Cold-inducible RNA binding protein alleviates iron overload-induced neural ferroptosis under perinatal hypoxia insult.

Cold-inducible RNA binding protein (CIRBP), a stress response protein, protects cells from mild hypothermia or hypoxia by stabilizing specific mRNAs and promoting their translation. Neurons subjected to hypobaric hypoxia insult trigger various cell death programs. One of these is ferroptosis, a novel non-apoptotic form of programmed cell death, which is characterized by excessive iron ion accumulation and lipid peroxidation. Here, we establish that CIRBP can regulate neuronal ferroptosis both in vivo and in vitro. We observe that hypoxia leads to neuronal death via intracellular ferrous iron overload and impaired antioxidant systems, accompanied by suppressed CIRBP expression. Genetic enrichment of CIRBP in hippocampal neurons CIRBPTg mice bred with Emx1-Cre mice attenuates hypoxia-induced cognitive deficits and neuronal degeneration. Mechanistically, CIRBP alleviates neuronal ferroptosis and intracellular ferrous ion accumulation by binding to the mitochondrial ferritin (FTMT) 3'UTR to stabilize mRNA and promote its translation. Our novel study shows the critical role of CIRBP in the progression of ferroptosis, and provides promising therapeutic target for hypoxia-induced neurological diseases.

Cold stress induces colitis-like phenotypes in mice by altering gut microbiota and metabolites.

Introduction: The modernized lifestyle has been paralleled by an epidemic of inflammatory bowel disease (IBD). Excessive consumption of cold beverages is especially common among the modern humans. However, whether cold stress contributes directly to the gut barrier and gut-brain axis is not clear. Methods: We conducted a cold stress model induced by cold water. The mice were treated with 14 consecutive days of intragastric cold or common water administration. We observed changes in gut transit and gut barrier in the colon. We also employed RNA sequencing-based transcriptomic analysis to identify the genes potentially driving gut injury, and simultaneously examined the gut microbiota and metabolites in the feces. Results: We found that cold stress disturbed the intestinal function and increased gut permeability. A set of core genes related to immune responses were consistently overexpressed in the cold stress group. Additionally, cold stress induced decreased bacterial diversity, ecological network, and increased pathogens mainly belonging to Proteobacteria. The dopamine signaling pathway-related metabolites were largely reduced in the cold stress group. Conclusion: This study revealed that cold stress could trigger an IBD-like phenotype in mice, implying that cold stress is a possible risk factor for IBD development.

NLRP3 deficiency protects against hypobaric hypoxia induced neuroinflammation and cognitive dysfunction.

As increasing number of people migrated to high altitude, highland encephalopathy and hypoxia-induced cognitive impairment arouse public attention. Yet, its underlying mechanisms remain unclear. Emerging evidence has implied neuroinflammation and neuronal loss may be involved. In the present study, we investigated the neuroinflammation and neuronal loss in mice after hypoxic insult. Our reports showed hypobaric hypoxia exposure for 3 weeks led to impaired spatial exploration and short-term memory in mice, concomitant with neuron loss. In addition, hypoxia induced neuroinflammation and NLRP3 inflammasome activation. Besides, to explore the role of the inflammasome in hypoxia-induced cognitive dysfunction, NLRP3 knockout mice were applied and the results showed that NLRP3 could negatively regulate GPX4 to modify antioxidant capacity. In summary, our work demonstrated that hypoxia exposure led to neuroinflammation and neuronal-deletion, which may be the key events in the process of hypoxia induced cognitive impairment. NLRP3 inflammasome promoted antioxidant deficiency by negatively regulating GPX4.

Lead Exposure Induced Neural Stem Cells Death via Notch Signaling Pathway and Gut-Brain Axis.

Numerous studies have examined the effects of lead (Pb) on cognitive ability. It is essential for the brain to maintain its functions through the differentiation of neural stem cells into various types of cells. Despite this, it remains unclear how Pb exposure affects neural stem cells and how it does, so the Pb-exposed mice were treated with the Notch inhibitor DAPT after we established the Pb exposure models. Neuronal stem cells and autophagy were assessed by immunofluorescence staining and western blot. The microbiota of the feces was also analyzed using the 16S rRNA amplicon sequencing technique. In this study, we found that Pb exposure caused neural injuries and deficits in neural stem cells, whereas DAPT rescued the damage. With DAPT, Pb-induced autophagy was partially reversed. Exposure to Pb also reduced inflammation and damaged gut barrier function. Furthermore, Pb exposure led to low bacterial diversity, an increase in pathogen abundance, and an unusual mode of interaction. Taken together, this study revealed that damages in neural stem cells contributed largely to cognitive impairment during Pb exposure, and this process was partially dependent on the Notch pathway and gut dysbiosis.

Resetting Proteostasis of CIRBP with ISRIB Suppresses Neural Stem Cell Apoptosis under Hypoxic Exposure.

Neurological disorders are often progressive and lead to disabilities with limited available therapies. Epidemiological evidence implicated that prolonged exposure to hypoxia leads to neurological damage and a plethora of complications. Neural stem cells (NSCs) are a promising tool for neurological damage therapy in terms of their unique properties. However, the literature on the outcome of NSCs exposed to severe hypoxia is scarce. In this study, we identified a responsive gene that reacts to multiple cellular stresses, marked cold-inducible RNA-binding protein (CIRBP), which could attenuate NSC apoptosis under hypoxic pressure. Interestingly, ISRIB, a small-molecule modulator of the PERK-ATF4 signaling pathway, could prevent the reduction and apoptosis of NSCs in two steps: enhancing the expression of CIRBP through the protein kinase R- (PKR-) like endoplasmic reticulum kinase (PERK) and activating transcription factor 4 (ATF4) axis. Taken together, CIRBP was found to be a critical factor that could protect NSCs against apoptosis induced by hypoxia, and ISRIB could be acted upstream of the axis and may be recruited as an open potential therapeutic strategy to prevent or treat hypoxia-induced brain hazards.

Insight into the Effects of High-Altitude Hypoxic Exposure on Learning and Memory.

The earth land area is heterogeneous in terms of elevation; about 45% of its land area belongs to higher elevation with altitude above 500 meters compared to sea level. In most cases, oxygen concentration decreases as altitude increases. Thus, high-altitude hypoxic stress is commonly faced by residents in areas with an average elevation exceeding 2500 meters and those who have just entered the plateau. High-altitude hypoxia significantly affects advanced neurobehaviors including learning and memory (L&M). Hippocampus, the integration center of L&M, could be the most crucial target affected by high-altitude hypoxia exposure. Based on these points, this review thoroughly discussed the relationship between high-altitude hypoxia and L&M impairment, in terms of hippocampal neuron apoptosis and dysfunction, neuronal oxidative stress disorder, neurotransmitters and related receptors, and nerve cell energy metabolism disorder, which is of great significance to find potential targets for medical intervention. Studies illustrate that the mechanism of L&M damaged by high-altitude hypoxia should be further investigated based on the entire review of issues related to this topic.

[Berberine hydrochloride attenuates liver injury induced by acute hypoxic exposure by inhibiting TNF-α/caspase-8/caspase-3 signaling pathway].

Objective To investigate the protective effect and mechanism of berberine hydrochloride (BBR) on liver after acute hypoxic exposure. Methods C57BL/6 mice were divided into three groups consisting of normoxic group, hypoxic exposure group, and hypoxic exposure combined with BBR group. On the 7th day of the experiment, mice were sacrificed and liver tissue was collected. The pathological changes of liver tissue were observed by HE staining. The mRNA levels of interleukin-1ß (IL-1ß), IL-6, tumor necrosis factor-α (TNF-α), and inducible nitric oxide synthase (iNOS) in liver tissue were detected by real time quantitative PCR. The protein levels of TNF-α, cleaved-caspase-3 (c-caspase-3), and caspase-8 in liver tissue were detected by Western blotting. The apoptosis of mouse liver tissue was detected by TUNEL. Results After 7 days of hypoxic exposure, the body mass and liver mass of mice decreased significantly, and the liver tissue damage was obvious; the mRNA levels of TNF-α and IL-1ß and the protein levels of caspase-8 and c-caspase-3 in liver tissue cells significantly increased, and the apoptosis level of liver tissue cells markedly increased as well. BBR treatment significantly increased the body mass and liver mass of mice exposed to hypoxia for 7 days, decreased the mRNA level of TNF-α and the protein expressions of caspase-8 and c-caspase-3, and reduced the apoptosis of liver tissue cells. Conclusion BBR may attenuate liver injury induced by hypoxic exposure by inhibiting TNF-α/caspase-8/caspase-3 signaling pathway.

Cirbp-PSD95 axis protects against hypobaric hypoxia-induced aberrant morphology of hippocampal dendritic spines and cognitive deficits.

Hypobaric hypoxia (HH) is a typical characteristic of high altitude environment and causes a spectrum of pathophysiological effects, including headaches, gliovascular dysfunction and cognitive retardation. Here, we sought to understand the mechanisms underlying cognitive deficits under HH exposure. Our results showed that hypobaric hypoxia exposure impaired cognitive function and suppressed dendritic spine density accompanied with increased neck length in both basal and apical hippocampal CA1 region neurons in mice. The expression of PSD95, a vital synaptic scaffolding molecule, is down-regulated by hypobaric hypoxia exposure and post-transcriptionally regulated by cold-inducible RNA-binding protein (Cirbp) through 3'-UTR region binding. PSD95 expressing alleviates hypoxia-induced dendritic spine morphology changes of hippocampal neurons and memory deterioration. Moreover, overexpressed Cirbp in hippocampus rescues HH-induced abnormal expression of PSD95 and attenuates hypoxia-induced dendritic spine injury and cognitive retardation. Thus, our findings reveal a novel mechanism that Cirbp-PSD-95 axis appears to play an essential role in HH-induced cognitive dysfunction in mice.

Hypoxia-sensitive long noncoding RNA CASC15 promotes lung tumorigenesis by regulating the SOX4/ß-catenin axis.

BACKGROUND: Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) are involved in the hypoxia-related cancer process and play pivotal roles in enabling malignant cells to survive under hypoxic stress. However, the molecular crosstalk between lncRNAs and hypoxia signaling cascades in non-small cell lung cancer (NSCLC) remains largely elusive. METHODS: Firstly, we identified differentially expressed lncRNA cancer susceptibility candidate 15 (CASC15) as associated with NSCLC based on bioinformatic data. The clinical significance of CASC15 in lung cancer was investigated by Kaplan-Meier survival analysis. Then, we modulated CASC15 expression in NSCLC cell lines by RNAi. CCK-8 and transwell assays were carried out to examine the effects of CASC15 on proliferation and migration of NSCLC cells. Upstream activator and downstream targets of CASC15 were validated by luciferase reporter assay, qRT-PCR, Western blotting, and chromatin immunoprecipitation (ChIP). Lastly, RNA in situ hybridization (RNA-ISH) and immunohistochemistry (IHC) were performed to confirm the genetic relationships between CASC15 and related genes in clinical samples. RESULTS: CASC15 was highly expressed in NSCLC tissues and closely associated with poor prognosis. Loss-of-function analysis demonstrated that CASC15 was essential for NSCLC cell migration and growth. Mechanistic study revealed that CASC15 was transcriptionally activated by hypoxia signaling in NSCLC cells. Further analysis showed that hypoxia-induced CASC15 transactivation was mainly dependent on hypoxia-inducible factor 1α (HIF-1α) and hypoxia response elements (HREs) located in CASC15 promoter. CASC15 promotes the expression of its chromosomally nearby gene, SOX4. Then SOX4 functions to stabilize ß-catenin protein, thereby enhancing the proliferation and migration of NSCLC cells. HIF-1α/CASC15/SOX4/ß-catenin pathway was activated in a substantial subset of NSCLC patients. CONCLUSIONS: HIF-1α/CASC15/SOX4/ß-catenin axis plays an essential role in the development and progression of NSCLC. The present work provides new evidence that lncRNA CASC15 holds great promise to be used as novel biomarkers for NSCLC. Blocking the HIF-1α/CASC15/SOX4/ß-catenin axis can serve as a potential therapeutic strategy for treating NSCLC.

[Transmembrane prostate androgen-induced protein 1 (PMEPA1) promotes the migration and maintains mesenchymal-like phenotype of breast cancer cells].

OBJECTIVE: To investigate the role of transmembrane prostate androgen-induced protein 1 (PMEPA1), an important gene downstream of transforming growth factor-ß (TGF-ß) signaling, in the process of breast cancer cell migration and epithelial-mesenchymal transition. METHODS: We treated MDA-MB-231 breast cancer cells with TGF-ß and TGF-ß inhibitor SB431542, and then detect the level of PMEPA1 using Western blotting. PMEPA1-specific siRNA was designed and its knockdown efficiency was tested by quantitative real-time PCR (qRT-PCR). After the expression of PMEPA1 in MDA-MB-231 cells was successfully silenced, the wound-healing assay and Transwell(TM) assay were used to investigate the effect of PMEPA1 silencing on the migration of MDA-MB-231 cells. Moreover, phalloidin was used to label the actin cytoskeleton of breast cancer cells to observe the effect of PMEPA1 silencing on cell morphology. RESULTS: In breast cancer cells, PMEPA1 was upregulated by classical TGF-ß/Smad signaling pathway. Silencing of PMEPA1 significantly inhibited the migration ability of MDA-MB-231 cells and promoted the process of mesenchymal-epithelial transition. CONCLUSION: Over-expressed PMEPA1 can promote cell migration and maintain the mesenchymal-like morphology of breast cancer cells.