心房利钠肽(nppa/anf)和脑利钠肽(nppb/bnp)形成基因簇,在发育中的心脏腔室中表达。尽管表达受限,在心脏发育中的功能尚未通过突变分析得到证实.这归因于功能冗余;然而,它们在顺式中的基因组位置阻碍了正式分析。使用基因组编辑,我们已经为nppa和nppb产生了突变体,发现单个突变体与野生型没有区别,而nppa/nppb双突变体显示心脏形态发生缺陷和心包水肿。房室管(AVC)标记物的分析显示bmp4,tbx2b,has2和versican表达到双突变体的心房中。这种扩大的表达与心房中的细胞外基质增加相关。使用透明质酸生物传感器测量心脏果冻(心脏细胞外基质),我们证实了nppa/nppb双突变体的心脏果冻扩增。最后,bmp4敲除挽救了双突变体中has2表达和心脏果冻的扩增。这明确表明nppa和nppb在心脏发育过程中冗余地功能限制了AVC的基因表达,防止心房中过多的心脏果冻合成。
Atrial natriuretic peptide (nppa/anf) and brain natriuretic peptide (nppb/bnp) form a gene cluster with expression in the chambers of the developing heart. Despite restricted expression, a function in cardiac development has not been demonstrated by mutant analysis. This is attributed to functional redundancy; however, their genomic location in cis has impeded formal analysis. Using genome editing, we have generated mutants for nppa and nppb, and found that single mutants were indistinguishable from wild type, whereas nppa/nppb double mutants displayed heart morphogenesis defects and pericardial oedema. Analysis of atrioventricular canal (AVC) markers show expansion of bmp4, tbx2b, has2 and versican expression into the atrium of double mutants. This expanded expression correlates with increased extracellular matrix in the atrium. Using a biosensor for hyaluronic acid to measure the cardiac jelly (cardiac extracellular matrix), we confirmed cardiac jelly expansion in nppa/nppb double mutants. Finally, bmp4 knockdown rescued the expansion of has2 expression and cardiac jelly in double mutants. This definitively shows that nppa and nppb function redundantly during cardiac development to restrict gene expression to the AVC, preventing excessive cardiac jelly synthesis in the atrial chamber.