| 1. |
- Petit, Marleen MR, et al.
(författare)
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Smooth muscle expression of lipoma preferred partner is mediated by an alternative intronic promoter that is regulated by serum response factor/myocardin.
- 2008
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Ingår i: Circulation research. - 1524-4571. ; 103:1, s. 61-9
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Tidskriftsartikel (refereegranskat)abstract
- Lipoma preferred partner (LPP) was recently recognized as a smooth muscle marker that plays a role in smooth muscle cell migration. In this report, we focus on the transcriptional regulation of the LPP gene. In particular, we investigate whether LPP is directly regulated by serum response factor (SRF). We show that the LPP gene contains 3 evolutionarily conserved CArG boxes and that 1 of these is part of an alternative promoter in intron 2. Quantitative RT-PCR shows that this alternative promoter directs transcription specifically to smooth muscle containing tissues in vivo. By using chromatin immunoprecipitation, we demonstrate that 2 of the CArG boxes, including the promoter-associated CArG box, bind to endogenous SRF in cultured aortic smooth muscle cells. Electrophoretic mobility-shift assays show that the conserved CArG boxes bind SRF in vitro. In reporter experiments, we show that the alternative promoter has transcriptional capacity that is dependent on SRF/myocardin and that the promoter associated CArG box is required for that activity. Finally, we show by quantitative RT-PCR that the alternative promoter is strongly downregulated in SRF-deficient embryonic stem cells and in smooth muscle tissues derived from conditional SRF knockout mice. Collectively, our data demonstrate that expression of LPP in smooth muscle is mediated by an alternative promoter that is regulated by SRF/myocardin.
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| 2. |
- Wasteson, Per, 1974, et al.
(författare)
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Developmental origin of smooth muscle cells in the descending aorta in mice.
- 2008
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Ingår i: Development (Cambridge, England). - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 135:10, s. 1823-32
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Tidskriftsartikel (refereegranskat)abstract
- Aortic smooth muscle cells (SMCs) have been proposed to derive from lateral plate mesoderm. It has further been suggested that induction of SMC differentiation is confined to the ventral side of the aorta, and that SMCs later migrate to the dorsal side. In this study, we investigate the origin of SMCs in the descending aorta using recombination-based lineage tracing in mice. Hoxb6-cre transgenic mice were crossed with Rosa 26 reporter mice to track cells of lateral plate mesoderm origin. The contribution of lateral plate mesoderm to SMCs in the descending aorta was determined at different stages of development. SMC differentiation was induced in lateral plate mesoderm-derived cells on the ventral side of the aorta at embryonic day (E) 9.0-9.5, as indicated by expression of the SMC-specific reporter gene SM22alpha-lacZ. There was, however, no migration of SMCs from the ventral to the dorsal side of the vessel. Moreover, the lateral plate mesoderm-derived cells in the ventral wall of the aorta were replaced by somite-derived cells at E10.5, as indicated by reporter gene expression in Meox1-cre/Rosa 26 double transgenic mice. Examination of reporter gene expression in adult aortas from Hoxb6-cre/Rosa 26 and Meox1-cre/Rosa 26 double transgenic mice suggested that all SMCs in the adult descending aorta derive from the somites, whereas no contribution was recorded from lateral plate mesoderm.
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| 3. |
- Wasteson, Per, 1974
(författare)
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Developmental origin and molecular regulation of vascular smooth muscle cells
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Several pathologies of the vascular system have been suggested to be dependent on the smooth muscle cells (SMCs) that build up the vessel wall. Aortic SMCs have been proposed to derive from lateral plate mesoderm. It has further been suggested that induction of SMC differentiation is confined to the ventral side of the aorta and that cells later migrate to the dorsal side. In this thesis, the developmental origin of aortic SMCs was investigated using recombination-based lineage tracing in mice. It was shown that aortic SMCs are derived from the somites and not from lateral plate mesoderm. Moreover, vascular SMCs are not recruited by a ventral-to-dorsal migration. Lateral plate mesoderm-derived SMCs on the ventral side of the aorta were shown to express SMC markers early in development. It was however demonstrated that these cells are replaced by SMCs of somitic origin at E10.5. Lipoma preferred partner (LPP) has recently been identified as a SMC marker involved in cell migration. In this thesis, the transcriptional regulation of the LPP gene was studied. In particular it was investigated whether LPP transcription is dependent on serum response factor (SRF)/myocardin. With bioinformatic tools, an alternative transcriptional promoter was predicted within the LPP gene. This promoter was further analyzed using quantitative RT-PCR, chromatin immunoprecipitation, electrophoretic mobility-shift assays, luciferase reporter experiments and SRF-deficient cells/tissues. It was demonstrated that the alternative promoter binds SRF in vitro. It was also shown that it has transcriptional capacity, which is dependent on SRF/myocardin. The alternative promoter directs LPP expression in SMCs in vivo. Finally, a carotid artery ligation model was used in this thesis to investigate the proposed roles of angiotensin II (Ang II) and platelet-derived growth factor B (PDGF-B) in neointimal hyperplasia. Experiments were performed in wild type mice and PDGF-B retention motif knockout mice. It was shown that PDGF-B mRNA was increased by carotid artery ligation while expression of PDGF receptor was unaffected. The ligation induced a neointima formation that was further accelerated by Ang II administration. Neointima formation was unaffected by knockout of the PDGF-B retention motif or inhibition of the PDGF receptor .
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