Two distal Sp1-binding cis-elements regulate fibroblast growth factor receptor 1 (FGFR1) gene expression in myoblasts

Area of Science:

• Molecular Biology
• Developmental Biology
• Genetics

Background:

• Skeletal myoblast proliferation and differentiation depend on fibroblast growth factor receptor 1 (FGFR1) gene expression.
• Previous studies identified both distal and proximal promoter regions crucial for FGFR1's developmentally regulated activity.

Purpose of the Study:

• To elucidate the molecular mechanisms governing FGFR1 promoter activity in proliferating myoblasts.
• To characterize the role of the distal promoter region in regulating FGFR1 gene expression.

Main Methods:

• Functional analysis of a 242 bp distal promoter segment using a minimal thymidine kinase promoter.
• Site-directed mutagenesis and transfection assays to assess Sp1 binding sites.
• Electromobility shift assays to verify Sp1 binding specificity.

Main Results:

• A 242 bp distal promoter segment, located >1 kb upstream, significantly enhanced transcription.
• Two functional Sp1 binding sites within this segment were identified as critical for FGFR1 promoter activity.
• Synergistic binding of Sp1 to these sites enhanced transcriptional activity, with differential binding observed between myoblasts and fibroblasts.

Conclusions:

• Establishes a molecular mechanism for FGFR1 gene regulation during myoblast proliferation via distal promoter Sp1 sites.
• Highlights the synergistic role of Sp1 binding in driving FGFR1 expression in myoblasts.
• Demonstrates cell-specific regulation of FGFR1 promoter activity by Sp1, with higher activity in myoblasts compared to fibroblasts.