of spines and tau hyperphosphorylation in TBI mouse models. Taken together, hypothermia pre‐treatment reverses TBI‐induced chronic AD‐like pathology and behaviour deficits in RBM3 expression dependent manner, RBM3 may be a potential target for neurodegeneration diseases including Alzheimer disease.

The prognostic and clinicopathological significance of RBM3 in the survival of patients with tumor: A Prisma-compliant meta-analysis

BACKGROUND

RNA-binding motif protein 3 (RBM3) plays an important role in carcinogenesis and tumor progression. However, the prognostic role of RBM3 in human carcinomas remains controversial. Therefore, we took a meta-analysis to research the association between the overall survival of patients with cancer and the expression of RBM3.

METHODS

Systematic literature research identified 17 potentially eligible studies comprising 4976 patients in ten different cancer types. Two researchers independently screened the content and quality of studies and extracted data. Correlations of RBM3 expression and survival were analyzed and the hazard ratios (HRs) with 95% confidence intervals (95% CIs) were calculated.

RESULTS

In the pooled analysis, overexpression of RBM3 was related to improved overall survival (OS), recurrence-free survival (RFS), and disease-free survival (DFS) in patients with cancer having a pooled HR of 0.61 (HR = 0.61; 95% CI: 0.47-0.69), 0.57 (HR = 0.60; 95% CI: 0.50-0.71) and 0.54 (HR 0.54; 95% CI: 0.38-0.78). Besides, subgroup analysis proved that overexpression of RBM3 was related to improved OS in colorectal cancer (HR = 0.61, 95% CI: 0.43-0.86), melanoma (HR = 0.32, 95% CI: 0.20-0.52), and gastric cancer (HR = 0.51, 95% CI: 0.35-0.73). However, subgroup analysis according to tumor type revealed that overexpression of RBM3 was not related to better OS in breast carcinoma (HR = 0.52, 95% CI: 0.17-0.61).

CONCLUSIONS

Our results indicated that RBM3 overexpression was significantly predictive of better prognosis in various human cancers. For certain tumors, overexpression RBM3 might be a marker of improved survival in humans with cancer, except for breast cancer.

Hypothermic neuroprotection against acute ischemic stroke: The 2019 update

Acute ischemic stroke is a leading cause of death and disability worldwide. Therapeutic hypothermia has long been considered as one of the most robust neuroprotective strategies. Although the neuroprotective effects of hypothermia have only been confirmed in patients with global cerebral ischemia after cardiac arrest and in neonatal hypoxic ischemic encephalopathy, establishing standardized protocols and strictly controlling the key parameters may extend its application in other brain injuries, such as acute ischemic stroke. In this review, we discuss the potential neuroprotective effects of hypothermia, its drawbacks evidenced in previous studies, and its potential clinical application for acute ischemic stroke especially in the era of reperfusion. Based on the different conditions between bench and bedside settings, we demonstrate the importance of vascular recanalization for neuroprotection of hypothermia by analyzing numerous literatures regarding hypothermia in focal cerebral ischemia. Then, we make a thorough analysis of key parameters of hypothermia and introduce novel hypothermic therapies. We advocate in favor of the process of clinical translation of intra-arterial selective cooling infusion in the era of reperfusion and provide insights into the prospects of hypothermia in acute ischemic stroke.

CIRBP Ameliorates Neuronal Amyloid Toxicity via Antioxidative and Antiapoptotic Pathways in Primary Cortical Neurons

It is generally accepted that the amyloid β (Aβ) peptide toxicity contributes to neuronal loss and is involved in the initiation and progression of Alzheimer's disease (AD). Cold-inducible RNA-binding protein (CIRBP) is reported to be a general stress-response protein, which is induced by different stress conditions. Previous reports have shown the neuroprotective effects of CIRBP through the suppression of apoptosis via the Akt and ERK pathways. The objective of this study is to examine the effect of CIRBP against Aβ-induced toxicity in cultured rat primary cortical neurons and attempt to uncover its underlying mechanism. Here, MTT, LDH release, and TUNEL assays showed that CIRBP overexpression protected against both intracellular amyloid β- (iAβ-) induced and Aβ _25-35-induced cytotoxicity in rat primary cortical neurons. Electrophysiological changes responsible for iAβ-induced neuronal toxicity, including an increase in neuronal resting membrane potentials and a decrease in K⁺ currents, were reversed by CIRBP overexpression. Western blot results further showed that Aβ _25-35 treatment significantly increased the level of proapoptotic protein Bax, cleaved caspase-3, and cleaved caspase-9 and decreased the level of antiapoptotic factor Bcl-2, but were rescued by CIRBP overexpression. Furthermore, CIRBP overexpression prevented the elevation of ROS induced by Aβ _25-35 treatment by decreasing the activities of oxidative biomarker and increasing the activities of key enzymes in antioxidant system. Taken together, our findings suggested that CIRBP exerted protective effects against neuronal amyloid toxicity via antioxidative and antiapoptotic pathways, which may provide a promising candidate for amyloid-based AD prevention or therapy.

RBM3 and CIRP expressions in targeted temperature management treated cardiac arrest patients-A prospective single center study

BACKGROUND

Management of cardiac arrest patients includes active body temperature control and strict prevention of fever to avoid further neurological damage. Cold-shock proteins RNA-binding motif 3 (RBM3) and cold inducible RNA-binding protein (CIRP) expressions are induced in vitro in response to hypothermia and play a key role in hypothermia-induced neuroprotection.

OBJECTIVE

To measure gene expressions of RBM3, CIRP, and inflammatory biomarkers in whole blood samples from targeted temperature management (TTM)-treated post-cardiac arrest patients for the potential application as clinical biomarkers for the efficacy of TTM treatment.

METHODS

A prospective single center trial with the inclusion of 22 cardiac arrest patients who were treated with TTM (33°C for 24 hours) after ROSC was performed. RBM3, CIRP, interleukin 6 (IL-6), monocyte chemotactic protein 1 (MCP-1), and inducible nitric oxide synthase (iNOS) mRNA expressions were quantified by RT-qPCR. Serum RBM3 protein concentration was quantified using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

RBM3 mRNA expression was significantly induced in post-cardiac arrest patients in response to TTM. RBM3 mRNA was increased 2.2-fold compared to before TTM. A similar expression kinetic of 1.4-fold increase was observed for CIRP mRNA, but did not reached significancy. Serum RBM3 protein was not increased in response to TTM. IL-6 and MCP-1 expression peaked after ROSC and then significantly decreased. iNOS expression was significantly increased 24h after return of spontaneous circulation (ROSC) and TTM.

CONCLUSIONS

RBM3 is temperature regulated in patients treated with TTM after CA and ROSC. RBM3 is a possible biomarker candidate to ensure the efficacy of TTM treatment in post-cardiac arrest patients and its pharmacological induction could be a potential future intervention strategy that warrants further research.

Robust RBM3 and β-klotho expression in developing neurons in the human brain

RNA binding motif 3 (RBM3) is a powerful neuroprotectant that inhibits neurodegenerative cell death in vivo and is a promising therapeutic target in brain ischemia. RBM3 is increased by the hormone fibroblast growth factor 21 (FGF21) in an age- and temperature-dependent manner in rat cortical neurons. FGF21 receptor binding is controlled by the transmembrane protein β-klotho, which is mostly absent in the adult brain. We discovered that RBM3/β-klotho is unexpectedly high in the human infant vs. adult brain (hippocampus/prefrontal cortex). The use of tissue homogenates in that study precluded a comparison of RBM3/β-klotho expression among different CNS cell-types, thus, omitted key evidence (i.e. confirmation of neuronal expression) that would otherwise provide a critical link to support their possible direct neuroprotective effects in humans. This report addresses that knowledge gap. High-quality fixed human hippocampus, cortex, and hypothalamic tissues were acquired from the NIH Neurobiobank (<1 yr (premature born) infants, 1 yr, 4 yr, and 34 yr). Dual labeling of cell-type markers vs. RBM3/β-klotho revealed enriched staining of targets in neurons in the developing brain. Identifying that RBM3/β-klotho is abundant in neurons in the immature brain is fundamentally important to guide protocol design and conceptual frameworks germane to future testing of these neuroprotective pathways in humans.

Therapeutic Hypothermia and Neuroprotection in Acute Neurological Disease

Therapeutic hypothermia has consistently been shown to be a robust neuroprotectant in many labs studying different models of neurological disease. Although this therapy has shown great promise, there are still challenges at the clinical level that limit the ability to apply this routinely to each pathological condition. In order to overcome issues involved in hypothermia therapy, understanding of this attractive therapy is needed. We review methodological concerns surrounding therapeutic hypothermia, introduce the current status of therapeutic cooling in various acute brain insults, and review the literature surrounding the many underlying molecular mechanisms of hypothermic neuroprotection. Because recent work has shown that body temperature can be safely lowered using pharmacological approaches, this method may be an especially attractive option for many clinical applications. Since hypothermia can affect multiple aspects of brain pathophysiology, therapeutic hypothermia could also be considered a neuroprotection model in basic research, which would be used to identify potential therapeutic targets. We discuss how research in this area carries the potential to improve outcome from various acute neurological disorders.

Post-TTM Rebound Pyrexia after Ischemia-Reperfusion Injury Results in Sterile Inflammation and Apoptosis in Cardiomyocytes

Introduction

Fever is frequently observed after acute ischemic events and is associated with poor outcome and higher mortality. Targeted temperature management (TTM) is recommended for neuroprotection in comatose cardiac arrest survivors, but pyrexia after rewarming is proven to be detrimental in clinical trials. However, the cellular mechanisms and kinetics of post-TTM rebound pyrexia remain to be elucidated. Therefore, we investigated the effects of cooling and post-TTM pyrexia on the inflammatory response and apoptosis in a cardiomyocyte ischemia-reperfusion (IR) injury model.

Methods

HL-1 cardiomyocytes were divided into the following groups to investigate the effect of oxygen-glucose deprivation/reperfusion (OGD/R), hypothermia (33.5°C), and pyrexia (40°C): normoxia controls maintained at 37°C and warmed to 40°C, OGD/R groups maintained at 37°C and cooled to 33.5°C for 24 h with rewarming to 37°C, and OGD/R pyrexia groups further warmed from 37 to 40°C. Caspase-3 and RBM3 were assessed by Western blot and TNF-α, IL-6, IL-1β, SOCS3, iNOS, and RBM3 transcriptions by RT-qPCR.

Results

OGD-induced oxidative stress (iNOS) in cardiomyocytes was attenuated post-TTM by cooling. Cytokine transcriptions were suppressed by OGD, while reperfusion induced significant TNF-α transcription that was exacerbated by cooling. Significant inductions of TNF-α, IL-6, IL-1β, and SOCS3 were observed in noncooled, but not in cooled and rewarmed, OGD/R-injured cardiomyocytes. Further warming to pyrexia induced a sterile inflammatory response in OGD/R-injured groups that was attenuated by previous cooling, but no inflammation was observed in pyrexic normoxia groups. Moreover, cytoprotective RBM3 expression was induced by cooling but suppressed by pyrexia, correlating with apoptotic caspase-3 activation.

Conclusion

Our findings show that maintaining a period of post-TTM “therapeutic normothermia” is effective in preventing secondary apoptosis-driven myocardial cell death, thus minimizing the infarct area and further release of mediators of the innate sterile inflammatory response after acute IR injury.

The RNA-Binding Protein RBM3 Promotes Neural Stem Cell (NSC) Proliferation Under Hypoxia

Neural stem cells (NSCs) reside physiologically in a hypoxic niche to maintain self-renewal and multipotency. Whereas mild hypoxia is known to promote NSC proliferation, severe hypoxia in pathological conditions exerts the reverse effect. The multi-functional RNA-binding protein RBM3 is abundant in NSCs and can be regulated by hypoxic exposure. Although RBM3 has been shown to accelerate cell growth in many cell types, whether and how it affects NSC proliferation in hypoxic environment remains largely unknown. In this study, we tested how RBM3 regulates cell proliferation under hypoxia in C17.2 mouse NSC cell line and in primary mouse NSCs from both the forebrain of postnatal day 0 (P0) mice and the subgranular zone (SGZ) of adult mice. Our results demonstrated that RBM3 expression was highly sensitive to hypoxia, and NSCs were arrested in G0/G1 phase by 5, 2.5, and 1% O₂ treatment. When we overexpressed RBM3, hypoxia-induced cell cycle arrest in G0/G1 phase was relieved and more cell transit into S phase was observed. Furthermore, cell viability under hypoxia was also increased by RBM3. In contrast, in RBM3-depleted primary NSCs, less BrdU-incorporated cells were detected, indicating exacerbated cell cycle arrest in G1 to S phase transition. Instead, overexpressed RBM3 significantly increased proliferation ratio in primary NSCs. Our findings indicate RBM3 as a potential target to maintain the proliferation capacity of NSCs under hypoxia, which can be important in NSC-based therapies of acute brain injury and chronic neurodegenerative diseases.

Cold-inducible protein RBM3 mediates hypothermic neuroprotection against neurotoxin rotenone via inhibition on MAPK signalling

Mild hypothermia and its key product, cold-inducible protein RBM3, possess robust neuroprotective effects against various neurotoxins. However, we previously showed that mild hypothermia fails to attenuate the neurotoxicity from MPP+ , one of typical neurotoxins related to the increasing risk of Parkinson disease (PD). To better understand the role of mild hypothermia and RBM3 in PD progression, another known PD-related neurotoxin, rotenone (ROT) was utilized in this study. Using immunoblotting, cell viability assays and TUNEL staining, we revealed that mild hypothermia (32°C) significantly reduced the apoptosis induced by ROT in human neuroblastoma SH-SY5Y cells, when compared to normothermia (37°C). Meanwhile, the overexpression of RBM3 in SH-SY5Y cells mimicked the neuroprotective effects of mild hypothermia on ROT-induced cytotoxicity. Upon ROT stimulation, MAPK signalling like p38, JNK and ERK, and AMPK and GSK-3β signalling were activated. When RBM3 was overexpressed, only the activation of p38, JNK and ERK signalling was inhibited, leaving AMPK and GSK-3β signalling unaffected. Similarly, mild hypothermia also inhibited the activation of MAPKs induced by ROT. Lastly, it was demonstrated that the MAPK (especially p38 and ERK) inhibition by their individual inhibitors significantly decreased the neurotoxicity of ROT in SH-SY5Y cells. In conclusion, these data demonstrate that RBM3 mediates mild hypothermia-related neuroprotection against ROT by inhibiting the MAPK signalling of p38, JNK and ERK.

RBM3 promotes neurogenesis in a niche-dependent manner via IMP2-IGF2 signaling pathway after hypoxic-ischemic brain injury

Hypoxic ischemia (HI) is an acute brain threat across all age groups. Therapeutic hypothermia ameliorates resulting injury in neonates but its side effects prevent routine use in adults. Hypothermia up-regulates a small protein subset that includes RNA-binding motif protein 3 (RBM3), which is neuroprotective under stressful conditions. Here we show how RBM3 stimulates neuronal differentiation and inhibits HI-induced apoptosis in the two areas of persistent adult neurogenesis, the subventricular zone (SVZ) and the subgranular zone (SGZ), while promoting neural stem/progenitor cell (NSPC) proliferation after HI injury only in the SGZ. RBM3 interacts with IGF2 mRNA binding protein 2 (IMP2), elevates its expression and thereby stimulates IGF2 release in SGZ but not SVZ-NSPCs. In summary, we describe niche-dependent regulation of neurogenesis after adult HI injury via the novel RBM3-IMP2-IGF2 signaling pathway.

Therapeutic hypothermia is a potent tool in the treatment of neonatal hypoxic-ischemic (HI) injury, yet the underlying mechanisms remain unclear. Here, authors demonstrate how the RNA-binding motif protein RBM3, which is induced by mild cooling while global translation rate is slowed down, contributes substantially to neuroregeneration after adult HI injury, specifically in the subventricular zone and subgranular zone.

Mild hypothermia causes a shift in the alternative splicing of cold-inducible RNA-binding protein transcripts in Syrian hamsters

Cold-shock proteins are thought to participate in the cold-tolerant nature of hibernating animals. We previously demonstrated that an alternative splicing may allow rapid induction of functional cold-inducible RNA-binding protein (CIRBP) in the hamster heart. The purpose of the present study was to determine the major cause of the alternative splicing in Syrian hamsters. RT-PCR analysis revealed that CIRBP mRNA is constitutively expressed in the heart, brain, lung, liver, and kidney of nonhibernating euthermic hamsters with several alternative splicing variants. In contrast, the short variant containing an open-reading frame for functional CIRBP was dominantly found in the hibernating animals. Keeping the animals in a cold and dark environment did not cause a shift in the alternative splicing. Induction of hypothermia by central administration of an adenosine A₁-receptor agonist reproduced the shift in the splicing pattern. However, the agonist failed to shift the pattern when body temperature was kept at 37°C, suggesting that central adenosine A₁ receptors are not directly linked to the shift of the alternative splicing. Rapid reduction of body temperature to 10°C by isoflurane anesthesia combined with cooling did not alter the splicing pattern, but maintenance of mild hypothermia (~28°C) for 2 h elicited the shift in the pattern. The results suggest that animals need to be maintained at mild hypothermia for an adequate duration to induce the shift in the alternative splicing. This is applicable to natural hibernation because hamsters entering hibernation show a gradual decrease in body temperature, being maintained at mild hypothermia for several hours.

Neuroprotection by Therapeutic Hypothermia

Hypothermia therapy is an old and important method of neuroprotection. Until now, many neurological diseases such as stroke, traumatic brain injury, intracranial pressure elevation, subarachnoid hemorrhage, spinal cord injury, hepatic encephalopathy, and neonatal peripartum encephalopathy have proven to be suppressed by therapeutic hypothermia. Beneficial effects of therapeutic hypothermia have also been discovered, and progress has been made toward improving the benefits of therapeutic hypothermia further through combination with other neuroprotective treatments and by probing the mechanism of hypothermia neuroprotection. In this review, we compare different hypothermia induction methods and provide a summarized account of the synergistic effect of hypothermia therapy with other neuroprotective treatments, along with an overview of hypothermia neuroprotection mechanisms and cold/hypothermia-induced proteins.

Skeletal muscle cold shock and heat shock protein mRNA response to aerobic exercise in different environmental temperatures

The response of cold shock proteins to exercise and environmental temperature in human skeletal muscle is not known. The purpose of this study was to determine the early mRNA response of human stress proteins to endurance exercise and environmental temperatures. Seven recreationally trained males cycled for 1 hour at 60% VO_2peak in 7°C, 20°C, and 33°C with biopsies taken pre- and 3 hours post-exercise. Gene expression for heat shock and cold shock proteins were analyzed using qRT-PCR on muscle biopsy samples from the vastus lateralis. RBM3 mRNA was reduced 1.43 ± 0.10 fold (p = 0.006) while there was a trend for CIRP to decrease1.27 ± 0.14 fold (p = 0.059) from pre- to 3 h post-exercise. CIRP and RBM3 mRNA were not different between temperatures (p = 0.273 and p = 0.686, respectively). HSP70 mRNA was 2.27 ± 0.23 fold higher 3 h post-exercise when compared to pre-exercise (p = 0.002) but was not significantly different between temperatures (p = 0.103). HSP27, HSP90, and HSF1 mRNA did not change from pre- to post-exercise (p = 0.052, p = 0.324, p = 0.795) and were not different between temperatures (p = 0.247, p = 0.134, p = 0.808). These data indicate that exposure to mild heat and cold during aerobic exercise have limited effect on the skeletal muscle mRNA expression of heat shock and cold shock proteins. However, skeletal muscle mRNA of cold shock proteins decrease, while HSP70 mRNA increases in response to a low to moderate intensity aerobic exercise bout.

A New Vision for Therapeutic Hypothermia in the Era of Targeted Temperature Management: A Speculative Synthesis

Three decades of animal studies have reproducibly shown that hypothermia is profoundly cerebroprotective during or after a central nervous system (CNS) insult. The success of hypothermia in preclinical acute brain injury has not only fostered continued interest in research on the classic secondary injury mechanisms that are prevented or blunted by hypothermia but has also sparked a surge of new interest in elucidating beneficial signaling molecules that are increased by cooling. Ironically, while research into cold-induced neuroprotection is enjoying newfound interest in chronic neurodegenerative disease, conversely, the scope of the utility of therapeutic hypothermia (TH) across the field of acute brain injury is somewhat controversial and remains to be fully defined. This has led to the era of Targeted Temperature Management, which emphasizes a wider range of temperatures (33–36°C) showing benefit in acute brain injury. In this comprehensive review, we focus on our current understandings of the novel neuroprotective mechanisms activated by TH, and discuss the critical importance of developmental age germane to its clinical efficacy. We review emerging data on four cold stress hormones and three cold shock proteins that have generated new interest in hypothermia in the field of CNS injury, to create a framework for new frontiers in TH research. We make the case that further elucidation of novel cold responsive pathways might lead to major breakthroughs in the treatment of acute brain injury, chronic neurological diseases, and have broad potential implications for medicines of the distant future, including scenarios such as the prevention of adverse effects of long-duration spaceflight, among others. Finally, we introduce several new phrases that readily summarize the essence of the major concepts outlined by this review—namely, Ultramild Hypothermia, the “Responsivity of Cold Stress Pathways,” and “Hypothermia in a Syringe.”

AU-rich element-binding proteins in colorectal cancer

Trans-acting factors controlling mRNA fate are critical for the post-transcriptional regulation of inflammation-related genes, as well as for oncogene and tumor suppressor expression in human cancers. Among them, a group of RNA-binding proteins called “Adenylate-Uridylate-rich elements binding proteins” (AUBPs) control mRNA stability or translation through their binding to AU-rich elements enriched in the 3’UTRs of inflammation- and cancer-associated mRNA transcripts. AUBPs play a central role in the recruitment of target mRNAs into small cytoplasmic foci called Processing-bodies and stress granules (also known as P-body/SG). Alterations in the expression and activities of AUBPs and P-body/SG assembly have been observed to occur with colorectal cancer (CRC) progression, indicating the significant role AUBP-dependent post-transcriptional regulation plays in controlling gene expression during CRC tumorigenesis. Accordingly, these alterations contribute to the pathological expression of many early-response genes involved in prostaglandin biosynthesis and inflammation, along with key oncogenic pathways. In this review, we summarize the current role of these proteins in CRC development. CRC remains a major cause of cancer mortality worldwide and, therefore, targeting these AUBPs to restore efficient post-transcriptional regulation of gene expression may represent an appealing therapeutic strategy.

Infants Uniquely Express High Levels of RBM3 and Other Cold-Adaptive Neuroprotectant Proteins in the Human Brain

Neuroprotective cold-shock proteins (CSPs) are abundant in the normothermic neonatal rodent brain but decrease with advancing neurodevelopmental age and are low or absent in the adult brain. It has not been established if neurodevelopmental age alters the baseline expression of CSPs in the human brain. Here, we tested the hypothesis that protein levels of RNA-binding motif 3 (RBM3), reticulon-3 (RTN3), and cold-induced RNA-binding protein (CIRBP) are abundant in the normothermic developing human brain but low-to-absent in adults. We also tested if β-klotho (KLB) is expressed in the developing brain; KLB functions as a coreceptor that controls tissue-specific binding and activity of the systemically circulating thermogenic hormone fibroblast growth factor 21 (FGF21), and is predominantly expressed in the liver, pancreas, and in adipose cells. Methods: Hippocampi and anterior prefrontal cortices (aPFCs/BA10) from a total of 20 male and 20 female subjects were obtained from the NIH NeuroBioBank. CSP and KLB levels were measured in: infants < 1 year old (n = 8), toddlers aged 1-2 years (n = 8), children aged 3-5 years (n = 7), 18-year-old adolescents (n = 8), and adults aged 31-34 years (n = 8). An equal number of male and female (n = 4 each) samples were pooled into each age group, except in the 3- to 5-year-olds which comprised 3 male and 4 female specimens due to sample availability. In total, 78 whole-brain tissues were dissociated using a bead-based Precellys homogenizer to generate equivalent homogenates, and levels of protein targets subsequently analyzed by Western blotting. Results: Infants had the highest levels of RBM3 and other CSPs in the brain compared to all other ages. In the hippocampus, CSPs were detected predominantly in infants. In the aPFC, CSP levels were highest in infants, moderate-to-low in toddlers/children, and below assay detection limits in adolescents/adults. Germane to the thermogenic FGF21/KLB signaling axis, our results confirm that KLB is absent in the adult hippocampus/aPFC as reported by others. In contrast, we report for the first time that KLB is abundant in the early developing human brain; KLB levels were highest in the infant hippocampus/aPFC and moderately expressed in toddlers. RBM3 is a potent neuroprotective CSP. Thus, the impact of these findings on the observed efficacy of therapeutic hypothermia in neonatal brain injury merits further investigation.