Anti-MESP1 (aa 63-91) polyclonal antibody

Identifying the genetic etiology of congenital heart disease (CHD) has been challenging despite being one of the most common congenital malformations in humans. We previously identified a microdeletion in a patient with a ventricular septal defect containing over 40 genes including MESP1 (mesoderm posterior basic helix-loop-helix transcription factor 1). Because of the importance of MESP1 as an early regulator of cardiac development in both in vivo and in vitro studies, we tested for MESP1 mutations in 647 patients with congenital conotruncal and related heart defects. We identified six rare, nonsynonymous variants not seen in ethnically matched controls and one likely race-specific nonsynonymous variant. Functional analyses revealed that three of these variants altered activation of transcription by MESP1. Two of the deleterious variants are located within the conserved HLH domain and thus impair the protein-protein interaction of MESP1 and E47. The third deleterious variant was a loss-of-function frameshift mutation. Our results suggest that pathologic variants in MESP1 may contribute to the development of CHD and that additional protein partners and downstream targets could likewise contribute to the wide range of causes for CHD. (C) 2015 Wiley Periodicals, Inc.

MESP1 represents an essential transcription factor to guarantee coordinated cardiac development. The expression of MESP1 is thought to be the first sign that a cell has been committed to the cardiac lineage. We analyzed the coding sequence of MESP1 in 215 patients with congenital heart disease. Our results show that the sequence of exon 1 is highly variable with up to seven alterations in individual samples. Five base pair positions (c.157_G>C A53P, rs6496598; c.174_A>C P58P, rs28377352; c.182_T>G L61R, rs28368490; c.669_C>G F223L, rs2305440; c.687_T>G P229P, rs2305441) are particularly variable. In almost half of the samples a 12 base pair insertion after position 55 (c.165_166insGTGCCGAGCCCC P55insVPSP, rs71934166) coding for VPSP was detected which was strongly correlated with the appearance of further amino acid changes (c.157_G>C A53P, c.182_T>G L61R, c.669_C>G F223L). Two missense mutations (c.33_G>C E11D, rs190259690; c.528_A>T T176S) were detected in two patients but were absent in the controls. The assessment of the biological activity of altered MESP1 proteins in a luciferase reporter assay showed an enhanced activity of the c.33_G>C E11D mutation and a reduction of the insertion without an accompanying change of c.182_T>G L61R. The modified biological properties of mutated MESP1 proteins might be associated with the appearance of certain pathological phenotypes of congenital heart disease. (C) 2013 Elsevier Masson SAS. All rights reserved.