MEK5 is activated by shear stress, activates ERK5 and induces KLF4 to modulate TNF responses in human dermal microvascular endothelial cells

Microcirculation. 2011 Feb;18(2):102-17. doi: 10.1111/j.1549-8719.2010.00071.x.


Objective: ECs lining arteries respond to LSS by suppressing pro-inflammatory changes, in part through the activation of MEK5, ERK5 and induction of KLF4. We examined if this anti-inflammatory pathway operates in human ECs lining microvessels, the principal site of inflammatory responses.

Methods: We used immunofluorescence microscopy of human skin to assess ERK5 activation and KLF4 expression in HDMECs in situ. We applied LSS to or overexpressed MEK5/CA in cultured HDMECs and assessed gene expression by microarrays and qRT-PCR and protein expression by Western blotting. We assessed effects of MEK5/CA on TNF responses using qRT-PCR, FACS and measurements of HDMEC monolayer electrical resistance. We used siRNA knockdown to assess the role of ERK5 and KLF4 in these responses.

Results: ERK5 phosphorylation and KLF4 expression is observed in HDMECs in situ. LSS activates ERK5 and induces KLF4 in cultured HDMECs. MEK5/CA-transduced HDMECs show activated ERK5 and increased KLF4, thrombomodulin, eNOS, and ICAM-1 expression. MEK5 induction of KLF4 is mediated by ERK5. MEK5/CA-transduced HDMECs are less responsive to TNF, an effect partly mediated by KLF4.

Conclusions: MEK5 activation by LSS inhibits inflammatory responses in microvascular ECs, in part through ERK5-dependent induction of KLF4.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cells, Cultured
  • Endothelial Cells / drug effects*
  • Endothelial Cells / metabolism*
  • Enzyme Activation
  • Gene Expression Profiling
  • Gene Knockdown Techniques
  • Humans
  • Kruppel-Like Transcription Factors / antagonists & inhibitors
  • Kruppel-Like Transcription Factors / biosynthesis*
  • Kruppel-Like Transcription Factors / genetics
  • MAP Kinase Kinase 5 / antagonists & inhibitors
  • MAP Kinase Kinase 5 / genetics
  • MAP Kinase Kinase 5 / metabolism*
  • Mitogen-Activated Protein Kinase 7 / metabolism*
  • Oligonucleotide Array Sequence Analysis
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / genetics
  • Shear Strength
  • Stress, Mechanical
  • Tumor Necrosis Factor-alpha / pharmacology*


  • GKLF protein
  • Kruppel-Like Transcription Factors
  • RNA, Messenger
  • RNA, Small Interfering
  • Tumor Necrosis Factor-alpha
  • Mitogen-Activated Protein Kinase 7
  • MAP Kinase Kinase 5
  • MAP2K5 protein, human