Purification and partial characterization of two forms of Ca2+-activated neutral protease from calf brain synaptosomes and spinal cord

Malik, Mazhar N.; Fenko, Michael D.; Wı́sniewski, Henryk M.

doi:10.1007/bf00964171

Cited by 41 publications

(36 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The same changes of granular disintegration of neurofilaments can be reproduced in excised nerves where it has been demonstrated to be a calcium dependent phenomenon Micko, 1978, 1979). A calcium activated protease has been isolated from brain and spinal cord and identified in peripheral nerve (Kamakura et al, 1981;Malik et al, 1983;Zimrnerrnan and Schlaepfer, 1982). Homologous patterns of neurofilament fragmentation in transected sciatic nerve fibers and in the calcium activated proteolysis of isolated neurofilaments by isolated protease suggest that the protease is activated in Wallerian degeneration .…”

Section: Discussionmentioning

confidence: 98%

Changes in intra‐axonal calcium distribution following nerve crush

1986

View full text Add to dashboard Cite

We used the oxalate-pyroantimonate method to demonstrate the ultrastructural distribution of calcium within rat sciatic nerve 4 h after a crush injury. In normal nerve there are discrete gradients of axoplasmic calcium precipitate with the amount of precipitate decreasing in the axoplasm beneath the Schmidt Lantermann clefts and in the paranodal regions at the node of Ranvier. Near the crush site a marked increase in endoneurial and intra-axonal calcium precipitate correlated with morphologic evidence of axonal degeneration. More distant from the crush site, both in the distal segment destined to degenerate and in the proximal segment destined to regenerate, the most prominent finding was a loss of the normal gradient of precipitate beneath the Schmidt Lantermann clefts. The calcium influx at the crush site corresponds to the known role of calcium in triggering degeneration. The alterations in the distal axon may be an early stage leading to degeneration. Alteration in calcium distribution in the proximal nerve stump may play a role in the regulation of the response to injury.

show abstract

Section: Discussionmentioning

confidence: 98%

Changes in intra‐axonal calcium distribution following nerve crush

1986

View full text Add to dashboard Cite

show abstract

“…Calpain I is fully active at micromolar concentrations of Ca2+ while calpain I1 requires higher concentrations of Ca" , generally in the millimolar range (Pant and Gainer, 1980;Mellgren, 1980). Calpain appears to have a neutral pH optimum, at pH 7-8, and is potentially inhibited by reagents that react with sulfhydryl groups (Suzuki et al, 1981 ;Malik et al, 1983) or proteineous inhibitors, e.g. calpastatin (Waxman and Krebs, 1978).…”

mentioning

confidence: 99%

Calpain‐Induced Proteolysis of Normal Human Tau and Tau Associated with Paired Helical Filaments

Ling

Księżak-Reding

1995

European Journal of Biochemistry

108

View full text Add to dashboard Cite

The major components of neurofibrillary tangles (NFT) in Alzheimer's disease are bundles of paired helical filaments (PHF) which are primarily composed of highly phosphorylated tau proteins (PHF-tau).To further understand the mechanism of PHF accumulation in NFT, we examined the calpain-induced proteolysis of highly purified and primarily non-aggregated PHF and normal tau proteins with various contents of phosphate isolated from either fetal (F-tau) or adult human brain (N-tau). The extent of proteolysis was determined by decreases in tau immunoreactivity using Western-blot analysis and a panel of site-specific tau antibodies (Alz 50, Tau-2, Tau 14, Tau-I, AT8, E-11, AH-1 and PHF-1). We found that full-size polypeptides of N-tau and F-tau were similarly and rapidly proteolyzed in vitro by calpain (calpain 11, 3.3 units/mg protein) during a 10-min incubation at 3 0 T , and that their half lives (t,,J were 1.5 min and 1.8 min, respectively. Analysis of immunoblots suggests that full-length polypeptides of tau are first degraded into large fragments similar in size to that generated endogenously, then into smaller fragments. Since both endogenous and in-vim-generated tau fragments retained N-terminal epitopes, the results suggest that most of the calpain-sensitive sites may be located in the C-terminal half of the tau molecule. In contrast, PHF were extremely resistant to degradation and only a fivefold higher concentration of calpain (1 6.7 units/mg protein) induced partial proteolysis of PHF. A major calpain-generated fragment was a 45-kDa polypeptide derived from the C-terminal region of PHF-tau, which forms a core of filaments. The results suggest that the inaccessibility of potential calpain-digestion sites in the filament core could contribute to the resistance of PHF to calpain and subsequently lead to the accumulation of PHF in Alzheimer's disease. The results also suggest that hyperphosphorylation of tau may be mariginally involved in the resistance of PHF to degradation by calpain. Ultrastructural examination revealed that, in contrast to previous studies with trypsin, calpain did not alter the morphologic appearance of filaments; after incubation with calpain, the majority of PHF remained short and disperse and the number of PHF aggregated into NFT-like clusters was not significantly increased. The results suggest that the role of calpain in promoting the aggregation and clustering of filaments is limited.

show abstract

“…67 In an in vitro study, MAP2 and calspectin were broken down calciumdependently (Table 2), but clathrin was not. The calpain inhibitors 35 NEM, E-64, and leupeptin inhibited the degradation of MAP2 and calspectin, whereas pepstatin A, an inhibitor of cathepsin D (which is known to degrade cytoskeletal proteins 36 ), had no such effect. The three calcium channel blockers were also ineffective when used at concentrations corresponding to the 10 mg/kg p.o.…”

Section: A B C D Ementioning

confidence: 98%

Nilvadipine attenuates ischemic degradation of gerbil brain cytoskeletal proteins.

Kuwaki

Satoh

Ono

et al. 1989

Stroke

View full text Add to dashboard Cite

A ccumulating evidence shows that calcium L \ channel blockers have protective effects J. \ , against cerebral ischemia, 1 and this protection has been attributed not only to the vascular effects of these drugs 2 but also to their direct effects on nervous tissue.3 Nilvadipine, 4 a new dihydropyridine-derived calcium channel blocker, possesses advantages over known blockers in having a selective relaxant effect on the basilar artery and prolonged facilitation of blood flow. A previous study has shown that nilvadipine was effective in reducing ischemia in models of chronic coronary artery occlusion in dogs. 5 Recently, one of us demonstrated 67 that transient cerebral ischemia induced marked decreases in concentrations of microtubule-associated protein 2 (MAP2) and calspectin in gerbil brains. These cytoskeleton-related proteins are presumed to play a critical role in neuronal activity, such as mem-

show abstract

Purification and partial characterization of two forms of Ca2+-activated neutral protease from calf brain synaptosomes and spinal cord

Cited by 41 publications

References 22 publications

Changes in intra‐axonal calcium distribution following nerve crush

Changes in intra‐axonal calcium distribution following nerve crush

Calpain‐Induced Proteolysis of Normal Human Tau and Tau Associated with Paired Helical Filaments

Nilvadipine attenuates ischemic degradation of gerbil brain cytoskeletal proteins.

Contact Info

Product

Resources

About