Multicellular evolution by reprograming cell cycle regulation
Prof. Bradley Olson, Division of Biology
Kansas State University
Project dates: 2013-2014
The long term objective of this project is to better understand the genetic basis of multicellular evolution. Despite multicellular evolution being a fundamental, and cancer relevant process, the genetic pathways required for multicellularity to evolve are poorly understood. This project will determine the genes important for multicellular evolution in a novel, metazoan relevant multicellular model system, the Volvocine algae, whose members include closely related unicellular and multicellular species. Importantly, the Volvocine algae regulate their cell cycle with homologs of the retinoblastoma (RB) tumor suppressor, where evolutionary changes in its function are linked to multicellular evolution. In Aim 1 of this proposal, cell cycle regulated gene expression will be determined by deep sequencing all messenger RNA (RNA-seq) in unicellular Chlamydomonas compared to multicellular Gonium. Second, RNA-seq will also be performed in Chlamydomonas and Gonium strains lacking RB (encoded by the MAT3 gene) to determine which genes have expression defects compared to wild-type and between the two species. This process will then be repeated in a pseudo-multicellular Chlamydomonas strain caused by the presence of the Gonium RB. In Aim 2, the promoter occupancy by the RB protein in Chlamydomonas and Gonium will be determined by chromatin immunoprecipitation, followed by deep sequencing (ChIP-seq) of RB bound genetic loci. These RB bound loci will be compared between Chlamydomonas and Gonium as well as to the expression data from Aim 1. In summary, this project will make significant advancements in our understanding of the genetic determinants of multicellularity, as well as determine the genome-wide architecture of the RB pathway in unicellular Chlamydomonas compared to multicellular Gonium.