TY - JOUR
T1 - Homozygous Expression of Mutant ELOVL4 Leads to Seizures and Death in a Novel Animal Model of Very Long-Chain Fatty Acid Deficiency
AU - Hopiavuori, Blake R.
AU - Deák, Ferenc
AU - Wilkerson, Joseph L.
AU - Brush, Richard S.
AU - Rocha-Hopiavuori, Nicole A.
AU - Hopiavuori, Austin R.
AU - Ozan, Kathryn G.
AU - Sullivan, Michael T.
AU - Wren, Jonathan D.
AU - Georgescu, Constantin
AU - Szweda, Luke
AU - Awasthi, Vibhudutta
AU - Towner, Rheal
AU - Sherry, David M.
AU - Anderson, Robert E.
AU - Agbaga, Martin Paul
N1 - Funding Information:
The authors thank the following individuals for their various contributions to this work: Wojciech Kedzierski for providing the Elovl4 wt/mut and transgenic mice expressing the mouse WT ELOVL4 under the involucrin promoter; Nicolas Bazan for providing antibodies (VGluT1, VGluT2, and NTT4), as well as for the intellectual discussion; Mark Dittmar for animal care oversight as well as for specialized housing facilities construction and management; Willard Freeman, William Sonntag, Nawajes Mandal, Sreemathi Logan, and Nicole Ashpole for their intellectual discussions; Raju Rajala for the critical review of this manuscript and intellectual discussion; Faizah Bhatti for providing the initial neonatal incubator for housing experimental mice; Gary White, Roman Wolf, and Madeline Buddha for providing baboon brains; Ben Fowler at the OMRF Imaging Facility for the expertise and use of TEM equipment; Megan Stiles, Negar S. Rahman, Fauzziya Muhammad, Andria Hedrick, Nataliya Smith, Debra Saunders, Clair Crewe, and Albert Orock for the technical assistance; Joel McRae, Dallas Barnet, and Adeline Machalinski for managing the breeding and maintenance of all animal lines. The monoclonal antibody against VGluT1 (clone N28/9) was developed by and/or obtained from the UC Davis/NIH NeuroMab Facility, supported by NIH grant U24NS050606 and maintained by the Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, CA, 95616. The monoclonal anti-Synaptic Vesicle protein 2 (SV2) developed by K Buckley and RB Kelly was obtained from the Developmental Studies Hybridoma Bank, created by the NICHD of the NIH and maintained at The University of Iowa, Department of Biology, Iowa City, IA, 52242. Dr. Hopiavuori, Dr. Anderson, Dr. Agbaga, and Mr. Brush have a US Patent application (US20170014365) for the use of VLC-SFA in the treatment of human disease.
Funding Information:
The monoclonal antibody against VGluT1 (clone N28/9) was developed by and/or obtained from the UC Davis/NIH NeuroMab Facility, supported by NIH grant U24NS050606 and maintained by the Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, CA, 95616. The monoclonal anti-Synaptic Vesicle protein 2 (SV2) developed by K Buckley and RB Kelly was obtained from the Developmental Studies Hybridoma Bank, created by the NICHD of the NIH and maintained at The University of Iowa, Department of Biology, Iowa City, IA, 52242.
Funding Information:
Funding This work was supported by National Institutes of Health Grants R01EY00871, R01EY04149, R21NS090117, and P30EY021725 to REA; F31NS089358 to BRH; Reynolds Oklahoma Center on Aging Collaborative Grant to REA and Fellowship to BRH; Research to Prevent Blindness (Departmental); Presbyterian Health Foundation to FD; and Knights Templar Eye Foundation and Bright Focus Foundation Inc. grants to MPA.
Publisher Copyright:
© 2017, The Author(s).
PY - 2018/2/1
Y1 - 2018/2/1
N2 - Lipids are essential components of the nervous system. However, the functions of very long-chain fatty acids (VLC-FA; ≥ 28 carbons) in the brain are unknown. The enzyme ELOngation of Very Long-chain fatty acids-4 (ELOVL4) catalyzes the rate-limiting step in the biosynthesis of VLC-FA (Agbaga et al., Proc Natl Acad Sci USA 105(35): 12843–12848, 2008; Logan et al., J Lipid Res 55(4): 698–708, 2014), which we identified in the brain as saturated fatty acids (VLC-SFA). Homozygous mutations in ELOVL4 cause severe neuropathology in humans (Ozaki et al., JAMA Neurol 72(7): 797–805, 2015; Mir et al., BMC Med Genet 15: 25, 2014; Cadieux-Dion et al., JAMA Neurol 71(4): 470–475, 2014; Bourassa et al., JAMA Neurol 72(8): 942–943, 2015; Aldahmesh et al., Am J Hum Genet 89(6): 745–750, 2011) and are post-natal lethal in mice (Cameron et al., Int J Biol Sci 3(2): 111–119, 2007; Li et al., Int J Biol Sci 3(2): 120–128, 2007; McMahon et al., Molecular Vision 13: 258–272, 2007; Vasireddy et al., Hum Mol Genet 16(5): 471–482, 2007) from dehydration due to loss of VLC-SFA that comprise the skin permeability barrier. Double transgenic mice with homozygous knock-in of the Stargardt-like macular dystrophy (STDG3; 797-801_AACTT) mutation of Elovl4 with skin-specific rescue of wild-type Elovl4 expression (S+Elovl4mut/mut mice) develop seizures by P19 and die by P21. Electrophysiological analyses of hippocampal slices showed aberrant epileptogenic activity in S+Elovl4mut/mut mice. FM1-43 dye release studies showed that synapses made by cultured hippocampal neurons from S+Elovl4mut/mut mice exhibited accelerated synaptic release kinetics. Supplementation of VLC-SFA to cultured hippocampal neurons from mutant mice rescued defective synaptic release to wild-type rates. Together, these studies establish a critical, novel role for ELOVL4 and its VLC-SFA products in regulating synaptic release kinetics and epileptogenesis. Future studies aimed at understanding the molecular mechanisms by which VLC-SFA regulate synaptic function may provide new targets for improved seizure therapies.
AB - Lipids are essential components of the nervous system. However, the functions of very long-chain fatty acids (VLC-FA; ≥ 28 carbons) in the brain are unknown. The enzyme ELOngation of Very Long-chain fatty acids-4 (ELOVL4) catalyzes the rate-limiting step in the biosynthesis of VLC-FA (Agbaga et al., Proc Natl Acad Sci USA 105(35): 12843–12848, 2008; Logan et al., J Lipid Res 55(4): 698–708, 2014), which we identified in the brain as saturated fatty acids (VLC-SFA). Homozygous mutations in ELOVL4 cause severe neuropathology in humans (Ozaki et al., JAMA Neurol 72(7): 797–805, 2015; Mir et al., BMC Med Genet 15: 25, 2014; Cadieux-Dion et al., JAMA Neurol 71(4): 470–475, 2014; Bourassa et al., JAMA Neurol 72(8): 942–943, 2015; Aldahmesh et al., Am J Hum Genet 89(6): 745–750, 2011) and are post-natal lethal in mice (Cameron et al., Int J Biol Sci 3(2): 111–119, 2007; Li et al., Int J Biol Sci 3(2): 120–128, 2007; McMahon et al., Molecular Vision 13: 258–272, 2007; Vasireddy et al., Hum Mol Genet 16(5): 471–482, 2007) from dehydration due to loss of VLC-SFA that comprise the skin permeability barrier. Double transgenic mice with homozygous knock-in of the Stargardt-like macular dystrophy (STDG3; 797-801_AACTT) mutation of Elovl4 with skin-specific rescue of wild-type Elovl4 expression (S+Elovl4mut/mut mice) develop seizures by P19 and die by P21. Electrophysiological analyses of hippocampal slices showed aberrant epileptogenic activity in S+Elovl4mut/mut mice. FM1-43 dye release studies showed that synapses made by cultured hippocampal neurons from S+Elovl4mut/mut mice exhibited accelerated synaptic release kinetics. Supplementation of VLC-SFA to cultured hippocampal neurons from mutant mice rescued defective synaptic release to wild-type rates. Together, these studies establish a critical, novel role for ELOVL4 and its VLC-SFA products in regulating synaptic release kinetics and epileptogenesis. Future studies aimed at understanding the molecular mechanisms by which VLC-SFA regulate synaptic function may provide new targets for improved seizure therapies.
KW - Brain lipids
KW - ELOVL4
KW - Seizure
KW - Synaptic dysregulation
KW - Synaptic vesicle fusion kinetics
KW - Very long-chain saturated fatty acids
UR - http://www.scopus.com/inward/record.url?scp=85034624937&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85034624937&partnerID=8YFLogxK
U2 - 10.1007/s12035-017-0824-8
DO - 10.1007/s12035-017-0824-8
M3 - Article
C2 - 29168048
AN - SCOPUS:85034624937
SN - 0893-7648
VL - 55
SP - 1795
EP - 1813
JO - Molecular Neurobiology
JF - Molecular Neurobiology
IS - 2
ER -