Proteasome inhibition in medaka brain induces the features of Parkinson's disease.

Recent findings suggest that a defect in the ubiquitin-proteasome system plays an important role in the pathogenesis of Parkinson's disease (PD). A previous report (McNaught et al. 2004) demonstrated that rats systemically injected with proteasome inhibitors exhibited PD-like clinical symptoms and pathology. However, because these findings have not been consistently replicated, this model is not commonly used to study PD. We used medaka fish to test the effect of systemic administration of proteasome inhibitors because of the high level of accessibility of the cerebrospinal fluid in fish. We injected lactacystin or epoxomicin into the CSF of medaka. With proteasome inhibition in the medaka brain, selective dopaminergic and noradrenergic cell loss was observed. Furthermore, treated fish exhibited reduced spontaneous movement. Treatment with proteasome inhibitors also induced the formation of inclusion bodies resembling Lewy bodies, which are characteristic of PD. Treatment with 6-OHDA also induced dopaminergic cell loss but did not produce inclusion bodies. These findings in medaka are consistent with previous results reporting that non-selective proteasome inhibition replicates the cardinal features of PD: locomotor dysfunction, selective dopaminergic cell loss, and inclusion body formation.

Identification of bikunin as an endogenous inhibitor of dynorphin convertase in human cerebrospinal fluid.

Dynorphin-converting enzymes constitute a group of peptidases capable of converting dynorphins to enkephalins. Through the action of these enzymes, the dynorphin-related peptides bind to delta-opioid instead of kappa-opioid receptors, leading to a change in the biological function of the neuropeptides. In this article, we describe the identification of the protein bikunin as an endogenous, competitive inhibitor of a dynorphin-converting enzyme in human cerebrospinal fluid. This protein is present together with its target enzyme in the same body fluids. The K(M) value of the convertase was found to be 9 microm, and the K(i) value of the inhibitor was 1.7 nm. The finding indicates that bikunin may play a significant role as a regulatory mechanism of neuropeptides, where one bioactive peptide is converted to a shorter sequence, which in turn, can affect the action of its longer form.

Activity of cysteine protease inhibitors in human brain tumors.

BACKGROUND: Cysteine proteases (mainly cathepsins B and L) are thought to play an important role in the progress of cancer, including brain tumors. Together with other proteases, they hydrolyze the extracellular matrix and basement membrane proteins, thus enabling the tumor to grow and spread. Therefore cysteine protease inhibitors are regarded as protective factors, able to prevent tumor growth and dissemination. MATERIAL AND METHODS: In this study, the activity of cysteine protease inhibitors (CPIs) was investigated in material derived from patients with brain tumors (astrocytoma and meningioma). The activity of CPIs was measured as antipapain activity in tissue homogenates, cerebrospinal fluid, and serum, with N-benzoyl-DL-arginine-2-naphthylamide hydrochloride (BANA) as a substrate, according to Barret's method. RESULTS: Tumorous tissues showed higher activity of cysteine protease inhibitors than control tissues, but this difference proved to be statistically insignificant. The activity of CPIs was lower in cerebrospinal fluid and serum from patients with brain tumors. CONCLUSIONS: The activity of CPIs measured in brain tumor tissue cannot be taken as a marker of any type of tumor, whereas CPI activity in cerebrospinal fluid and serum may be considered a marker of meningioma. In meningioma patients the level of CPIs may be too low to prevent the host tissues from the growing tumor.

Serum and cerebrospinal fluid cystatin C levels in vascular and Alzheimer's dementia.

INTRODUCTION: Cystatin C, a cysteine protease inhibitor, has been implicated in the neurodegenerative and repair processes of the nervous system, and the deposition of the same protein together with beta amyloid peptide was found as cerebral amyloid angiopathy (CAA) in different types of dementias. OBJECTIVE AND METHODS: Because of the differential diagnostic importance, serum and cerebrospinal fluid (CSF) cystatin C levels of 24 late onset Alzheimer's demented (AD) and 16 ischemic type of vascular demented (VD) probands were compared with 17 aged control (AC) persons. RESULTS: The serum and CSF cystatin levels were found in the normal range in all groups. The ischemic VD probands had the tendency to have higher cystatin C levels than the AD. No correlation has been found with the severity and duration of dementia and with the other measured parameters. CONCLUSION: These results indicate that lower than normal CSF cystatin C level is not a diagnostic marker in ischemic VD and CAA related to AD.

No mutations in cystatin C gene in cerebral amyloid angiopathy with cystatin C deposition.

To investigate the relationship between cerebral amyloid angiopathy (CAA) and cystatin C, we studied five CAA patients on whose cerebral blood vessels colocalization of cystatin C and beta-protein was recognized immunohistochemically. One patient was suspected as familial CAA and the other patients were sporadic cases. Two patients had low concentration of cystatin C in their cerebrospinal fluid (CSF) as we have previously reported in CAA patients. Enzyme-linked immunosorbent assay (ELISA) revealed that cystatin C and beta-protein have been included at the ratio of about 1:100 in the crude amyloid fibrils of one patient. Using a monoclonal antibody (MAb) against cystatin C, we performed affinity chromatography and immunoblotting on her amyloid fibril fraction. Eluate showed a band with a mol wt of 14,000 and the N-terminal 14 amino acid residues of 14-kDa protein were identical with that of cystatin C. This molecular weight is not identical to that of the truncated form of cystatin C deposited in hereditary cerebral hemorrhage with amyloidosis in Iceland (HCHWA-I), but that of normal cystatin C. DNA sequence analysis of five patients showed no point mutations in the cystatin C gene. Cystatin C and beta-protein colocalization, which was recognized in amyloid lesions of CAA, suggests that cystatin C deposition may be related to beta-protein deposition. We hypothesize that cystatin C deposition in sporadic cerebral amyloid angiopathy with cystatin C deposition (SCCAA) involves a different mechanism from that in HCHWA-I, which may be related to low CSF concentration of cystatin C without amino acid substitutions.

Cultured leptomeningeal cells secrete cerebrospinal fluid proteins.

To extrapolate the function of the leptomeninges, we examined the profile of the proteins secreted from the cultured leptomeningeal cells prepared from 1-2-day-old rats. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the medium conditioned with the cultured cells, 20-25 differentially distinctive protein bands were noted. Through several chromatographic procedures (Sephadex G-75, Mono Q, and 7C8-300), altogether 18 proteins were purified to homogeneity, and the partial amino acid sequence of each protein was determined. Homology search revealed that the major proteins included prostaglandin-D-synthase or beta-trace protein, insulin-like growth factor (IGF)-II, IGF-binding protein-2, apolipoprotein E, beta 2-microglobulin, cystatin C, transferrin, peptidyl-prolyl cis-trans isomerase or cyclophilin C, secreted protein acidic and rich in cysteine, ubiquitin, lysozyme C, extracellular superoxide dismutase, and collagen alpha-1 (III). Most of these proteins are known to be the major brain-derived protein constituents of CSF and are thought to play important roles in certain biological events in the brain. Considering the morphological features, the present findings suggest the importance of the leptomeninges as an origin of such proteins in CSF.

Leukoencephalopathy-related cerebral amyloid angiopathy with cystatin C deposition.

BACKGROUND: We have described sporadic cases of cerebral amyloid angiopathy with cerebral hemorrhage showing a low cystatin C level in the cerebrospinal fluid detected by enzyme-linked immunosorbent assay. Recently, several cases of leukoencephalopathy in patients with cerebral amyloid angiopathy have been reported. We describe a sporadic case of leukoencephalopathy with cystatin C-type cerebral amyloid angiopathy diagnosed during life by enzyme-linked immunosorbent assay. CASE DESCRIPTION: A 74-year-old man who had suffered from progressive dementia for 3 years was admitted with right hemiparesis, dysarthria, and ataxia. MRI revealed pontine infarction and multiple lacunar state with leukoaraiosis. We suspected cystatin C-type cerebral amyloid angiopathy because of the low level of cystatin C in the cerebrospinal fluid. The patient died of sepsis 3 months later, and the presence of leukoencephalopathy with cerebral amyloid angiopathy was confirmed by autopsy. Immunohistological examination disclosed cystatin C and beta-protein deposition in amyloid structures of the cortical cerebral arteries. CONCLUSIONS: Measurement of cystatin C in the cerebrospinal fluid by enzyme-linked immunosorbent assay is a useful method of diagnosing leukoencephalopathy related to sporadic cystatin C-type cerebral amyloid angiopathy.