Studies on myosin light chain phosphorylation in intact platelets, utilizing a cell-penetrating thiol protease inhibitor

Tsujinaka, Toshimasa; Kajiwara, Y; Kambayashi, Jun-ichi; Sakon, Masato; Mori, Takesada

doi:10.1016/0049-3848(88)90372-6

Cited by 13 publications

(7 citation statements)

References 12 publications

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“…The dipeptidyl aldehydes calpeptin (CBZ-Leunorleucinal) and E-64d (epoxysuccinyl derivative) are relatively specific calpain inhibitors, though they do inhibit cathepsin B moderately (Tamai et al, 1987;Tsujinaka et al, 1988;McGowan et al, 1989). Calpeptin is a weak inhibitor of the multicatalytic proteinase complex (MPC; Saito and Nixon, 1993;Figueiredo-Pereira et al, 1994) in comparison to the other calpain inhibitors, CP 1 and CP 2 , which inhibit all four catalytic sites of MPC fairly strongly.…”

Section: Discussionmentioning

confidence: 99%

“…Although the physiological function of calpain is still not completely understood, there is evidence for roles in activation of protein kinase C, processing of hormones, and protein turnover (Suzuki et al, 1987;Croall and DeMartino, 1990;Banik et al, 1992). Increased calpain activity is thought to play an important role in tissue destruction in spinal cord and brain injury, demyelinating diseases (e.g., multiple sclerosis [MS]), muscular dystrophy, ischemia, Alzheimer's disease, glutamate neurotoxicity, and cataract formation (Tsujinaka et al, 1988;Siman and Noszek, 1988;Shearer and David, 1990;Nixon et al, 1994;Posmantur et al, 1994;Bartus et al, 1994;Banik et al, 1995;Bartus, 1997).…”

Section: Introductionmentioning

confidence: 99%

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New inhibitors of calpain prevent degradation of cytoskeletal and myelin proteins in spinal cord in vitro

et al. 1998

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We have determined the effects of the calpain inhibitors AK275 and AK295 upon purified m-calpain and calcium-mediated degradation of neurofilament protein (NFP) in rat spinal cord in vitro. After incubation, the soluble radioactivity and/or extent of myelin basic protein (MBP) or NFP degradation was determined. Fifty percent of caseinolytic activity was inhibited by both inhibitors at 0.6 microM concentration, while more than 90% inhibition was seen at 1.6 microM. In contrast, 37% and 64% inhibition of MBP degradation was seen with AK295 and AK275, respectively, at 10 microM concentration. The extent of NFP degradation in spinal cord was quantified from immunoblot enhanced chemiluminescence. The calcium-mediated breakdown of NFP was inhibited by both AK275 and AK295, and the inhibition was dose-dependent. A 50% inhibition of NFP degradation was seen with AK295 at 10 microM and was almost completely inhibited at 25-50 microM. AK295 was slightly more potent than AK275. These studies suggest that these potent calpain inhibitors may be used therapeutically to provide neuroprotection in vivo in experimental central nervous system trauma and ischemia.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New inhibitors of calpain prevent degradation of cytoskeletal and myelin proteins in spinal cord in vitro

et al. 1998

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“…A number of endogenous calpain substrates have been reported so far. These may be classified into three categories: (1) Cytoskeletal proteins such as actin binding protein [Truglia and Stracher, 1981], talin [Beckerle et al, 1986], filamin [Verhallen et al, 1987], and spectrin ; (2) Enzyme proteins such as protein kinase C (PKC) [Kishimoto et al, 1983[Kishimoto et al, , 1989, cAMP-dependent protein kinase (A-Kinase) [Beer et al, 1984], myosin light chain kinase (MLCK) [Tsujinaka et al, 1988a], phospholipase C (PLC) [Low et al, 1984], and tyrosine kinase (pp60src) [Oda et al, 1993]; and (3) Receptor proteins such as EGF receptor [Cassel and Glaser, 1982;King and Gates, 1985] and PDGF receptor [Ek and Heldin, 1986]. Thus, calpain may be involved in a variety of cellular processes mediated by Ca 21 via the limited proteolysis of various proteins.…”

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confidence: 99%

Identification of μ-, m-calpains and calpastatin and capture of μ-calpain activation in endothelial cells

et al. 1997

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The presence of the calpain-calpastatin system in human umbilical vein endothelial cells (HUVEC) was investigated by means of ion exchange chromatography, Western blot analysis, and Northern blot analysis. On DEAE anion exchange chromatography, calpain and calpastatin activities were eluted at approximately 0.30 M and 0.15-0.25 M NaCl, respectively. For half-maximal activity, the protease required 800 microM Ca2+, comparable to the Ca2+ requirement of m-calpain. By Western blot analysis, the large subunit of mu-calpain (80 kDa) was found to be eluted with calpastatin (110 kDa). Both the large subunit of m-calpain (80 kDa) and calpastatin were detected in the respective active fractions. By Northern blot analysis, mRNAs for large subunits of mu- and m-calpains were detected in single bands, each corresponding to approximately 3.5 Kb. Calpastatin mRNA was observed in two bands corresponding to approximately 3.8 and 2.6 Kb. Furthermore, the activation of mu-calpain in HUVEC by a calcium ionophore was examined, using an antibody specifically recognizing an autolytic intermediate form of mu-calpain large subunit (78 kDa). Both talin and filamin of HUVEC were proteolyzed in a calcium-dependent manner, and the reactions were inhibited by calpeptin, a cell-permeable calpain specific inhibitor. Proteolysis of the cytoskeleton was preceded by the appearance of the autolytic intermediate form of mu-calpain, while the fully autolyzed postautolysis form of mu-calpain (76 kDa) remained below detectable levels at all time points examined. These results indicate that the calpain-calpastatin system is present in human endothelial cells and that mu-calpain may be involved in endothelial cell function mediated by Ca2+ via the limited proteolysis of various proteins.

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“…A role for calpain to down‐regulate protein kinase C has been proposed [20]. Calpain alters by limited proteolysis protein kinase C [21] and calcium/calmodulin‐regulated enzymes [22,23]. Taken together, the results suggest that calpain contributes to the control of serine/threonine protein phosphorylation during platelet activation.…”

Section: Discussionmentioning

confidence: 94%

Calpain controls the balance between protein tyrosine kinase and tyrosine phosphatase activities during platelet activation

et al. 1999

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Studies on myosin light chain phosphorylation in intact platelets, utilizing a cell-penetrating thiol protease inhibitor

Cited by 13 publications

References 12 publications

New inhibitors of calpain prevent degradation of cytoskeletal and myelin proteins in spinal cord in vitro

New inhibitors of calpain prevent degradation of cytoskeletal and myelin proteins in spinal cord in vitro

Identification of μ-, m-calpains and calpastatin and capture of μ-calpain activation in endothelial cells

Calpain controls the balance between protein tyrosine kinase and tyrosine phosphatase activities during platelet activation

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