Proteomic analysis in aortic media of patients with Marfan syndrome reveals increased activity of calpain 2 in aortic aneurysms.
BACKGROUND
Marfan syndrome (MFS) is a heritable disorder of connective tissue, affecting principally skeletal, ocular, and cardiovascular systems. The most life-threatening manifestations are aortic aneurysm and dissection. We investigated changes in the proteome of aortic media in patients with and without MFS to gain insight into molecular mechanisms leading to aortic dilatation.


RESULTS
Aortic samples were collected from 46 patients. Twenty-two patients suffered from MFS, 9 patients had bicuspid aortic valve, and 15 patients without connective tissue disorder served as controls. Aortic media was isolated and its proteome was analyzed in 12 patients with the use of 2-dimensional difference gel electrophoresis and mass spectrometry. We found higher amounts of filamin A C-terminal fragment, calponin 1, vinculin, microfibril-associated glycoprotein 4, and myosin-10 heavy chain in aortic media of MFS aneurysm samples than in controls. Regulation of filamin A C-terminal fragmentation was validated in all patient samples by immunoblotting. Cleavage of filamin A and the calpain substrate spectrin was increased in the MFS and bicuspid aortic valve groups. Extent of cleavage correlated positively with calpain 2 expression and negatively with the expression of its endogenous inhibitor calpastatin.


CONCLUSIONS
Our observation demonstrates for the first time upregulation of the C-terminal fragment of filamin A in dilated aortic media of MFS and bicuspid aortic valve patients. In addition, our results present evidence that the cleavage of filamin A is highly likely the result of the protease calpain. Increased calpain activity might explain, at least in part, histological alterations in dilated aorta.
Pilop
Christiane
C
Departments of Nephrology and Hypertension, University Hospital of Bern, Bern, Switzerland.
Aregger
Fabienne
F
Gorman
Robert C
RC
Brunisholz
Rene
R
Gerrits
Bertran
B
Schaffner
Thomas
T
Gorman
Joseph H
JH
Matyas
Gabor
G
Carrel
Thierry
T
Frey
Brigitte M
BM
D000328:Adult; D001011:Aorta / Q000201:enzymology* / Q000473:pathology; D001014:Aortic Aneurysm / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D003285:Contractile Proteins / Q000737:chemistry / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D064448:Filamins; D006801:Humans; D008297:Male; D008382:Marfan Syndrome / Q000150:complications* / Q000473:pathology*; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism; D008875:Middle Aged; D017434:Protein Structure, Tertiary; D040901:Proteomics; D013049:Spectrin / Q000378:metabolism; D017540:Tunica Media / Q000201:enzymology / Q000473:pathology
D002135:Calcium-Binding Proteins; D003285:Contractile Proteins; D064448:Filamins; D008840:Microfilament Proteins; D013049:Spectrin; C033668:calpastatin; D002154:Calpain; C569870:CAPN2 protein, human