Knockdown of Porf-2 restores visual function after optic nerve crush injury

Retinal ganglion cells (RGCs), the sole output neurons in the eyes, are vulnerable to diverse insults in many pathological conditions, which can lead to permanent vision dysfunction. However, the molecular and cellular mechanisms that contribute to protecting RGCs and their axons from injuries are not completely known. Here, we identify that Porf-2, a member of the Rho GTPase activating protein gene group, is upregulated in RGCs after optic nerve crush. Knockdown of Porf-2 protects RGCs from apoptosis and promotes long-distance optic nerve regeneration after crush injury in both young and aged mice in vivo. In vitro, we find that inhibition of Porf-2 induces axon growth and growth cone formation in retinal explants. Inhibition of Porf-2 provides long-term and post-injury protection to RGCs and eventually promotes the recovery of visual function after crush injury in mice. These findings reveal a neuroprotective impact of the inhibition of Porf-2 on RGC survival and axon regeneration after optic nerve injury, providing a potential therapeutic strategy for vision restoration in patients with traumatic optic neuropathy.

Intravitreal injection of Huperzine A promotes retinal ganglion cells survival and axonal regeneration after optic nerve crush

Traumatic optic neuropathy (TON) is a condition that causes massive loss of retinal ganglion cells (RGCs) and their axonal fibers, leading to visual insufficiency. Several intrinsic and external factors can limit the regenerative ability of RGC after TON, subsequently resulting in RGC death. Hence, it is important to investigate a potential drug that can protect RGC after TON and enhance its regenerative capacity. Herein, we investigated whether Huperzine A (HupA), extracted from a Chinese herb, has neuroprotective effects and may enhance neuronal regeneration following the optic nerve crush (ONC) model. We compared the three modes of drug delivery and found that intravitreal injection of HupA could promote RGC survival and axonal regeneration after ONC. Mechanistically, HupA exerted its neuroprotective and axonal regenerative effects through the mTOR pathway; these effects could be blocked by rapamycin. To sum up, our findings suggest a promising application of HupA in the clinical treatment of traumatic optic nerve.

Alteration in ventral tegmental area and default mode network interplay and prediction of coma recovery in patients with sTBI

Purpose

To investigate the role of VTA and DMN in modulating human consciousness in patient with sTBI.

Methods

We mapped an atlas of VTA in the brainstem and a total of 19 region of interests in the ventral and dorsal DMN onto functional magnetic resonance imaging in 28 patients with sTBI and 28 healthy controls. We assessed the functional connectivity alteration in subcortical VTA and cortical DMN nodes in patients of coma. We evaluated the spatially distribution of FC alteration in VTA and DMN nodes after sTBI and evaluated their predictive value for coma recovery.

Results

There was a decrease in FC between VTA and DMN in patients compared to controls. After decomposition, the FC between VTA and 10 DMN nodes were decreased whereas the FC within 2 DMN nodes were increased in patients with acute coma. The FC alteration in DMN nodes provided useful information for the early prediction of 6-month coma recovery in patients with sTBI.

Conclusions

We provide initial evidence for the decreased FC between VTA and massive DMN nodes in patients with coma in acute phase of sTBI. We found that the FC alteration within DMN is more useful than the FC alteration between VTA and DMN for predicting coma recovery in patients with sTBI. VTA and DMN connectivity mapping provides an opportunity to advance the cortical-subcortical mechanism of human consciousness.

Default mode network overshadow executive control network in coma emergence and awakening prediction of patients with sTBI

OBJECTIVE

We aimed to explore the pathogenesis of traumatic coma related to functional connectivity (FC) within the default mode network (DMN), within the executive control network (ECN) and between the DMN and ECN and to investigate its capacity for predicting awakening.

METHODS

We carried out resting-state functional magnetic resonance imaging (fMRI) examinations on 28 traumatic coma patients and 28 age-matched healthy controls. DMN and ECN nodes were split into regions of interest (ROIs), and node-to-node FC analysis was conducted on individual participants. To identify coma pathogenesis, we compared the pairwise FC differences between coma patients and healthy controls. Meanwhile, we divided the traumatic coma patients into different subgroups based on their clinical outcome scores at 6 months postinjury. Considering the awakening prediction, we calculated the area under the curve (AUC) to evaluate the predictive ability of changed FC pairs.

RESULTS

We found a massive pairwise FC alteration in the patients with traumatic coma compared to the healthy controls [45% (33/74) pairwise FC located in the DMN, 27% (20/74) pairwise FC located in the ECN, and 28% (21/74) pairwise FC located between the DMN and ECN]. Moreover, in the awake and coma groups, there were 67% (12/18) pairwise FC alterations located in the DMN and 33% (6/18) pairwise FC alterations located between the DMN and ECN. We also indicated that pairwise FC that showed a predictive value of 6-month awakening was mainly located in the DMN rather than in the ECN. Specifically, decreased FC between the right superior frontal gyrus and right parahippocampal gyrus (in the DMN) showed the highest predictive ability (AUC = 0.827).

CONCLUSION

In the acute phase of severe traumatic brain injury (sTBI), the DMN plays a more prominent role than the ECN and the DMN-ECN interaction in the emergence of traumatic coma and the prediction of 6-month awakening.

Transcriptome Analyses Reveal Systematic Molecular Pathology After Optic Nerve Crush

The function of glial cells in axonal regeneration after injury has been the subject of controversy in recent years. Thus, deeper insight into glial cells is urgently needed. Many studies on glial cells have elucidated the mechanisms of a certain gene or cell type in axon regeneration. However, studies that manipulate a single variable may overlook other changes. Here, we performed a series of comprehensive transcriptome analyses of the optic nerve head over a period of 90 days after optic nerve crush (ONC), showing systematic molecular changes in the optic nerve head (ONH). Furthermore, using weighted gene coexpression network analysis (WGCNA), we established gene module programs corresponding to various pathological events at different times post-ONC and found hub genes that may be potential therapeutic targets. In addition, we analyzed the changes in different glial cells based on their subtype markers. We revealed that the transition trend of different glial cells depended on the time course, which provides clues for modulating glial function in further research.

Maf1 regulates axonal regeneration of retinal ganglion cells after injury

Retinal ganglion cells (RGCs) are the sole output neurons that carry visual information from the eye to the brain. Due to various retinal and optic nerve diseases, RGC somas and axons are vulnerable to damage and lose their regenerative capacity. A basic question is whether the manipulation of a key regulator of RGC survival can protect RGCs from retinal and optic nerve diseases. Here, we found that Maf1, a general transcriptional regulator, was upregulated in RGCs from embryonic stage to adulthood. We determined that the knockdown of Maf1 promoted the survival of RGCs and their axon regeneration through altering the activity of the PTEN/mTOR pathway, which could be blocked by rapamycin. We further observed that the inhibition of Maf1 prevented the retinal ganglion cell complex from thinning after optic nerve crush. These findings reveal a neuroprotective effect of knocking down Maf1 on RGC survival after injury and provide a potential therapeutic strategy for traumatic optic neuropathy.

Paroxetine ameliorates prodromal emotional dysfunction and late-onset memory deficit in Alzheimer's disease mice

Background

Neuropsychiatric symptoms (NPS) such as depression, anxiety, apathy, and irritability occur in prodromal phases of clinical Alzheimer’s disease (AD), which might be an increased risk for later developing AD. Here we treated young APP/PS1 AD model mice prophylactically with serotonin-selective re-uptake inhibitor (SSRI) paroxetine and investigated the protective role of anti-depressant agent in emotional abnormalities and cognitive defects during disease progress.

Methods

To investigate the protective role of paroxetine in emotional abnormalities and cognitive defects during disease progress, we performed emotional behaviors of 3 months old APP/PS1 mouse following oral administration of paroxetine prophylactically starting at 1 month of age. Next, we tested the cognitive, biochemical and pathological, effects of long term administration of paroxetine at 6 months old.

Results

Our results showed that AD mice displayed emotional dysfunction in the early stage. Prophylactic administration of paroxetine ameliorated the initial emotional abnormalities and preserved the eventual memory function in AD mice.

Conclusion

Our data indicate that prophylactic administration of paroxetine ameliorates the emotional dysfunction and memory deficit in AD mice. These neuroprotective effects are attributable to functional restoration of glutamate receptor (GluN2A) in AD mice.

Take it seriously or not: postoperative pneumocephalus in CSDH patients?

Background: Pneumocephalus is a common finding after burr-hole drainage of chronic subdural hematoma (CSDH). Its effects have not been specifically studied.Methods: A retrospective analysis was performed in 140 patients with CSDH with single burr-hole drainage. The pre- and postoperative volumes of intracranial hematoma and the postoperative volume of pneumocephalus were calculated and analyzed with their relationships with Glasgow Coma Scale (GCS) and Glasgow Outcome Scale (GOS) scores.Results: The preoperative hematoma volume and the patient ages are positively correlated with the 1-day postoperative pneumocephalus volume (p < 0.001, p < 0.01). There is no correlation between postoperative pneumocephalus volume and GCS/GOS scores (p > 0.05) and there is no difference of GCS/GOS scores or CSDH recurrence rate between patients with and without pneumocephalus (p > 0.05). The age and the volume of 1-day postoperative pneumocephalus are positively correlated with the absorbing rate of pneumocephalus (p < 0.01, p < 0.001).Conclusions: The pneumocephalus at a certain range has no effect on the prognosis of patients with CSDH and requires no specific intervention due to its self-absorbing capacity in the normal progress after surgery.HighlightsNo correlation between postoperative pneumocephalus volume and GCS/GOS scores.No difference of GCS/GOS or recurrence between patients with pneumocephalus or not.Pneumocephalus at certain range has no effect on the prognosis of patients.

CRMP2 improves memory deficits by enhancing the maturation of neuronal dendritic spines after traumatic brain injury

Our recent study investigated the role of collapsin response mediator protein-2 (CRMP2) on dendritic spine morphology and memory function after traumatic brain injury (TBI). First, we examined the density and morphology of dendritic spines in Thy1-GFP mice on the 1 st day (P1D) and 7th day (P7D) after controlled cortical impact injury (CCI). The dendritic spine density in the hippocampus was decreased on P1D, in which mainly mushroom-type and thin-type spines were lost. The density of dendritic spines was increased on P7D, most of which were of the thin type. Next, we explored the expression of CRMP2 on P1D and P7D. CRMP2 expression was decreased on P1D, but the levels of the CRMP2 breakdown product were increased. On P7D, the expression pattern was the opposite. Then, we constructed CRMP2 overexpression and knockdown plasmids and transfected them into cultured neurons in vitro. CRMP2 increased the dendritic spine density of cultured neurons and the proportion of mushroom-type spines, while CRMP2-shRNA reduced the dendritic spine density and the proportion of mushroom-type spines. To determine the role of CRMP2 in dendritic spines after TBI, we stereotactically injected the CRMP2 overexpression and knockdown viruses into the hippocampus and found that CRMP2 increased the dendritic spine density and the proportion of mushroom-type spines after TBI. Meanwhile, as suggested by the morphological changes, fear conditioning behavioral experiments confirmed that CRMP2 improved memory deficits after TBI.

A New Model of Repetitive Traumatic Brain Injury in Mice

Repetitive traumatic brain injury (rTBI) is a major health care concern that causes substantial neurological impairment. To better understand rTBI, we introduced a new model of rTBI in mice induced by sudden rotation in the coronal plane combined with lateral translation delivered twice at an interval of 24 h. By routine histology, histological examination of Prussian blue-stained sections revealed the presence of microbleed in the corpus callosum and brain stem. Amyloid precursor protein (β-APP) and neurofilament heavy-chain (NF-200) immunohistochemistry demonstrated axonal injury following rTBI. Swelling, waving, and enlargement axons were observed in the corpus callosum and brain stem 24 h after injury by Bielschowsky staining. Ultrastructural studies by electron microscopy provided further insights into the existence and progression of axonal injury. rTBI led to widespread astrogliosis and microgliosis in white matter, as well as significantly increased levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β. rTBI mice showed a significantly increased loss of righting reflex (LRR) duration within each time point compared with that of sham animals, which was under 15 min. rTBI mice exhibited depression-like behavior at 1 month. rTBI mice also demonstrated deficits in MWM testing. These results suggested that this model might be suitable for investigating rTBI pathophysiology and evaluating preclinical candidate therapeutics.

Effect of α7nAChR on learning and memory dysfunction in a rat model of diffuse axonal injury

Diffuse axonal injury (DAI) is the predominant effect of severe traumatic brain injury and significantly contributes to cognitive deficits. The mechanisms that underlie these cognitive deficits are often associated with complex molecular alterations. α7nAChR, one of the abundant and widespread nicotinic acetylcholine receptors (nAChRs) in the brain, plays important physiological functions in the central nervous system. However, the relationship between temporospatial alterations in the α7nAChR and DAI-related learning and memory dysfunction are not completely understood. Our study detected temporospatial alterations of α7nAChR in vulnerable areas (hippocampus, internal capsule, corpus callosum and brain stem) of DAI rats and evaluated the development and progression of learning and memory dysfunction via the Morris water maze (MWM). We determined that α7nAChR expression in vulnerable areas was mainly reduced at the recovery of DAI in rats. Moreover, the escape latency of the injured group increased significantly and the percentages of the distance travelled and time spent in the target quadrant were significantly decreased after DAI. Furthermore, α7nAChR expression in the vulnerable area was significantly positively correlated with MWM performance after DAI according to regression analysis. In addition, we determined that a selective α7nAChR agonist significantly improved learning and memory dysfunction. Rats in the α7nAChR agonist group showed better learning and memory performance than those in the antagonist group. These results demonstrate that microstructural injury-induced alterations of α7nAChR in the vulnerable area are significantly correlated with learning and memory dysfunctions after DAI and that augmentation of the α7nAChR level by its agonist contributes to the improvement of learning and memory function.

4-Phenylbutyrate Ameliorates Anxiety Disorder by Inhibiting Endoplasmic Reticulum Stress after Diffuse Axonal Injury

Diffuse axonal injury (DAI) is accompanied frequently by adverse sequelae and psychiatric disorders, such as anxiety, leading to a decreased quality of life, social isolation, and poor outcomes in patients. The mechanisms regulating psychiatric disorders post-DAI are not well elucidated, however. Previous studies showed that endoplasmic reticulum (ER) stress functions as a pivotal factor in neurodegeneration disease. In this study, we showed that DAI can trigger ER stress and unfolded protein response (UPR) activation in both the acute and chronic periods, leading to cell death and anxiety disorder. Treatment with 4-phenylbutyrate (4-PBA) is able to inhibit the UPR and cell apoptosis and relieve the anxiety disorder in our DAI model. Later (14 days post-DAI) 4-PBA treatment, however, can restore only the related gene expression of ER stress and UPR but not the psychiatric disorder. Therefore, the early (5 min after DAI) administration of 4-PBA might be a therapeutic approach for blocking the ER stress/UPR-induced cell death and anxiety disorder after DAI.

A neuronal molecular switch through cell-cell contact that regulates quiescent neural stem cells

The quiescence of radial neural stem cells (rNSCs) in adult brain is regulated by environmental stimuli. However, little is known about how the neurogenic niche couples the external signal to regulate activation and transition of quiescent rNSCs. Here, we reveal that long-term excitation of hippocampal dentate granule cells (GCs) upon voluntary running leads to activation of adult rNSCs in the subgranular zone and thereby generation of newborn neurons. Unexpectedly, the role of these excited GC neurons in NSCs depends on direct GC-rNSC interaction in the local niche, which is through down-regulated ephrin-B3, a GC membrane-bound ligand, and attenuated transcellular EphB2 kinase-dependent signaling in the adjacent rNSCs. Furthermore, constitutively active EphB2 kinase sustains the quiescence of rNSCs during running. These findings thus elucidate the physiological significance of GC excitability on adult rNSCs under external environments and indicate a key-lock switch regulation via cell-cell contact for functional transition of rNSCs.

Inhibition of miRNA-21 promotes retinal ganglion cell survival and visual function by modulating Müller cell gliosis after optic nerve crush

BACKGROUND

Müller cell gliosis not only plays an important physiological role by maintaining retinal neuronal homeostasis but is also associated with multiple pathological events in the retina, including optic nerve crush (ONC) injury. Modulating Müller cell gliosis contributes to the creation of a permissive environment for neuronal survival. However, the underlying mechanism of Müller cell gliosis has remained elusive.

OBJECTIVE

To investigate the underlying mechanism of Müller cell gliosis after ONC.

METHODS

Rats with ONC injury were transfected with miRNA-21 (miR-21) agomir (overexpressing miR-21) or antagomir (inhibiting miR-21) via intravitreous injection. Immunofluorescence and western blotting were performed to confirm the effects of miR-21 on Müller cell gliosis. The retinal nerve fiber layer (RNFL) thickness was measured using optical coherence tomography and the positive scotopic threshold response (pSTR) was recorded using electroretinogram.

RESULTS

In the acute phase (14 days) after ONC, compared with the crushed group, inhibiting miR-21 promoted Müller cell gliosis, exhibiting thicker processes and increased GFAP expression. In the chronic phase (35 days), inhibiting miR-21 ameliorated Müller cell gliosis, which exhibited thicker and denser processes and increased GFAP expression. Retinal ganglion cell (RGC) counts in retinas showed that the number of surviving RGCs increased significantly in the antagomir group. The thickness of the RNFL increased significantly, and pSTR showed significant preservation of the amplitudes in the antagomir group.

CONCLUSIONS

Inhibition of miR-21 promotes RGC survival, RNFL thickness and the recovery of RGC function by modulating Müller cell gliosis after ONC.

Neuronal GAP-Porf-2 transduces EphB1 signaling to brake axon growth

Axonal outgrowth and guidance require numerous extracellular cues and intracellular mediators that transduce signals in the growth cone to regulate cytoskeletal dynamics. However, the way in which cytoskeletal effectors respond to these signals remains elusive. Here, we demonstrate that Porf-2, a neuron-expressed RhoGTPase-activating protein, plays an essential role in the inhibition of initial axon growth by restricting the expansion of the growth cone in a cell-autonomous manner. Furthermore, the EphB1 receptor is identified as an upstream controller that binds and regulates Porf-2 specifically upon extracellular ephrin-B stimulation. The activated EphB forward signal deactivates Rac1 through the GAP domain of Porf-2, which inhibits growth cone formation and brakes axon growth. Our results therefore provide a novel GAP that regulates axon growth and braking sequentially through Eph receptor-independent and Eph receptor-dependent pathways.

Exploring Optic Nerve Axon Regeneration

Background:

Traumatic optic nerve injury is a leading cause of irreversible blindness across the world and causes progressive visual impairment attributed to the dysfunction and death of retinal ganglion cells (RGCs). To date, neither pharmacological nor surgical interventions are sufficient to halt or reverse the progress of visual loss. Axon regeneration is critical for functional recovery of vision following optic nerve injury. After optic nerve injury, RGC axons usually fail to regrow and die, leading to the death of the RGCs and subsequently inducing the functional loss of vision. However, the detailed molecular mechanisms underlying axon regeneration after optic nerve injury remain poorly understood.

Methods:

Research content related to the detailed molecular mechanisms underlying axon regeneration after optic nerve injury have been reviewed.

Results:

The present review provides an overview of regarding potential strategies for axonal regeneration of RGCs and optic nerve repair, focusing on the role of cytokines and their downstream signaling pathways involved in intrinsic growth program and the inhibitory environment together with axon guidance cues for correct axon guidance. A more complete understanding of the factors limiting axonal regeneration will provide a rational basis, which contributes to develop improved treatments for optic nerve regeneration. These findings are encouraging and open the possibility that clinically meaningful regeneration may become achievable in the future.

Conclusion:

Combination of treatments towards overcoming growth-inhibitory molecules and enhancing intrinsic growth capacity combined with correct guidance using axon guidance cues is crucial for developing promising therapies to promote axon regeneration and functional recovery after ON injury.

Transforming growth factor beta induced (TGFBI) is a potential signature gene for mesenchymal subtype high-grade glioma

Previous study revealed that higher expression of transforming growth factor beta induced (TGFBI) is correlated to poorer cancer-specific survival and higher proportion of tumor necrosis and Fuhrman grades III and IV in clear cell renal cell carcinomas. However, the relationships between TGFBI expression and malignant phenotypes of gliomas remain unclear. We downloaded and analyzed data from seven GEO datasets (GSE68848, GSE4290, GSE13041, GSE4271, GSE83300, GSE34824 and GSE84010), the TCGA database and the REMBRANDT database to investigate whether TGFBI could be a biomarker of glioma. From microarray data (GSE68848, GSE4290) and RNA-seq data (TCGA), TGFBI expression levels were observed to correlate positively with pathological grade, and TGFBI expression levels were significantly higher in gliomas than in normal brain tissues. Furthermore, in GSE13041, GSE4271 and the TCGA cohort, TGFBI expression in the mesenchymal (Mes) subtype high-grade glioma (HGG) was significantly higher than that in the proneural subtype. Kaplan-Meier survival analysis of GBM patients in the GSE83300 dataset, REMBRANDT and TCGA cohort revealed that patients in the top 50% TGFBI expression group survived for markedly shorter periods than those in the bottom 50%. Analysis of grade III gliomas showed that the median survival time was significantly shorter in the TGFBI high expression group than in the TGFBI low expression group. In addition, we found that TGFBI expression levels might relate to several classical molecular characterizations of glioma, such as, IDH mutation, TP53 mutation, EGFR amplification, etc. These results suggest that TGFBI expression positively correlates with glioma pathological grades and that TGFBI is a potential signature gene for Mes subtype HGG and a potential prognostic molecule.

Rac1 Guides Porf-2 to Wnt Pathway to Mediate Neural Stem Cell Proliferation

The molecular and cellular mechanisms underlying the anti-proliferative effects of preoptic regulator factor 2 (Porf-2) on neural stem cells (NSCs) remain largely unknown. Here, we found that Porf-2 inhibits the activity of ras-related C3 botulinum toxin substrate 1 (Rac1) protein in hippocampus-derived rat NSCs. Reduced Rac1 activity impaired the nuclear translocation of β-catenin, ultimately causing a repression of NSCs proliferation. Porf-2 knockdown enhanced NSCs proliferation but not in the presence of small molecule inhibitors of Rac1 or Wnt. At the same time, the repression of NSCs proliferation caused by Porf-2 overexpression was counteracted by small molecule activators of Rac1 or Wnt. By using a rat optic nerve crush model, we observed that Porf-2 knockdown enhanced the recovery of visual function. In particular, optic nerve injury in rats led to increased Wnt family member 3a (Wnt3a) protein expression, which we found responsible for enhancing Porf-2 knockdown-induced NSCs proliferation. These findings suggest that Porf-2 exerts its inhibitory effect on NSCs proliferation via Rac1-Wnt/β-catenin pathway. Porf-2 may therefore represent and interesting target for optic nerve injury recovery and therapy.

Rho GTPase-activating proteins: Regulators of Rho GTPase activity in neuronal development and CNS diseases

The Rho family of small GTPases was considered as molecular switches in regulating multiple cellular events, including cytoskeleton reorganization. The Rho GTPase-activating proteins (RhoGAPs) are one of the major families of Rho GTPase regulators. RhoGAPs were initially considered negative mediators of Rho signaling pathways via their GAP domain. Recent studies have demonstrated that RhoGAPs also regulate numerous aspects of neuronal development and are related to various neurodegenerative diseases in GAP-dependent and GAP-independent manners. Moreover, RhoGAPs are regulated through various mechanisms, such as phosphorylation. To date, approximately 70 RhoGAPs have been identified; however, only a small portion has been thoroughly investigated. Thus, the characterization of important RhoGAPs in the central nervous system is crucial to understand their spatiotemporal role during different stages of neuronal development. In this review, we summarize the current knowledge of RhoGAPs in the brain with an emphasis on their molecular function, regulation mechanism and disease implications in the central nervous system.

Ommaya reservoir implantation for the treatment of contralateral progressive traumatic subdural effusion secondary to decompressive craniectomy: a case report

This report describes a new method for the treatment of traumatic subdural effusion (TSE). Following Ommaya reservoir implantation, a patient with contralateral progressive TSE secondary to decompressive craniectomy after traumatic brain injury made a good postoperative recovery.

Rapid increase in cystic volume of an anaplastic astrocytoma misdiagnosed as neurocysticercosis: A case report

Reports describing a rapid increase in the cystic volume of anaplastic astrocytoma (AA) in a short time frame are rare. The present study reports the case of a 68-year-old male who was admitted to the No. 9 People's Hospital, Shanghai Jiaotong University School of Medicine (Shanghai, China), with a small cystic brain lesion and positive immunological testing for cysticercosis. Head magnetic resonance imaging (MRI) showed a cystic lesion, 6 mm in diameter, in the left frontal lobe. Neurocysticercosis was suspected and the patient was treated with a clinical trial of albendazole and steroids. A period of 25 days later, the patient's condition had deteriorated, and MRI revealed a cystic lesion in the left frontal lobe; thereafter, the cystic lesion was removed and a diagnosis of AA was established. The tumor was soft, ivory white and gelatinous due to myxoid degeneration. In this case, tumor-related angiogenesis and microvascular extravasation (blood-brain barrier disruption) may have been the main cause of the rapid increase in the cystic volume in such a short time frame. The similarity of the glioma and cysticercus antigens may have been the cause of the positive reactions in the cystic fluid. The present study reports the rare occurrence of a rapid increase of cystic volume and potential diagnostic difficulties.

Porf-2 Inhibits Neural Stem Cell Proliferation Through Wnt/β-Catenin Pathway by Its GAP Domain

Neural stem cell (NSC) proliferation and differentiation play a pivotal role in the development of brain, the plasticity of the brain network, and the repair for brain function in CNS diseases. The mechanisms regulating NSC behavior are not well elucidated. Previous studies showed porf-2 functions as a modulator in central nerve system development. We here show that porf-2, a conserved family of RhoGAPs, is highly and specifically expressed in NSCs. We also demonstrate that porf-2 inhibits the proliferation of NSCs in vivo and in vitro, but has no effect on NSC differentiation. We investigated which domain is required for the role of porf-2 on NSC proliferation. By using neurosphere formation and Edu assay we confirmed the GAP domain is necessary for its function. In addition, we surveyed a few classical pathways on NSC proliferation and found that porf-2 inhibits NSC proliferation by suppressing the β-catenin nuclear translocation. Taken together, we show for the first time that porf-2 inhibits NSC proliferation through Wnt/β-catenin pathway by its GAP domain.

Glial cells activation potentially contributes to the upregulation of stromal cell-derived factor-1α after optic nerve crush in rats

Stromal cell-derived factor-1α (SDF-1α) plays an important role after injury. However, little is known regarding its temporal and spatial expression patterns or how it interacts with glial cells after optic nerve crush injury. We characterized the temporal and spatial expression pattern of SDF-1α in the retina and optic nerve following optic nerve crush and demonstrated that SDF-1α is localized to the glial cells that are distributed in the retina and optic nerve. CXCR4, the receptor for SDF-1α, is expressed along the ganglion cell layer (GCL). The relative expression levels of Sdf-1α mRNA and SDF-1α protein in the retina and optic nerve 1, 2, 3, 5, 7, 10 and 14 days after injury were determined using real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay, respectively, and the Cxcr4 mRNA expression was determined using real-time PCR. Immunofluorescence and immunohistochemical approaches were used to detect the localization of SDF-1α and CXCR4 after injury. The upregulation of Sdf-1α and Cxcr4 mRNA was detected as early as day one after injury in the retina and day two in the optic nerve, the expression peaks 5-7 days after injury. The expression of Sdf-1α and Cxcr4 mRNA was maintained for at least 14 days after the optic nerve crush injury. Furthermore, SDF-1α-positive zones were distributed locally in the reactive glial cells, which suggested potential autocrine stimulation. CXCR4 was mainly expressed in the GCL, which was also adjacent to the the glial cells. These findings suggest that following optic nerve crush, the levels of endogenous SDF-1α and CXCR4 increase in the retina and optic nerve, where activated glial cells may act as a source of increased SDF-1α protein.

Exploring temporospatial changes in glucose metabolic disorder, learning, and memory dysfunction in a rat model of diffuse axonal injury

Diffuse axonal injury (DAI) is the predominant effect of severe traumatic brain injury and contributes significantly to cognitive deficits. The mechanisms underlying these cognitive deficits are often associated with complex metabolic alterations. However, the relationships between temporospatial alterations in cerebral glucose metabolism and the pathophysiology of DAI-related learning and memory dysfunction are not yet completely understood. We used a small animal positron emission tomography (PET) scanner with 2-[F-18]-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) as a molecular probe to evaluate temporospatial glucose metabolism in vulnerable areas of rats with DAI. The Morris water maze (MWM) was used to evaluate the development and progression of learning and memory dysfunction. Compared to the sham-treated group, PET-MRI fusion images showed that glucose metabolism was reduced in animals with DAI. In addition, the standardized uptake value (SUV) of ¹⁸F-FDG was significantly decreased in the sensorimotor cortex, hippocampus, corpus callosum, caudate putamen, brain stem, and cerebellum at days 1, 3, and 7 after injury. SUV returned to baseline levels by 30 days after injury. The escape latency of the injured group was significantly increased, and the percentages of distance travelled and time spent in the target quadrant were significantly decreased 1 month after injury. These effects persisted for 3 months. SUVs in the hippocampus at the acute stage were significantly correlated with MWM performance during the recovery stage of DAI. These results demonstrate that microstructural injury-induced hypometabolism in the hippocampus at the acute stage are all significantly correlated with learning and memory dysfunctions during the recovery stage of DAI.

In vitro and in vivo radiosensitization induced by hydroxyapatite nanoparticles

BACKGROUND

Previous study showed that hydroxyapatite nanoparticles (nano-HAPs) inhibited glioma growth in vitro and in vivo; and in a drug combination, they could reduce adverse reactions. We investigated the possible enhancement of radiosensitivity induced by nano-HAPs.

METHODS

In vitro radiosensitization of nano-HAPs was measured using a clonogenic survival assay in human glioblastoma U251 and breast tumor brain metastatic tumor MDA-MB-231BR cells. DNA damage and repair were measured using γH2AX foci, and mitotic catastrophe was determined by immunostaining. The effect of nano-HAPs on in vivo tumor radiosensitivity was investigated in a subcutaneous and an orthotopic model.

RESULTS

Nano-HAPs enhanced each cell line's radiosensitivity when the exposure was 1 h before irradiation, and they had no significant effect on irradiation-induced apoptosis or on the activation of the G2 cell cycle checkpoint. The number of γH2AX foci per cell was significantly large at 24 h after the combination modality of nano-HAPs + irradiation compared with single treatments. Mitotic catastrophe was also significantly increased at an interval of 72 h in tumor cells receiving the combined modality compared with the individual treatments. In a subcutaneous model, nano-HAPs caused a larger than additive increase in tumor growth delay. In an orthotopic model, nano-HAPs significantly reduced tumor growth and extended the prolongation of survival induced by irradiation.

CONCLUSIONS

These results show that nano-HAPs can enhance the radiosensitivity of tumor cells in vitro and in vivo through the inhibition of DNA repair, resulting in an increase in mitotic catastrophe.

Predictive value of the SLC22A18 protein expression in glioblastoma patients receiving temozolomide therapy

Background

Our previous study showed that SLC22A18 downregulation and promoter methylation were associated with the development and progression of glioma and the elevated expression of SLC22A18 was found to increase the sensitivity of glioma U251 cells to the anticancer drug 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). In this study, we investigated the predictive value of SLC22A18 promoter methylation and protein expression in glioblastoma multiforme (GBM) patients receiving temozolomide (TMZ) therapy.

Patients and methods

SLC22A18 promoter methylation and protein expression were examined by methylation-specific polymerase chain reaction (MSP) and Western blotting respectively, then we compared SLC22A18 promoter methylation and protein expression in tumor cell explants in regard to prediction of TMZ response and survival time of 86 GBM patients.

Results

SLC22A18 promoter methylation was detected in 61 of 86 (71%) samples, whereas 36 of 86 (42%) cases were scored positive for SLC22A18 protein expression. Overall SLC22A18 promoter methylation was significantly related to SLC22A18 protein expression, but a subgroup of cases did not follow this association. Multivariate Cox regression analysis indicated that SLC22A18 protein expression, but not promoter methylation, was significantly correlated with TMZ therapy. SLC22A18 protein expression predicted a significantly shorter overall survival in 51 patients receiving TMZ therapy, whereas no differences in overall survival were observed in 35 patients without TMZ therapy.

Conclusions

These results show that lack of SLC22A18 protein expression is superior to promoter methylation as a predictive tumor biomarker in GBM patients receiving temozolomide therapy.

Relationship between SATB1 expression and prognosis in astrocytoma

Special AT-rich-sequence-binding protein 1 (SATB1), a new type of gene regulator, has been reported to be expressed in various human cancers and may be associated with malignancy. The aim of this study was to investigate the expression of SATB1 in astrocytoma and to determine its prognostic value for the overall survival of patients with astrocytoma. The expression of SATB1 protein and messenger RNA (mRNA) in human astrocytoma specimens was examined using immunohistochemistry and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The relationship between SATB1 expression and O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status was also investigated. Spearman's correlation coefficient was used to describe the association between SATB1 expression and the clinical parameters of astrocytoma patients. SATB1 protein and mRNA were expressed at significant levels in astrocytoma specimens. SATB1 expression was positively correlated with astrocytoma pathological grade but negatively correlated with the life span of astrocytoma patients. SATB1 expression was also significantly lower in astrocytoma specimens with MGMT promoter methylation than in those without MGMT promoter methylation. Our findings suggest that SATB1 may have an important role as a positive regulator of astrocytoma development and progression and that SATB1 might be a useful molecular marker for predicting the prognosis of patients with astrocytoma and could be a novel target for treating astrocytoma.

Upregulation of SATB1 is associated with the development and progression of glioma

Background

Special AT-rich sequence-binding protein-1 (SATB1) has been reported to be expressed in several human cancers and may have malignant potential. This study was aimed at investigating the expression and potential role of SATB1 in human glioma.

Method

The relationship between SATB1 expression, clinicopathological parameters, Ki67 expression and MGMT promoter methylation status was evaluated, and the prognostic value of SATB1 expression in patients with gliomas was analyzed. SATB1-specific shRNA sequences were synthesized, and U251 cells were transfected with SATB1 RNAi plasmids. Expression of SATB1 mRNA and protein was investigated by RT-PCR and immunofluoresence staining and western blotting. The expression of c-Met, SLC22A18, caspase-3 and bcl-2 protein was determined by western blotting. U251 cell growth and adherence was detected by methyl thiazole tetrazolium assay. The apoptosis of U251 cells was examined with a flow cytometer. The adherence, invasion, and in vitro angiogenesis assays of U251 cells were done. The growth and angiogenesis of SATB1 low expressing U251 cells was measured in an in vivo xenograft model.

Results

Of 70 tumors, 44 (62.9%) were positive for SATB1 expression. SATB1 expression was significantly associated with a high histological grade and with poor survival in univariate and multivariate analyses. SATB1 expression was also positively correlated with Ki67 expression but negatively with MGMT promoter methylation in glioma tissues. SATB1 shRNA expression vectors could efficiently induce the expression of SLC22A18 protein, increase the caspase-3 protein, inhibit the expression of SATB1, c-Met and bcl-2 protein, the growth, invasion, metastasis and angiogenesis of U251 cells, and induce apoptosis in vitro. Furthermore, the tumor growth of U251 cells expressing SATB1 shRNA were inhibited in vivo, and immunohistochemical analyses of tumor sections revealed a decreased vessel density in the animals where shRNA against SATB1 were expressed.

Conclusions

SATB1 may have an important role as a positive regulator of glioma development and progression, and that SATB1 might be a useful molecular marker for predicting the prognosis of glioma.

Hydroxyapatite nanoparticles inhibit the growth of human glioma cells in vitro and in vivo

Hydroxyapatite nanoparticles (nano-HAPs) have been reported to exhibit antitumor effects on various human cancers, but the effects of nano-HAPs on human glioma cells remain unclear. The aim of this study was to explore the inhibitory effect of nano-HAPs on the growth of human glioma U251 and SHG44 cells in vitro and in vivo. Nano-HAPs could inhibit the growth of U251 and SHG44 cells in a dose- and time-dependent manner, according to methyl thiazoletetrazolium assay and flow cytometry. Treated with 120 mg/L and 240 mg/L nano-HAPs for 48 hours, typical apoptotic morphological changes were noted under Hoechst staining and transmission electron microscopy. The tumor growth of cells was inhibited after the injection in vivo, and the related side effects significantly decreased in the nano-HAP-and-drug combination group. Because of the function of nano-HAPs, the expression of c-Met, SATB1, Ki-67, and bcl-2 protein decreased, and the expression of SLC22A18 and caspase-3 protein decreased noticeably. The findings indicate that nano-HAPs have an evident inhibitory action and induce apoptosis of human glioma cells in vitro and in vivo. In a drug combination, they can significantly reduce the adverse reaction related to the chemotherapeutic drug 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU).

Correlation of low SLC22A18 expression with poor prognosis in patients with glioma

We investigated the expression of the putative tumor suppressor SLC22A18 to evaluate it as a prognostic marker in glioma patients. Immunohistochemical and Western blot analyses of clinical tissue samples obtained from 120 patients with glioma were performed. Low expression of SLC22A18 was observed in 71.7% of patients. Loss of SLC22A18 expression in glioma was significantly related to pathological grade (p = 0.003). High pathological grade (World Health Organization III-IV) was correlated with negative (low or absent) expression of SLC22A18, which was correlated with a significantly shorter overall patient survival than in those with positive (high) expression (p = 0.007). Multivariate Cox regression analysis indicated that SLC22A18 expression level is an independent survival prognostic factor for patients with glioma (p = 0.011). Western blotting analysis confirmed decreased expression of SLC22A18 in glioma tissues compared with adjacent brain tissues. This study suggests that SLC22A18 functions as a tumor suppressor in glioma and represents a candidate biomarker for long-term survival in this disease.

Effect of 5-Aza-2'-deoxycytidine on SLC22A18 in glioma U251 cells

SLC22A18 [solute carrier family 22 (organic cation transporter) member 18] is located within the 11p15.5 cluster, and may be a new tumor suppressor gene; evidence of SLC22A18 hypermethylation is documented in several types of human cancers. In order to determine whether SLC22A18 hypermethylation is involved in glioma, we determined the SLC22A18 gene protein expression, mRNA expression and methylation status in glioma U251 cells before and after treatment with 5-Aza-2'‑deoxycytidine (5-Aza-CdR), and observed the change in growth. Glioma U251 cells treated with 5-Aza-CdR were analyzed by flow cytometry to identify any change in their cell cycle profiles. Tumors induced via the injection of untreated U251 cells were measured. Immunohistochemistry, reverse transcriptase-polymerase chain reaction (RT-PCR) and PCR-based methylation assay were carried out to determine SLC22A18 gene protein expression, mRNA expression and methylation status in glioma U251 cells before and after treatment with 5-Aza‑CdR. The treated cells showed an increase in their proportion in G1, from 79.2 to 83.5%, and a decrease in S phase, from 12.4 to 5.8%. The apoptotic rate increased from 6.4 to 15.8%. Tumors induced via the injection of untreated U251 cells were approximately 1.46 cm³ in size, whereas the tumors induced by U251 cells treated with 5-Aza-CdR averaged 0.88 cm³ in size. The expression levels of SLC22A18 protein and mRNA in U251 cells were increased following treatment with 5x10⁻⁷ M 5-Aza‑CdR. Prior to 5-Aza-CdR treatment, the SLC22A18 gene demonstrated hypermethylation and therefore could not be cleaved by HpaII and MspI. It is known that only the DNA digested with HpaII or MspI can be amplified. Following treatment with 5-Aza‑CdR, the SLC22A18 gene became demethylated, and could then be cleaved by both of the enzymes, and this failed to be amplified. 5-Aza-cdR may induce glioma U251 cell division and apoptosis and enhance demethylation and protein and mRNA expression of SLC22A18. The hypermethylation of SLC22A18 may be related to the transcriptional silencing of this gene. The growth inhibitory effects of 5-Aza-CdR treatment in vivo remain recognizable.

Promoter methylation and downregulation of SLC22A18 are associated with the development and progression of human glioma

Background

Downregulation of the putative tumor suppressor gene SLC22A18 has been reported in a number of human cancers. The aim of this study was to investigate the relationship between SLC22A18 downregulation, promoter methylation and the development and progression of human glioma.

Method

SLC22A18 expression and promoter methylation was examined in human gliomas and the adjacent normal tissues. U251 glioma cells stably overexpressing SLC22A18 were generated to investigate the effect of SLC22A18 on cell growth and adherence in vitro using the methyl thiazole tetrazolium assay. Apoptosis was quantified using flow cytometry and the growth of SLC22A18 overexpressing U251 cells was measured in an in vivo xenograft model.

Results

SLC22A18 protein expression is significantly decreased in human gliomas compared to the adjacent normal brain tissues. SLC22A18 protein expression is significantly lower in gliomas which recurred within six months after surgery than gliomas which did not recur within six months. SLC22A18 promoter methylation was detected in 50% of the gliomas, but not in the adjacent normal tissues of any patient. SLC22A18 expression was significantly decreased in gliomas with SLC22A18 promoter methylation, compared to gliomas without methylation. The SLC22A18 promoter is methylated in U251 cells and treatment with the demethylating agent 5-aza-2-deoxycytidine increased SLC22A18 expression and reduced cell proliferation. Stable overexpression of SLC22A18 inhibited growth and adherence, induced apoptosis in vitro and reduced in vivo tumor growth of U251 cells.

Conclusion

SLC22A18 downregulation via promoter methylation is associated with the development and progression of glioma, suggesting that SLC22A18 is an important tumor suppressor in glioma.

Elevated expression of solute carrier family 22 member 18 increases the sensitivity of U251 glioma cells to BCNU

Previous studies showed that solute carrier family 22 member 18 (SLC22A18) is involved in tumorigenesis. The aim of this study was to examine the role of SLC22A18 in glioma cells. Glioma U251 cells were transfected with the human SLC22A18 gene. Transfection of the empty vector pcDNA3.1 was used as a negative control. Sensitivity to BCNU was measured by Annexin V staining. The expression of caspase-3 and bcl-2 was determined by immunohistochemistry. The transfection was confirmed by PCR, RT-PCR and Western blotting. Augmented apoptotic cell death was observed in the SLC22A18-transfected cells, compared to the non-transfected cells or cells with the empty vector. Caspase-3 expression increased in U251-SLC22A18 cells, whereas the bcl-2 expression decreased. These results indicated that SLC22A18 has a pro-apoptotic function in glioma cells.

Expression of HGF and VEGF in the cerebral tissue of adult rats with chronic hydrocephalus after subarachnoid hemorrhage

The hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) are important cytokines with modulatory actions in the nervous system. The present study aimed to investigate the role and expression of HGF and VEGF in the cerebral tissue of adult rats with chronic hydrocephalus after subarachnoid hemorrhage. Adult female Wistar rats were randomly divided into 4 groups: a control group (n=20) and 3 experimental subgroups (n=60). Subarachnoid hemorrhage was induced by the injection of 0.4 ml of non-heparinized autologous arterial blood into the cisterna magna of experimental animals on day 0 with a second injection 2 days later. The rats were sacrificed within 24 h of magnetic resonance imaging (MRI) examination at 2, 4, or 6 weeks. The excised brains were studied by RT-PCR, immunohistochemical and Western blot analyses as we examined HGF and VEGF mRNA and protein expression. Chronic hydrocephalus was induced in 21 rats after subarachnoid hemorrhage. After 2 weeks, the expression of HGF and VEGF in the cerebral tissue was significantly increased in the experimental group compared to the controls, especially in periventricular white matter. Our results indicate that HGF and VEGF participate in the pathological injury and repair of cerebral tissue in rats with chronic hydrocephalus after subarachnoid hemorrhage.

c-Met antisense oligodeoxynucleotides increase sensitivity of human glioma cells to paclitaxel

Cell culture, tissue chemistry and flow cytometry were used to determine whether antisense c-Met oligodeoxynucleotides enhanced the sensitivity of human glioma cells to paclitaxel. A combination of paclitaxel with antisense c-Met oligodeoxynucleotides inhibited cell growth, induced apoptosis and induced c-Met protein expression in U251 and SHG44 human glioma cells more significantly than either paclitaxel or the oligodeoxynucleotides on their own (P<0.01). Thus, c-Met antisense oligodeoxynucleotides increase the sensitivity of human glioma cells to paclitaxel. Combined use of the two agents could be a novel and attractive strategy in human glioma treatment.

Diffuse axonal injury induced by simultaneous moderate linear and angular head accelerations in rats

Diffuse axonal injury (DAI) is one of the most common and important pathologic features of human traumatic brain injury (TBI), accounting for high mortality and development of persistent post-traumatic neurologic sequelae. Although a relatively high number of therapies have been shown to be effective in experimental models, there are currently few treatments that are effective for improving the prognosis of clinical DAI. A major reason is the failure of current models to validly reproduce the pathophysiological characteristics observed after clinical DAI. In the present study, we employed a specially designed, highly controllable model to induce a sudden rotation in the coronal plane (75 degrees rotation at 1.6x10(4) degrees/s) combined with lateral translation (1.57 cm displacement at 3.4x10(2) cm/s) to the rat's head. We were interested in discovering whether the combined accelerations could reproduce the pathophysiological changes analogous to those seen in human DAI. The axonal injury as assessed with amyloid protein precursor (APP) as a marker was consistently present in all injured rats. The commonly injured brain regions included the subcortical regions, deep white matter, corpus callosum and brain stem. The evolution of APP accumulations in brain sections depicted the detailed progression of axonal pathology. Ultrastructural studies gave further insights into the presence and progression of axonal injury. All injured rats exhibited transient physiological dysfunction, as well as immediate and dramatic neurological impairment that still persisted at 14 days after injury. These results suggest that this model reproduced the major pathophysiological changes analogous to those observed after severe clinical TBI and provides an attractive vehicle for experimental brain injury research.

Standardizing optic nerve crushes with an aneurysm clip

OBJECTIVES

Despite the widespread use of optic nerve injury models to simulate central nervous system injury, model protocols vary from laboratory to laboratory, making it difficult to directly compare findings between studies.

METHODS

To standardize the optic nerve crush injury model, the commercially available Yasargil aneurysm clip, which provides a consistent clamping force, was used to produce a crush injury to the rat optic nerve. Histology was verified with hematoxylin-eosin. The number of retinal ganglion cells (RGCs) was counted by fluorescent gold dye labeling.

RESULTS

Following nerve crush injury, the density of RGCs was substantially reduced in the aneurysm clip-operated group relative to the normal and sham-operated groups, and no discernable difference was noted between the latter two control groups.

DISCUSSION

The present findings suggest that Yasargil aneurysm clip effectively produces permanent injury to the optic nerve with evidence from retrograde tracing of RGCs and may provide a standard technique for optic nerve crush studies.

Diffuse axonal injury: novel insights into detection and treatment

Diffuse axonal injury (DAI) is one of the most common and important pathologic features of traumatic brain injury. The definitive diagnosis of DAI, especially in its early stage, is difficult. In addition, most therapeutic agents for patients with DAI are non-specific. The CT scan is widely used to identify signs of DAI. Although its sensitivity is limited to moderate to severe DAI, it remains a useful first-line imaging tool that may also identify co-morbid injuries such as intracerebral hemorrhage. Recently, investigations have sought to apply advanced imaging techniques and laboratory techniques to detect DAI. Meanwhile, some potential specific treatments that may protect injured axons or stimulate axonal regeneration have been developed. We review some new diagnostic technologies and specific therapeutic strategies for DAI.

c-Met-targeted RNA interference inhibits growth and metastasis of glioma U251 cells in vitro

Angiogenesis plays an essential role in tumor growth and metastasis and is a promising target for cancer therapy. c-Met, a receptor tyrosine kinase, and its ligand, hepatocyte growth factor (HGF), are critical in cellular proliferation, motility, invasion, and angiogenesis. The present study was designed to determine the role of c-Met in growth and metastasis of glioma U251 cells using RNA interference (RNAi) technology in vitro. We constructed three kinds of shRNA expression vectors aiming at the c-Met gene, then transfected them into glioma U251 cells by lipofectamine(TM) 2000. The level of c-Met mRNA was investigated by real-time polymerse chain reaction (RT-PCR). The protein expression of c-Met was observed by immunofluoresence staining and western blotting. U251 cell growth and adherence was detected by methyl thiazole tetrazolium assay. The apoptosis of U251 cells was examined with a flow cytometer. The adherence, invasion, and in vitro angiogenesis assays of U251 cells were done. We got three kinds of c-Met specific shRNA expression vectors which could efficiently inhibit the growth and metastasis of U251 cells and the expression of c-Met in U251 cells. RT-PCR, immunofluoresence staining and western blotting showed that inhibition rate for c-Met expression was up to 90%, 79% and 85%, respectively. The expression of c-Met can be inhibited by RNA interference in U251 cells, which can inhibit the growth and metastasis of U251 cell and induce cell apoptosis. These results indicate that RNAi of c-Met can be an effective antiangiogenic strategy for glioma.

Stabilization of hepatocyte growth factor mRNA by hypoxia-inducible factor 1

Hypoxia regulates expression of hepatocyte growth factor (HGF) by increasing its transcription and by stabilizing its mRNA. Despite the pivotal role of hypoxia-inducible factor 1 (HIF-1) in transcriptional activation of hypoxia-responsive genes, it is not known whether HIF-1 mediates hypoxia-induced stabilization of HGF mRNA. We constructed adenoviral vectors expressing either the wild-type HIF-1alpha (Ad2/HIF-1alpha/FL), a constitutively stable hybrid form of HIF-1alpha (Ad2/HIF-1alpha/VP16), or no transgene (Ad2/CMVEV). In rat glioma (C6) cells, human glioma (U251) cells human cardiac, vascular smooth muscle, and endothelial cells, infection with Ad2/HIF-1alpha/VP16 or Ad2/HIF-1alpha/FL increased HGF expression at both the mRNA and protein levels. Under normoxic conditions, the half-life of HGF mRNA was 43 min in C6 and U251 cells. Hypoxia and Ad2/HIF-1alpha/VP16 increased the half-life of HGF mRNA to 3.2 and 2.8 h, respectively, while Ad2/CMVEV had no effect. These studies are the first to demonstrate that overexpression of HIF-1alpha increases HGF mRNA stability. Our results also suggest that stabilization of HGF mRNA by hypoxia is mediated, at least in part, by HIF-1.

c-Met antisense oligodeoxynucleotides as a novel therapeutic agent for glioma: in vitro and in vivo studies of uptake, effects, and toxicity

BACKGROUND

c-Met, a receptor tyrosine kinase, and its ligand, hepatocyte growth factor, are critical in cellular proliferation, motility, and invasion and are known to be overexpressed in gliomas. The aim of our study was to investigate the uptake and effects of c-Met antisense oligodeoxynucleotides (ASODNs) on rat and human glioma cells in vitro and the uptake and toxicity of these nucleotides in rat carcinomatosis and brain tumor models.

MATERIALS AND METHODS

The three human cell lines (U87, BT325, SHG44) and the C6 rat glioma cell line were cultured. To study the uptake of oligodeoxynucleotides (ODNs) by glioma cells in vitro, cultured glioma cells readily incorporated caroboxyfluorescein-5-succimidyl ester (FAM) labeled phosphorothioate oligodeoxynucleotides, as demonstrated by immunofluorescence microscopy and flow cytometry. To study the effect of ASODNs treatment on c-Met expression in vitro, Expression of c-Met was assessed by immunofluorescence microscopy and reverse transcriptase polymerase chain reaction (RT-PCR) analysis. For animal studies of ODNs toxicity and uptake, eight rats underwent placement of cisternal catheters, under general anesthesia. Four rats were given 24 mug FAM-labeled ASODNs while the others were given a saline control injection. After a 24 h observation period, rats were sacrificed by barbiturate overdose, and their brains were studied.

RESULTS

For all cell lines, fluorescence was seen to increase with increasing ASODNs concentration. Cells treated in similar fashion were also analyzed by flow cytometry to graphically illustrate the differing fluorescence. Multiple glioma cell lines were tested, with similar results. c-Met ASODNs was found to be successfully incorporated from the media into cultured human glioma cells, even at concentrations as low as 2 muM. In addition, maintenance of the pH-dependent green fluorescence color, as seen by immunofluorescence microscopy and by using flow cytometry, indicated that the FAM was not contained within lysosomes. Immunofluorescence microscopy and RT-PCR analysis showed decreases in c-Met expression with oligodeoxynucleotides treatment. Uptake into tumor cells was also demonstrated in vivo, with no detectable toxicity at concentrations exceeding expected therapeutic levels.

CONCLUSION

These data are encouraging for further study of c-Met antisense oligodeoxynucleotides as a therapeutic modality for glioma.

Determining divergence times with a protein clock: update and reevaluation

A recent study of the divergence times of the major groups of organisms as gauged by amino acid sequence comparison has been expanded and the data have been reanalyzed with a distance measure that corrects for both constraints on amino acid interchange and variation in substitution rate at different sites. Beyond that, the availability of complete genome sequences for several eubacteria and an archaebacterium has had a great impact on the interpretation of certain aspects of the data. Thus, the majority of the archaebacterial sequences are not consistent with currently accepted views of the Tree of Life which cluster the archaebacteria with eukaryotes. Instead, they are either outliers or mixed in with eubacterial orthologs. The simplest resolution of the problem is to postulate that many of these sequences were carried into eukaryotes by early eubacterial endosymbionts about 2 billion years ago, only very shortly after or even coincident with the divergence of eukaryotes and archaebacteria. The strong resemblances of these same enzymes among the major eubacterial groups suggest that the cyanobacteria and Gram-positive and Gram-negative eubacteria also diverged at about this same time, whereas the much greater differences between archaebacterial and eubacterial sequences indicate these two groups may have diverged between 3 and 4 billion years ago.

Converting amino acid alignment scores into measures of evolutionary time: a simulation study of various relationships

Amino acid substitution tables are essential for the proper alignment of protein sequences, and alignment scores based on them can be transformed into distance measures by various means. In the simplest case, the negative log of the score is used. This Poisson relationship assumes that all sites are equally likely to change, however. A more accurate relationship would correct for different rates of change at each residue position. Recently, Grishin (J. Mol. Evol. 41:675-679, 1995) published a set of simple equations that correct for various circumstances, including different rates of change at different sites. We have used these equations in conjunction with similarity scores that take into account constraints on amino acid interchange. Simulation studies show a linear relationship between these calculated distances and the numbers of allowed mutations based on the observed variation of rate at all sites in various proteins.

Determining divergence times of the major kingdoms of living organisms with a protein clock

Amino acid sequence data from 57 different enzymes were used to determine the divergence times of the major biological groupings. Deuterostomes and protostomes split about 670 million years ago and plants, animals, and fungi last shared a common ancestor about a billion years ago. With regard to these protein sequences, plants are slightly more similar to animals than are the fungi. In contrast, phylogenetic analysis of the same sequences indicates that fungi and animals shared a common ancestor more recently than either did with plants, the greater difference resulting from the fungal lineage changing faster than the animal and plant lines over the last 965 million years. The major protist lineages have been changing at a somewhat faster rate than other eukaryotes and split off about 1230 million years ago. If the rate of change has been approximately constant, then prokaryotes and eukaryotes last shared a common ancestor about 2 billion years ago, archaebacterial sequences being measurably more similar to eukaryotic ones than are eubacterial ones.

Molecular cloning of silkworm (Bombyx mori) antichymotrypsin. A new member of the serpin superfamily of proteins from insects

The cDNA of silkworm (Bombyx mori) antichymotrypsin (sw-Achy) was cloned from larval fat body and its nucleotide sequence was determined. The deduced amino acid sequence of mature sw-Achy begins with Phe1 and ends with Phe384, with a preceding 16-amino-acid signal peptide. The amino-acid sequence similarities of sw-Achy with the serine-proteinase inhibitors (serpins) silkworm antitrypsin, tobacco hornworm alaserpin, human alpha-1-antitrypsin and human alpha-1-antichymotrypsin were 29.6%, 30.3%, 26.1%, and 25.0%, respectively. The highly conserved amino acids in other serpins are also conserved in sw-Achy. sw-Achy is thought to be a new member of the serpin family. Multiple alignment of sw-Achy with 23 other kinds of serpin by the progressive method produced a phylogenetic tree in which all four insect serpins are grouped separately within one branch. The reactive site of sw-Achy with alpha-chymotrypsin was identified as Thr343-Ser344 by direct amino-acid sequence analysis of cleaved and purified protein.