Regulation of alternative splicing of Gtf2ird1 and its impact on slow muscle promoter activity.
A human MusTRD (muscle TFII-I repeat domain (RD)-containing protein) isoform was originally identified in a yeast one-hybrid screen as a protein that binds the slow fibre-specific enhancer of the muscle gene troponin I slow [O'Mahoney, Guven, Lin, Joya, Robinson, Wade and Hardeman (1998) Mol. Cell. Biol. 18, 6641-6652]. MusTRD shares homology with the general transcription factor TFII-I by the presence of diagnostic I-RDs [Roy (2001) Gene 274, 1-13]. The human gene encoding MusTRD, GTF2IRD1 ( WBSCR11 / GTF3 ), was subsequently located on chromosome 7q11.23, a region deleted in the neurodegenerative disease, Williams-Beuren Syndrome [Osborne, Campbell, Daradich, Scherer, Tsui, Franke, Peoples, Francke, Voit, Kramer et al. (1999) Genomics 57, 279-284; Franke, Peoples and Francke (1999) Cytogenet. Cell. Genet. 86, 296-304; Tassabehji, Carette, Wilmot, Donnai, Read and Metcalfe (1999) Eur. J. Hum. Genet. 7, 737-747]. The haploinsufficiency of MusTRD has been implicated in the myopathic aspect of this disease, which manifests itself in symptoms such as lowered resistance to fatigue, kyphoscoliosis, an abnormal gait and joint contractures [Tassabehji, Carette, Wilmot, Donnai, Read and Metcalfe (1999) Eur. J. Hum. Genet. 7, 737-747]. Here, we report the identification of 11 isoforms of MusTRD in mouse skeletal muscles. These isoforms were isolated from a mouse skeletal muscle cDNA library and reverse transcription-PCR on RNA from various adult and embryonic muscles. The variability in these isoforms arises from alternative splicing of a combination of four cassettes and two mutually exclusive exons, all in the 3' region of the primary transcript of Gtf2ird1, the homologous mouse gene. The expression of some of these isoforms is differentially regulated spatially, suggesting individual regulation of the expression of these isoforms. Co-transfection studies in C2C12 muscle cell cultures reveal that isoforms differentially regulate muscle fibre-type-specific promoters. This indicates that the presence of different domains of MusTRD influences the activity exerted by this molecule on multiple promoters active in skeletal muscle.
Tay
Enoch S E
ES
Muscle Development Unit, Children's Medical Research Institute, Locked Bag 23, Westmead, NSW 2145, Australia.
Guven
Kim L
KL
Subramaniam
Nanthakumar
N
Polly
Patsie
P
Issa
Laura L
LL
Gunning
Peter W
PW
Hardeman
Edna C
EC
D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D004742:Enhancer Elements, Genetic / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D018657:Muscle Fibers, Slow-Twitch / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
D004268:DNA-Binding Proteins; C405493:GTF2IRD1 protein, human; C486558:Gtf2ird1 protein, mouse; D009124:Muscle Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; D015534:Trans-Activators; D014157:Transcription Factors