Mass Spectrometry Analysis of Wild-Type and Knock-in Q140/Q140 Huntington’s Disease Mouse Brains Reveals Changes in Glycerophospholipids Including Alterations in Phosphatidic Acid and Lyso-Phosphatidic Acid
Affiliations: [a] Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA | [b] Proteomics and Mass Spectrometry Facility and Department of Biochemistry and Molecular Pharmacology, UMASS Medical School, Worcester, MA, USA | [c] Departments of Medicine and Cell and Developmental Biology, UMASS Medical School, Worcester, MA, USA
Correspondence to: Kimberly B. Kegel-Gleason, Ph.D., MassGeneral Institute for Neurodegeneration (MIND), Department of Neurology, Massachusetts General Hospital, 114 16th Street, Room 2001, Charlestown, MA 02129, USA. Tel.: +1 617 724 8754; [email protected]
Background: Huntington’s disease (HD) is a neurodegenerative disease caused by a CAG expansion in the HD gene, which encodes the protein Huntingtin. Huntingtin associates with membranes and can interact directly with glycerophospholipids in membranes.
Objective: We analyzed glycerophospholipid profiles from brains of 11 month old wild-type (WT) and Q140/Q140 HD knock-in mice to assess potential changes in glycerophospholipid metabolism.
Methods: Polar lipids from cerebellum, cortex, and striatum were extracted and analyzed by liquid chromatography and negative ion electrospray tandem mass spectrometry analysis (LC-MS/MS). Gene products involved in polar lipid metabolism were studied using western blotting, immuno-electron microscopy and qPCR.
Results: Significant changes in numerous species of glycerophosphate (phosphatidic acid, PA) were found in striatum, cerebellum and cortex from Q140/Q140 HD mice compared to WT mice at 11 months. Changes in specific species could also be detected for other glycerophospholipids. Increases in species of lyso-PA (LPA) were measured in striatum of Q140/Q140 HD mice compared to WT. Protein levels for c-terminal binding protein 1 (CtBP1), a regulator of PA biosynthesis, were reduced in striatal synaptosomes from HD mice compared to wild-type at 6 and 12 months. Immunoreactivity for CtBP1 was detected on membranes of synaptic vesicles in striatal axon terminals in the globus pallidus.
Conclusions: These novel results identify a potential site of molecular pathology caused by mutant Huntingtin that may impart early changes in HD.