An emerging role of inflammasomes in spinal cord injury and spinal cord tumor.

Spinal cord injury (SCI) and spinal cord tumor are devastating events causing structural and functional impairment of the spinal cord and resulting in high morbidity and mortality; these lead to a psychological burden and financial pressure on the patient. These spinal cord damages likely disrupt sensory, motor, and autonomic functions. Unfortunately, the optimal treatment of and spinal cord tumors is limited, and the molecular mechanisms underlying these disorders are unclear. The role of the inflammasome in neuroinflammation in diverse diseases is becoming increasingly important. The inflammasome is an intracellular multiprotein complex and participates in the activation of caspase-1 and the secretion of pro-inflammatory cytokines such as interleukin (IL)-1ß and IL-18. The inflammasome in the spinal cord is involved in the stimulation of immune-inflammatory responses through the release of pro-inflammatory cytokines, thereby mediating further spinal cord damage. In this review, we highlight the role of inflammasomes in SCI and spinal cord tumors. Targeting inflammasomes is a promising therapeutic strategy for the treatment of SCI and spinal cord tumors.

Unusual form of the distal bone defect of ulna with neurofibromatosis type 1: A case report.

RATIONALE: Bone malformation occurs in 10% to 25% neurofibromatosis type 1 (NF-1) patients, and the manifestations are scoliosis, congenital arch and pseudo-joint formation, bone cyst, and pathologic fracture. However, a large segmental defect without obvious signs of bone destruction has rarely been reported. PATIENT CONCERNS: A 4.5-year-old male presented with a 4-year history of shortening of the right upper limb and radial head dislocation. The X-ray indicated a lack of the distal part of the right ulna and radial head dislocation. DIAGNOSIS: The X-ray showed obvious bone resorption at the right ulna distal, proximal stubble, and distal part of the epiphyseal residue, which was 4.3 mm shorter after 14 months. The patient was finally diagnosed with NF-1 according to the pathologic examination. INTERVENTIONS: The treatment included tumor resection, ulnar osteotomy, and fixation by an Ilizarov frame. OUTCOMES: The Ilizarov frame was removed after 2.7 months of surgery. The radial head was successfully repositioned, and the elbow joint function was significantly improved. No recurrence of the deformity was noted until now. LESSONS: Osteolysis (defect without bone destruction) is an extremely rare symptom in patients with NF1. Therefore, it is essential to make the right diagnosis by comprehensive and careful physical examination.

Bioenergetic state regulates innate inflammatory responses through the transcriptional co-repressor CtBP.

The innate inflammatory response contributes to secondary injury in brain trauma and other disorders. Metabolic factors such as caloric restriction, ketogenic diet, and hyperglycemia influence the inflammatory response, but how this occurs is unclear. Here, we show that glucose metabolism regulates pro-inflammatory NF-κB transcriptional activity through effects on the cytosolic NADH:NAD+ ratio and the NAD(H) sensitive transcriptional co-repressor CtBP. Reduced glucose availability reduces the NADH:NAD+ ratio, NF-κB transcriptional activity, and pro-inflammatory gene expression in macrophages and microglia. These effects are inhibited by forced elevation of NADH, reduced expression of CtBP, or transfection with an NAD(H) insensitive CtBP, and are replicated by a synthetic peptide that inhibits CtBP dimerization. Changes in the NADH:NAD+ ratio regulate CtBP binding to the acetyltransferase p300, and regulate binding of p300 and the transcription factor NF-κB to pro-inflammatory gene promoters. These findings identify a mechanism by which alterations in cellular glucose metabolism can influence cellular inflammatory responses.Several metabolic factors affect cellular glucose metabolism as well as the innate inflammatory response. Here, the authors show that glucose metabolism regulates pro-inflammatory responses through effects on the cytosolic NADH:NAD+ ratio and the NAD(H)-sensitive transcription co-repressor CtBP.

Activation of neuronal NMDA receptors induces superoxide-mediated oxidative stress in neighboring neurons and astrocytes.

Excitotoxic neuronal death is mediated in part by NMDA receptor-induced activation of NOX2, an enzyme that produces superoxide and resultant oxidative stress. It is not known, however, whether the superoxide is generated in the intracellular space, producing oxidative stress in the neurons responding to NMDA receptor activation, or in the extracellular space, producing oxidative stress in neighboring cells. We evaluated these alternatives by preparing cortical neuron cultures from p47(phox-/-) mice, which are unable to form a functional NOX2 complex, and transfecting the cultures at low density with GFP-tagged p47(phox) to reconstitute NOX2 activity in widely scattered neurons. NMDA exposure did not induce oxidative stress or cell death in the nontransfected, p47-phox(-/-) cultures, but did produce oxidative stress and neuronal death in neurons surrounding the transfected, NOX2-competent neurons. This cell-to-cell spread of NMDA-induced oxidative injury was blocked by coincubation with either superoxide dismutase or the anion channel blocker 4'-diisothiocyanostilbene-2,2'-disulphonate, confirming superoxide anion as the mediating oxidant. In neurons plated on a preexisting astrocyte layer, NMDA induced oxidative stress in both the neurons and the astrocytes, and this was also prevented by superoxide dismutase. These findings show that activation of NMDA receptors on one neuron can lead to oxidative stress and cell death in neighboring neurons and astrocytes by a process involving the extracellular release of superoxide by NOX2.

Functional architecture of atrophins.

Vertebrate genomes harbor two Atrophin genes, Atrophin-1 (Atn1) and Atrophin-2 (Atn2). The Atn1 locus produces a single polypeptide, whereas two different protein products are expressed from the Atn2 (also known as Rere) locus. A long, or full-length, form contains an amino-terminal MTA-2-homologous domain followed by an Atrophin-1-related domain. A short form, expressed via an internal promoter, consists solely of the Atrophin domain. Atrophin-1 can be co-immunoprecipitated along with Atrophin-2, suggesting that the Atrophins ordinarily function together. Mutations that disrupt the expression of the long form of Atrophin-2 disrupt early embryonic development. To determine the requirement for Atrophin-1 during development we generated a null allele. Somewhat surprisingly we found that Atrophin-1 function is dispensable. To gain a better understanding of the requirement for Atrophin function during development, an analysis of the functional domains of the three different gene products was carried out. Taken together, these data suggest that Atrophins function as bifunctional transcriptional regulators. The long form of Atrophin-2 has a transcriptional repression activity that is not found in the other Atrophin polypeptides and that is required for normal embryogenesis. Atrophin-1 and the short form of Atrophin-2, on the other hand, can act as potent and evolutionarily conserved transcriptional activators.

Loss of the retrograde motor for IFT disrupts localization of Smo to cilia and prevents the expression of both activator and repressor functions of Gli.

Sonic Hedgehog (Shh) signals are transduced into nuclear ratios of Gli transcriptional activator versus repressor. The initial part of this process is accomplished by Shh acting through Patched (Ptc) to regulate Smoothened (Smo) activity. The mechanisms by which Ptc regulates Smo, and Smo activity is transduced to processing of Gli proteins remain unclear. Recently, a forward genetic approach in mice identified a role for intraflagellar transport (IFT) genes in Shh signal transduction, downstream of Patched (Ptc) and Rab23. Here, we show that the retrograde motor for IFT is required in the mouse for the phenotypic expression of both Gli activator and repressor function and for effective proteolytic processing of Gli3. Furthermore, we show that the localization of Smo to primary cilia is disrupted in mutants. These data indicate that primary cilia act as specialized signal transduction organelles required for coupling Smo activity to the biochemical processing of Gli3 protein.

A focused and efficient genetic screening strategy in the mouse: identification of mutations that disrupt cortical development.

Although the mechanisms that regulate development of the cerebral cortex have begun to emerge, in large part through the analysis of mutant mice (Boncinelli et al. 2000; Molnar and Hannan 2000; Walsh and Goffinet 2000), many questions remain unanswered. To provide resources for further dissecting cortical development, we have carried out a focused screen for recessive mutations that disrupt cortical development. One aim of the screen was to identify mutants that disrupt the tangential migration of interneurons into the cortex. At the same time, we also screened for mutations that altered the growth or morphology of the cerebral cortex. We report here the identification of thirteen mutants with defects in aspects of cortical development ranging from the establishment of epithelial polarity to the invasion of thalamocortical axons. Among the collection are three novel alleles of genes for which mutant alleles had already been used to explore forebrain development, and four mutants with defects in interneuron migration. The mutants that we describe here will aid in deciphering the molecules and mechanisms that regulate cortical development. Our results also highlight the utility of focused screens in the mouse, in addition to the large-scale and broadly targeted screens that are being carried out at mutagenesis centers.

Characterization of a DRE-binding transcription factor from a halophyte Atriplex hortensis.

Environmental stresses, such as salinity, drought and cold, can induce the expression of a large amount of genes. Among these are many transcription factors that regulate the expression of downstream genes by specifically binding to cis-elements or forming transcriptional complexes with other proteins. In the present study, a DREB-like transcription factor gene, named AhDREB1, was isolated from a halophyte Atriplex hortensis. AhDREB1 encoded a protein containing a conserved EREBP/AP2 domain featuring the DREB family. In yeast one-hybrid analysis AhDREB1 protein was specifically bound to DRE elements and activated the expression of the reporter genes of HIS3 and LacZ. The AhDREB1 gene was expressed in roots, stems and leaves of A. hortensis. Salinity induced its expression in roots, but not in other organs. Overexpression of AhDREB1 in transgenic tobacco led to the accumulation of its putative downstream genes. The performance of the transgenic lines was also tested under stressed conditions and two lines were found to be stress-tolerant. These results suggest that the AhDREB1 protein functions as a DRE-binding transcription factor and play roles in the stress-tolerant response of A. hortensis.

AhCMO, regulated by stresses in Atriplex hortensis, can improve drought tolerance in transgenic tobacco.

Choline monooxygenase (CMO) catalyzes the committed step of glycine betaine (GlyBet) biosynthesis in many flowering plants. To investigate its effect on various stress tolerances in plant metabolic engineering, we isolated and characterized the CMO gene from Atriplex hortensis, a GlyBet natural accumulator, and introduced it into tobacco to examine the effect of GlyBet on plant drought and salt tolerance, respectively. In A. hortensis, the expression of AhCMO was induced 3-fold in the root and stem, as well as in the leaf, when plants were treated with 400 mM of NaCl, indicating that the acceleration of GlyBet biosynthesis under salt stress was achieved through the whole plant, including organs without chloroplasts. AhCMO transcription was also regulated by drought, ABA and circadian rhythm. Over-expression of AhCMO improved drought tolerance in transgenic tobacco when cultured in medium containing PEG-6000. The transgenic plants also have a better performance under salt stress.