Etude de la différenciation des cellules musculaires lisses in vitro (rôle du facteur de transcription NFAT2 et de l'organisation tridimensionnelle de la fibre élastique)

Les cellules musculaires lisses (CML) sont capables de moduler leur phénotype. Cette modulation phénotypique, associée à des propriétés de prolifération et de migration, est impliquée dans des processus physiopathologiques, tels que l'athérosclérose et l'hypertension. Les facteurs induisant ces variations phénotypiques sont mal connus. Dans ce manuscrit, j'ai exploré, l'étude, in vitro, du rôle du facteur de transcription NFAT2 dans le processus de différenciation des CML. L'état de différentiation des CML a été suivi à l'aide d'un marqueur de différenciation, sm-MHC, et d'un marqueur de dédifférenciation, 2PIA2. J'ai mis en évidence que la translocation nucléaire du NFAT2 est primordiale au maintien et à l'acquisition de l'état différencié des CML. De plus, j'ai montré que l'anticorps 2P1A2, reconnaissait un epitope conformationnel membranaire de l'isoforme non-musculaire de la myosine IIA qui possède une distribution près du noyau et orientée vers les pseudopodes de CML dédifférenciées. La différenciation est fonction de la fibre élastique. La fibre élastique est un des composants majeurs de la paroi artérielle. Les amines oxydases telles que la lysyloxydase sont importantes dans la formation de la trame élastique. Nous avons mis en évidence une relation entre la diminution d'une autre amine oxydase, la semi-carbazide sensitive amine oxydase (SSAO), l'amincissement de la fibre élastique et la dédifférenciation des CML dans la survenue des anévrismes aortiques humains.Smooth muscle cells (SMC) are capable of modulating their phenotype. This phenotypic modulation, associated with proliferation and migration properties, is implicated in physiopathological processes like arteriosclerosis and hypertension. Factors wich induce these phenotypic variations are poorly known. In this manuscript, I have explored, the study, in vitro, of the NFAT2 transcription factor role in SMC differentiation process. SMC differentiation state have been followed with the help of a differentiation marker, sm-MHC, and a dedifferentiation marker, 2P1A2. I emphasized that NFAT2 nuclear translocation is essential to the maintain and the acquisition of differentiated SMC state. Moreover, I showed that 2P1A2, recognized a membrane conformation epitope of the non-muscle myosin II A which have a distribution near the nucleus and oriented towards pseudopode in dedifferentiated SMC. SMC differentiation state is function of elastic fibre. Elastic fibres is one of major components of the arterial wall. Amine oxydases like lysil oxidase are important in the formation of elastic scaffold. We emphasized a relation between the decrease of an other amine oxydase, the semi-carbazide sensitive amine oxydase (SSAO), the decrease of elastic lamellar thickness and the dedifferentiation of SMC in the apparition of human aortic anevrysm.BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

Association between semicarbazide-sensitive amine oxidase, a regulator of the glucose transporter, and elastic lamellae thinning during experimental cerebral aneurysm development: laboratory investigation.: SSAO and experimental cerebral aneurysm

International audienceOBJECT: Amine oxidases play a key role in the polymerization and cross-linking of the collagens and elastic lamellae of the arterial wall. The loss of elastic lamellae integrity is one of the first steps in the genesis of a cerebral aneurysm. The authors investigated the relation between semicarbazide-sensitive amine oxidase (SSAO) and the organization of the cerebral arterial wall during aneurysm development. METHODS: Intracranial aneurysms were induced in rats via unilateral carotid artery ligation and renovascular hypertension. This modified Hashimoto model was used to create elevated blood pressure associated with shear stress in cerebral arteries. The authors immunohistologically investigated some markers of the extracellular matrix (Types I, III, and IV collagen and elastin), vascular smooth muscle cell differentiation (smooth muscle myosin heavy chain [sm-MHC], alpha-smooth muscle actin, and desmin), and amine oxidases (SSAO and lysyl oxidase [LOX]) in the cerebral arterial wall in control and treated rats 1, 2, 3, 4, and 6 months after the surgical procedure. RESULTS: The authors found severe disorganization and thinning of the elastic lamellae and a dramatic reduction in SSAO activity and immunostaining during cerebral aneurysm development. In contrast, LOX markers were slightly increased. Elastic lamellae thinning was highly correlated with decreases in SSAO (r = 0.76, p < 0.0001). There was also a correlation between sm-MHC and SSAO levels. CONCLUSIONS: The data suggested that cerebral hemodynamic modifications induce decreases in SSAO activity resulting in cell dedifferentiation and inducing dysregulation of glucose transport

Obtention d'anticorps monoclonaux specifiques des myocytes arteriels

SIGLECNRS AR 11784 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc