2′,3′-cyclic nucleotide phosphodiesterase (CNPase) as a target in neurodegenerative diseases

We review the structure, characteristics, post-translational modifications, and functioning of 2′,3′-cyclic nucleotide phosphodiesterase (CNPase) localized in the CNS myelin and Schwann cells, as well as previously unknown properties of this protein, which was identified in brain mitochondria. We summarize the data on the localization of CNPase in the cell, the specificity of its substrates, the characteristics of the N- and C-terminals of the molecule, and its interactions with proteins-partners and nucleic acids. We describe the possible role of CNPase in ageing and neurodegenerative diseases, such as Alzheimer’s disease and multiple sclerosis, with the main emphasis on the role of mitochondria in these processes.     

The myelin membrane-associated enzyme 2′,3′-cyclic nucleotide 3′-phosphodiesterase：on a highway to structure and function

The membrane-anchored myelin enzyme 2′,3′-cyclic nucleotide 3′-phosphodiesterase（CNPase） was discovered in the early 1960 s and has since then troubled scientists with its peculiar catalytic activity and high expression levels in the central nervous system. Despite decades of research, the actual physiological relevance of CNPase has only recently begun to unravel. In addition to a role in myelination, CNPase is also involved in local adenosine production in traumatic brain injury and possibly has a regulatory function in mitochondrial membrane permeabilization. Although research focusing on the CNPase phosphodiesterase activity has been helpful, several open questions concerning the protein function in vivo remain unanswered. This review is focused on past research on CNPase, especially in the fields of structural biology and enzymology, and outlines the current understanding regarding the biochemical and physiological significance of CNPase, providing ideas and directions for future research.     

Immunohistochemical study on the distribution of α and β subunits of S-100 protein in brain tumors

Summary The immunohistochemical distribution of and subunits of S-100 protein (S-100, S-100, respectively) in 138 cases of human brain tumors was investigated by the avidin-biotin immunoperoxidase method. Brain tumors can be divided into four groups: group 1 [S-100 (+) and/or S-100 (+)]; astrocytoma, glioblastoma, ependymoma, subependymoma, oligodendroglioma, choroid plexus papilloma, gangliocytoma, meningioma, chordoma, malignant melanoma. Group 2 [S-100 (+) and S-100 (-)]; pineoblastoma, pituitary adenoma, craniopharyngioma, rhabdomyosarcoma. Group 3 [S-100 (-) and S-100 (+)]; acoustic Schwannoma. Group 4 [S-100 (-) and S-100 (-)]; medulloblastoma, malignant lymphoma, germinoma. The S-100 immunoreactivity pattern in brain tumors was similar to those obtained using conventional anti-S-100 protein sera. In the first group of brain tumors both the number of positively stained tumor cells and the staining intensity were generally greater for S-100 than for S-100 with a few exceptions including one gemistocytic astrocytoma, one subependymoma, one malignant melanoma, and some cases of glioblastomas. As to the relationship between malignancy and S-100 protein in glioma, S-100 immunoreactivity decreased according to degree of malignancy, while that of S-100 varied, suggesting a heterogeneity of tumor cells in glioblastomas. Immunostaining for S-100 and S-100 might become a useful diagnostic procedure in brain tumors and may give us more detailed and precise data of S-100 protein in brain tumors.     

2′, 3′-Cyclic nucleotide 3′-phosphodiesterase activity in the cerebrospinal fluid of patients with demyelinating diseases

We aimed to study the level of CNPase activity in the cerebrospinal fluid of patients with demyelinating diseases and other neurological diseases, particularly multiple sclerosis, with reference to CSF myelin basic protein content. CNPase activity was measured paper chromatographically using radioactive 2′,3′-cAMP as a substrate. Myelin basic protein content was measured with a radioimmunoassay. The mean level of CNPase activity was significantly higher for multiple sclerosis than for nonneurological controls. Dividing the disease phases of multiple sclerosis into the three periods, the CNPase activity was found to be significantly elevated in the worsening period and reduced in the improving period and the inactive period. The level of CNPase activity in the cerebrospinal fluid of multiple sclerosis coincided with the clinical activity of the disease. The level of CNPase activity correlated well (r=0.84) with the level of myelin basic protein content in cerebrospinal fluid. The ratio for CNPase activity and myelin basic protein content in cerebrospinal fluid was almost the same as that in human central nerve myelin. We concluded that CNPase activity in the cerebrospinal fluid from neurological patients is an indicator of destruction of myelin in the central nervous system, and the measurement of CNPase activity in the cerebrospinal fluid of multiple sclerosis could be useful in the clinical management.     

Effects of adenosine 3′, 5′-cyclic monophosphate on thermoregulation in both rats and rabbits

Summary The effects of intraventricular administration of dibutyryl adenosine 3, 5-cyclic monophosphate (db cyclic AMP) on the thermoregulatory responses of unanesthetized rats and rabbits to different ambient temperatures (T_a) were assessed. Administration of db cyclic AMP (10–60 mM) produced dose-dependent hypothermia in both rats and rabbits at T_a 2–22 °C. The hypothermia in response to db cyclic AMP was due to decreased metabolic heat production and cutaneous vasodilatation. There was no change in respiratory evaporative heat loss. In contrast, in the heat (30–32 °C), db cyclic AMP administration produced dose-dependent hyperthermia in these animals. The hyperthermia was due to increased metabolism (due to muscular shivering) and decreased heat losses. The reduction in heat losses was shown by a decrease in both cutaneous circulation and respiratory evaporative heat loss. The data demonstrate that the thermoregulatory responses induced by central administration of db cyclic AMP are T_a-dependent.     

Contents of myelin-basic protein and S-100 in serum and brain tissue of neonatal rats with intrauterine infection-caused brain injury

INTRODUCTION Recent researches demonstrated that the disorder or delay of myeli- nation in central nervous system (CNS) relates to intrauterine infec- tion and brain injury in perinatal period. More and more researches showed that intrauterine infection w…     

γ-Enolase and glial fibrillary acidic protein in nervous system tumors

Summary A large series of central and peripheral nervous system tumors was studied for the presence of glial fibrillary acidic protein (GFAP) and -enolase (neuron-specific enolase, NSE), using specific monoclonal antibodies (mAbs). Occurrence in and specificity of GFAP to glial and mixed tumors was confirmed and depended on the malignancy grade and features such as meningeal invasion. Using a well-characterized mAb, -enolase was demonstrated in neuronal, as well as in a whole range of non-neuronal tumors. This lack of specificity of -enolase prohibits its use as an exclusive neuronal marker. Nevertheless quantization or comparison with other types of enolases could still prove to be useful in well-defined situations. The advantages inherent to mAbs and a highly sensitive detection system turn GFAP stainings into a specific and readily reproducible technique.Supported in part by FGWO (grant no. 3.0019.86) and by the Geconcerteerde Actie (grant no. 84/89-68, Brain specific proteins)     

Alternations of 14-3-3 θ and β protein levels in brain during experimental sepsis

The 14-3-3 family members play a crucial role in the determination of cell fate, exerting their antiapoptotic activity through directly interfering with the critical function of the mitochondrial core proapoptotic machinery. Dimerization of 14-3-3 is vital for the interaction with many of its client proteins and is regulated by phosphorylation. In a previous study, we observed time-dependent neuronal apoptosis during sepsis. Therefore, in the present study, we sought to evaluate the expression of 14-3-3 θ and β isoforms in septic brain and their association with apoptosis. Sepsis was induced by a CLP model in Wistar rats that were sacrificed at predefined time points. Flow cytometric analysis showed a sepsis-induced, time-dependent alteration of 14-3-3 θ and β isoforms in both Neun(+) and GFAP(+) cells. 14-3-3 θ was linearly correlated with apoptosis, and stratified analysis for alive and apoptotic neuronal cells demonstrated a gradual down-regulation of θ isoform in alive neurons and astrocytes. The phospho-P38 (pP38) MAP kinase levels were altered in a time-dependent manner during sepsis, presenting a peak at 6 hr post-CLP. A significant correlation between the two isoforms of 14-3-3 was observed in septic rats, with the θ isoform predominant at all time points. The hippocampus, Purkinje cells, and glia-like cells showed intense immunohistochemical reactivity for 14-3-3 θ isoform, whereas the choroid plexus showed constantly increased β isoform expression. Our results showed that sepsis alters the expression of both 14-3-3 θ and β isoforms in a time-, cell-, and topography-dependent manner.     

Cell apoptosis in perihematomal brain regions and expression of Caspase-3 protein in patients with hypertensive intracerebral hemorrhage

INTRODUCTION Hypertensive intracerebral hemorrhage (HICH) has high mortality and morbidity rates. But effective therapeutic methods are still needed at present. Recent evidences from laboratory models suggest that cell death in the perihematomal region ma…     

L-2-hydroxyglutaric aciduria and brain malignant tumors: a predisposing condition?

L-2-hydroxyglutaric aciduria is a rare metabolic encephalopathy displaying a subcortical leukoencephalopathy on MRI. Diagnosis rests on detection of an abnormal accumulation of L-2-hydroxyglutaric acid in body fluids. The authors report on four patients who developed a malignant brain tumor during the course of the disease. This association points to a possible role of L-2-hydroxyglutaric aciduria in predisposing to brain tumorigenesis.     

Induction of glutathione S-transferase,placental type in T9 glioma cells by dibutyryladenosine 3′,5′-cyclic monophosphate and modification of its expression by naturally occurring isothiocyanates

Summary The effect of dibutyryladenosine 3,5-cyclic monophosphate (dibutyryl cAMP) on the expression of glutathione S-transferase placental type (GST-P) was examined in rat glioma cell line using an immunohistochemical technique. Cultured T9 glioma cells were negative for GST-P activity under normal conditions. However, treatment with 1 mM dibutyryl cAMP produced GST-P expression in about 50% of the cells, as well as some morphological changes. The expression of GST-P was increased with addition of dibutyryl cAMP together with 1 g/ml allyl isothiocyanate (AITC) or 0.1 g/ml benzyl isothiocyanate (BITC). With these combinated treatments, almost all cultured cells showed a strong positive reaction for GST-P, although AITC or BITC alone elicited GST-P in only 5% of the cultured cells. The results of the present study indicate that dibutyryl cAMP causes functional as well as morphological differentiation of T9 glioma cells.     

Do animals and furniture items elicit different brain responses in human infants?

One of the earliest categorical distinctions to be made by preverbal infants is the animate–inanimate distinction. To explore the neural basis for this distinction in 7–8-month-olds, an equal number of animal and furniture pictures was presented in an ERP-paradigm. The total of 118 pictures, all looking different from each other, were presented in a semi-randomized order for 1000 ms each. Infants’ brain responses to exemplars from both categories differed systematically regarding the negative central component (Nc: 400–600 ms) at anterior channels. More specifically, the Nc was enhanced for animals in one subgroup of infants, and for furniture items in another subgroup of infants. Explorative analyses related to categorical priming further revealed category-specific differences in brain responses in the late time window (650–1550 ms) at right frontal channels: Unprimed stimuli (preceded by a different-category item) elicited a more positive response as compared to primed stimuli (preceded by a same-category item). In sum, these findings suggest that the infant’s brain discriminates exemplars from both global domains. Given the design of our task, we conclude that processes of category identification are more likely to account for our findings than processes of on-line category formation during the experimental session.     

Differential expression of β-catenin in human glioblastoma multiforme and normal brain tissue

Abstract

Angiogenesis is considered to play an important role in the development of malignant brain tumors, especially glioblastoma multiforme (GBM). Abnormal vascular construction with a glomeruloid appearance is characteristic of GBM. β-catenin is known as one of the adhesive molecules associated not only with cell adhesion and cell polarity, but also with carcinogenesis. We postulated the relevance of β-catenin to vigorous endothelial proliferation in human GBM because the vascular cells (VCs) are apt to lose their cell polarity. The object of this study is to compare the immunohistochemical localization of β-catenin in VCs between GBMs and normal brain tissues. Immunohistochemical analysis of P-eatenin for VCs in 32 GBMs and 10 normal brain tissues was performed. β-catenin was found concentrated in the areas of vascular cell-cell junction and internal surface of the vascular lumen in all normal brains. In contrast, β-catenin, in proliferating VCs in GBMs, was stained homogeneously and intensely in the cytoplasms of 26 cases (81.3%), in which nuclear staining of β-catenin was also recognized in four cases (12.5%). In conclusion, the intracellular localization of β-catenin in VCs of GBMs was found to be different from that of normal brain tissues. The changes of expression of β-catenin may be associated with the angiogenesis or transformation of the VCs in human GBM. [Neurol Res 2000; 22: 650-656]     

Effect of cyclovirobuxine D on human growth-associated protein 43 and neurocan expression in ischemic brain tissue of stroke-prone renovascular hypertensive rats*★

BACKGROUND： Experimental data indicate that human growth-associated protein 43 mRNA expression coincides with axonal growth during nerve ganglion development; while neurocan, secreted from astrocytes, can inhibit sprouting and elongation of the axonal growth cone. OBJECTIVE： To verify regulatory effects of cyclovirobuxine D （CVB-D） extracted from Chinese box branchlet on human growth-associated protein 43 （GAP-43）, and neurocan expression in brain tissue of stroke-prone renovascular hypertensive （RHRSP） rats, at different time points after cerebral ischemia/reperfusion. DESIGN： Randomized grouping design and controlled animal study. SETTING： This study was performed at the Center of Guangdong Hospital of Traditional Chinese Medicine （a national key laboratory） from March 2003 to September 2006. MATERIALS： 100 healthy male Sprague-Dawley rats, aged 2 3 months and weighing 90-120 g, were selected for this study. CVB-D was provided by Nanjing Xiaoying Pharmaceutical Factory （Batch number： 307701）. METHODS： The initial tip of renal arteries was clamped bilaterally for 10 weeks to establish the RHRSP model. 100 RHRSP rats were randomly divided into 4 groups： naive group （n = 10）, sham surgery group （n = 10）, CVB-D group （n = 40）, and lesion group （n = 40）. Rats in the naive group did not undergo any treatment, and cervical vessels of rats in the sham surgery group were exposed, but not blocked. The right middle cerebral artery of rats in the CVB-D group and lesion group were occluded to establish cerebral ischemia. Rats in the CVB-D group were intraperitoneally injected with CVB-D （6.48 mg/kg） every day and with saline （1.5 mL/injection） twice a day. Rats in the lesion group were intraperitoneally injected with saline （2 mL/injection）. MAIN OUTCOME MEASURES： Immunohistochemistry was applied to detect GAP-43 and neurocan expression in the ischemic penumbra region of CVB-D and lesion brains at 2 hours post-cerebral ischemia and at 1, 7, 14, and 30 days po     

Amyloid β precursor protein regulates neuron survival and maturation in the adult mouse brain

The amyloid-β precursor protein (APP) is a transmembrane protein that is widely expressed within the central nervous system (CNS). While the pathogenic dysfunction of this protein has been extensively studied in the context of Alzheimer's disease, its normal function is poorly understood, and reports have often appeared contradictory. In this study we have examined the role of APP in regulating neurogenesis in the adult mouse brain by comparing neural stem cell proliferation, as well as new neuron number and morphology between APP knockout mice and C57bl6 controls. Short-term EdU administration revealed that the number of proliferating EdU⁺ neural progenitor cells and the number of PSA-NCAM⁺ neuroblasts produced in the SVZ and dentate gyrus were not affected by the life-long absence of APP. However, by labelling newborn cells with EdU and then following their fate over-time, we determined that ~ 48% more newly generated EdU⁺ NeuN⁺ neurons accumulated in the granule cell layer of the olfactory bulb and ~ 57% more in the dentate gyrus of young adult APP knockout mice relative to C57bl6 controls. Furthermore, proportionally fewer of the adult-born olfactory bulb granule neurons were calretinin⁺. To determine whether APP was having an effect on neuronal maturation, we administered tamoxifen to young adult Nestin-CreER^T2::Rosa26-YFP and Nestin-CreER^T2::Rosa26-YFP::APP-knockout mice, fluorescently labelling ~ 80% of newborn (EdU⁺) NeuN⁺ dentate granule neurons formed between P75 and P105. Our analysis of their morphology revealed that neurons added to the hippocampus of APP knockout mice have shorter dendritic arbors and only half the number of branch points as those generated in C57bl6 mice. We conclude that APP reduces the survival of newborn neurons in the olfactory bulb and hippocampus, but that it does not influence all neuronal subtypes equally. Additionally, APP influences dentate granule neuron maturation, acting as a robust regulator of dendritic extension and arborisation.