Table 1 Transcription Factors Analyzed
Transcription factor | Family | Involved in |
|---|---|---|
NFATc1 | NFAT family | Activated by increased intracellular levels of Ca2 +. Promotes slow muscle gene program. (15). |
MEF2 | MADS box transcription factor | Act together with myogenin and MRF4 to sustain the muscle differentiation program (16). Binding site in mouse MyHC IIb (17). |
NFκB p65 (RelA) | Subunit in the NFκB-family | Involved in muscle atrophy. Activates MuRF1 (3). The NFκB molecules are dimeric complexes containing various combinations of p50, p52, p65, RelB, and c-Rel [reviewed in (18)]. |
Bcl-3 | IκB-family | Primarily nuclear localization. Binds p50 and p52 homodimers, which normally repress transcription. These complexes can also activate transcription (12,19). |
MyoD | MRF | Skeletal muscle development. Initiation of muscle cell program. Controls expression of transcription factors, cell cycle regulators as well as muscle structural genes [reviewed in (20)]. |
Myogenin | MRF | Skeletal muscle development. Muscle differentiation. Mediates activity-dependent control of AchR gene expression (21). |
Myf-5 | MRF | Skeletal muscle development. Initiation of muscle cell program. One of the earliest markers of myogenic commitment (22). |
MRF4 (Myf-6) | MRF | Skeletal muscle development. Muscle differentiation. Involved in expression of the adult Na channel (23). |
Foxo1 (FKHR) | Forkhead box family | Downstream effector of the IGF-1/PI3K/Akt pathway. Reduced levels of IGF-1 activate Foxo transcription factors, which induce MuRF1 and MAFbx gene expression (24). |
TRα1 | Thyroid hormone receptor | Involved in determining MyHC isoforms. Tra-1-deficient mice display a switch toward more MyHC type I (25). |
GR | Glucocorticoid receptor | Glucocorticoids are involved in muscle atrophy, probably via activation of GR. Can repress other transcription factors, eg, AP-1, NFκB, and Smad3 [reviewed in (26)]. |
Oct-1 | POU homeo-domain family | Binding site in mouse MyHC IIb promoter (17,27) and possibly also in Myf-5 promoters of bovine and avian muscle (28). |
Egr-3 | Human zinc-finger protein | A member of the immediate-early transcription factors involved in cellular growth and differentiation. Interacts with NFκB p65 and NFAT in T cells, and controls transcription of genes encoding inflammatory cytokines (29). |