RGD Reference Report - Role for IkappaBalpha, but not c-Rel, in skeletal muscle atrophy. - Rat Genome Database

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Role for IkappaBalpha, but not c-Rel, in skeletal muscle atrophy.

Authors: Judge, AR  Koncarevic, A  Hunter, RB  Liou, HC  Jackman, RW  Kandarian, SC 
Citation: Judge AR, etal., Am J Physiol Cell Physiol. 2007 Jan;292(1):C372-82. Epub 2006 Aug 23.
RGD ID: 2315576
Pubmed: PMID:16928772   (View Abstract at PubMed)
DOI: DOI:10.1152/ajpcell.00293.2006   (Journal Full-text)

Skeletal muscle atrophy is associated with a marked and sustained activation of nuclear factor-kappaB (NF-kappaB) activity. Previous work showed that p50 is one of the NF-kappaB family members required for this activation and for muscle atrophy. In this work, we tested whether another NF-kappaB family member, c-Rel, is required for atrophy. Because endogenous inhibitory factor kappaBalpha (IkappaBalpha) was activated (i.e., decreased) at 3 and 7 days of muscle disuse (i.e., hindlimb unloading), we also tested if IkappaBalpha, which binds and retains Rel proteins in the cytosol, is required for atrophy and intermediates of the atrophy process. To do this, we electrotransferred a dominant negative IkappaBalpha (IkappaBalphaDeltaN) in soleus muscles, which were either unloaded or weight bearing. IkappaBalphaDeltaN expression abolished the unloading-induced increase in both NF-kappaB activation and total ubiquitinated protein. IkappaBalphaDeltaN inhibited unloading-induced fiber atrophy by 40%. The expression of certain genes known to be upregulated with atrophy were significantly inhibited by IkappaBalphaDeltaN expression during unloading, including MAFbx/atrogin-1, Nedd4, IEX, 4E-BP1, FOXO3a, and cathepsin L, suggesting these genes may be targets of NF-kappaB transcription factors. In contrast, c-Rel was not required for atrophy because the unloading-induced markers of atrophy were the same in c-rel(-/-) and wild-type mice. Thus IkappaBalpha degradation is required for the unloading-induced decrease in fiber size, the increase in protein ubiquitination, activation of NF-kappaB signaling, and the expression of specific atrophy genes, but c-Rel is not. These data represent a significant advance in our understanding of the role of NF-kappaB/IkappaB family members in skeletal muscle atrophy, and they provide new candidate NF-kappaB target genes for further study.

RGD Manual Disease Annotations    Click to see Annotation Detail View
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
muscular atrophy  ISOCtsl (Rattus norvegicus)2315576; 2315576mRNA:increased expression:soleus (rat)RGD 
muscular atrophy  IEP 2315576mRNA:increased expression:soleus (rat)RGD 

Objects Annotated

Genes (Rattus norvegicus)
Ctsl  (cathepsin L)

Genes (Mus musculus)
Ctsl  (cathepsin L)

Genes (Homo sapiens)
CTSL  (cathepsin L)


Additional Information