L-β-N-methylamino-l-alanine (BMAA) nitrosation generates a cytotoxic DNA damaging alkylating agent: An unexplored mechanism for neurodegenerative disease.
L-β-N-methylamino-l-alanine (BMAA) is a non-proteinic amino acid, that is neurotoxic in vitro and in animals, and is implicated in the causation of amyotrophic lateral sclerosis and parkinsonism-dementia complex (ALS-PDC) on Guam. Given that natural amino acids can be N-nitrosated to form toxic alkylating agents and the structural similarity of BMAA to other amino acids, our hypothesis was that N-nitrosation of BMAA might result in a toxic alkylating agent, providing a novel mechanistic hypothesis for BMAA action.



We have chemically nitrosated BMAA with sodium nitrite to produce nitrosated BMAA (N-BMAA) which was shown to react with the alkyl-trapping agent, 4-(p-nitrobenzyl)pyridine, cause DNA strand breaks in vitro and was toxic to the human neuroblastoma cell line SH-SY5Y under conditions in which BMAA itself was minimally toxic.



Our results indicate that N-BMAA is an alkylating agent and toxin suggesting a plausible and previously unrecognised mechanism for the neurotoxic effects of BMAA.
Centre for Epidemiology, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
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G
Potjewyd
Centre for Epidemiology, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK; Manchester Institute for Biotechnology, University of Manchester, Manchester, UK.
P J
PJ
Day
Centre for Epidemiology, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
S
S
Shangula
Centre for Epidemiology, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
G P
GP
Margison
Centre for Epidemiology, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK. Electronic address: apovey@manchester.ac.uk.
A C
AC
Povey
D000477:Alkylating Agents / Q000633:toxicity*; D000599:Amino Acids, Diamino / Q000737:chemistry*; D045744:Cell Line, Tumor; D000087522:Cyanobacteria Toxins; D053904:DNA Breaks, Single-Stranded / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009447:Neuroblastoma; D009566:Nitrates; D015538:Nitrosation / Q000187:drug effects; D011725:Pyridines / Q000633:toxicity*
D000477:Alkylating Agents; D000599:Amino Acids, Diamino; D000087522:Cyanobacteria Toxins; D009566:Nitrates; D011725:Pyridines; C008633:4-(4-nitrobenzyl)pyridine; C001824:beta-N-methylamino-L-alanine
ALS; Alkylating agent; BMAA; N-nitrosation