Figure 2.
Type of alternative splicing events occurring in muscle-related transcription factors and impact on their functional activity.
| Type of alternative splicing | TFs | Effects on TF |
| Exon skipping/retention 
|
NFIX1/2/3 | NFIX2: regulator of fetal muscle genes |
| HEBα/β | HEBα: higher DNA binding and transcriptional activity
HEBβ: synergises with MyoD in early differentiation |
|
| PAX3Q+/− | PAX3Q-: stronger binding affinity and higher transcriptional activity | |
| PAX7Q+/− | NA | |
| PAX7GL+/− | PAX7GL-: increased binding affinity | |
| PAX7-2 | PAX7-2: reduced transcriptional activity | |
| E12/47
E2A-2/5 |
E2A-2/5: dominant negative activity | |
| MEF2A/B/C β | MEF2A/B/C β: higher transcriptional activity | |
| TCF4 A-R | TCF4 AD1-containing isoforms: higher transcriptional activity | |
| TCF4 FL/Δ | TCF4 FL/Δ: no correlation with transcriptional activity | |
Intron retention
|
TMyoD1α/β | NA |
| ID1A/B | ID1A: inhibits the formation of E12/MYOD heterodimers.
ID1B: prevents the assembly of E12/E12 homodimers. |
|
| ID3/3L | ID3L: reduced antagonistic activity versus E47 | |
Mutually exclusive exons
|
MEF2A/B/C α1/α2 | MEF2A/B/C α1: repressor of terminal differentiation MEF2A/B/C α2: activator of terminal differentiation |
| TCF4 A-R | TCF4 AD1-containing isoforms: higher transcriptional activity | |
Alternative 5’ or 3’ splice site usage
|
TCF4 A-R −/+ | TCF4 -/+: no correlation with transactivation activity |
| MEF2C γ | MEF2C γ: reduced transcriptional activity | |
Alternative 3’ terminal exon
|
CiMDFa/b | CiMDFb: higher myogenic effector function |
| PAX7A/B | PAX7A/B: myogenic commitment | |
| PAX3A/B | NA | |
| PAX3C/D | PAX3C: necessary for terminal myogenic differentiation
PAX3D: maintenance and/or proliferation of muscle precursor |
|
Premature termination codon (PTC)
|
TMyoD1γ | TMyoD1γ: role in the regulation of TmyoD1 expression |