title: Requirement of the spindle pole body for targeting and/or tethering proteins to the inner nuclear membrane.
abstract: Appropriate targeting of inner nuclear membrane (INM) proteins is important for nuclear function and architecture. To gain new insights into the mechanism(s) for targeting and/or tethering peripherally associated proteins to the INM, we screened a collection of temperature sensitive S. cerevisiae yeast mutants for defects in INM location of the peripheral protein, Trm1-II-GFP. We uncovered numerous genes encoding components of the Spindle Pole Body (SPB), the yeast centrosome. SPB alterations affect the localization of both an integral (Heh2) and a peripheral INM protein (Trm1-II-GFP), but not a nucleoplasmic protein (Pus1). In wild-type cells Trm1-II-GFP is evenly distributed around the INM, but in SPB mutants, Trm1-II-GFP mislocalizes as a spot(s) near ER-nucleus junctions, perhaps its initial contact site with the nuclear envelope. Employing live cell imaging over time in a microfluidic perfusion system to study protein dynamics, we show that both Trm1-II-GFP INM targeting and maintenance depend upon the SPB. We propose a novel targeting and/or tethering model for a peripherally associated INM protein that combines mechanisms of both integral and soluble nuclear proteins, and describe a role of the SPB in nuclear envelope dynamics that affects this process.
authors.affiliation: a Molecular, Cellular and Developmental Biology Interdisciplinary Program; The Ohio State University; Columbus, OH USA.
authors.forename: Greetchen
authors.initials: G
authors.lastname: Diaz-Muñoz
authors.forename: Terri A
authors.initials: TA
authors.lastname: Harchar
authors.forename: Tsung-Po
authors.initials: TP
authors.lastname: Lai
authors.forename: Kuo-Fang
authors.initials: KF
authors.lastname: Shen
authors.forename: Anita K
authors.initials: AK
authors.lastname: Hopper
mesh_terms: D009685:Nuclear Envelope / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D064048:Spindle Pole Bodies / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins
keywords: INM targeting; SPB; live cell imaging; nuclear membrane organization; yeast