Single-Cell Alternative Splicing Analysis with Expedition Reveals Splicing Dynamics during Neuron Differentiation.
Yan Song, Olga B Botvinnik, Michael T Lovci, Boyko Kakaradov, Patrick Liu, Jia L Xu, Gene W Yeo
Author Information
Yan Song: Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
Olga B Botvinnik: Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Bioinformatics and Systems Biology Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA.
Michael T Lovci: Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA.
Boyko Kakaradov: Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Bioinformatics and Systems Biology Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA.
Patrick Liu: Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
Jia L Xu: Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
Gene W Yeo: Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Bioinformatics and Systems Biology Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119077, Singapore; Molecular Engineering Laboratory, A(∗)STAR, Singapore 138632, Singapore. Electronic address: geneyeo@ucsd.edu.
Alternative splicing (AS) generates isoform diversity for cellular identity and homeostasis in multicellular life. Although AS variation has been observed among single cells, little is known about the biological or evolutionary significance of such variation. We developed Expedition, a computational framework consisting of outrigger, a de novo splice graph transversal algorithm to detect AS; anchor, a Bayesian approach to assign modalities; and bonvoyage, a visualization tool using non-negative matrix factorization to display modality changes. Applying Expedition to single pluripotent stem cells undergoing neuronal differentiation, we discover that up to 20% of AS exons exhibit bimodality. Bimodal exons are flanked by more conserved intronic sequences harboring distinct cis-regulatory motifs, constitute much of cell-type-specific splicing, are highly dynamic during cellular transitions, preserve reading frame, and reveal intricacy of cell states invisible to conventional gene expression analysis. Systematic AS characterization in single cells redefines our understanding of AS complexity in cell biology.
