Caused by a mutation of the SMN gene, spinal muscular atrophy (SMA) is an infantile and juvenile neurodegenerative disorder where motor neuron loss causes progressive paralysis. A new study published in the open access journal BMC Medicine details the first research focused on human muscle tissue atrophied due to a genetic condition, and sheds light on two distinct mechanisms at work in different forms of SMA.
A research team from Italy, led by Gerolamo Lanfranchi, analyzed muscle biopsies and genomic DNA from peripheral blood of four SMA I and five SMA III patients from the Neuromuscular Bank organised by Corrado Angelini at the University of Padova, to investigate which other muscle genes, other than the SMN defect, played a role in atrophy. They used microarray and quantitative real-time PCR to study at transcriptional level the effects of a defective SMN gene in skeletal muscles affected by the two forms of SMA: the most severe, type I (infantile), and the milder type III (juvenile).
SMA type I is also known as severe infantile SMA or Werdnig-Hoffmann disease. Manifesting rapidly in infants, babies diagnosed with type I SMA do not generally live past one year of age. SMA type III represents a milder form of the disorder. It has a later onset and affected patients may be able to walk but later lose this ability.
The two forms of SMA gave distinct expression signatures. The SMA III muscle transcriptome is close to normal, whereas in SMA I gene expression is significantly altered. Genes implicated in signal transduction were up-regulated in SMA III whereas those involved in energy metabolism and muscle contraction were consistently down-regulated in SMA I.
"Our work indicates that SMA I and III muscles are in different phases: the 'prolonged' atrophic condition typical of the SMA I muscle and the coexistence of atrophy and hypertrophy in SMA III muscle," says Lanfranchi.
Previous studies have investigated transcriptional changes in mouse or rat muscle atrophied due to physiopathological conditions, but this is the first to use human tissue affected by a genetic atrophic condition.
Notes to Editors:
1. Different atrophy-hypertrophy transcription pathways in muscles affected by severe and mild spinal muscular atrophy
Caterina Millino, Marina Fanin, Andrea Vettori, Paolo Laveder, Maria Luisa Mostacciuolo, Corrado Angelini and Gerolamo Lanfranchi
BMC Medicine (in press)
During embargo, article available here: http://www.biomedcentral.com/imedia/7947837032574727_article.pdf?random=43313
After the embargo, article available at the journal website: http://www.biomedcentral.com/bmcmed/
Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central's open access policy.
Article citation and URL available on request at email@example.com on the day of publication.
2. BMC Medicine publishes original research articles, technical advances and study protocols in any area of medical science or clinical practice. To be appropriate for BMC Medicine, articles need to be of special importance and broad interest. BMC Medicine (ISSN 1741-7015) is indexed/tracked/covered by PubMed, MEDLINE, BIOSIS, CAS, Scopus, EMBASE, Thomson Reuters (ISI) and Google Scholar.
3. BioMed Central (http://www.biomedcentral.com/) is an STM (Science, Technology and Medicine) publisher which has pioneered the open access publishing model. All peer-reviewed research articles published by BioMed Central are made immediately and freely accessible online, and are licensed to allow redistribution and reuse. BioMed Central is part of Springer Science+Business Media, a leading global publisher in the STM sector.
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.