MicroRNA-181c Ameliorates Cognitive Impairment Induced by Chronic Cerebral Hypoperfusion in Rats

Impact of Codonopsis decoction on cerebral blood flow and cognitive function in rats with chronic cerebral ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

Some species of Codonopsis (local name in Shanxi: Ludang) have long demonstrated high medicinal and economic value. Radix Codonopsis, the dried root of Codonopsis pilosula (Franch.) Nannf. (C. pilosula), Codonopsis pilosula var. modesta (Nannf.) L.D.Shen (C. pilosula var. modesta), or Codonopsis pilosula subsp. tangshen (Oliv.) D.Y.Hong (C. pilosula subsp. tangshen), was recorded as a traditional Chinese medicine back in the Qing Dynasty in Ben Cao Cong Xin. Radix Codonopsis, a valuable medicinal herb certified by the Chinese National Geographic Indication, is known for invigorating the spleen, nourishing the lungs, promoting blood circulation, and generating fluid properties. Given that chronic cerebral ischemia (CCI) is often associated with the symptoms of qi and blood deficiencies and fluid depletion, we explored the potential of Codonopsis decoction in the treatment of CCI.

STUDY AIMS

We investigated the effects of Codonopsis decoction on cerebral blood flow (CBF) and cognitive function in rats with bilateral carotid artery occlusion after surgery; explored whether Codonopsis decoction alleviates pathological injuries in brain tissue of rats after 2-VO surgery; and assessed the impact of Codonopsis decoction on the expression of chemokines, hypoxia-inducible factors, and inflammatory mediators in rats after 2-VO surgery.

MATERIALS AND METHODS

We used a 2-VO rat model to simulate CCI. We used a laser speckle imaging (LSI) system to observe changes in CBF before and after surgery. The goal was to examine variations in CBF at different time points after 2-VO surgery. For 4 weeks, the rats were orally administered Codonopsis decoction at doses of 2.7, 5.4, and 10.8 g/kg/day, or Ginaton at a dose of 43.2 mg/kg/day. To assess the effect of Codonopsis on cerebral hypoperfusion symptoms in rats, we conducted the Morris water maze (MWM), Barnes maze (BM), and forelimb grip strength tests. Additionally, pathological experiments including hematoxylin and eosin, Nissl, and Luxol fast blue staining were conducted. Furthermore, we used western blotting to detect changes in the levels of proteins such as the chemotactic factor CKLF1 and hypoxia-inducible actor 1-alpha (HIF-1α).

RESULTS

One week after 2-VO surgery, cerebral arterial blood supply in the rats rapidly reduced to approximately 43.39% ± 3.53% of the preoperative level. Cerebral cortex perfusion reached its nadir within 24 h of surgery, gradually recovering and stabilizing by the fourth week after surgery. An integration of the results from the BM, MWM, and grip strength tests, which assessed cognitive function and forelimb strength in rats after 2-VO surgery, unequivocally revealed that Codonopsis treatment significantly reduced the latency period and increased the number of platform crossings in the MWM test. Ginaton exhibited a comparable effect. Moreover, both Codonopsis and Ginaton decreased the number of errors and the time required to locate the target hole in the BM test. Histopathological staining revealed that Codonopsis and Ginaton could ameliorate pathological damage in rats after CCI and reduce the release of factors such as CKLF1 and HIF-1α.

CONCLUSION

Codonopsis decoction exerted its protective effects on CCI rats possibly by modulating the levels of chemokines, hypoxia-inducible factors, and neuroinflammatory mediators.

Effects of Gallic Acid on Memory Deficits and Electrophysiological Impairments Induced by Cerebral Ischemia/Reperfusion in Rats Following Exposure to Ambient Dust Storm

We aimed to investigate the probable protective effects of gallic acid (GA) on cognitive deficits, hippocampal long term potentiation (LTP) impairments, and molecular changes induced by cerebral ischemia/reperfusion (I/R) in rats following exposure to ambient dust storm. After pretreatment with GA (100 mg/kg), or vehicle (Veh) (normal saline, 2 ml/kg) for ten days, and 60 minutes' exposure to dust storm including PM (PM, 2000-8000 g/m3) every day, 4-vessel occlusion (4VO) type of I/R was induced. Three days after I/R induction, we evaluated behavioral, electrophysiological, histopathological, molecular and brain tissue inflammatory cytokine changes. Our findings indicated that pretreatment with GA significantly reduced cognitive impairments caused by I/R (P < 0.05) and hippocampal LTP impairments caused by I/R after PM exposure (P < 0.001). Additionally, after exposure to PM, I/R significantly elevated the tumor necrosis factor α content (P < 0.01) and miR-124 level (P < 0.001) while pre-treatment with GA reduced the level of miR-124 (P < 0.001). Histopathological results also revealed that I/R and PM caused cell death in the hippocampus CA1 area (P < 0.001) and that GA decreased the rate of cell death (P < 0.001). Our findings show that GA can prevent brain inflammation, and thus cognitive and LTP deficits caused by I/R, PM exposure, or both.

MicroRNA expression within neuronal-derived small extracellular vesicles in frontotemporal degeneration

MicroRNAs (miRNAs) are small non-coding RNA that are powerful regulators of gene expression and can affect the expression of hundreds of genes. miRNAs can be packed in small extracellular vesicles (SEV) and released into the extracellular space by neurons and microglia to act locally as well as pass through the blood-brain barrier and act systemically. We sought to understand the differences in neuronal SEV miRNA expression between frontotemporal dementia (FTD), Alzheimer's disease (AD), and healthy aging. Plasma was obtained from FTD, AD, and healthy aging participants that were matched based on age, sex, and race/ethnicity. Additionally, a subset of participants also provided paired cerebrospinal fluid samples to compare neuronal SEV miRNAs in plasma and cerebrospinal fluid. Neuronal SEV were isolated using differential ultracentrifugation and antibody conjugated Dynabeads® for the neuronal surface marker, L1CAM. RNA sequencing was performed. 12 FTD, 11 with AD, and 10 healthy aging participants were enrolled in the study. In FTD, SEV miRNA-181c was downregulated compared to healthy controls. In AD, miRNA-122 and miRNA-3591 were downregulated compared to those in healthy controls and FTD. Using an FDR <0.2, only miRNA-21-5p was found to have increased expression in the cerebrospinal fluid compared to plasma in a group of AD and FTD participants. SEV miRNA-181c is significantly downregulated in FTD compared to healthy controls and may mediate its effects through microglial-directed neuroinflammation and interaction with TAR DNA-binding protein 43 (TDP-43) based on pathway analysis. Additionally, the FOXO and Hippo pathways may be important mediators of FTD, based on pathway analysis. Lastly, because only one SEV miRNA was differentially expressed between the plasma and cerebrospinal fluid in paired samples, plasma represents an appropriate biofluid for studying neuronal SEV miRNA.

Trehalose Attenuates Learning and Memory Impairments in Aged Rats via Overexpression of miR-181c

MicroRNAs have been recognized as important regulators of the aging process. Trehalose, a natural disaccharide, displays protective effects against neuronal impairment through several mechanisms. However, little is known about the interactive effects of aging and trehalose on behavioral function and underlying miRNA expression patterns in the hippocampus of young and old rats. Male Wistar rats were divided into four groups. Two groups of aged (24 months) and young (4 months) rats were administered 2% trehalose solution for 30 days. Two other groups of aged and young rats received regular tap water. At the end of treatment, rats were assessed for cognitive behavior using the Morris water maze test. The expression level of miR-181c and mir-34c was also measured by qRT-PCR. We found that trehalose treatment reduced learning and memory impairment in old rats compared to control old animals (p < 0.05). In contrast, cognitive performance was not significantly improved in trehalose-treated young rats in comparison with young controls (p > 0.05). We also showed that the expression level of miR-181c was significantly increased in trehalose-treated rats (p < 0.01). However, analysis of miR-34c expression level indicated no significant difference between trehalose-treated old rats and non-treated old animals (p > 0.05). Our results indicated that trehalose treatment improved learning and memory function in aged rats by targeting miR-181c. Therefore, trehalose administration may provide a therapeutic strategy to ameliorate age-associated cognitive impairment.

Genetic Deficiency of MicroRNA-15a/16-1 Confers Resistance to Neuropathological Damage and Cognitive Dysfunction in Experimental Vascular Cognitive Impairment and Dementia

Chronic cerebral hypoperfusion-derived brain damage contributes to the progression of vascular cognitive impairment and dementia (VCID). Cumulative evidence has shown that microRNAs (miRs) are emerging as novel therapeutic targets for CNS disorders. In this study, it is sought to determine the regulatory role of miR-15a/16-1 in VCID. It is found that miR-15a/16-1 knockout (KO) mice exhibit less cognitive and sensorimotor deficits following VCID. Genetic deficiency of miR-15a/16-1 in VCID mice also mitigate myelin degeneration, axonal injury, and neuronal loss. Mechanistically, miR-15a/16-1 binds to the 3'-UTR of AKT3 and IL-10RA. Genetic deletion of miR-15a/16-1 increases AKT3 and IL-10RA expression in VCID brains, and intranasal delivery of AKT3 and IL-10RA siRNA-loaded nanoparticles partially reduce brain protection and cognitive recovery in miR-15a/16-1 KO mice after VCID. In conclusion, the miR-15a/16-1-IL/10RA/AKT3 axis plays a critical role in regulating vascular brain damage and cognitive decline after VCID. Targeting miR-15a/16-1 is a novel therapeutic approach for the treatment of VCID.

The Role of miR-181c in Mechanisms of Diabetes-Impaired Angiogenesis: An Emerging Therapeutic Target for Diabetic Vascular Complications

Diabetes mellitus is estimated to affect up to 700 million people by the year 2045, contributing to an immense health and economic burden. People living with diabetes have a higher risk of developing numerous debilitating vascular complications, leading to an increased need for medical care, a reduced quality of life and increased risk of early death. Current treatments are not satisfactory for many patients who suffer from impaired angiogenesis in response to ischaemia, increasing their risk of ischaemic cardiovascular conditions. These vascular pathologies are characterised by endothelial dysfunction and abnormal angiogenesis, amongst a host of impaired signaling pathways. Therapeutic stimulation of angiogenesis holds promise for the treatment of diabetic vascular complications that stem from impaired ischaemic responses. However, despite significant effort and research, there are no established therapies that directly stimulate angiogenesis to improve ischaemic complications such as ischaemic heart disease and peripheral artery disease, highlighting the immense unmet need. However, despite significant effort and research, there are no established therapies that directly stimulate angiogenesis in a clinical setting, highlighting the immense unmet need. MicroRNAs (miRNAs) are emerging as powerful targets for multifaceted diseases including diabetes and cardiovascular disease. This review highlights the potential role of microRNAs as therapeutic targets for rescuing diabetes-impaired angiogenesis, with a specific focus on miR-181c, which we have previously identified as an important angiogenic regulator. Here we summarise the pathways currently known to be regulated by miR-181c, which include the classical angiogenesis pathways that are dysregulated in diabetes, mitochondrial function and axonal guidance, and describe how these relate both directly and indirectly to angiogenesis. The pleiotropic actions of miR-181c across multiple key angiogenic signaling pathways and critical cellular processes highlight its therapeutic potential as a novel target for treating diabetic vascular complications.

Effect of circular RNA, mmu_circ_0000296, on neuronal apoptosis in chronic cerebral ischaemia via the miR-194-5p/Runx3/Sirt1 axis

Chronic cerebral ischaemia (CCI) is a common pathological disorder, which is associated with various diseases, such as cerebral arteriosclerosis and vascular dementia, resulting in neurological dysfunction. As a type of non-coding RNA, circular RNA is involved in regulating the occurrence and development of diseases, such as ischaemic brain injury. Here, we found that HT22 cells and hippocampus treated with CCI had low expression of circ_0000296, Runx3, Sirt1, but high expression of miR-194-5p. Overexpression of circ_0000296, Runx3, Sirt1, and silenced miR-194-5p significantly inhibited neuronal apoptosis induced by CCI. This study demonstrated that circ_0000296 specifically bound to miR-194-5p; miR-194-5p bound to the 3'UTR region of Runx3 mRNA; Runx3 directly bound to the promoter region of Sirt1, enhancing its transcriptional activity. Overexpression of circ_0000296 by miR-194-5p reduced the negative regulatory effect of miR-194-5p on Runx3, promoted the transcriptional effect of Runx3 on Sirt1, and inhibited neuronal apoptosis induced by CCI. mmu_circ_0000296 plays an important role in regulating neuronal apoptosis induced by CCI through miR-194-5p/Runx3/Sirt1 pathway.

Roles of Exosomes and Exosomal MicroRNAs in Postoperative Sleep Disturbance

Postoperative sleep disturbance (PSD) often occurs in elderly patients after major surgery and exerts harmful effects on postoperative recovery. PSD may increase the incidence of postoperative fatigue, severe anxiety and depression, pain sensitivity, and cognitive dysfunction, which can cause or aggravate neurodegenerative diseases via amyloid aggregation and tau accumulation. Exosomes are important carriers that mediate the transfer of active substances and genetic information among cells. Recent evidence has shown that exosomes are involved in the pathogenesis of end-organ morbidity caused by sleep disorders via increasing amyloid plaque formation, transmitting tau protein, regulating neuroinflammation, and increasing blood-brain barrier permeability. Additionally, exosomes may be useful for delivering therapeutic genetic materials, such as microRNAs (miRNAs) and proteins, to exert neuroprotective effects and reduce cognitive impairment. However, the molecular mechanisms underlying this process remain to be fully elucidated. This review focuses on exosome-related pathways and the modulatory role of exosomal miRNAs on the pathogenesis of sleep disturbance and neurodegeneration. Moreover, we discuss the advantages of reducing neurotoxic proteins via exosomal intervention and miRNA regulation. Future research in exosome administration may offer new insights into PSD-related pathomechanisms and therapeutics.

Regulatory microRNAs and vascular cognitive impairment and dementia

Vascular cognitive impairment and dementia (VCID) is defined as a progressive dementia disease related to cerebrovascular injury and often occurs in aged populations. Despite decades of research, effective treatment for VCID is still absent. The pathological processes of VCID are mediated by the molecular mechanisms that are partly modulated at the post-transcriptional level. As small endogenous non-coding RNAs, microRNAs (miRs) can regulate target gene expression through post-transcriptional gene silencing. miRs have been reported to play an important role in the pathology of VCID and have recently been suggested as potential novel pharmacological targets for the development of new diagnosis and treatment strategies in VCID. In this review, we summarize the current understanding of VCID, the possible role of miRs in the regulation of VCID and attempt to envision future therapeutic strategies. Since manipulation of miR levels by either pharmacological or genetic approaches has shown therapeutic effects in experimental VCID models, we also emphasize the potential therapeutic value of miRs in clinical settings.

SQSTM1/ p62 oligomerization contributes to Aβ-induced inhibition of Nrf2 signaling

SQSTM1/p62, also known as sequestosome 1 (SQSTM1) or p62, is an intracellular protein induced by stress and functions as an adaptor molecule in diverse cellular processes. Oxidative damage induced by overproduction of amyloid-β (Aβ) and the impairment of endogenous antioxidant Nrf2 signaling have been documented in the brains of Alzheimer's disease (AD) patients. The causes of the inactivation of Nrf2 signaling under Aβ-induced oxidative stress are unclear, and p62 might be involved in this process. In this study, APP/PS1 transgenic mice, Aβ intrahippocampal injection rat model, and SH-SY5Y cells were used to reveal that the alterations in the oligomeric state of p62 participated in the regulation of Nrf2 signaling under Aβ insult. The present in vivo and in vitro studies revealed that short-term treatment of Aβ activated Nrf2 signaling, while long-term Aβ treatment inhibited it through either canonical or noncanonical Nrf2 activation pathway. p62 oligomerization was largely attenuated under long-term Aβ treatment. The reduction of p62 oligomerization weakened p62 sequestration to Keap1, leading to Nrf2 signaling inhibition. Our findings provide a better understanding of p62-mediated modulation on Nrf2 activity and highlight a potential therapeutic target of p62 in AD.

MicroRNA-153 impairs hippocampal synaptic vesicle trafficking via downregulation of synapsin I in rats following chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion (CCH) promotes the development of Alzheimer's pathology. However, whether and how CCH impairs the synaptic vesicle trafficking is still unclear. In the present study, we found that the hippocampal glutamatergic vesicle trafficking was impaired as indicated by a significant shortened delayed response enhancement (DRE) phase in CA3-CA1 circuit and decreased synapsin I in CCH rats suffering from bilateral common carotid artery occlusion (2VO). Further study showed an upregulated miR-153 in the hippocampus of 2VO rats. In vitro, overexpression of miR-153 downregulated synapsin I by binding the 3'UTRs of SYN1 mRNAs, which was prevented by its antisense AMO-153 and miRNA-masking antisense oligodeoxynucleotides (SYN1-ODN). In vivo, the upregulation of miR-153 elicited similar reduced DRE phase and synapsin I deficiency as CCH. Furthermore, miR-153 knockdown rescued the downregulated synapsin I and shortened DRE phase in 2VO rats. Our results demonstrate that CCH impairs hippocampal glutamatergic vesicle trafficking by upregulating miR-153, which suppresses the expression of synapsin I at the post-transcriptional level. These results will provide important references for drug research and treatment of vascular dementia.

Adenosine A2A Receptors in Bone Marrow-Derived Cells Attenuate Cognitive Impairment in Mice After Chronic Hypoperfusion White Matter Injury

The mechanism of cognitive dysfunction caused by ischemic white matter lesions is unclear. To explore the effect and mechanism of different cell-derived adenosine A_2A receptor (A_2AR) in cognitive impairment caused by chronic hypoperfusion white matter lesions (CHWMLs), we destroyed the bone marrow hematopoietic capacity of the recipient mice using radiation irradiation followed by establishing the selectively inactivated or reconstituted A_2AR models with the transplanting bone marrow from global A_2AR gene knockout or wild-type mice into wild-type or gene knockout mice, respectively. Then Morris Water Maze (MWM), ELISA, immunohistochemistry, and Bielschowsky silver staining were used to assess the effect and mechanism of the cognitive function in chronic cerebral blood flow hypoperfusion (CCH) model. Selectively reconstructing bone marrow-derived cells (BMDCs) A_2AR (WT → KO group) and activated total adenosine A_2AR with CGS21680 (CCH + CGS group) improved the cognitive related index. Activation of BMDC A_2AR suppressed expression of inflammatory cytokines in peripheral blood and reduced the number of activated microglia cells co-localized with cystatin F in local brain, consequently inhibited white matter lesions. On the contrary, selective inactivation of adenosine A_2AR (KO → WT group) and activation of non-BMDC A_2AR with CGS21680 (KO → WT + CGS group) served the opposite effects. These results suggested that BMDC A_2AR could inhibit white matter lesions and attenuate cognitive impairment after CHWMLs, whereas non-BMDC A_2ARs aggravate cognitive impairment. The systemic inflammatory response and local activated microglia with cystatin F high expression were involved in the process of cognitive function recovery with BMDC A_2AR. The overall trend is that BMDC A_2ARs play a leading role.

Intracranial Self-Stimulation Modulates Levels of SIRT1 Protein and Neural Plasticity-Related microRNAs

Deep brain stimulation (DBS) of reward system brain areas, such as the medial forebrain bundle (MFB), by means of intracranial self-stimulation (ICSS), facilitates learning and memory in rodents. MFB-ICSS has been found capable of modifying different plasticity-related proteins, but its underlying molecular mechanisms require further elucidation. MicroRNAs (miRNAs) and the longevity-associated SIRT1 protein have emerged as important regulatory molecules implicated in neural plasticity. Thus, we aimed to analyze the effects of MFB-ICSS on miRNAs expression and SIRT1 protein levels in hippocampal subfields and serum. We used OpenArray to select miRNA candidates differentially expressed in the dentate gyrus (DG) of ICSS-treated (3 sessions, 45' session/day) and sham rats. We further analyzed the expression of these miRNAs, together with candidates selected after bibliographic screening (miR-132-3p, miR-134-5p, miR-146a-5p, miR-181c-5p) in DG, CA1, and CA3, as well as in serum, by qRT-PCR. We also assessed tissue and serum SIRT1 protein levels by Western Blot and ELISA, respectively. Expression of miR-132-3p, miR-181c-5p, miR-495-3p, and SIRT1 protein was upregulated in DG of ICSS rats (P < 0.05). None of the analyzed molecules was regulated in CA3, while miR-132-3p was also increased in CA1 (P = 0.011) and serum (P = 0.048). This work shows for the first time that a DBS procedure, specifically MFB-ICSS, modulates the levels of plasticity-related miRNAs and SIRT1 in specific hippocampal subfields. The mechanistic role of these molecules could be key to the improvement of memory by MFB-ICSS. Moreover, regarding the proposed clinical applicability of DBS, serum miR-132 is suggested as a potential treatment biomarker.

Light exercise without lactate elevation induces ischemic tolerance through the modulation of microRNA in the gerbil hippocampus

Previously we studied the possible neuroprotective effects of ischemia-resistant exercise in a gerbil model of transient whole-brain ischemia and evaluated the histology, expression of specific proteins, and brain function under different conditions. The present study investigated the neuroprotective effects of light exercise, without lactate elevation, in a gerbil model of ischemia/reperfusion injury. Transient whole-brain ischemia was induced by occlusion of the bilateral common carotid arteries for 5 min. A group of animals was subjected to treadmill exercise before ischemia induction. Hippocampal neuronal damage and miRNA expression, as well as behavioral deficits and plasma lactate levels, were evaluated. Light exercise suppressed hippocampal neuron loss and preserved short-term memory. Moreover, 14 miRNAs (mmu-miR-211-3p, -327, -451b, -711, -3070-3p, -3070-2-3p, -3097-5p, -3620-5p, -6240, -6916-5p, -6944-5p, 7083-5p, -7085-5p, and -7674-5p) were upregulated and 6 miRNAs (mmu-miR-148b-3p, -152-3p, -181c-5p, -299b-5p, -455-3p, and -664-3p) were downregulated due to ischemia. However, the expression of these miRNAs remained unchanged when animals performed light exercise before the ischemic event. Differentially expressed miRNAs regulate multiple biological processes such as inflammation, metabolism, and cell death. These findings suggest that light exercise reduces neuronal death and behavioral deficits after transient ischemia by regulating hippocampal miRNAs.

Gallic acid affects blood-brain barrier permeability, behaviors, hippocampus local EEG, and brain oxidative stress in ischemic rats exposed to dusty particulate matter

Dust storms are environmental natural events that transport high concentrations of particulate matter (PM) in living spaces. Recent epidemiological studies have shown that air pollution is associated with stroke. In the present study we aimed to investigate the probable protective effects of gallic acid (GA) on blood-brain barrier (BBB) disruption, brain oxidative stress, anxiety, depression, locomotion behaviors, and changes of hippocampal local electroencephalogram (local EEG) power induced by 4-vessel transient occlusion (4VO I/R) following exposure to dusty PM in rats. Male Wistar rats were divided randomly into eight groups: (1) vehicle+Sham (Veh + Sh), (2) vehicle+4VO I/R (Veh + I/R), (3) gallic acid+sham (GA + Sh), (4) gallic acid+4VO I/R (GA + I/R), (5) vehicle+PM (Veh + PM), (6) PM + 4VO I/R (PM + I/R), (7) gallic acid+PM + Sham (GA + PM + Sh), and (8) gallic acid+PM + 4Vo I/R (GA + PM + I/R). 4VO type of I/R was induced after 10 days of pretreatment by GA 100 mg/kg/2 ml/ip, or 2 ml/kg/ip, normal saline as vehicle (Veh) and exposure to dust storm composed of dusty PM (DPM, 2000-8000 μg/m3), 60 min daily for consecutive 10 days) simultaneously. Seventy-two hours after I/R induction, all behavioral tests and BBB permeability evaluation were done. Hippocampus local EEG was recorded just before and 72 h after I/R induction, and finally brain tissue oxidative stress was assayed. Data showed that 4VO I/R following exposure to DPM increased BBB permeability (p < 0.001), brain oxidative stress (p < 0.001), induced anxiety (p < 0.001), depression (p < 0.01), locomotion impairment (p < 0.001), superoxide dismutase (SOD) activity, and local EEG power also were decreased in PM + Sh (p < 0.001). Pretreatment with GA reversed BBB permeability and MDA. Our findings suggest that GA is a probable protective agent against adverse effects of both I/R and exposure to DPM and also in I/R subjects exposed to DPM. The beneficial effects of GA may induce by its antioxidative and anti-inflammatory properties.

Role of microRNA-126 in vascular cognitive impairment in mice

Vascular dementia (VaD) affects cognition and memory. MicroRNA-126 (miR-126) is an angiogenic microRNA that regulates vascular function. In this study, we employ a multiple microinfarction (MMI) model to induce VaD in mice, and investigate VaD-induced cognitive dysfunction, white matter (WM) damage, glymphatic dysfunction and the role of miR-126 in mediating these effects. Male six-to eight-months old C57/BL6 mice (WT) were subject to MMI model, and cerebral blood flow (CBF), vessel patency, glymphatic function, cognitive function, and serum miR-126 expression were measured. Mice were sacrificed at 28 days after MMI. To investigate the role of miR-126 in VaD, cognitive function, water channel integrity and glymphatic function were assessed in male, six-to eight months old conditional-knockout endothelial cell miR-126 (miR-126^EC-/-), and control (miR-126^fl/fl) mice. MMI in WT mice induces significant cognitive deficits, decreases CBF and vessel patency; evokes astrocytic and microglial activation, increases inflammation, axonal/WM damage; decreases synaptic plasticity and dendritic spine density, instigates water channel and glymphatic dysfunction, and decreases serum miR-126 expression. MiR-126^EC-/- mice exhibit significant cognitive impairment, decreased CBF, myelin density and axon density, increased inflammation, and significant water channel and glymphatic dysfunction compared to miR-126^fl/fl mice. Reduction of endothelial miR-126 expression may mediate cognitive impairment in MMI-induced VaD.

Lower serum expression of miR-181c-5p is associated with increased plasma levels of amyloid-beta 1-40 and cerebral vulnerability in normal aging

Background

Previous studies have shown that expression levels of miR-181c are downregulated by amyloid-β (Aβ) deposition and chronic cerebral hypoperfusion, both factors largely associated with the development of AD. Moreover, reduced 2-[18F]fluoro-2-deoxy-D-glucose (FDG)-PET brain metabolism and volume loss of regions of the medial temporal lobe have been generally recognized as hallmarks of AD. Based on this evidence, we have here investigated potential associations between serum levels of miR-181c-5p and these AD signatures in asymptomatic elderly subjects.

Methods

Ninety-five normal elderly subjects underwent clinical, cognitive, structural MRI, and FDG-PET explorations. Serum expression levels of miR-181c-5p and plasma Aβ concentrations were further analyzed in this cohort. Regression analyses were performed to assess associations between serum miR-181c-5p levels and cognitive functioning, plasma Aβ, structural and metabolic brain changes.

Results

Decreased serum expression of miR-181c-5p was associated with increased plasma levels of Aβ_1–40, deficits in cortical glucose metabolism, and volume reduction of the entorhinal cortex. No significant associations were found between lower miR-181c-5p levels and cognitive deficits or cortical thinning.

Conclusions

These findings suggest that deregulation of serum miR-181c-5p may indicate cerebral vulnerability in late life.

Recent developments in transcriptional and translational regulation underlying long-term synaptic plasticity and memory

Formation of long-term synaptic plasticity that underlies long-term memory requires new protein synthesis. Years of research has elucidated some of the transcriptional and translational mechanisms that contribute to the production of new proteins. Early research on transcription focused on the transcription factor cAMP-responsive element binding protein. Since then, other transcription factors, such as the Nuclear Receptor 4 family of proteins that play a role in memory formation and maintenance have been identified. In addition, several studies have revealed details of epigenetic mechanisms consisting of new types of chemical alterations of DNA such as hydroxymethylation, and various histone modifications in long-term synaptic plasticity and memory. Our understanding of translational control critical for memory formation began with the identification of molecules that impinge on the 5′ and 3′ untranslated regions of mRNAs and continued with the appreciation for local translation near synaptic sites. Lately, a role for noncoding RNAs such as microRNAs in regulating translation factors and other molecules critical for memory has been found. This review describes the past research in brief and mainly focuses on the recent work on molecular mechanisms of transcriptional and translational regulation that form the underpinnings of long-term synaptic plasticity and memory.

MicroRNAs in brain development and cerebrovascular pathophysiology

MicroRNAs (miRNAs) are a class of highly conserved non-coding RNAs with 21-25 nucleotides in length and play an important role in regulating gene expression at the posttranscriptional level via base-paring with complementary sequences of the 3'-untranslated region of the target gene mRNA, leading to either transcript degradation or translation inhibition. Brain-enriched miRNAs act as versatile regulators of brain development and function, including neural lineage and subtype determination, neurogenesis, synapse formation and plasticity, neural stem cell proliferation and differentiation, and responses to insults. Herein, we summarize the current knowledge regarding the role of miRNAs in brain development and cerebrovascular pathophysiology. We review recent progress of the miRNA-based mechanisms in neuronal and cerebrovascular development as well as their role in hypoxic-ischemic brain injury. These findings hold great promise, not just for deeper understanding of basic brain biology but also for building new therapeutic strategies for prevention and treatment of pathologies such as cerebral ischemia.

Exploring the Roles of CREBRF and TRIM2 in the Regulation of Angiogenesis by High-Density Lipoproteins

Angiogenesis, the process of forming new blood vessels, is crucial in the physiological response to ischemia, though it can be detrimental as part of inflammation and tumorigenesis. We have previously shown that high-density lipoproteins (HDL) modulate angiogenesis in a context-specific manner via distinct classical signalling pathways, enhancing hypoxia-induced angiogenesis while suppressing inflammatory-driven angiogenesis. Whether additional novel targets exist to account for these effects are unknown. A microarray approach identified two novel genes, cyclic-adenosine-monophosphate-response-element-binding protein 3 regulatory factor (CREBRF) and tripartite motif-containing protein 2 (TRIM2) that were upregulated by reconstituted HDL (rHDL). We measured CREBRF and TRIM2 expression in human coronary artery endothelial cells following incubation with rHDL and exposure to either hypoxia or an inflammatory stimulus. We found that CREBRF and TRIM2 mRNA were significantly upregulated by rHDL, particularly in response to its phospholipid component 1-palmitoyl-2-linoleoyl-phosphatidylcholine, however, protein expression was not significantly altered. Knockdown of TRIM2 impaired endothelial cell tubulogenesis in vitro in both hypoxia and inflammation, implying a necessary role in angiogenesis. Furthermore, TRIM2 knockdown attenuated rHDL-induced tubule formation in hypoxia, suggesting that it is important in mediating the pro-angiogenic action of rHDL. Our study has implications for understanding the regulation of angiogenesis in both of these pathophysiological contexts by HDL.

Brain Energy and Oxygen Metabolism: Emerging Role in Normal Function and Disease

Dynamic metabolic changes occurring in neurons are critically important in directing brain plasticity and cognitive function. In other tissue types, disruptions to metabolism and the resultant changes in cellular oxidative state, such as increased reactive oxygen species (ROS) or induction of hypoxia, are associated with cellular stress. In the brain however, where drastic metabolic shifts occur to support physiological processes, subsequent changes to cellular oxidative state and induction of transcriptional sensors of oxidative stress likely play a significant role in regulating physiological neuronal function. Understanding the role of metabolism and metabolically-regulated genes in neuronal function will be critical in elucidating how cognitive functions are disrupted in pathological conditions where neuronal metabolism is affected. Here, we discuss known mechanisms regulating neuronal metabolism as well as the role of hypoxia and oxidative stress during normal and disrupted neuronal function. We also summarize recent studies implicating a role for metabolism in regulating neuronal plasticity as an emerging neuroscience paradigm.

MicroRNA-181c inhibits cigarette smoke-induced chronic obstructive pulmonary disease by regulating CCN1 expression

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an obstinate pulmonary disease, causing irreversible alveoli collapse and increasing the risk for cardiovascular disease. Accumulating evidence has shown that the dysregulation of miRNAs is crucially involved in the pathogenesis and development of COPD. However, the effects and role of microRNA-181c (miR-181c) have not been investigated in a murine model of COPD.

METHODS

miR-181c expression was detected in human lung tissue samples of 34 patients, an in vivo murine model of CS exposure, and primary human bronchial epithelial cells (HBECs) by qRT-PCR. Degeneration of lung tissue, necrosis, infiltration and neutrophil cells were assessed with H&E and flow cytometry. Interleukin (IL)-6 and IL-8 levels were determined by an enzyme-linked immunosorbent assay and qRT-PCR. Luciferase reporter assay and correlation analyses were used to confirm and measure the levels between miR-181c and its target CCN1.

RESULTS

We showed that miR-181c was significantly down-regulated in lung tissues from patients with COPD compared to individuals who had never smoked (p < 0.01). We also observed a down-regulation of miR-181c in HBECs and a mouse model after cigarette smoke (CS) exposure. Functional assays demonstrated that miR-181c over-expression decreased the inflammatory response, neutrophil infiltration, reactive oxygen species (ROS) generation, and inflammatory cytokines induced by CS, while its down-regulation produced the opposite effects. Subsequent investigation found that CCN1 was a direct target of miR-181c. CCN1 expression was increased in lung tissues of COPD patients, and was negatively correlated with miR-181c expression in human COPD samples (p < 0.01).

CONCLUSIONS

Taken together, our data suggest the critical roles of miR-181c and its target CCN1 in COPD development, and provide potential therapeutic targets for COPD treatment.

Linking deregulation of non-coding RNA to the core pathophysiology of Alzheimer's disease: An integrative review

The human genome encodes a vast repertoire of protein non-coding RNAs (ncRNA), some specific to the brain. MicroRNAs, which interfere with the translation of target mRNAs, are of particular interest since their deregulation has been implicated in neurodegenerative disorders like Alzheimer's disease (AD). However, it remains challenging to link the complex body of observations on miRNAs and AD into a coherent framework. Using extensive graphical support, this article discusses how a diverse panoply of miRNAs convergently and divergently impact (and are impacted by) core pathophysiological processes underlying AD: neuroinflammation and oxidative stress; aberrant generation of β-amyloid-42 (Aβ42); anomalies in the production, cleavage and post-translational marking of Tau; impaired clearance of Aβ42 and Tau; perturbation of axonal organisation; disruption of synaptic plasticity; endoplasmic reticulum stress and the unfolded protein response; mitochondrial dysfunction; aberrant induction of cell cycle re-entry; and apoptotic loss of neurons. Intriguingly, some classes of miRNA provoke these cellular anomalies, whereas others act in a counter-regulatory, protective mode. Moreover, changes in levels of certain species of miRNA are a consequence of the above-mentioned anomalies. In addition to miRNAs, circular RNAs, piRNAs, long non-coding RNAs and other types of ncRNA are being increasingly implicated in AD. Overall, a complex mesh of deregulated and multi-tasking ncRNAs reciprocally interacts with core pathophysiological mechanisms underlying AD. Alterations in ncRNAs can be detected in CSF and the circulation as well as the brain and are showing promise as biomarkers, with the ultimate goal clinical exploitation as targets for novel modes of symptomatic and course-altering therapy.