Junb regulates arterial contraction capacity, cellular contractility, and motility via its target Myl9 in mice
Alexander H. Licht, … , Thomas Korff, Marina Schorpp-Kistner
Alexander H. Licht, … , Thomas Korff, Marina Schorpp-Kistner
Published June 14, 2010
Citation Information: J Clin Invest. 2010;120(7):2307-2318. https://doi.org/10.1172/JCI41749.
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Research Article Vascular biology

Junb regulates arterial contraction capacity, cellular contractility, and motility via its target Myl9 in mice

Abstract

Cellular contractility and, thus, the ability to alter cell shape are prerequisites for a number of important biological processes such as cytokinesis, movement, differentiation, and substrate adherence. The contractile capacity of vascular smooth muscle cells (VSMCs) is pivotal for the regulation of vascular tone and thus blood pressure and flow. Here, we report that conditional ablation of the transcriptional regulator Junb results in impaired arterial contractility in vivo and in vitro. This was exemplified by resistance of Junb-deficient mice to DOCA-salt–induced volume-dependent hypertension as well as by a decreased contractile capacity of isolated arteries. Detailed analyses of Junb-deficient VSMCs, mouse embryonic fibroblasts, and endothelial cells revealed a general failure in stress fiber formation and impaired cellular motility. Concomitantly, we identified myosin regulatory light chain 9 (Myl9), which is critically involved in actomyosin contractility and stress fiber assembly, as a Junb target. Consistent with these findings, reexpression of either Junb or Myl9 in Junb-deficient cells restored stress fiber formation, cellular motility, and contractile capacity. Our data establish a molecular link between the activator protein–1 transcription factor subunit Junb and actomyosin-based cellular motility as well as cellular and vascular contractility by governing Myl9 transcription.

Authors

Alexander H. Licht, Tobias Nübel, Anja Feldner, Nathalie Jurisch-Yaksi, Marco Marcello, Elena Demicheva, Jun-Hao Hu, Bettina Hartenstein, Hellmut G. Augustin, Markus Hecker, Peter Angel, Thomas Korff, Marina Schorpp-Kistner

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Figure 6

Reexpression of Junb or Myl9 in Junb–/– cells restores stress fiber formation, cellular motility, and contraction capability.

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Reexpression of Junb or Myl9 in Junb–/– cells restores stress fiber form...
(A and B) Reexpression of Junb or Myl9 in Junb–/– MEFs restores Myl9 expression, as confirmed by immunoblot analysis of nuclear and total extracts from wild-type MEFs (co) or Junb–/– MEFs that were left untreated or retrovirally transduced. RCC1, Hsc70, and β-actin served as control for equal quality and loading. Results of densitometric quantification of blots are shown. (C and D) Immunofluorescence staining for F-actin and phosphorylated Myl9 (p-Myl9) on Junb–/– MEFs transduced with an empty vector or Junb- or Myl9-encoding retroviral expression vector. Scale bars: 10 μm. In C and D, one representative staining of at least 3 independent cell preparations is shown (n ≥ 3). (E and F) Relative wound closure of control and Junb–/– MEFs and of the same cells transduced with empty vector or Junb- or Myl9-containing vector subjected to scratch wounding. Values were calculated from images of the wound area taken at 0, 8, and 18 hours after wounding. ***P < 0.005. (G) Relative collagen gel contraction by wild-type or Junb–/– MEFs transduced with empty vector or Junb- or Myl9-encoding retroviral expression vector. Gel contraction capability was determined 96 hours after seeding as percentage of the initial gel surface area that was set to 100%. Results represent the mean ± SD of 3 independent experiments (n = 3), each performed in triplicate (E and G). Bonferroni multiple comparisons test was applied for statistical analysis. ***P < 0.001.