Diphosphorylation of platelet myosin ex vivo in the initial phase of activation by thrombin

Itoh, Kazuyuki; Hara, Takeo; Yamada, Fumiko; Shibata, Nobuhiko

doi:10.1016/0167-4889(92)90084-o

Cited by 21 publications

(11 citation statements)

References 24 publications

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“…To ascertain whether ROCK plays a necessary role for MLC phosphorylation during PMA-induced apoptosis, we then tested the effects of ML-7, an inhibitor of MLCK (Itoh et al, 1992), and Y27632 on MLC phosphorylation in TF-1 cells during PMA treatment. As expected, PMA-induced MLC phosphorylation was diminished by Y27632 pre-treatment, but not by the MLCK inhibitor ML-7, ranging from 1 to 20 µM (Fig.…”

Section: Resultsmentioning

confidence: 99%

Caspase activation during phorbol ester-induced apoptosis requires ROCK-dependent myosin-mediated contraction

Lai

Hsieh

Chang

2003

Journal of Cell Science

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Treatment of cells with phorbol ester, phorbol-12-myristate-13-acetate(PMA), triggers differentiation or apoptosis, depending on the cell type. In this study, we used an erythroblastic cell line, TF-1, to investigate the molecular mechanism that determines the cell fate in response to PMA exposure. Upon PMA treatment in the presence of serum or lysophosphatidic acid (LPA),TF-1 cells exhibited contraction followed by apoptosis. By contrast, under serum-free conditions, cells became adherent and survived after PMA treatment. Here, we show that the pathway of Rho kinase (ROCK)/myosin light chain (MLC)phosphorylation/myosin-mediated contraction was activated in PMA-induced apoptotic cells in serum-containing medium, but not in the adherent and survived cells. Pretreatment of cells with a specific ROCK inhibitor, Y27632,not only abrogated MLC phosphorylation and membrane contraction, but also prevented PMA-induced activation of caspase-3 and subsequent cell death,indicating that ROCK-dependent myosin-mediated contraction elicits an upstream signal required for caspase-3 activation in PMA-induced apoptosis. Interestingly, we further found that caspases-8 and -10 are the initiator caspases in PMA-induced apoptosis and a ROCK-dependent enhancement of specific complex formation between the Fas-associated death domain (FADD) and pro-caspase-10 in pro-apoptotic cells. In summary, these results revealed that, following PMA treatment, the upregulation of the RhoA/ROCK pathway contributes to a cellular context that switches-on myosin-mediated contraction, which provides a mechanism for triggering apoptotic induction mediated by caspase-8 and -10.

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Section: Resultsmentioning

confidence: 99%

Caspase activation during phorbol ester-induced apoptosis requires ROCK-dependent myosin-mediated contraction

Lai

Hsieh

Chang

2003

Journal of Cell Science

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“…MLCK phosphorylates myosin light-chain (MLC) resulting in activation of actinmyosin interaction (Adelstein & Conti, 1975). In platelets, the 20 kDa MLC was phosphorylated during platelet activation induced by several agonists, such as thrombin (Itoh et al, 1992). In addition, it has been reported that the release reaction and aggregation are associated with the Ca2+-dependent phosphorylation of 20 kDa MLC (Nishikawa et al, 1980).…”

Section: Introductionmentioning

confidence: 99%

Thromboxane A₂‐mediated shape change: independent of Gq‐phospholipase C‐Ca²⁺ pathway in rabbit platelets

Ohkubo

Nakahata

Ohizumi

1996

British J Pharmacology

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1 Thromboxane A2 (TXA2) receptor-mediated signal transduction was investigated in washed rabbit platelets to clarify the mechanisms of induction of shape change and aggregation. 2 The TXA2 agonist, U46619 (1 nM to 10 gM) caused shape change and aggregation in a concentration-dependent manner. A forty-times higher concentration of U46619 was needed for aggregation (ECm of 0.58 gM) than shape change (ECm of 0.013 FM). The aggregation occurred only when external 1 mm Ca2+ was present, but the shape change could occur in the absence of Ca2 .3 SQ29548 at 30 nM and GR32191B at 0.3 gM (TXA2 receptor antagonists) competitively inhibited U46619-induced shape change and aggregation with similar potency, showing that both aggregation and shape change induced by U46619 were TXA2 receptor-mediated events. However, ONO NT-126 at 1 nM, another TXA2 receptor antagonist, inhibited U46619-induced aggregation much more potently than the shape change, suggesting the possible existence of TXA2 receptor subtypes.4 ONO NT-126 (2 nM to 3 gM) by itself caused a shape change without aggregation in a concentrationdependent manner, independent of external Ca2+. Therefore, ONO NT-126 is a partial agonist at the TXA2 receptor in rabbit platelets.

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“…Relative phosphorylation level of MLC20 in MM1 cells was estimated from the signal of P-MLC20 normalized with the signal of MLC20, which was obtained by immunoblotting using MY21 monoclonal Abs on the duplicate blot. The absolute phosphorylation level of MLC20 was estimated using the extracts from cultured human endothelial cells (as internal control) by the comparison of signal density reacted to PMLC20 Abs with in situ MLC20 phosphorylation level determined by the previously reported urea-PAGE immunoblotting method using anti-MLC20 Abs (36).…”

Section: Estimation Of Mlc20 Phosphorylation In Situmentioning

confidence: 99%

Small GTP-binding Protein Rho Stimulates the Actomyosin System, Leading to Invasion of Tumor Cells

Yoshioka¹,

Matsumura²,

Akedo³

et al. 1998

Journal of Biological Chemistry

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113

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Diphosphorylation of platelet myosin ex vivo in the initial phase of activation by thrombin

Cited by 21 publications

References 24 publications

Caspase activation during phorbol ester-induced apoptosis requires ROCK-dependent myosin-mediated contraction

Caspase activation during phorbol ester-induced apoptosis requires ROCK-dependent myosin-mediated contraction

Thromboxane A₂‐mediated shape change: independent of Gq‐phospholipase C‐Ca²⁺ pathway in rabbit platelets

Small GTP-binding Protein Rho Stimulates the Actomyosin System, Leading to Invasion of Tumor Cells

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Diphosphorylation of platelet myosin ex vivo in the initial phase of activation by thrombin

Cited by 21 publications

References 24 publications

Caspase activation during phorbol ester-induced apoptosis requires ROCK-dependent myosin-mediated contraction

Caspase activation during phorbol ester-induced apoptosis requires ROCK-dependent myosin-mediated contraction

Thromboxane A2‐mediated shape change: independent of Gq‐phospholipase C‐Ca2+ pathway in rabbit platelets

Small GTP-binding Protein Rho Stimulates the Actomyosin System, Leading to Invasion of Tumor Cells

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Thromboxane A₂‐mediated shape change: independent of Gq‐phospholipase C‐Ca²⁺ pathway in rabbit platelets