Let-7

Definition

Let-7 is a family of microRNAs that play a crucial role in the regulation of gene expression, particularly during developmental processes and cellular differentiation. These small RNA molecules inhibit target mRNA expression by binding to complementary sequences, leading to translational repression or degradation, which is essential for maintaining cellular homeostasis and proper gene regulation.

5 Must Know Facts For Your Next Test

1. Let-7 was one of the first microRNAs discovered and is known for its role in regulating developmental timing in organisms such as Caenorhabditis elegans.
2. The expression of let-7 is often decreased in various cancers, indicating its potential role as a tumor suppressor by inhibiting oncogenic pathways.
3. Let-7 targets several key oncogenes and transcription factors involved in cell proliferation and differentiation, such as RAS and MYC.
4. Let-7 is regulated by other factors, including transcription factors and signaling pathways, highlighting its integration into broader regulatory networks.
5. The study of let-7 has implications for therapeutic strategies in cancer treatment, as restoring let-7 expression could help inhibit tumor growth.

Review Questions

• How does let-7 contribute to the regulation of gene expression during development?
  • Let-7 plays a significant role in the regulation of gene expression during development by controlling the timing and differentiation of cells. It achieves this by binding to complementary mRNA sequences, which leads to translational repression or degradation of target genes. By inhibiting specific oncogenes and transcription factors, let-7 helps ensure that developmental processes occur in an orderly manner, preventing premature cell division and promoting proper cellular identity.
• Discuss the implications of altered let-7 expression in cancer biology.
  • Altered expression levels of let-7 are frequently observed in various types of cancer. Its downregulation is associated with increased cell proliferation and tumorigenesis since let-7 normally inhibits several oncogenes like RAS. The loss of let-7 allows for unchecked growth signals and promotes aggressive tumor characteristics. This has led researchers to consider let-7 as a potential therapeutic target; restoring its function could provide a means to suppress tumor development and progression.
• Evaluate the role of let-7 within the context of post-transcriptional regulation and its broader significance in cellular processes.
  • Let-7 exemplifies the importance of post-transcriptional regulation by influencing mRNA stability and translation, thereby affecting protein synthesis without altering DNA sequences. This microRNA integrates into complex regulatory networks that govern cell growth, differentiation, and response to environmental signals. By modulating these processes, let-7 not only maintains cellular homeostasis but also plays a pivotal role in pathologies like cancer. Its study highlights the potential for microRNAs as therapeutic targets in various diseases, making them significant players in modern molecular biology.

Related terms

MicroRNA: A class of small, non-coding RNA molecules that regulate gene expression by binding to complementary mRNA sequences, leading to silencing of the target genes.

Transcriptional Regulation: The process by which the transcription of specific genes is increased or decreased, influencing the amount of messenger RNA (mRNA) produced and ultimately affecting protein synthesis.

Post-transcriptional Regulation: The control of gene expression at the RNA level after transcription has occurred, including mRNA splicing, editing, transport, stability, and translation.