Acquired CCN2 deficiency increases aortic
metalloproteinase activity
Matrix metalloproteinases (MMPs) play a key role in aneurysm formation
and rupture in several experimental models. To clarify whether CCN2
deletion regulates MMPs levels and/or activity in the aortic wall, a
gelatin zymography was performed using protein lysates from the whole
aorta. In CCN2-KO mice, MMP-2 and MMP-9 activity was increased compared
to WT mice (Figure 5A ). Ang II infusion further increased this
activity both in WT and CCN2 deleted mice. MMP-8 levels were also
evaluated by western blot. CCN2 deletion increased relative MMP-8
concentration of both latent and active protein, and this was also
observed in response to Ang II administration in WT and CCN2-KO mice
(Figure 5B ). Additionally, the location of increased MMP
activity was assessed in thoracic descending aorta sections by in
situ zymography. In aortas of WT mice, the autofluorescence of elastic
layers can be distinguished, and no MMP activity was detected. Ang II
administration resulted in local positive MMP-fluorescence (assessed by
gelatin-degradation). However, in CCN2-KO mice there was lower
elastin-fluorescence but increased MMP-fluorescence between the elastic
layers, which was further increased by Ang II (Figure 5C ).