[Changes of some proteins expression of the spinal cord and muscles in infantile spinal muscular atrophy]

The various types of childhood spinal muscular atrophy (SMA) represent a spectrum of clinical disorders resulting from the degeneration of motor neurons (MN). The genetic defect has been recently localized to chromosome 5q in the region 11.2-13.3. Under normal conditions, half of the motor neurons die during embryonic development, while the remaining 50% survive to innervate muscle fibers and form neuromuscular junctions. Numerous studies using in vivo and in vitro models have shown that survival of MNs depends on the presence of trophic factors of neuronal and muscular origin. However, at the present time, no molecular mechanisms can be proposed to account for the nature and the sequence of the interactions leading to the formation and maintenance of a functional neuromuscular junction. To gain a better understanding of the SMA disorders, an alternative to genetic studies consists in analyzing the molecular mechanisms underlying this pathology. Variations in the expression of proteins, for instance, might reflect the pathological phenotype. We thought it possible to detect differences in the protein(s) which would correlate with the molecular deficit of childhood SMA. We, therefore, compared the patterns of human protein expression from normal controls and SMA spinal cord and muscle. Significant variations in the expression of some proteins, which have been quantified by a computerized Bio-Image electrophoresis system, have been found. In particular, two proteins, a and b (126 kDa and 112 kDa) which are very probably common to spinal cord and muscle show a marked increase of their expression in children with SMA.(ABSTRACT TRUNCATED AT 250 WORDS)