NGN3 oscillatory expression controls the timing of human pancreatic endocrine differentiation

Abstract

Understanding protein expression dynamics is crucial for the mechanistic understanding of cell differentiation. We investigate the dynamics of NGN3, a transcription factor critical for pancreatic endocrine development, including their function and decoding mechanisms. A knock-in endogenous reporter shows that the expression of NGN3 protein oscillates with a 13-hour periodicity in human iPS-derived endocrine progenitors and is switched off as cells differentiate to {beta}-like and -like cells. Increasing the stability of NGN3 protein results in one broad peak of expression instead of oscillations, with a larger peak to trough fold-change. This leads to precocious endocrine differentiation to both {beta}-like and -like cells and precocious expression of key NGN3 target genes. Single-cell analysis of dynamics, mathematical modelling and bioinformatics suggest that decoding of NGN3 oscillations occurs by fold-change detection via an incoherent feedforward motif that explains both normal and precocious differentiation. Our findings suggest that oscillatory NGN3 dynamics control the timing of differentiation, but not fate specification.