The Spatiotemporal Expression of Notch1 and Numb and Their Functional Interaction during Cardiac Morphogenesis

Abstract

Numb family proteins (NFPs), including Numb and Numblike (Numbl), are commonly known for their role as cell fate determinants for multiple types of progenitor cells, mainly due to their function as Notch inhibitors. Previous studies have shown that myocardial NFP double knockout (MDKO) hearts display an up-regulated Notch activation and various defects in cardiac progenitor cell differentiation and cardiac morphogenesis. Whether enhanced Notch activation causes these defects in MDKO is not fully clear. To answer the question, we examined the spatiotemporal patterns of Notch1 expression, Notch activation, and Numb expression in the murine embryonic hearts using multiple approaches including RNAScope, and Numb and Notch reporter mouse lines. To further interrogate the interaction between NFPs and Notch signaling activation, we deleted both Notch1 or RBPJk alleles in the MDKO. We examined and compared the phenotypes of Notch1 knockout, NFPs double knockout, Notch1; Numb; Numbl and RBPJk; Numb; Numbl triple knockouts. Our study showed that Notch1 is expressed and activated in the myocardium at several stages, and Numb is enriched in the epicardium and did not show the asymmetric distribution in the myocardium. Cardiac-specific Notch1 deletion causes multiple structural defects and embryonic lethality. Notch1 or RBPJk deletion in MDKO did not rescue the structural defects in the MDKO but partially rescued the defects of cardiac progenitor cell differentiation, cardiomyocyte proliferation, and trabecular morphogenesis. Our study concludes that NFPs regulate progenitor cell differentiation, cardiomyocyte proliferation, and trabecular morphogenesis partially through Notch1 and play more roles than inhibiting Notch1 signaling during cardiac morphogenesis.

The benign nature and rare occurrence of cardiac myxoma as a possible consequence of the limited cardiac proliferative/ regenerative potential: a systematic review

“… The downregulation of BMP expression may contribute to the CM development [ 136 , 137 ]. BMPs: Bone Morphogenetic Proteins CPCs: Cardiac Progenitor Cells CM: Cardiac Myxoma Notch signaling pathway Involved in the process of cardiac morphogenesis [ 140 – 143 ]. Involved in the process of cardiomyocyte proliferation and differentiation [ 144 – 146 ].…”

“…Similarly, it interacts with activins and PI3K/AKT pathway to promote mesenchymal state in CPCs. The notch pathway interacts with p21, c-myc, snail1/2, TGF-beta and in EMT it interacts with Dll4, Jag1, BMP2, Alk3/6 and other key regulatory genes [ 142 , 143 ]. ,In EMT, it also works through important interactions with snail1/2-TGFbeta .…”

Charting the Path: Navigating Embryonic Development to Potentially Safeguard against Congenital Heart Defects

“…Among those factors, modulators of the WNT signaling pathway play a critical role in cardiac specification and differentiation, through stabilization and nuclear translocation of β-catenin, which, in turn, regulates the expression of cardiogenic genes [ 107 , 108 , 109 , 110 , 111 , 112 , 113 ]. NOTCH receptors and ligands are also important cardiogenic mediators through cell–cell communication, controlling the differentiation of cardiac progenitor cells into various cardiac lineages during heart development [ 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 126 ]. Bone morphogenetic proteins (BMPs), which are key regulators of embryonic development, promote the differentiation of cardiac mesoderm and regulate the formation of heart structures, through the expression of cardiac-specific transcription factors critical for cardiomyocyte differentiation [ 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 ].…”

Hypoplastic Left Heart Syndrome: Signaling & Molecular Perspectives, and the Road Ahead

“…Notch signaling is evolutionarily a conserved cascade that is vital for cell-cell communication, tissue boundary maintenance, cellular fate determination, renewal, and differentiation of stem cells (Figure 4) [7,13,[53][54][55][56][57][58][59]. Biphasic Notch modulation plays a pivotal role in differentiating murine embryonic stem cells (mESC) and iPSC, considering that Notch signaling activation augments mesodermal induction in early-stage differentiation [60].…”