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  • 1
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 52 (1993), S. 220-226 
    ISSN: 0730-2312
    Keywords: vitamin D3 ; prostaglandin E2 ; cAMP ; phosphoinositide ; GTP-binding protein ; osteoblast ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We investigated the effects of vitamin D3 on the signaling pathways by prostaglandin E2 (PGE2) in osteoblast-like MC3T3-E1 cells. The pretreatment with 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), an active form of vitamin D3, significantly inhibited cAMP accumulation induced by 10 μM PGE2 in a dose-dependent manner in the range between 1 pM and 1 nM. This effect of 1,25-(OH)2D3 was dependent on the time of pretreatment up to 8 h. 1,25-(OH)2D3 also inhibited the cAMP accumulation induced by NaF, a GTP-binding protein activator, or forskolin which directly activates adenylate cyclase. On the other hand, 1,25-(OH)2D3 significantly inhibited PGE2-induced IP3 formation in a dose-dependent manner between 10 pM and 1 nM. However, 1,25-(OH)2D3 had little effect on NaF-induced IP3 formation. The pretreatment with 24,25-dihydroxyvitamin D3, an inactive form of vitamin D3, affected neither cAMP accumulation nor IP3 formation induced by PGE2. These results strongly suggest that 1,25-(OH)2D3 modulates the signaling by PGE2 in osteoblast-like cells as follows: the inhibitory effect on the cAMP production is exerted at a point downstream from adenylate cyclase and the inhibitory effect on the phosphoinositide hydrolysis is exerted at the point between the PGE2 receptor and GTP-binding protein, probably Gi2.
    Additional Material: 6 Ill.
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  • 2
    ISSN: 0730-2312
    Keywords: prostaglandin F2α ; phospholipase D ; protein kinase C ; pertussis toxin ; GTP-binding protein ; osteoblast ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We previously reported that prostaglandin F2α (PGF2α) receptor is coupled to pertussis toxin (PTX)-sensitive GTP-binding protein (G protein) in osteoblast-like MC3T3-E1 cells [Miwa et al. (1990): Biochem Biophys Res Commun 171:1229-1235]. In the present study, we examined the effect of PGF2α on the activation of phosphatidylcholine-hydrolyzing phospholipase D in MC3T3-E1 cells. PGF2α stimulated the formation of choline in a dose-dependent manner in the range between 10 nM and 10 μM. The formation of choline was stimulated by 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester. 4α-Phorbol 12,13-didecanoate, a PKC-nonactivating phorbol ester, had little effect on choline formation. The formation of choline stimulated by a combination of PGF2α and TPA was additive. Staurosporine, an inhibitor for protein kinases, which inhibited the effect of TPA on choline formation, dose-dependently enhanced the formation of choline induced by PGF2α. NaF, an activator of G protein, stimulated the formation of choline. The formation of choline stimulated by a combination of PGF2α and NaF was not additive. NaF-induced formation of choline was dose-dependently enhanced by staurosporine. PTX dose-dependently inhibited the PGF2α-induced formation of choline. These results strongly suggest that PGF2α activates phospholipase D independently from the activation of PKC in osteoblast-like cells and PTX-sensitive G protein is involved in the PGF2α-induced phospholipase D activation. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 54 (1994), S. 487-493 
    ISSN: 0730-2312
    Keywords: prostaglandin F2α ; calcium influx ; tyrosine kinase ; phosphoinositide ; osteoblast ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We previously reported that pertussis toxin-sensitive GTP-binding protein is involved in prostaglandin F2α (PGF2α)-induced phosphoinositide (PI) hydrolysis in osteoblast-like MC3T3-E1 cells [Miwa et al. (1990): Biochem Biophys Res Commun 171:1229-1235]. In the present study, we investigated the mechanism of PGF2α-induced Ca2+ influx in MC3T3-E1 cells. PGF2α-induced formation of total inositol phosphates (IPs) was markedly reduced by the depletion of extracellular Ca2+ with EGTA. On the other hand, the depletion of extracellular Ca2+ had little effect on PGF2α-induced inositol 1,4,5-trisphosphate formation. PGF2α stimulated 45Ca2+ influx dose dependently, attaining a maximum effect at 10 nM. Dose of PGF2α above 10 nM caused less than maximal stimulation. Genistein, an inhibitor of protein tyrosine kinase, which by itself had little effect on 45Ca2+ influx, significantly suppressed the PGF2α-induced 45Ca2+ influx in a dose-dependent manner in the range between 1 μg/ml and 0.1 mg/ml. Sodium orthovanadate, an inhibitor of protein tyrosine phosphatases, enhanced the PGF2α-induced 45Ca2+ influx. Genistein also suppressed the PGF2α-induced total IPs formation dose dependently in the range between 1 μg/ml and 0.1 mg/ml. However, it had little effect on the PGF2α-induced inositol 1,4,5-trisphosphate formation. The pretreatment with pertussis toxin had little effect on the PGF2α-induced 45Ca2+ influx. These results strongly suggest that PGF2α stimulates Ca2+ mobilization from extracellular space and PI hydrolysis via independent pathways in osteoblast-like cells, and the PGF2α-induced Ca2+ influx is regulated by protein tyrosine kinase, resulting in the promotion of PI hydrolysis.
    Additional Material: 7 Ill.
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  • 4
    ISSN: 0730-2312
    Keywords: endothelin-1 ; phospholipase D ; arachidonic acid ; osteoblasts ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In a previous study, we have shown that endothelin-1 (ET-1) activates phospholipase D independently from protein kinase C in osteoblast-like MC3T3-E1 cells. It is well recognized that phosphatidylycholine hydrolysis by phospholipase D generates phosphatidic acid, which can be further degraded by phosphatidic acid phosphohydrolase to diacylglycerol. In the present study, we investigated the role of phospholipase D activation in ET-1-induced arachidonic acid release and prostaglandin E2 (PGE2) synthesis in osteoblast-like MC3T3-E1 cells. ET-1 stimulated arachidonic acid release dose-dependently in the range between 0.1 nM and 0.1 μM. Propranolol, an inhibitor of phosphatidic acid phosphohydrolase, significantly inhibited the ET-1-induced arachidonic acid release in a dose-dependent manner as well as the ET-1-induced diacylglycerol formation. 1,6-bis-(cyclohexyloxyminocarbonylamino)-hexane (RHC-80267), an inhibitor of diacylglycerol lipase, significantly suppressed the ET-1-induced arachidonic acid release. The pretreatment with propranolol and RHC-80267 also inhibited the ET-1-induced PGE2 synthesis. These results strongly suggest that phosphatidylcholine hydrolysis by phospholipase D is involved in the arachidonic acid release induced by ET-1 in osteoblast-like cells. J. Cell. Biochem. 64:376-381. © 1997 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 228 (1990), S. 23-30 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Postural muscles have many type I myofibers, which reacted strongly for acid-stable myosin ATPase and were unreactive for alkali-stable myosin ATPase (Ariano et al., J. Histochem. Cytochem., 21:51-55, 1973; Armstrong et al., Am. J. Anat., 163:87-98, 1982; Smith et al., J. Neurophysiol., 40:503-513, 1977). House shrews (Suncus murinus) keep abducting their limbs in locomotion and hardly lift their trunk off the ground. The limb muscles of Suncus were examined by histochemical methods to determine whether the locomotory and postural behavior is related to the proportion of type I myofibers. The observation of whole cross sections from the triceps surae, flexor digitorum superficialis, quadriceps femoris, and caudally situated muscles in the thigh showed that all myofibers of these muscles were unreactive for acid-stable myosin ATPase and strongly reactive for alkali-stable myosin ATPase: Those were classified as type II myofibers. Type II myofibers showed a weak (type IIB), moderate (type IIAB), or strong (type IIA) reaction for NADH tetrazolium reductase. Part of type IIA myofibers reacted weakly to moderately for menadione-linked glycerol-3-phosphate dehydrogenase (m-GPD), which predominated in the soleus muscle. Type IIAB, type IIB, and the remainder of type IIA myofibers reacted strongly for m-GPD. The limb muscles contained subtypes of type II myofibers but no type I myofibers. In Suncus murinus, type I myofibers specialized for a postural maintenance may not be required because all myofibers function exclusively for propulsion.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 242 (1995), S. 483-490 
    ISSN: 0003-276X
    Keywords: Muscle ; Supraspinatus ; Infraspinatus ; Myofiber type ; Myofiber-type composition ; Histochemistry ; Sheep ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: The m. supraspinatus stabilizes the shoulder joint to bear the body weight, and the m. infraspinatus assists in extension and flexion of the joint in sheep. Postural muscles have many SO myofibers, whereas locomotory muscles have numerous fast-twitch myofibers. In sheep the distribution of myofiber types within the two muscles, necessary for a better understanding of postural function, remains to be clarified.Methods: Muscle samples were removed from the whole transverse sections of the dorsal, middle, and ventral compartments of the m. supraspinatus and m. infraspinatus of sheep. Myofibers were classified into FG, FOG, SO-1, and SO-2 myofibers by histochemical methods.Results: The distribution of SO myofibers changed more greatly in the m. supraspinatus (15.0-99.1%) than in the m. infraspinatus (24.5-62.3%). SO myofibers were concentrated markedly in the caudal and deep regions near the spine and fossa of the scapula in the m. supraspinatus and distributed more in the medial part than in the lateral part in the m. infraspinatus. Such changes were caused by increases in percentage of SO-2 myofibers and not SO-1 myofibers. The craniolateral regions of the m. supraspinatus and the caudolateral regions of the m. infraspinatus had many fast-twitch (FOG plus FG) myofibers suited for rapid extension and flexion of the shoulder joint.Conclusions: The m. supraspinatus has the compartmentalized, deep, and caudal regions occupied by SO myofibers, which seem to be specialized for maintenance of the joint extension. The medial region of the m. infraspinatus may assist in the joint stabilization. © 1995 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 230 (1991), S. 339-346 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The muscles of the pectoral girdle in domestic animals attach the forelimbs to the trunk and function as the suspensory apparatus. In the present study the composition of the pectoral girdle musculature of sheep by myofiber types was examined. Myofibers showing a strong reaction for alkali-stable myosin ATPase were classified into fast-twitch/glycolytic (FG) myofibers with a weak activity for NADH tetrazolium reductase (NADH-TR) and fast-twitch/oxidative/glycolytic (FOG) myofibers with a moderate and strong NADH-TR activity. Myofibers showing a weak reaction for alkali-stable myosin ATPase and a strong activity for NADH-TR were classified as slow-twitch/oxidative (SO) myofibers. The SO myofibers that showed a granular and striped pattern of diformazan deposits in NADH-TR activity were classified as SO-1 myofibers, whereas the SO myofibers characterized by a reticular pattern of diformazan deposits were classified as SO-2 myofibers. The trapezius, rhomboideus cervicis, and pectoralis descendens muscles situated superficially in the cranial regions of the back and chest had about 50% SO (SO-1 plus SO-2) myofibers. The deeply situated serratus ventralis cervicis and thoracis muscles had 37.5% SO myofibers. These five muscles included more SO-2 myofibers with large diameters than did all other muscles, and had about 50% and more cross-sectional area of SO myofibers. The other muscles had less than 32% SO myofibers and fewer SO-2 myofibers. The FOG and FG myofibers accounted for 50% or less in the muscles examined. Many muscles of the pectoral girdle had many fast-twitch (FOG plus FG) myofibers; they seem to meet locomotory requirements. In the pectoral girdle musculature, the SO myofibers were not necessarily distributed more in the deep regions than in the superficial regions. The distribution of SO myofibers appears to meet postural requirements for stabilizing the shoulder and brachium and for supporting the trunk.
    Additional Material: 5 Ill.
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  • 8
    ISSN: 0730-2312
    Keywords: heat shock protein 27 ; arachidonic acid ; protein kinase C ; osteoblast ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Exposure of osteoblast-like MC3T3-E1 cells to sodium arsenite (arsenite) increased the level of heat shock protein 27 (hsp27). The effect of arsenite was dose-dependent in the range of 50 to 200 μM. Arsenite also stimulated arachidonic acid release dose-dependently in the range between 50 and 200 μM in these cells. Both indomethacin, an inhibitor of cyclooxygenase, and nordihydroguaiaretic acid, a lipoxygenase inhibitor, significantly enhanced the arsenite-induced accumulation of hsp27. Melittin, an activator of phospholipase A2, significantly enhanced the arsenite-induced accumulation of hsp27. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester, inhibited the arsenite-induced accumulation of hsp27. In contrast, 4α-phorbol 12, 13-didecanoate (4α-PDD), a PKC-nonactivating phorbol ester, had little effect. TPA suppressed the arsenite-induced arachidonic acid release, but 4α-PDD had little effect. Arsenite no longer affected cAMP accumulation, inositol phosphates formation nor the formation of choline and phosphocholine in these cells. These results suggest that the response to stress of hsp27 is coupled with the metabolic activity of the arachidonic acid cascade, and the activation of PKC inhibits the induction of hsp27 through the suppression of arachidonic acid release in osteoblast-like cells. © 1996 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 57 (1995), S. 251-255 
    ISSN: 0730-2312
    Keywords: phospholipase D ; protein kinase C ; tyrosine kinase ; osteoblast ; TPA ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: It has recently been shown that the activation of protein kinase C (PKC) induces protein tyrosine phosphorylation in osteoblast-like MC3T3-E1 cells. We previously reported that the activation of PKC stimulates phosphatidylcholine-hydrolyzing phospholipase D in these cells. In this study, we examined whether protein tyrosine kinase is involved in the PKC-induced activation of phospholipase D in MC3T3-E1 cells. Genistein, an inhibitor of protein tyrosine kinases, which by itself had little effect on choline formation, significantly suppressed the formation of choline induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of PKC, in a dose-dependent manner. Tyrphostin, an inhibitor of protein tyrosine kinases chemically distinct from genistein, also dose-dependently suppressed the TPA-induced formation of choline. Sodium orthovandate, an inhibitor of protein tyrosine phosphatases, significantly enhanced the TPA-induced formation of choline in a dose-dependent manner. These results strongly suggest that protein tyrosine kinase regulates phospholipase D activity at a point downstream from PKC in osteoblast-like cells.
    Additional Material: 5 Ill.
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  • 10
    ISSN: 0730-2312
    Keywords: glucocorticoid ; vasopressin ; angiotensin II ; phosphoinositide ; protein kinase C ; aortic smooth muscle cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: It has been reported that glucocorticoid modifies phosphoinositide (PI) hydrolysis stimulated by vasoactive agents in vascular smooth muscle cells. In the present study, we investigated the point at which glucocorticoid affects vasopressin-induced PI hydrolysis in primary cultured rat aortic smooth muscle cells. The pretreatment with dexamethasone significantly amplified the formation of inositol trisphosphate (IP3) induced by vasopressin in a dose-dependent manner in a range of 1 pM to 10 nM. The effect of dexamethasone was dependent on the time of pretreatment up to 8 h. Dexamethasone had little effect on the number of vasopressin receptor and its affinity to vasopressin. The pretreatment with dexamethasone also amplified the formation of IP3 induced by NaF, a GTP-binding protein activator, or angiotensin II. 12-O-Tetradecanoylphorbol-13-acetate, a protein kinase C (PKC)-activating phorbol ester, significantly reduced the dexamethasone-induced enhancement of IP3 formation stimulated by vasopressin, angiotensin II or NaF. 4α-Phorbol-12, 13-didecanoate, a PKC-nonactivating phorbol ester, had little effect on the enhancement by dexamethasone. These results strongly suggest that glucocorticoid amplifies vasopressin-induced PI hydrolysis at a point downstream from GTP-binding protein in primary cultured rat aortic smooth muscle cells, and that the activation of PKC has a negative feedback effect on the amplification by glucocorticoid of vasopressin-induced PI hydrolysis.
    Additional Material: 7 Ill.
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