Cell-to-cell variability of alternative RNA splicing

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Gene expression exhibits significant cell-to-cell variability, even in identical cell populations.
• Alternative splicing is a major mechanism of gene expression, but its role in cellular heterogeneity remains unclear.

Purpose of the Study:

• To investigate the contribution of alternative splicing to cell-to-cell heterogeneity in gene expression.
• To quantify mRNA isoform ratio variability in endogenous genes using single-molecule imaging.

Main Methods:

• Single-molecule imaging techniques were employed to visualize and quantify mRNA isoforms.
• The study focused on two endogenous genes: CAPRIN1 and MKNK2.
• Analysis included non-transformed diploid cells and HeLa cells.

Main Results:

• mRNA isoform variability in non-transformed cells closely approached the theoretical minimum, indicating tight regulation.
• HeLa cells exhibited significantly higher mRNA isoform variability compared to non-transformed cells.
• Differences in splicing factor activity were identified as a potential source of increased heterogeneity.

Conclusions:

• Mammalian cells actively minimize fluctuations in mRNA isoform ratios through precise regulation of the splicing machinery.
• The observed low variability in non-transformed cells suggests a conserved mechanism for maintaining gene expression consistency.
• Cellular context, such as transformation status, can influence the degree of mRNA isoform heterogeneity.