Real-time imaging reveals that noninvasive mammary epithelial acini can contain motile cells

To determine how extracellular signal–regulated kinases (ERK) 1/2 promote mammary tumorigenesis, we examined the real-time behavior of cells in an organotypic culture of the mammary glandular epithelium. Inducible activation of ERK1/2 in mature acini elicits cell motility and disrupts epithelial architecture in a manner that is reminiscent of ductal carcinoma in situ; however, motile cells do not invade through the basement membrane and branching morphogenesis does not take place. ERK1/2-induced motility causes cells to move both within the cell monolayer that contacts the basement membrane surrounding the acinus and through the luminal space of the acinus. E-cadherin expression is reduced after ERK1/2 activation, but motility does not involve an epithelial–mesenchymal transition. Cell motility and the disruption of epithelial architecture require a Rho kinase– and myosin light chain kinase–dependent increase in the phosphorylation of myosin light chain 2. Our results identify a new mechanism for the disruption of architecture in epithelial acini and suggest that ERK1/2 can promote noninvasive motility in preinvasive mammary tumors.

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An increase or a decrease in myosin II phosphorylation inhibits macrophage motility.

The Journal of Cell Biology ◽

10.1083/jcb.114.2.277 ◽

1991 ◽

Vol 114 (2) ◽

pp. 277-283 ◽

Cited By ~ 54

Author(s):

A K Wilson ◽

G Gorgas ◽

W D Claypool ◽

P de Lanerolle

Keyword(s):

Cell Motility ◽

Light Chain ◽

Mammalian Cells ◽

Inverse Relationship ◽

Myosin Light Chain ◽

Myosin Ii ◽

Active Form ◽

Chemotaxis Assay ◽

Mlc20 Phosphorylation ◽

Number Of Cells

Myosin II purified from mammalian non-muscle cells is phosphorylated on the 20-kD light chain subunit (MLC20) by the Ca2+/calmodulin-dependent enzyme myosin light chain kinase (MLCK). The importance of MLC20 phosphorylation in regulating cell motility was investigated by introducing either antibodies to MLCK (MK-Ab) or a Ca2+/calmodulin-independent, constitutively active form of MLCK (MK-) into macrophages. The effects of these proteins on cell motility were then determined using a quantitative chemotaxis assay. Chemotaxis is significantly diminished in macrophages containing MK-Ab compared to macrophages containing control antibodies. Moreover, there is an inverse relationship between the number of cells that migrate and the amount of MK-Ab introduced into cells. Interestingly, there is also an inverse relationship between the number of cells that migrate and the amount of MK- introduced into cells. Other experiments demonstrated that MK-Ab decreased intracellular MLC20 phosphorylation while MK- increased MLC20 phosphorylation. MK- also increased the amount of myosin associated with the cytoskeleton. These data demonstrate that the regulation of MLCK is an important aspect of cell motility and suggest that MLC20 phosphorylation must be maintained within narrow limits during translational motility by mammalian cells.

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Viable “Haemophilus somnus” Induces Myosin Light-Chain Kinase-Dependent Decrease in Brain Endothelial Cell Monolayer Resistance

Infection and Immunity ◽

10.1128/iai.00028-07 ◽

2007 ◽

Vol 75 (9) ◽

pp. 4572-4581 ◽

Cited By ~ 7

Author(s):

E. Behling-Kelly ◽

David McClenahan ◽

K. S. Kim ◽

C. J. Czuprynski

Keyword(s):

Endothelial Cell ◽

Light Chain ◽

Myosin Light Chain Kinase ◽

Myosin Light Chain ◽

Cell Monolayer ◽

Brain Endothelial Cell ◽

Endothelial Cell Monolayer ◽

Necrosis Factor Alpha ◽

Haemophilus Somnus

ABSTRACT “Haemophilus somnus” causes thrombotic meningoencephalitis in cattle. Our laboratory has previously reported that H. somnus has the ability to adhere to, but not invade, bovine brain endothelial cells (BBEC) in vitro. The goal of this study was to determine if H. somnus alters brain endothelial cell monolayer integrity in vitro, in a manner that would be expected to contribute to inflammation of the central nervous system (CNS). Monolayer integrity was monitored by measuring transendothelial electrical resistance (TEER) and albumin flux. BBEC incubated with H. somnus underwent rapid cytoskeletal rearrangement, significant increases in albumin flux, and reductions in TEER. Decreased monolayer TEER was preceded by phosphorylation of the myosin regulatory light chain and was partially dependent on tumor necrosis factor alpha and myosin light-chain kinase but not interleukin-1β. Neither heat-killed H. somnus, formalin-fixed H. somnus, nor purified lipooligosaccharide altered monolayer integrity within a 2-h incubation period, whereas conditioned medium from H. somnus-treated BBEC caused a modest reduction in TEER. The data from this study support the hypothesis that viable H. somnus alters integrity of the blood-brain barrier by promoting contraction of BBEC and increasing paracellular permeability of the CNS vasculature.

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Real-time evaluation of myosin light chain kinase activation in smooth muscle tissues from a transgenic calmodulin-biosensor mouse

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0308742101 ◽

2004 ◽

Vol 101 (16) ◽

pp. 6279-6284 ◽

Cited By ~ 91

Author(s):

E. Isotani ◽

G. Zhi ◽

K. S. Lau ◽

J. Huang ◽

Y. Mizuno ◽

...

Keyword(s):

Smooth Muscle ◽

Real Time ◽

Light Chain ◽

Myosin Light Chain Kinase ◽

Myosin Light Chain ◽

Kinase Activation ◽

Muscle Tissues ◽

Time Evaluation

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Morphometric Analysis of Rat Prostate Development: Roles of MEK/ERK and Rho Signaling Pathways in Prostatic Morphogenesis

Biomolecules ◽

10.3390/biom11121829 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1829

Author(s):

Wen-Yang Hu ◽

Parivash Afradiasbagharani ◽

Ranli Lu ◽

Lifeng Liu ◽

Lynn A. Birch ◽

...

Keyword(s):

Cell Proliferation ◽

Signaling Pathways ◽

Light Chain ◽

Myosin Light Chain ◽

Molecular Mechanisms ◽

Rho Kinase ◽

Branching Morphogenesis ◽

Kinase Signaling ◽

Prostate Cell ◽

Prostate Development

The molecular mechanisms underlying prostate development can provide clues for prostate cancer research. It has been demonstrated that MEK/ERK signaling downstream of androgen-targeted FGF10 signaling directly induces prostatic branching during development, while Rho/Rho-kinase can regulate prostate cell proliferation. MEK/ERK and Rho/Rho kinase regulate myosin light chain kinase (MLCK), and MLCK regulates myosin light chain phosphorylation (MLC-P), which is critical for cell fate, including cell proliferation, differentiation, and apoptosis. However, the roles and crosstalk of the MEK/ERK and Rho/Rho kinase signaling pathways in prostatic morphogenesis have not been examined. In the present study, we used numerical and image analysis to characterize lobe-specific rat prostatic branching during postnatal organ culture and investigated the roles of FGF10-MEK/ERK and Rho/Rho kinase signaling pathways in prostatic morphogenesis. Prostates exhibited distinctive lobe-specific growth and branching patterns in the ventral (VP) and lateral (LP) lobes, while exogenous FGF10 treatment shifted LP branching towards a VP branching pattern. Treatment with inhibitors of MEK1/2, Rho, Rho kinase, or MLCK significantly inhibited VP growth and blocked branching morphogenesis, further supporting critical roles for MEK/ERK and Rho/Rho kinase signaling pathways in prostatic growth and branching during development. We propose that MLCK-regulated MLC-P may be a central downstream target of both signaling pathways in regulating prostate morphogenesis.

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