What occurs to mRNA levels as TNF-α levels rise in undifferentiated muscle cells?

• A. They remain unchanged.
• B. They increase significantly.
• C. They decrease significantly.
• D. They produce a diverse set of transcripts.

Answer: (C)

In the context of undifferentiated muscle cells and the influence of TNF-α (tumor necrosis factor-alpha), as TNF-α levels rise, the levels of mRNA decrease significantly. TNF-α is a pro-inflammatory cytokine that plays a critical role in various cellular processes, including inflammation and apoptosis.

When TNF-α is present in elevated amounts, it can trigger signaling pathways that lead to a state of cellular stress or inflammation. This often results in the downregulation of mRNA for proteins that are necessary for growth and maintenance. In undifferentiated muscle cells, this can particularly manifest as a decreased expression of genes that are involved in muscle development and function.

The decrease in mRNA levels reflects the cells' response to the inflammatory environment instigated by TNF-α. This response can impair the muscle cells' ability to proliferate or differentiate properly, which is often observed in various pathophysiological conditions. Hence, the significant reduction in mRNA levels under the influence of rising TNF-α is well-supported by the understanding of how inflammatory cytokines affect cellular processes.