Analysis of supramolecular assemblies of NE81, the first lamin-like protein in a unicellular organism

• Applicant: Professor Dr. Ralph Gräf
• Subject Area: Cell Biology ; Evolutionary Cell and Developmental Biology (Zoology)
• Term: from 2010 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 180581162

Lamins build the nuclear lamina and are required for mechanical stabilization of cells, chromatin organization, gene expression, cell cycle progression and cell migration. This became evident by the pathogenesis of laminopathies, which are caused by mutations in genes encoding lamin A/C. Despite these functions of universal importance, lamins have so far only been found in metazoans. With Dictyostelium NE81 we have now identified a protein associated with the inner nuclear envelope, whose properties justify denomination as a lamin-like protein in a lower eukaryote. This is based both on its primary sequence and an initial functional characterization. Here we propose a work schedule that aims at the verification of NE81 as a primitive lamin and the analysis of its putative lamin-like functions. First, we will generate and analyze NE81 depletion mutants, mutants in CDK1 kinase target sequences and isoprenylation mutants. Second, we will examine the expected assembly properties of NE81 on the biochemical and microscopic level. Third, we will characterize the role of the enzymatic machinery for prelamin processing, which is completely conserved in Dictyostelium and is expected to be required for NE81 function. Fourth we intend to verify putative binding partners of NE81 at the nuclear envelope and its binding to chromatin. The discovery of a lamin-like protein in a unicellular organism is not only very interesting in the light of evolution, it could also provide a simple experimental platform for studies of the molecular basis of laminopathies.

• DFG Programme: Research Grants