Myelin proteomics: the past, the unexpected and the future

Abstract

Myelin proteomics has been the subject of intense research over the last decade, and its profiling has achieved good results by both in-gel and mass spectrometry-based techniques. 1280 proteins have been identified, a number expected to increase. Some of the identified proteins are as yet not established as true components of myelin. There appears to be a limit in our ability to discover markers of myelin biogenesis, function and disease. Myelin can be easily isolated free of contaminants, thanks to its lipidic nature, which however necessitates pretreatment with detergents before mass spectrometry analysis. Here, the key issue of solubilization of myelin proteins for mass spectrometry measurements is addressed. An in-depth characterization of the myelin proteome would have a profound impact on our knowledge of its pathology and physiology. Future quantitative proteomic studies of the low-abundance myelin protein complement, likely representing key regulatory components, may in future provide molecular description of the dysmyelinating/demyelinating diseases.

Keywords::

• mass spectrometry
• myelin sheath
• proteomic analysis
• targeted-proteomics
• two dimensional gel electrophoresis

Acknowledgement

This work was supported by the Italian Ministry of Health ‘Ricerca Corrente’ and from contributions derived from ‘Cinque per mille dell’IRPEF’. The authors also acknowledge contributions from the “Renal Child Foundation” and “Compagnia di San Paolo”.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• The interest in characterization of myelin proteomic repertoire has grown continually over the years, and its profiling has achieved good results by both in-gel and mass spectrometry-based techniques.

• The most abundant myelin proteins (myelin basic protein, proteolipid protein, myelin protein zero, myelin-associated glycoprotein) were separated and identified using proteomic approaches.

• The number of identified myelin peptides (1280) appears still limited, some of which are as yet not ascribed bona fide to the myelin proteome

• Myelin isolation is easily achieved, but solubilization of its proteins is a key issue for their identification.

• High-resolution mass spectrometry-based proteomics has progressed tremendously with large-scale identification and quantification of proteins; such developments will enable complete analysis of myelin proteome.

• 2DE will be fundamental to assess the solubilization treatments and as preliminary study.

• Proteomics approaches to myelin can provide a valuable resource to understand myelin biogenesis, function and pathology.

• Identification of the low-abundance proteins expressed in the myelin proteome likely represents the future goal, with profound impact on pathophysiology of demyelinating diseases.

Notes