Format

Send to

Choose Destination
Acta Neuropathol Commun. 2016 Feb 3;4:8. doi: 10.1186/s40478-016-0280-0.

New insights into the protein aggregation pathology in myotilinopathy by combined proteomic and immunolocalization analyses.

Author information

1
Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, Buerkle-de-la-Camp-Platz 1, D-44789, Bochum, Germany.
2
Medizinisches Proteom-Center, Ruhr-University Bochum, D-44801, Bochum, Germany.
3
Department of Pathology and Neuromuscular Unit, Institute of Neuropathology, IDIBELL-Hospital Universitari de Bellvitge and Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain.
4
Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians University of Munich, D-80336, Munich, Germany.
5
Department of Cytology, Institute of Anatomy, Ruhr-University Bochum, D-44801, Bochum, Germany.
6
Clinical Neurogenetics, National Institutes of Health, MSC 9404, Bethesda, MD, USA.
7
Institute of Neuropathology, University Hospital Erlangen, D-91054, Erlangen, Germany.
8
Institute for Cell Biology, University of Bonn, D-53121, Bonn, Germany.
9
Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, Buerkle-de-la-Camp-Platz 1, D-44789, Bochum, Germany. rudolf.kley@rub.de.

Abstract

INTRODUCTION:

Myofibrillar myopathies are characterized by progressive muscle weakness and impressive abnormal protein aggregation in muscle fibers. In about 10 % of patients, the disease is caused by mutations in the MYOT gene encoding myotilin. The aim of our study was to decipher the composition of protein deposits in myotilinopathy to get new information about aggregate pathology.

RESULTS:

Skeletal muscle samples from 15 myotilinopathy patients were included in the study. Aggregate and control samples were collected from muscle sections by laser microdissection and subsequently analyzed by a highly sensitive proteomic approach that enables a relative protein quantification. In total 1002 different proteins were detected. Seventy-six proteins showed a significant over-representation in aggregate samples including 66 newly identified aggregate proteins. Z-disc-associated proteins were the most abundant aggregate components, followed by sarcolemmal and extracellular matrix proteins, proteins involved in protein quality control and degradation, and proteins with a function in actin dynamics or cytoskeletal transport. Forty over-represented proteins were evaluated by immunolocalization studies. These analyses validated our mass spectrometric data and revealed different regions of protein accumulation in abnormal muscle fibers. Comparison of data from our proteomic analysis in myotilinopathy with findings in other myofibrillar myopathy subtypes indicates a characteristic basic pattern of aggregate composition and resulted in identification of a highly sensitive and specific diagnostic marker for myotilinopathy.

CONCLUSIONS:

Our findings i) indicate that main protein components of aggregates belong to a network of interacting proteins, ii) provide new insights into the complex regulation of protein degradation in myotilinopathy that may be relevant for new treatment strategies, iii) imply a combination of a toxic gain-of-function leading to myotilin-positive protein aggregates and a loss-of-function caused by a shift in subcellular distribution with a deficiency of myotilin at Z-discs that impairs the integrity of myofibrils, and iv) demonstrate that proteomic analysis can be helpful in differential diagnosis of protein aggregate myopathies.

PMID:
26842778
PMCID:
PMC4739336
DOI:
10.1186/s40478-016-0280-0
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for BioMed Central Icon for PubMed Central
Loading ...
Support Center