The functional organization of nuclear membrane proteins and development of new technology for studies of cell signaling

Abstract: The eukaryotic cell is defined by the nucleus, which is delimited by a double membrane structure termed the nuclear envelope (NE). The NE is implicated in a multitude of different processes, for example chromatin organization. During mitosis in higher eukaryotes the nucleus is disassembled to allow the formation of the mitotic spindle, which segregates the duplicated chromosomes between daughter cells. We have characterized a novel transmembrane protein of the inner nuclear membrane. Because of its distribution along spindle microtubule during mitosis, we termed the protein Samp1 (Spindle associated membrane protein 1). Samp1 is the founding member of transmembrane proteins that define a novel membrane domain that we have termed the SE (spindle endomembrane). Furthermore, we have shown that in interphase Samp1 specifically interacts with the centrosome and A-type lamina network proteins. Moreover, Samp1 contains an evolutionary highly conserved N-terminal tail containing two putative zinc fingers.Recent studies indicate local caspase activity in dendrites or axons during development and in neurodegenerative disorders. Here I present the development of a novel and unique system to monitor protease activity at sub-cellular resolution in live cells. This system relies on a cleavable FRET sensor that is anchored to the cytoskeleton. Using this system we demonstrate local caspase activation of the soma in neuronaly differentiated cells. We also used the anchored FRET sensors to monitor caspase activation after treatment with the Alzheimer’s decease related amyloid-β peptide.Moreover we have improved a NF-ĸB decoy delivery system. The system consists of a cell penetrating peptide, transportan-10, covalently linked to a peptide nucleic acid sequence that hybridizes with a nonanucleotide sequence in the decoy. We show that this system effectively delivered the decoy and inhibited an inflammatory response in primary rat glial cells.