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Neuregulin decreases protein degradation in skeletal muscle
Author(s) -
Hellyer Nathan J,
Mantilla Carlos B,
Argadine Heather M,
Sieck Gary C
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.757.34
Subject(s) - phosphorylation , neuregulin 1 , protein kinase b , neuregulin , microbiology and biotechnology , erbb , tyrosine phosphorylation , tyrosine , skeletal muscle , diaphragm (acoustics) , protein degradation , biology , medicine , receptor tyrosine kinase , receptor , chemistry , endocrinology , signal transduction , biochemistry , physics , acoustics , loudspeaker
Neuregulin (NRG) is a member of the epidermal growth factor family, with 3 types varying in their structure and cellular expression but not in their receptor‐binding domain. NRG‐2 and NRG‐3 are primarily membrane bound, while NRG‐1 can be secreted. NRG‐1 is present in phrenic motor neurons. We previously reported that exogenous NRG containing only the receptor‐binding domain, increases protein synthesis in rat diaphragm. This effect was significantly inhibited by LY294002 indicating a PI 3‐kinase dependent mechanism. We also reported that NRG increases Akt phosphorylation. Interestingly, Akt phosphorylation is positively correlated with skeletal muscle growth and inversely correlated with atrophy. In this study, we hypothesized that NRG reduces protein degradation in rat diaphragm. Diaphragms were harvested from 4‐week old rats and incubated in the presence or absence of exogenous NRG. Protein degradation was measured by quantifying muscle tyrosine release via a fluorimetric assay. We found that NRG treatment resulted in a 50% reduction in tyrosine release from diaphragm preparations, indicating a reduction in basal protein degradation rates. These results suggest that phrenic motoneuron‐derived NRG‐1 regulates muscle protein synthesis and degradation rates, thereby playing a role in matching muscle fiber and motoneuron properties within motor units.