Cardiac progenitor cells (CPCs) must control their number and fate to sustain the rapid heart growth during development, yet the intrinsic factors and environment governing these processes remain unclear. Here, we show that deletion of the ancient cell-fate regulator Numb (Nb) and its homologue Numblike (Nbl) depletes CPCs in second pharyngeal arches (PA2s) and is associated with an atrophic heart. With histological, flow cytometric and functional analyses, we find that CPCs remain undifferentiated and expansive in the PA2, but differentiate into cardiac cells as they exit the arch. Tracing of Nb- and Nbl-deficient CPCs by lineage-specific mosaicism reveals that the CPCs normally populate in the PA2, but lose their expansion potential in the PA2. These findings demonstrate that Nb and Nbl are intrinsic factors crucial for the renewal of CPCs in the PA2 and that the PA2 serves as a microenvironment for their expansion
Animal experimentation: All the animals were treated humanely according to AALAC and NIH guidelines (Johns Hopkins Medical Institutions are fully accredited by the AALAC) and the current study was conducted under the animal protocol (MO10M444) approved by the Animal Care and Use Committee at Johns Hopkins University.
- Robb Krumlauf, Reviewing Editor, Stowers Institute for Medical Research, United States
© 2014, Shenje et al
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