title: The Power of Human Protective Modifiers: PLS3 and CORO1C Unravel Impaired Endocytosis in Spinal Muscular Atrophy and Rescue SMA Phenotype.
abstract: Homozygous loss of SMN1 causes spinal muscular atrophy (SMA), the most common and devastating childhood genetic motor-neuron disease. The copy gene SMN2 produces only ∼10% functional SMN protein, insufficient to counteract development of SMA. In contrast, the human genetic modifier plastin 3 (PLS3), an actin-binding and -bundling protein, fully protects against SMA in SMN1-deleted individuals carrying 3-4 SMN2 copies. Here, we demonstrate that the combinatorial effect of suboptimal SMN antisense oligonucleotide treatment and PLS3 overexpression-a situation resembling the human condition in asymptomatic SMN1-deleted individuals-rescues survival (from 14 to >250 days) and motoric abilities in a severe SMA mouse model. Because PLS3 knockout in yeast impairs endocytosis, we hypothesized that disturbed endocytosis might be a key cellular mechanism underlying impaired neurotransmission and neuromuscular junction maintenance in SMA. Indeed, SMN deficit dramatically reduced endocytosis, which was restored to normal levels by PLS3 overexpression. Upon low-frequency electro-stimulation, endocytotic FM1-43 (SynaptoGreen) uptake in the presynaptic terminal of neuromuscular junctions was restored to control levels in SMA-PLS3 mice. Moreover, proteomics and biochemical analysis revealed CORO1C, another F-actin binding protein, whose direct binding to PLS3 is dependent on calcium. Similar to PLS3 overexpression, CORO1C overexpression restored fluid-phase endocytosis in SMN-knockdown cells by elevating F-actin amounts and rescued the axonal truncation and branching phenotype in Smn-depleted zebrafish. Our findings emphasize the power of genetic modifiers to unravel the cellular pathomechanisms underlying SMA and the power of combinatorial therapy based on splice correction of SMN2 and endocytosis improvement to efficiently treat SMA.
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Seyyedmohsen
authors: S
authors: Hosseinibarkooie
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Miriam
authors: M
authors: Peters
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Laura
authors: L
authors: Torres-Benito
authors: Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany.
authors: Raphael H
authors: RH
authors: Rastetter
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Kristina
authors: K
authors: Hupperich
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Andrea
authors: A
authors: Hoffmann
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Natalia
authors: N
authors: Mendoza-Ferreira
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Anna
authors: A
authors: Kaczmarek
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Eva
authors: E
authors: Janzen
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Janine
authors: J
authors: Milbradt
authors: Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
authors: Tobias
authors: T
authors: Lamkemeyer
authors: IONIS Pharmaceuticals, 2855 Carlsbad, CA 92008, USA.
authors: Frank
authors: F
authors: Rigo
authors: IONIS Pharmaceuticals, 2855 Carlsbad, CA 92008, USA.
authors: C Frank
authors: CF
authors: Bennett
authors: Biocenter, Institute for Zoology, Neurophysiology, University of Cologne, 50674 Cologne, Germany.
authors: Christoph
authors: C
authors: Guschlbauer
authors: Biocenter, Institute for Zoology, Neurophysiology, University of Cologne, 50674 Cologne, Germany.
authors: Ansgar
authors: A
authors: Büschges
authors: Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany; Biocenter, Institute for Zoology, Developmental Biology, University of Cologne, 50674 Cologne, Germany.
authors: Matthias
authors: M
authors: Hammerschmidt
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
authors: Markus
authors: M
authors: Riessland
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany.
authors: Min Jeong
authors: MJ
authors: Kye
authors: Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany.
authors: Christoph S
authors: CS
authors: Clemen
authors: Institute of Human Genetics, University of Cologne, 50931 Cologne Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany. Electronic address: brunhilde.wirth@uk-koeln.de.
authors: Brunhilde
authors: B
authors: Wirth
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001369:Axons / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins; D004195:Disease Models, Animal; D004705:Endocytosis / Q000235:genetics*; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins / Q000235:genetics* / Q000378:metabolism*; D009134:Muscular Atrophy, Spinal / Q000235:genetics* / Q000473:pathology*; D009469:Neuromuscular Junction / Q000378:metabolism / Q000473:pathology; D016376:Oligonucleotides, Antisense; D010641:Phenotype; D017729:Presynaptic Terminals / Q000378:metabolism; D011726:Pyridinium Compounds / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D055533:Survival of Motor Neuron 1 Protein / Q000235:genetics; D055540:Survival of Motor Neuron 2 Protein / Q000235:genetics; D009435:Synaptic Transmission / Q000235:genetics; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D002352:Carrier Proteins; C034037:F-actin-binding proteins; C073804:FM1 43; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D016376:Oligonucleotides, Antisense; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; C526471:SMN1 protein, human; C526477:SMN2 protein, human; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; C026742:plastin; C072061:coronin proteins; D002118:Calcium