Changes in fibronectin mRNA splicing with in vitro passage

Area of Science:

• Cellular senescence
• Molecular biology
• Extracellular matrix

Background:

• Senescent human fibroblasts exhibit altered fibronectin (FN) production, resulting in larger molecules with modified binding characteristics.
• The precise molecular mechanisms underlying these FN alterations in senescence remain incompletely understood.

Purpose of the Study:

• To investigate whether alternative splicing of fibronectin precursor messenger RNA (mRNA) contributes to the observed changes in fibronectin molecules during cellular senescence.
• To quantify changes in the incorporation of alternatively spliced regions within fibronectin mRNA in senescent fibroblasts.

Main Methods:

• Utilized reverse transcription and polymerase chain reaction (RT-PCR) to analyze fibronectin mRNA splicing.
• Examined splicing patterns at all three alternatively spliced regions of fibronectin precursor mRNA.
• Quantified the incorporation of specific alternatively spliced regions in senescent versus non-senescent cells.

Main Results:

• Analysis revealed significant alterations in fibronectin mRNA splicing in senescent human fibroblasts compared to controls.
• Specifically, the incorporation of the ED-A region into fibronectin mRNA demonstrated a substantial increase, approximately 8-fold, with in vitro passage.
• Changes were observed in two out of the three alternatively spliced regions studied.

Conclusions:

• Alternative splicing of fibronectin precursor mRNA is a key mechanism contributing to the production of larger fibronectin molecules with altered properties in senescent human fibroblasts.
• The significant upregulation of the ED-A region in fibronectin mRNA highlights a specific splicing event associated with cellular senescence.
• These findings provide novel insights into the molecular basis of extracellular matrix remodeling during senescence.