GADD45a Promoter Regulation by a Functional Genetic Variant Associated with Acute Lung InjuryReport as inadecuate




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Rationale

Growth arrest DNA damage inducible alpha GADD45a is a stress-induced gene we have shown to participate in the pathophysiology of ventilator-induced lung injury VILI via regulation of mechanical stress-induced Akt ubiquitination and phosphorylation. The regulation of GADD45a expression by mechanical stress and its relationship with acute lung injury ALI susceptibility and severity, however, remains unknown.

Objectives

We examined mechanical stress-dependent regulatory elements MSRE in the GADD45a promoter and the contribution of promoter polymorphisms in GADD45a expression and ALI susceptibility.

Methods and Results

Initial studies in GADD45a knockout and heterozygous mice confirmed the relationship of GADD45a gene dose to VILI severity. Human lung endothelial cells EC transfected with a luciferase vector containing the full length GADD45a promoter sequence −771 to +223 demonstrated a >4 fold increase in GADD45a expression in response to 18% cyclic stretch CS, 4 h compared to static controls while specific promoter regions harboring CS-dependent MSRE were identified using vectors containing serial deletion constructs of the GADD45a promoter. In silico analyses of GADD45a promoter region −371 to −133 revealed a potential binding site for specificity protein 1 SP1, a finding supported by confirmed SP1 binding with the GADD45a promoter and by the significant attenuation of CS-dependent GADD45a promoter activity in response to SP1 silencing. Separately, case-control association studies revealed a significant association of a GADD45a promoter SNP at −589 rs581000, G>C with reduced ALI susceptibility. Subsequently, we found allelic variation of this SNP is associated with both differential GADD45a expression in mechanically stressed EC 18% CS, 4 h and differential binding site of interferon regulatory factor 7 IRF7 at this site.

Conclusion

These results strongly support a functional role for GADD45a in ALI-VILI and identify a specific gene variant that confers risk for ALI.



Author: Sumegha Mitra, Michael S. Wade, Xiaoguang Sun, Nurgul Moldobaeva, Carlos Flores, Shwu-Fan Ma, Wei Zhang, Joe G. N. Garcia , Jeffr

Source: http://plos.srce.hr/



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