When hypertrophic growth is induced in neonatal rat cardiocytes by stretching, the cardiocytes express high levels of brain-type natriuretic peptide (BNP) and the proprotein-processing enzyme furin. A BNP precursor, ␥BNP, possesses a furin-cleavable Arg-X-X-Arg motif, which is cleaved when ␥BNP is processed to form BNP-45. The Arg-X-X-Arg motif is found in many precursors of growth factors and growth-related proteins. To determine if furin converts ␥BNP to BNP-45 as well as other unidentified growth-promoting protein precursors to their active form that may induce hypertrophic growth in cardiocytes, we used two protease inhibitor systems, synthetic peptidyl chloromethyl ketones (CMK) (decArg-Val-Lys-Arg-CMK and dec-Phe-Ala-Lys-Arg-CMK; where dec is decanoyl) and vaccinia vector-integrated native and variant ␣ 1 -antitrypsins. The furin-specific inhibitors, dec-Arg-Val-Lys-Arg-CMK and variant ␣ 1 -antitrypsin with the inhibitory determinant Arg-X-X-Arg, suppressed the stretch-induced hypertrophic growth of cardiocytes as well as the processing of ␥BNP to BNP-45. The other serine protease inhibitors and variant ␣ 1 -antitrypsin against elastase, or thrombin, however, neither suppressed the hypertrophic growth nor prevented the processing of ␥BNP to BNP-45. Thus, we suggest that furin catalyzes the conversion of ␥BNP to BNP-45 as well as growth-promoting proproteins to their active form, which might induce hypertrophic growth in cardiocytes.When cardiocytes undergo the stretch force, they adapt by developing cellular hypertrophy. Because cardiocytes are terminally differentiated and cannot proliferate by cell division, they exhibit hypertrophic growth, an increase in cell size and protein content. The hypertrophic growth of cardiocytes is attained through a series of multiple gene expressions (1-4) and phosphorylation reactions (4, 5) as follows: expression of immediate early genes such as c-fos, c-jun, and Egr-1; consequent protein kinase cascade of phosphorylation reactions and expression of peptide growth factors such as fibroblast growth factor and transforming growth factor-␤ (TGF-␤) 1 ; cardiac regulatory peptides such as atrial natriuretic peptide (ANP) and brain-type natriuretic peptide (BNP); the contractile proteins myosin light chain-2 and fetal-type ␤-myosin heavy chain; and probably extracellular matrix-degrading metalloproteinases at a remodeling step (6). Some these proteins are produced as precursors, including TGF-␤ (7, 8), ANP (9, 10), BNP (10), and metalloproteinases including membrane-type matrix metalloproteinase (11) and stromelysin-3 (12). The precursors are cleaved to the active forms by endoproteases. Because TGF-␤, BNP, membrane-type matrix metalloproteinase, and stromelysin-3 contain a cleavage site for the proprotein-processing endoprotease furin (7, 10 -12), we examined whether furin might be another candidate gene expressed during the hypertrophic growth of cardiocytes.Furin belongs to the yeast Kex2 endoprotease family, to which the neuroendocrine cell-specific endoproteases PC2 and P...

Parkinson's disease (PD) is the second most frequent neurodegenerative disorder after Alzheimer's disease. The main clinical features of PD include tremor, bradykinesia, rigidity and postural instability. The primary pathology of PD is degeneration of dopaminergic neurons in the substantia nigra pars compacta, resulting in loss of the nigrostriatal pathway and a reduction of dopamine contents in the striatum. The biochemical and cellular changes that occur following the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) are remarkably similar to that seen in idiopathic PD. Recent evidence shows that oxidative stress contributes to the cascade leading to dopaminergic cell degeneration in PD. However, oxidative stress is intimately linked to other components of neurodegenerative process, such as nitric oxide stress and inflammation. Recently, there is convincing evidence for the involvement of nitric oxide that reacts with superoxide to produce peroxynitrite and ultimately hydroxyl radical production. In view of these new insights, however, the role of reactive nitrogen species, reactive oxygen species and inflammation against MPTP neurotoxicity is not fully understood. In this review, we discuss the possible role of reactive nitrogen species, reactive oxygen species and inflammation in the dopaminergic neurons against MPTP neurotoxicity.

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There is growing evidence indicating that reactive nitrogen species (RNS) and reactive oxygen species (ROS) are a major contributor to the pathogenesis and progression of Parkinson's disease. Here we investigated whether edaravone (free radical scavenger), minocycline (inducible nitric oxide synthase, iNOS inhibitor), 7-nitroindazole (neuronal NOS, nNOS inhibitor), fluvastatin (endothelial NOS, eNOS activator) and pitavastatin (eNOS activator) can protect against MPTP neurotoxicity in mice under the same condition. The present study showed that 7-nitroindazole could protect dose-dependently against the striatal dopamine depletions in mice 5 days after MPTP treatment. In contrast, edaravone, minocycline, fluvastatin and pitavastatin did not show the neuroprotective effect on MPTP-induced striatal dopamine depletion. Our immunohistochemical study showed that TH (tyrosine hydroxylase) and DAT (dopamine transporter) immunoreactivity was decreased significantly in the striatum and substantia nigra 5 days after MPTP treatment. The administration of 7-nitroindazole showed a protective effect against the severe reductions in levels of TH and DAT immunoreactivity in the striatum and substantia nigra 5 days after MPTP treatment. Furthermore, our Western blot analyses study showed the remarkable loss of TH protein levels in the striatum 5 days after MPTP treatment. In contrast, 7-nitroindazole prevented a significant loss in TH protein levels in the striatum 5 days after MPTP treatment. On the other hand, GFAP (glial fibrillary acidic protein) immunoreactivity increased significantly in the striatum and substantia nigra, 5 days after MPTP treatment. 7-Nitroindazole ameliorated severe increases in number of GFAP immunoreactive astrocytes in the striatum and substantia nigra 5 days after MPTP treatment. Furthermore, our Western blot analyses study showed the increase of GFAP protein levels in the striatum 5 days after MPTP treatment. 7-Nitroindazole prevented a significant increase in the GFAP protein levels in the striatum 5 days after MPTP treatment. The present results indicate that 7-nitroindazole can protect dose-dependently against the striatal dopamine depletions in mice 5 days after MPTP treatment. In contrast, edaravone, minocycline, fluvastatin and pitavastatin did not show the neuroprotective effect on MPTP-induced striatal dopamine depletions. These findings demonstrate that the overexpression of nNOS may play a major role in the neurotoxic processes of MPTP, as compared to the production of ROS, the overexpression of iNOS and the modulation of eNOS. Thus, our findings provide strong evidence for neuroprotective properties of nNOS inhibitor in this animal model of Parkinson's disease.

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