title: The alteration of serine transporter activity in a cell line model of amyotrophic lateral sclerosis (ALS).
abstract: The alteration of d-serine levels is associated with the pathogenesis of sporadic ALS and mutant SOD1 (G93A) animal model of ALS. However, the exact mechanism of d-serine transport is not known in ALS. To better understand the distribution of d-serine in ALS, we determined the activity and the expression of serine transporter in a motor neuronal cell line model of ALS (NSC-34/hSOD1G93Acells). The uptake of [3H]d-serine was significantly lower in NSC-34/hSOD1G93Acells than in control NSC-34 and NSC-34/hSOD1wtcells. In contrast, the uptake of [3H]l-serine, precursor of d-serine, was markedly increased in NSC-34/hSOD1G93Acells compared to control NSC-34 and NSC-34/hSOD1wtcells. Both [3H]d-serine and [3H]l-serine uptake were saturable in these cells. The estimated Michaelis-Menten constant, Km, for d-serine uptakes was higher in NSC-34/hSOD1G93Acells than in NSC-34/hSOD1wtcells while the Kmfor l-serine uptake was 2 fold lower in NSC-34/hSOD1G93Acells than in control cells. [3H]d-serine and [3H]l-serine uptakes took place in a Na+-dependent manner, and both uptakes were significantly inhibited by system ASC (alanine-serine-cysteine) substrates. As a result of small interfering RNA experiments, we found that ASCT2 (SLC1A5) and ASCT1 (SLC1A4) are involved in [3H]d-serine and [3H]l-serine uptake in NSC-34/hSOD1G93Acells, respectively. The level of SLC1A4 mRNA was significantly increased in NSC-34/hSOD1G93Acompared to NSC-34 and NSC-34/hSOD1wtcells. In contrast, the level of SLC7A10 mRNA was relatively lower in NSC-34/hSOD1G93Acells than the control cells. Together, these data suggest that the pathological alteration of d- and l-serine uptakes in ALS is driven by the affinity change of d-and l-serine uptake system.
authors.affiliation: College of Pharmacy and Research Center for Cell Fate Control, Sookmyung Women's University, Seoul, Republic of Korea.
authors.forename: Na-Young
authors.initials: NY
authors.lastname: Lee
authors.affiliation: Laboratory for Neuronal Gene Regulation and Epigenetics, Center for NeuroMedicine, Korea Institute of Science and Technology, Seoul, Republic of Korea.
authors.forename: Yunha
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Laboratory for Neuronal Gene Regulation and Epigenetics, Center for NeuroMedicine, Korea Institute of Science and Technology, Seoul, Republic of Korea; Boston University Alzheimer's Disease Center and Department of Neurology, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Hoon
authors.initials: H
authors.lastname: Ryu
authors.affiliation: College of Pharmacy and Research Center for Cell Fate Control, Sookmyung Women's University, Seoul, Republic of Korea. Electronic address: yskang@sookmyung.ac.kr.
authors.forename: Young-Sook
authors.initials: YS
authors.lastname: Kang
mesh_terms: D026962:Amino Acid Transport System ASC / Q000235:genetics / Q000378:metabolism*; D027182:Amino Acid Transport System y+ / Q000235:genetics / Q000378:metabolism; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D008822:Mice, Transgenic; D015778:Minor Histocompatibility Antigens / Q000235:genetics / Q000378:metabolism; D009046:Motor Neurons / Q000378:metabolism* / Q000473:pathology; D012694:Serine / Q000378:metabolism*; D000072105:Superoxide Dismutase-1 / Q000235:genetics / Q000378:metabolism
chemical_list: D026962:Amino Acid Transport System ASC; D027182:Amino Acid Transport System y+; D015778:Minor Histocompatibility Antigens; C000606290:SOD1 protein, human; C498847:Slc1a4 protein, mouse; C498850:Slc1a5 protein, mouse; C412624:Slc7a10 protein, mouse; D012694:Serine; D000072105:Superoxide Dismutase-1
keywords: Amyotrophic lateral sclerosis (ALS); Motor neuron disease; d-Serine; l-Serine