Involvement of a cell surface protein and an ecto-protein kinase in myogenesis

Chen, Xiao‐Yong; Lo, Theodore C. Y.

doi:10.1042/bj2790475

Cited by 18 publications

(22 citation statements)

References 49 publications

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“…Under our experimental conditions, multinucleated myotubes were first observed in day-4 culture, and the fusion indices reached 27% and 70% on day 5 and day 6, respectively (Fig. 2;Chen and Lo, 1991b). Thus changes in the Myf-4 and Myf-5 transcript levels occurred before the appearance of myotubes.…”

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 81%

“…9). This probably explained why both mutants F72 and D1/S4 were impaired in myogenesis (DAmore and Lo, 1988;Chen and Lo, 1991b). Thus these mutant studies show that both the ecto-protein kinase and the 112 kDa protein may function by activating the expression of NCAM and Myf-4.…”

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 88%

“…When grown in the presence of BrdUrd or phloretin, only 35% of the normal p112 level could be detected in the day-3 L6 cultures (Chen and Lo, 1991b). The fusion indices of BrdUrd-and phloretin-grown day-6 cultures were 0% and 15%, respectively ( Fig.…”

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 95%

“…Detection and quantitation of various mRNAs were carried out as described in Figures 2 and 3. A-D Transcript levels in L6 cells tant D1 was grown in 1% and 10% horse serum, about 93% and 26% of the normal L6 p112 levels was detected in these myoblasts, respectively (Chen and Lo, 1991b). This mutant was able to form myotubes only when grown in 1%, but not in lo%, horse serum (Chen and Lo, 1989).…”

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 97%

“…If this were the case, then mutants defective in either the ecto-protein kinase or the 112 kDa protein should possess normal levels of the Myf-4, MLC, MHC, and TnT transcripts. We have previously shown that, mutants F72 and D1/S4 possessed around 37% of the normal p112 (Chen and Lo, 1991b). The former was defective only in the ecto-protein kinase (38% of the L6 level), whereas the latter was altered only in the 112 kDa protein (35% of the L6 level).…”

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 99%

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Use of p112‐deficient myoblasts to determine the temporal order of the in vitro expression of myogenic components

Chen

1993

Journal Cellular Physiology

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The present investigation examines the function and site(s) of involvement of an ecto-protein kinase and its substrate protein (a cell surface 112 kDa protein) in the in vitro myogenic pathway. The phosphorylated 112 kDa protein (p112) has recently been shown to be involved in myogenesis. Not much information is currently available on the role of the ecto-protein kinase and the 112 kDa protein in modulating the expression of the myogenic factors and various muscle-specific proteins. Five different p112-deficient rat myoblasts were used to examine the temporal order of the in vitro expression of the myogenic components; namely, L6 myoblasts treated with BrdUrd or phloretin, a conditional p112-defective mutant (clone D1), an ecto-protein kinase-deficient mutant (clone F72), and a mutant defective in the 112 kDa protein (clone D1/S4). All these p112-deficient myoblasts were also impaired in myogenesis. The absence of p112, ecto-protein kinase, and/or the 112 kDa protein was found to have no effect on the Myf-5 mRNA level. However, the expected increase in NCAM and Myf-4 mRNAs was not observed in any of the p112-deficient myoblasts examined. This suggests that the p112 site of action is probably located upstream of the Myf-4 and NCAM sites in the myogenic pathway. While 7-28 fold increases in the MLC, MHC, and TnT transcripts were observed during myogenesis, such increases were not observed in the p112-deficient myoblasts. However, when mutant D1/S4 was transfected with the myf-4 cDNA, expression of Myf-4 in the transfectant resulted in increased level of the MLC, MHC, and TnT mRNAs, and in myotube formation, even though the Myf-5 and NCAM mRNA levels and p112 were not altered. This suggests that p112 may function by activating transcription of Myf-4, which will subsequently promote the expression of muscle-specific proteins and myotube formation. In the absence of p112, Myf-5 cannot activate the expression of Myf-4, NCAM, MLC, MHC, TnT, and myotube formation. If all these components are involved in the same myogenic pathway, then p112 may be acting downstream from Myf-5, and upstream from NCAM and Myf-4.

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Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 81%

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 88%

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 95%

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 97%

Section: Expression Of Muscle-specific Regulatory Factorsmentioning

confidence: 99%

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Use of p112‐deficient myoblasts to determine the temporal order of the in vitro expression of myogenic components

Chen

1993

Journal Cellular Physiology

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Ecto-alkaline phosphatase activity identified at physiological pH range on intact P19 and HL-60 cells is induced by retinoic acid

et al. 2000

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The activity of membrane-bound alkaline phosphatase (ALP) expressed on the external surface of cultured murine P19 teratocarcinoma and human HL-60 myeloblastic leukemia cells was studied at physiological pH using p-nitrophenylphosphate (pNPP) as substrate. The rate of substrate hydrolysis catalyzed by intact viable cells remained constant for eight successive incubations of 30 min and was optimal at micromolar substrate concentrations over the pH range 7.4-8.5. The value of apparent K(m) for pNPP in P19 and HL-60 cells was 120 microM. Hydrolytic activity of the ecto-enzyme at physiological pH decreased by the addition of levamisole, a specific and noncompetitive inhibitor of ALP (K(i) P19 = 57 microM; K(i) HL-60 = 50 microM). Inhibition of hydrolysis was reversed by removal of levamisole within 30 min. Retinoic acid (RA), which promotes the differentiation of P19 and HL-60 cells, induced levamisole-sensitive ecto-phosphohydrolase activity at pH 7.4. After its autophosphorylation by ecto-kinase activity, a 98-kDa membrane protein in P19 cells was found to be sensitive to ecto-ALP, and protein dephosphorylation increased after incubation of cells with RA for 24 h and 48 h. Orthovanadate, an inhibitor of all phosphatase activities, blocked the levamisole-sensitive dephosphorylation of the membrane phosphoproteins, while (R)-(-)-epinephrine reversed the effect by complexation of the inhibitor. The results demonstrate that the levamisole-sensitive phosphohydrolase activity on the cell surface is consistent with ecto-ALP activity degrading both physiological concentrations of exogenously added substrate and endogenous surface phosphoproteins under physiological pH conditions. The dephosphorylating properties of ecto-ALP are induced by RA, suggesting a specific function in differentiating P19 teratocarcinoma and HL-60 myeloblastic leukemia cells.

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The brain of the cell

Marks¹

1996

Protein Phosphorylation

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Involvement of a cell surface protein and an ecto-protein kinase in myogenesis

Cited by 18 publications

References 49 publications

Use of p112‐deficient myoblasts to determine the temporal order of the in vitro expression of myogenic components

Use of p112‐deficient myoblasts to determine the temporal order of the in vitro expression of myogenic components

Ecto-alkaline phosphatase activity identified at physiological pH range on intact P19 and HL-60 cells is induced by retinoic acid

The brain of the cell

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