A novel cell immunoassay to measure survival of motor neurons protein in blood cells.
BACKGROUND
The motor neuron degenerative disease spinal muscular atrophy (SMA) is the leading genetic cause of infant mortality and is caused by mutations in the survival of motor neurons (SMN) gene that reduce the expression levels of the SMN protein. A major goal of current therapeutic approaches is to increase SMN levels in SMA patients. The purpose of this study was to develop a reliable assay to measure SMN protein levels from peripheral blood samples.


METHODS
We developed a novel cell immunoassay to quantitatively measure SMN levels from peripheral blood mononuclear cells (PBMCs) using a single anti-SMN antibody.


RESULTS
SMN levels determined by the cell immunoassay are comparable to levels determined by Western blot, but in contrast, the immunoassay does not involve cell lysis, requires a small amount of patient material, and can be done on a large number of samples simultaneously. SMN levels from PBMCs are not influenced by cell type heterogeneity.


CONCLUSIONS
SMN levels measured from total PBMCs provide an important snapshot of SMN protein expression, which should be a useful aid in SMA diagnosis, and a surrogate marker of efficacy of treatment in SMA clinical trials.
Kolb
Stephen J
SJ
Howard Hughes Medical Institute And Department of Biochemistry & Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6148, USA. skolb@mail.med.upenn.edu
Gubitz
Amelie K
AK
Olszewski
Robert F
RF
Ottinger
Elizabeth
E
Sumner
Charlotte J
CJ
Fischbeck
Kenneth H
KH
Dreyfuss
Gideon
G
D001324:Autoantigens; D015153:Blotting, Western / Q000379:methods; D002452:Cell Count / Q000379:methods; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007223:Infant; D009000:Monocytes / Q000378:metabolism; D009046:Motor Neurons / Q000473:pathology*; D017411:Ribonucleoproteins, Small Nuclear / Q000097:blood*; D014897:Spinal Muscular Atrophies of Childhood / Q000097:blood* / Q000473:pathology*; D055517:snRNP Core Proteins
D001324:Autoantigens; D017411:Ribonucleoproteins, Small Nuclear; C526417:SNRPN protein, human; D055517:snRNP Core Proteins