Basic fibroblast growth factor inhibits type I collagen gene expression in osteoblastic MC3T3-E1 cells

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Collagen is a crucial protein in bone structure and integrity.
• Basic fibroblast growth factor (bFGF) plays a role in cellular processes, including bone cell function.
• Understanding the regulation of collagen synthesis is vital for bone biology.

Purpose of the Study:

• To investigate the effect of basic fibroblast growth factor (bFGF) on type I collagen gene expression in osteoblastic cells.
• To determine the molecular mechanisms by which bFGF influences collagen synthesis.
• To identify regulatory elements within the alpha 1(I) collagen promoter responsive to bFGF.

Main Methods:

• Osteoblastic MC3T3-E1 cells were stably transfected with reporter gene constructs (ColCAT 3.6 and ColCAT 2.3) containing the alpha 1(I) collagen promoter.
• Cells were treated with varying concentrations of bFGF.
• Collagenase-digestible protein (CDP) incorporation, alpha 1(I) procollagen mRNA levels, gene transcription, and promoter activity were measured.

Main Results:

• bFGF inhibited [3H]proline incorporation into CDP, indicating reduced collagen synthesis.
• bFGF significantly decreased alpha 1(I) procollagen mRNA levels and gene transcription.
• bFGF inhibited the activity of the full-length alpha 1(I) collagen promoter (ColCAT 3.6) but stimulated a deletion mutant (ColCAT 2.3).

Conclusions:

• bFGF inhibits collagen synthesis in osteoblastic cells through a transcriptional mechanism.
• The alpha 1(I) collagen promoter contains DNA sequences that mediate bFGF's inhibitory effect on type I collagen gene expression in bone.