Transcriptomic changes arising during light-induced sporulation in Physarum polycephalum
1 International Max Planck Research School, Magdeburg, Germany
2 Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany
3 Institute for Biochemistry University of Cologne, Joseph-Stelzmann-Str. 52, Cologne, Germany
4 Max Planck Institute for Dynamics of Complex Technical Systems and Magdeburg Centre for Systems Biology (MaCS), Otto von Guericke University, Magdeburg, Germany
5 Berlin Center for Genomics in Biodiversity Research Leibniz Institute for Freshwater Ecology and Inland Fisheries, Müggelseedamm 301, D-12587 Berlin, Germany
6 Magdeburg Centre for Systems Biology (MaCS), Otto von Guericke University, Sandtorstr. 1, D-39106 Magdeburg, Germany
BMC Genomics 2010, 11:115 doi:10.1186/1471-2164-11-115Published: 17 February 2010
Physarum polycephalum is a free-living amoebozoan protist displaying a complex life cycle, including alternation between single- and multinucleate stages through sporulation, a simple form of cell differentiation. Sporulation in Physarum can be experimentally induced by several external factors, and Physarum displays many biochemical features typical for metazoan cells, including metazoan-type signaling pathways, which makes this organism a model to study cell cycle, cell differentiation and cellular reprogramming.
In order to identify the genes associated to the light-induced sporulation in Physarum, especially those related to signal transduction, we isolated RNA before and after photoinduction from sporulation- competent cells, and used these RNAs to synthesize cDNAs, which were then analyzed using the 454 sequencing technology. We obtained 16,669 cDNAs that were annotated at every computational level. 13,169 transcripts included hit count data, from which 2,772 displayed significant differential expression (upregulated: 1,623; downregulated: 1,149). Transcripts with valid annotations and significant differential expression were later integrated into putative networks using interaction information from orthologs.
Gene ontology analysis suggested that most significantly downregulated genes are linked to DNA repair, cell division, inhibition of cell migration, and calcium release, while highly upregulated genes were involved in cell death, cell polarization, maintenance of integrity, and differentiation. In addition, cell death- associated transcripts were overrepresented between the upregulated transcripts. These changes are associated to a network of actin-binding proteins encoded by genes that are differentially regulated before and after light induction.