1 Cells use sophisticated molecular circuits to interpret and respond to extracellular signal 2 factors, such as hormones and cytokines, which are often released in a temporally varying fashion.
3In this study, we focus on type I interferon (IFN) signaling in human epithelial cells and combine 4 microfluidics, time-lapse microscopy, and computational modeling to investigate how the IFN-5 responsive regulatory network operates in single cells to process repetitive IFN stimulation. We 6 found that IFN-a pretreatments lead to opposite effects, priming versus desensitization, 7 depending on the input durations. These effects are governed by a regulatory network composed 8 of a fast-acting positive feedback loop and a delayed negative feedback loop, mediated by 9 upregulation of ubiquitin-specific peptidase 18 (USP18). We further revealed that USP18 10 upregulation can only be initiated at the G1 and early S phases of cell cycle upon the treatment 11 onset, resulting in heterogeneous and delayed induction kinetics in single cells. This cell cycle 12 gating provides a temporal compartmentalization of feedback control processes, enabling 13 duration-dependent desensitization to repetitive stimulations. Moreover, our results, highlighting 14 the importance of IFN dynamics, may suggest time-based strategies for enhancing the 15 effectiveness of IFN pretreatment in clinical applications against viruses, such as SARS-CoV-2.Under physiological conditions, cells often encounter environmental cues that change 2 over time. Many hormones, cytokines, and signal factors are released in a temporally varying 3 fashion. Increasing evidence demonstrated that cells can use complex signaling networks to 4 interpret the dynamic patterns of these inputs and initiate appropriate cellular responses [1, 2].
5For example, the mitogen-activated protein kinase Hog1 pathway in the yeast S. cerevisiae 6 responds to the various frequencies of oscillating osmotic stress and differentially control the 7 growth rate under stress [3][4][5]. Moreover, the gene regulatory program mediated by the yeast 8 general stress responsive transcription factors (TFs) Msn2 and Msn4 can decode various input 9 pulses and induce differential gene expression [6][7][8][9]. In mammalian systems, it has been shown 10 that the nuclear factor kB (NFkB) pathway can process the pulsatile stimulation of tumor necrosis 11 factor-a (TNF-a) to determine the timing and specificity of downstream gene expression [10][11][12].
12Similarly, the p53 tumor suppressor differentially regulates target genes and cell fates by 13 processing temporal patterns of DNA damage cues [13][14][15]. Intriguingly, many of these studies 14 observed that individual cells exhibit widely different behaviors even to the same stimuli, and, as 15 a result, population-based measurements may obscure the actual response dynamics of 16 individual cells, leading to inaccurate interpretation of the data. Furthermore, these observed cell-17 to-cell variabilities play important roles in enhancing the diversity of ph...
