The cytoskeletal protein ezrin regulates EC proliferation and angiogenesis via TNF-α–induced transcriptional repression of cyclin A
Raj Kishore, Gangjian Qin, Corinne Luedemann, Evelyn Bord, Allison Hanley, Marcy Silver, Mary Gavin, David Goukassain, Douglas W. Losordo
Raj Kishore, Gangjian Qin, Corinne Luedemann, Evelyn Bord, Allison Hanley, Marcy Silver, Mary Gavin, David Goukassain, Douglas W. Losordo
View: Text | PDF | Corrigendum | Erratum
Research Article Vascular biology

The cytoskeletal protein ezrin regulates EC proliferation and angiogenesis via TNF-α–induced transcriptional repression of cyclin A

Abstract

TNF-α modulates EC proliferation and thereby plays a central role in new blood vessel formation in physiologic and pathologic circumstances. TNF-α is known to downregulate cyclin A, a key cell cycle regulatory protein, but little else is known about how TNF-α modulates EC cell cycle and angiogenesis. Using primary ECs, we show that ezrin, previously considered to act primarily as a cytoskeletal protein and in cytoplasmic signaling, is a TNF-α–induced transcriptional repressor. TNF-α exposure leads to Rho kinase–mediated phosphorylation of ezrin, which translocates to the nucleus and binds to cell cycle homology region repressor elements within the cyclin A promoter. Overexpression of dominant-negative ezrin blocks TNF-α–induced modulation of ezrin function and rescues cyclin A expression and EC proliferation. In vivo, blockade of ezrin leads to enhanced transplanted EC proliferation and angiogenesis in a mouse hind limb ischemia model. These observations suggest that TNF-α regulates angiogenesis via Rho kinase induction of a transcriptional repressor function of the cytoskeletal protein ezrin and that ezrin may represent a suitable therapeutic target for processes dependent on EC proliferation.

Authors

Raj Kishore, Gangjian Qin, Corinne Luedemann, Evelyn Bord, Allison Hanley, Marcy Silver, Mary Gavin, David Goukassain, Douglas W. Losordo

×

Figure 2

Options: View larger image (or click on image) Download as PowerPoint
TNF-α translocates ezrin to the nucleus. (A) Representative laser confoc...
TNF-α translocates ezrin to the nucleus. (A) Representative laser confocal microscopy images showing nuclear translocation and colocalization of ezrin (green stain) with nuclei stained with propidium iodide (PI; red stain) in TNF-α–treated cells (yellow in the merged images). (B) Whole-cell (WC), cytoplasmic (C), and nuclear (N) extracts from BAECs stimulated with serum alone or treated with TNF-α were analyzed for ERM protein expression by Western blots. (C) Representative PCR gel photograph showing amplification of 250 bp of the cyclin A promoter encompassing CHR elements, using DNA from anti-ezrin antibody chromatin immunoprecipitates from serum-treated or TNF-α–treated cells. Isotype-matched rabbit anti-IgG antibody was used as a control for ChIP.