Self-organization vs Watchmaker: stochastic gene expression and cell differentiation

A stable transfection assay was used to test the mechanism by which embryonic globin gene transcription is stimulated in adult erythroid cells exposed to butyric acid and its analogs. To test the appropriate expression and inducibility of chicken globin genes in murine erythroleukemia (MEL) cells, an adult chicken beta-globin gene construct was stably transfected. The chicken beta-globin gene was found to be coregulated with the endogenous adult mouse alpha-globin gene following induction of erythroid differentiation of the transfected MEL cells by incubation with either 2% dimethyl sulfoxide (DMSO) or 1 mM sodium butyrate (NaB). In contrast, a stably transfected embryonic chicken beta-type globin gene, rho, was downregulated during DMSO-induced MEL cell differentiation. However, incubation with NaB, which induces MEL cell differentiation, or alpha-amino butyrate, which does not induce differentiation of MEL cells, resulted in markedly increased levels of transcription from the stably transfected rho gene. Analysis of histone modification showed that induction of rho gene expression was not correlated with increased bulk histone acetylation. A region of 5'-flanking sequence extending from -569 to -725 bp upstream of the rho gene cap site was found to be required for both downregulation of rho gene expression during DMSO-induced differentiation and upregulation by treatment with NaB or alpha-amino butyrate. These data are support for a novel mechanism by which butyrate compounds can alter cellular gene expression through specific DNA sequences. The results reported here are also evidence that 5'-flanking sequences are involved in the suppression of embryonic globin gene expression in terminally differentiated adult erythroid cells.

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Quantifying the contribution of chromatin dynamics to stochastic gene expression reveals long, locus-dependent periods between transcriptional bursts

BMC Biology ◽

10.1186/1741-7007-11-15 ◽

2013 ◽

Vol 11 (1) ◽

pp. 15 ◽

Cited By ~ 35

Author(s):

José Viñuelas ◽

Gaël Kaneko ◽

Antoine Coulon ◽

Elodie Vallin ◽

Valérie Morin ◽

...

Keyword(s):

Gene Expression ◽

Stochastic Gene Expression ◽

Chromatin Dynamics

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Abstract 647: Identification of Platelet Derived Growth Factors A, B, C and D Specific Role in Vascular Remodeling

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.35.suppl_1.647 ◽

2015 ◽

Vol 35 (suppl_1) ◽

Author(s):

Maria Gonzalez Diez ◽

Anton Razuvaev ◽

Ulf Hedin ◽

Anders Hamsten

Keyword(s):

Gene Expression ◽

Cell Differentiation ◽

Blood Vessel ◽

Platelet Activation ◽

T Cell Activation ◽

Vascular Remodeling ◽

Cell Activation ◽

Opposite Effect ◽

Specific Role ◽

Biological Processes

Restenosis is a major complication after coronary angioplasty and stenting. The major cause of restenosis is neointimal hyperplasia, which results from an excessive proliferative response of vascular smooth muscle cells (VSMC) to mechanical injury. Platelet derived growth factor (PDGF) family members (A, B, C, D) are known to be related to vascular remodeling. However whether this role is specific for each one or overlapping remains to be elucidated. Aim: To assess the specific role of PDGF family members (A, B, C, D) in vascular remodeling after injury. Methods: We used an established model of balloon injury in rat carotid artery. The endothelium of the intima is mechanically removed. The animals (n=10/group) were sacrificed at different time points after injury (0-2-20 hours, 2-5-15 days, 6-12 weeks). mRNA from carotid arteries were isolated for gene expression studies using microarray gene expression. Results: PDGFs are differentially expressed in vascular remodeling (mRNA, A adj P val=3.28E-06, B adj P val=4.52E-8, C adj P val=5,91E-15, D adj P val=2,64E-18). Also the expression profile differs among them. We selected the genes highly correlated with each of the PDGFs (Spearman correlation, │rs >0.7│) and identified the most preeminent biological pathways associated to each one. PDGF-A positively correlates with program cell death. On the other hand, PDGF-B and C have some overlapping biological processes. There is positive correlation with blood vessel morphogenesis and angiogenesis (B), cell differentiation (B and C), DNA replication (B and C), antigen presentation and T-cell activation/differentiation (B and C). However, there is negative correlation with platelet activation (B) and cell adhesion (B and C). PDGF-D positively correlates with blood vessel morphogenesis and angiogenesis (like B) and cell differentiation (B, C), but is negatively correlated with T-cell activation/proliferation (opposite effect to B and C), apoptosis (opposite effect to A) and platelet activation (B). Conclusion: We identified specific biological processes for PDGF- A, B, C and D. Despite some overlapping, each one plays a specific role within vascular remodeling.

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