Project description:B-cell leukemia 11b (BCL11B) is a transcription factor known as an essential regulator of T lymphocytes and neuronal development during embryogenesis. A genome-wide association study (GWAS) showed that a gene desert region downstream of BCL11B, known to function as a BCL11B enhancer, harbors single nucleotide polymorphisms (SNPs) associated with increased arterial stiffness. However, a role for BCL11B in the adult cardiovascular system is unknown. Based on these human findings, we sought to examine the relation between BCL11B and arterial function. Here we report that BCL11B is expressed in the vascular smooth muscle (VSM) where it regulates vascular stiffness. RNA sequencing of aortas from WT and Bcl11b null mice (BSMKO) identified the cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) as the most significant differentially regulated signaling pathway in BSMKO compared to WT mice. BSMKO aortas showed decreased levels of PKG1, increased levels of Ca++-calmodulin-dependent serine/threonine phosphatase calcineurin (PP2B) and their common phosphorylation target, vasodilator-stimulated phosphoprotein (pVASPS239), a regulator of cytoskeletal actin rearrangements. Decreased pVASPS239 in BSMKO aortas was associated with increased actin polymerization (F/G actin ratio). Functionally, aortic force, stress, wall tension and stiffness, measured ex vivo in organ baths, were increased in BSMKO aortas, and BSMKO mice had increased pulse wave velocity, the in vivo index of arterial stiffness. Despite having no effect on blood pressure or microalbuminuria, increased arterial stiffness in BSMKO mice was associated with increased incidence of cerebral microbleeds compared to age-matched WT littermates. In conclusion, we have identified VSM BCL11B as a crucial regulator of aortic smooth muscle function and a potential therapeutic target for vascular stiffness.
Project description:Smooth muscle cells (SMCs) are important in a number of physiological systems and organs, including the cardiovascular system. The hallmark property of differentiated SMCs is the ability to contract, but contractile SMCs themselves show a range of phenotypes allowing prolonged tonic contraction in vascular smooth muscle or rapid phasic contraction in tissues such as bladder. Another distinctive characteristic, in contrast with terminally differentiated striated muscle cells, is that SMCs exhibit phenotypic plasticity. Vascular SMCs are able to modulate their phenotype along a continuum between a contractile phenotype, characteristic of healthy blood vessels, and a more proliferative âsyntheticâ phenotype, so-named for the enhanced synthesis and secretion of extracellular matrix components. Synthetic phenotype cells are found in a number of pathological situations such as atherosclerosis and arterial injury. We used mouse exon-junction (MJAY) arrays to gain insights into both the global contribution of alternative splicing events in re-shaping the transcriptome of dedifferentiating mouse aorta and bladder SMCs, and into the underlying regulatory mechanisms of the alternative splicing program. Affymetrix splice junction arrays (MJAY) were used to profile changes in both alternative splicing and transcript levels during the phenotypic modulation of smooth muscle cells when placed in culture. RNA extracted from intact aorta and bladder smooth muscle tissue was used for differentiated samples. For dedifferentiated, proliferative samples smooth muscle cells were enzymatically dispersed and grown in tissue culture for a week. Triplicate RNA samples were prepared from smooth muscle tissue of mouse aorta and bladder (differentiated) and from smooth muscle cells from each tissue cultured for 7 days (proliferative). The samples allowed comparison of alternative splicing (and other transcriptome) changes between differentiated and proliferative smooth muscle cell samples from two distinct types of smooth muscle cell, as well as allowing direct comparison of aorta (tonic smooth muscle) and bladder (phasic smooth muscle).
Project description:Aortic aneurysm is a life-threatening cardiovascular disorder due to the predisposition for dissection and rupture. Genetic studies have proved the involvement of the transforming growth factor-β (TGF-β) pathway in aortic aneurysm. Smad4 is the central mediator of canonical TGF-β signaling. However, the exact role of Smad4 confined to the smooth muscle cells (SMCs) in the pathogenesis of aortic aneurysm is largely unknown. Furthermore, whether TGF-β signaling disruption in SMCs could directly trigger aortic wall inflammation remains poorly investigated. Recently, we revealed a pivotal role of smooth muscle Smad4 signaling in maintaining aortic wall homeostasis and protecting against the development of aortic aneurysm and dissection. To evaluate the underlying mechanism by which Smad4 regulate VSMC functions and affects aneurysm formation and development, Smooth muscle specific Smad4 Knockout mice and the control littermate were sacrificed at 6 weeks old, and their aortic ateries were collected.We combined 3-5 vessels for one sample, and 2 samples for each phenotype. Subsequently, a total of 400ng RNA was used following Affymetrix instruction and 2 ug of cRNA were hybridized for 16 hr at 45°. GeneChips were scanned using the Scanner 7G and the data was analyzed with Expression Console using Affymetrix default analysis settings and global scaling as normalization method. RMA analysis was employed to evaluate the gene expression. We used microarrays to detect the global gene expression in the aortic arteries of smooth muscle cell specific Smad4 knockout mice (Smad4-KO)compared with wild type littermates (WT) at 6 weeks old and identified distinct classes of altered genes.
Project description:To explore global molecular changes in smooth muscle in response to PDGFR activation, primary human bladder smooth muscle cells were treated with 1 nM PDGF-BB (hereafter PDGF) for 0, 4 or 24 h. Total RNA were prepared, and analyzed using expression profiling, and subjected to bioinformatic and functional interrogation. To identify molecular signatures of bladder smooth muscle peturbed by PDGF, primary human bladder smooth muscle cells were treated with 1 nM PDGF-BB (hereafter PDGF) for 0, 4 or 24 h.