title: Detection of presenilin-1 homodimer formation in intact cells using fluorescent lifetime imaging microscopy.
abstract: Presenilin-1 (PS1) is a multipass transmembrane domain protein, which is believed to be the catalytic component of the gamma-secretase complex. The complex is comprised of four major components: PS1, nicastrin, Aph-1, and Pen-2. The exact stoichiometric relationship between the four components remains unclear. It has been shown that gamma-secretase exists as high molecular weight complexes, suggesting the possibility of dimer/multimer formation. We combined a biochemical approach with a novel morphological microscopy assay to analyze PS1 dimer formation and subcellular distribution in situ, in intact mammalian cells. Both coimmunoprecipitation and fluorescent lifetime imaging microscopy approaches showed that wildtype PS1 molecules form dimers. Moreover, PS1 holoproteins containing the D257A mutation also come into close enough proximity to form a dimer, suggesting that cleavage within the loop is not necessary for dimer formation. Taken together these data suggest that PS1 dimerization occurs during normal PS1 function.
authors.affiliation: Alzheimer Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Charlestown, MA 02129, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: Herl
authors.forename: Alberto
authors.initials: A
authors.lastname: Lleo
authors.forename: Anne V
authors.initials: AV
authors.lastname: Thomas
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Nyborg
authors.forename: Karen
authors.initials: K
authors.lastname: Jansen
authors.forename: Todd E
authors.initials: TE
authors.lastname: Golde
authors.forename: Bradley T
authors.initials: BT
authors.lastname: Hyman
authors.forename: Oksana
authors.initials: O
authors.lastname: Berezovska
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D019281:Dimerization; D031541:Fluorescence Resonance Energy Transfer; D008565:Membrane Proteins / Q000378:metabolism* / Q000502:physiology; D008856:Microscopy, Fluorescence / Q000379:methods*; D053764:Presenilin-1
chemical_list: D008565:Membrane Proteins; D053764:Presenilin-1