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Regulation of cell motility by mitogen-activated protein kinase.

Klemke RL, Cai S, Giannini AL, Gallagher PJ, de Lanerolle P, Cheresh DA - J. Cell Biol. (1997)

Bottom Line: Inhibition of MAP kinase activity causes decreased MLCK function, MLC phosphorylation, and cell migration on extracellular matrix proteins.In vitro results support these findings since ERK-phosphorylated MLCK has an increased capacity to phosphorylate MLC and shows increased sensitivity to calmodulin.Thus, we define a signaling pathway directly downstream of MAP kinase, influencing cell migration on the extracellular matrix.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.

ABSTRACT
Cell interaction with adhesive proteins or growth factors in the extracellular matrix initiates Ras/mitogen-activated protein (MAP) kinase signaling. Evidence is provided that MAP kinase (ERK1 and ERK2) influences the cells' motility machinery by phosphorylating and, thereby, enhancing myosin light chain kinase (MLCK) activity leading to phosphorylation of myosin light chains (MLC). Inhibition of MAP kinase activity causes decreased MLCK function, MLC phosphorylation, and cell migration on extracellular matrix proteins. In contrast, expression of mutationally active MAP kinase kinase causes activation of MAP kinase leading to phosphorylation of MLCK and MLC and enhanced cell migration. In vitro results support these findings since ERK-phosphorylated MLCK has an increased capacity to phosphorylate MLC and shows increased sensitivity to calmodulin. Thus, we define a signaling pathway directly downstream of MAP kinase, influencing cell migration on the extracellular matrix.

Show MeSH
MLCK, exposed to activated ERK or buffer (control) for  40 min, was allowed to phosphorylate MLC in the presence of varying concentrations of calmodulin as described in Materials and  Methods. Data are expressed as the percent of maximal MLCK  activity (i.e., MLCK phosphorylated by ERK in the presence  of 1,000 nM calmodulin, which represents 1.5 μmol 32P/min/mg  MLCK). Each point represents the mean ± SE of at least three  experiments.
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Figure 6: MLCK, exposed to activated ERK or buffer (control) for 40 min, was allowed to phosphorylate MLC in the presence of varying concentrations of calmodulin as described in Materials and Methods. Data are expressed as the percent of maximal MLCK activity (i.e., MLCK phosphorylated by ERK in the presence of 1,000 nM calmodulin, which represents 1.5 μmol 32P/min/mg MLCK). Each point represents the mean ± SE of at least three experiments.

Mentions: To further examine the change in MLCK activity after phosphorylation by MAP kinase, MLCK was incubated in the presence or absence of mutationally active ERK, and the MLCK was then allowed to phosphorylate MLC in the presence of varying concentrations of calmodulin. As shown in Fig. 6, MLCK phosphorylated by ERK has increased sensitivity to calmodulin over a wide range of concentrations. In fact, half-maximal ERK-activated MLCK required two to threefold less calmodulin than MLCK not activated by ERK. Together, these findings reveal that phosphorylation of MLCK by MAP kinase leads to increased MLCK activity and a decreased requirement for calmodulin.


Regulation of cell motility by mitogen-activated protein kinase.

Klemke RL, Cai S, Giannini AL, Gallagher PJ, de Lanerolle P, Cheresh DA - J. Cell Biol. (1997)

MLCK, exposed to activated ERK or buffer (control) for  40 min, was allowed to phosphorylate MLC in the presence of varying concentrations of calmodulin as described in Materials and  Methods. Data are expressed as the percent of maximal MLCK  activity (i.e., MLCK phosphorylated by ERK in the presence  of 1,000 nM calmodulin, which represents 1.5 μmol 32P/min/mg  MLCK). Each point represents the mean ± SE of at least three  experiments.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139771&req=5

Figure 6: MLCK, exposed to activated ERK or buffer (control) for 40 min, was allowed to phosphorylate MLC in the presence of varying concentrations of calmodulin as described in Materials and Methods. Data are expressed as the percent of maximal MLCK activity (i.e., MLCK phosphorylated by ERK in the presence of 1,000 nM calmodulin, which represents 1.5 μmol 32P/min/mg MLCK). Each point represents the mean ± SE of at least three experiments.
Mentions: To further examine the change in MLCK activity after phosphorylation by MAP kinase, MLCK was incubated in the presence or absence of mutationally active ERK, and the MLCK was then allowed to phosphorylate MLC in the presence of varying concentrations of calmodulin. As shown in Fig. 6, MLCK phosphorylated by ERK has increased sensitivity to calmodulin over a wide range of concentrations. In fact, half-maximal ERK-activated MLCK required two to threefold less calmodulin than MLCK not activated by ERK. Together, these findings reveal that phosphorylation of MLCK by MAP kinase leads to increased MLCK activity and a decreased requirement for calmodulin.

Bottom Line: Inhibition of MAP kinase activity causes decreased MLCK function, MLC phosphorylation, and cell migration on extracellular matrix proteins.In vitro results support these findings since ERK-phosphorylated MLCK has an increased capacity to phosphorylate MLC and shows increased sensitivity to calmodulin.Thus, we define a signaling pathway directly downstream of MAP kinase, influencing cell migration on the extracellular matrix.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.

ABSTRACT
Cell interaction with adhesive proteins or growth factors in the extracellular matrix initiates Ras/mitogen-activated protein (MAP) kinase signaling. Evidence is provided that MAP kinase (ERK1 and ERK2) influences the cells' motility machinery by phosphorylating and, thereby, enhancing myosin light chain kinase (MLCK) activity leading to phosphorylation of myosin light chains (MLC). Inhibition of MAP kinase activity causes decreased MLCK function, MLC phosphorylation, and cell migration on extracellular matrix proteins. In contrast, expression of mutationally active MAP kinase kinase causes activation of MAP kinase leading to phosphorylation of MLCK and MLC and enhanced cell migration. In vitro results support these findings since ERK-phosphorylated MLCK has an increased capacity to phosphorylate MLC and shows increased sensitivity to calmodulin. Thus, we define a signaling pathway directly downstream of MAP kinase, influencing cell migration on the extracellular matrix.

Show MeSH