CNS myelin structural modification induced in vitro by phospholipases A2

• Published in: Biochimica et biophysica acta 2016-01, Vol.1858 (1), p.123-129
• Main Authors: Yunes Quartino, Pablo J., Pusterla, Julio M., Galván Josa, Victor M., Fidelio, Gerardo D., Oliveira, Rafael G.
• Format: Article
• Language: English
• Subjects: Air - analysis; Animals; Bee Venoms - chemistry; Bee Venoms - enzymology; Bees; Cattle; Demyelination; Elapid Venoms - chemistry; Elapid Venoms - enzymology; Elapidae; Hydrolysis; Isoenzymes - chemistry; Isoenzymes - isolation & purification; Langmuir monolayers; Myelin; Myelin Sheath - chemistry; Myelin Sheath - ultrastructure; Pancreas - chemistry; Pancreas - enzymology; Phospholipases; Phospholipases A2 - chemistry; Phospholipases A2 - isolation & purification; Saxs; Scattering, Small Angle; Solutions; Spinal Cord - chemistry; Surface Properties; Swine; Water - chemistry; X-Ray Diffraction
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2015.10.017

Myelin is the self-stacked membrane surrounding axons; it is also the target of several pathological and/or neurodegenerative processes like multiple sclerosis. These processes involve, among others, the hydrolytic attack by phospholipases. In this work we describe the changes in isolated myelin structure after treatment with several secreted PLA2 (sPLA2), by using small angle x-ray scattering (SAXS) measurements. It was observed that myelin treated with all the tested sPLA2s (from cobra and bee venoms and from pig pancreas) preserved the lamellar structure but displayed an enlarged separation between membranes in certain zones. Additionally, the peak due to membrane asymmetry was clearly enhanced. The coherence length was also lower than the non-treated myelin, indicating increased disorder. These SAXS results were complemented by Langmuir film experiments to follow myelin monolayer hydrolysis at the air/water interface by a decrease in electric surface potential at different surface pressures. All enzymes produced hydrolysis with no major qualitative difference between the isoforms tested. [Display omitted] •SAXS detects changes in structure of myelin under phospholipase A2 attack.•Part of myelin keeps the normal periodicity but other part expands.•Only a fraction of phospholipids is actually degraded.•Myelin qualitatively preserves its lamellar structure.•Both, venom and non-venom phospholipases attack myelin.