12
Angiogenesis. 2012 Dec;15(4):543-54.
The angiogenesis suppressor gene AKAP12 is under
the epigenetic control of HDAC7 in endothelial
cells.
Turtoi A, Mottet D, Matheus N, Dumont B, Peixoto P, Hennequière V, Deroanne C, Colige A, De Pauw E,
Bellahcène A, Castronovo V.
Abstract
Histone deacetylases (HDACs) are a family of 18 enzymes that deacetylate lysine residues of
both histone and nonhistone proteins and to a large extent govern the process of angiogene-
sis. Previous studies have shown that specifc inhibition of HDAC7 blocks angiogenesis both
in vitro
and
in vivo
. However, the underlying molecular mechanisms are not fully understood
and hence preclude any meaningful development of suitable therapeutic modalities. The
goal of the present study was to further the understanding of HDAC7 epigenetic control of
angiogenesis in human endothelial cells using the proteomic approach. The underlying problem
was approached through siRNA-mediated gene-expression silencing of HDAC7 in human
umbilical vein endothelial cells (HUVECs). To this end, HUVEC proteins were extracted and
proteomically analyzed. The emphasis was placed on up-regulated proteins, as these may
represent potential direct epigenetic targets of HDAC7. Among several proteins, A-kinase
anchor protein 12 (AKAP12) was the most reproducibly up-regulated protein following
HDAC7 depletion. This overexpression of AKAP12 was responsible for the inhibition of
migration and tube formation in HDAC7-depleted HUVEC. Mechanistically, H3 histones asso-
ciated with AKAP12 promoter were acetylated following the removal of HDAC7, leading
to an increase in its mRNA and protein levels. AKAP12 is responsible for protein kinase C
mediated phosphorylation of signal transducer and activator of transcription 3 (STAT3). Phos-
phorylated STAT3 increasingly binds to the chromatin and AKAP12 promoter and is necessary
for maintaining the elevated levels of AKAP12 following HDAC7 knockdown. We demons-
trated for the frst time that AKAP12 tumor/angiogenesis suppressor gene is an epigenetic
target of HDAC7, whose elevated levels lead to a negative regulation of HUVEC migration
and inhibit formation of tube-like structures.
Blood. 2012 May 24;119(21):5048-56.
Matrix metalloproteinase-2 governs lymphatic
vessel formation as an interstitial collagenase.
Detry B, Erpicum C, Paupert J, Blacher S, Maillard C, Bruyère F, Pendeville H, Remacle T, Lambert V, Balsat
C, Ormenese S, Lamaye F, Janssens E, Moons L, Cataldo D, Kridelka F, Carmeliet P, Thiry M, Foidart JM,
Struman I, Noël A.
Abstract
Lymphatic dysfunctions are associatedwith several human diseases, including lymphedema and
metastatic spread of cancer. Although it is well recognized that lymphatic capillaries attach
directly to interstitial matrix mainly composed of fbrillar type I collagen, the interactions
occurring between lymphatics and their surrounding matrix have been overlooked. In this
study, we demonstrate how matrix metalloproteinase (MMP)-2 drives lymphatic morphoge-
nesis through Mmp2-gene ablation in mice, mmp2 knockdown in zebrafsh and in 3D-culture
systems, and through MMP2 inhibition. In all models used
in vivo
(3 murine models and thora-
cic duct development in zebrafsh) and
in vitro
(lymphatic ring and spheroid assays), MMP2
blockage or down-regulation leads to reduced lymphangiogenesis or altered vessel branching.
Our data show that lymphatic endothelial cell (LEC) migration through collagen fbers is afec-
ted by physical matrix constraints (matrix composition, density, and cross-linking). Transmis-
sion electron microscopy and confocal refection microscopy using DQ-collagen highlight the
contribution of MMP2 to mesenchymal-like migration of LECs associated with collagen fber
remodeling. Our fndings provide new mechanistic insight into how LECs negotiate an inters-
titial type I collagen barrier and reveal an unexpected MMP2-driven collagenolytic pathway
for lymphatic vessel formation and morphogenesis.