Cell-shape-dependent modulation of p52(PAI-1) gene expression involves a secondary response pathway

Area of Science:

• Molecular Biology
• Cell Biology
• Gene Regulation

Background:

• Cellular microfilament organization and cell-to-substrate adhesion influence gene expression.
• The p52(PAI-1) gene in rats is known to be regulated by agents affecting cell shape.
• Understanding shape-dependent gene regulation is crucial for deciphering cellular responses.

Purpose of the Study:

• To investigate the biochemical mechanisms of shape-dependent p52(PAI-1) gene regulation.
• To examine the role of transcriptional and post-transcriptional events in response to shape modulators.
• To elucidate the involvement of protein synthesis in the regulation of p52(PAI-1) expression.

Main Methods:

• Utilized v-ras-transformed rat kidney (KNRK) cells.
• Administered shape modulators: sodium n-butyrate (NaB) and cytochalasin D (CD).
• Assessed gene expression using run-off transcription, mRNA analysis, protein synthesis assays, and inhibitors like actinomycin D and cycloheximide (CX).

Main Results:

• NaB and CD treatment stimulated p52(PAI-1) gene transcription and increased mRNA and protein levels.
• Inhibition of RNA synthesis by actinomycin D blocked NaB/CD-induced p52(PAI-1) expression.
• Cycloheximide (CX) pretreatment attenuated induction, suggesting a protein-synthesis-dependent secondary response pathway.

Conclusions:

• Full stimulation of p52(PAI-1) expression by shape modulators involves transcriptional activation.
• The pathway requires de novo RNA synthesis.
• p52(PAI-1) gene regulation by cell shape modulators is mediated through a secondary-response, protein-synthesis-dependent pathway.