Micrornas (mirnas)

Definition

Micrornas (miRNAs) are small, non-coding RNA molecules, typically about 21-24 nucleotides in length, that play a crucial role in the regulation of gene expression. They primarily function by binding to complementary sequences in messenger RNAs (mRNAs), leading to mRNA degradation or inhibition of translation. By modulating gene expression, miRNAs are key players in various biological processes, including development, cell differentiation, and responses to environmental stimuli.

5 Must Know Facts For Your Next Test

1. miRNAs are encoded by specific genes and can regulate multiple target mRNAs, making them powerful regulators of gene expression.
2. They play significant roles in key biological processes such as development, immune response, and apoptosis (programmed cell death).
3. Aberrant miRNA expression is linked to various diseases, including cancer, where they can act as oncogenes or tumor suppressors.
4. miRNAs are involved in post-transcriptional regulation, meaning they act after the mRNA has been created but before it is translated into protein.
5. Techniques such as microarray analysis and next-generation sequencing are commonly used for profiling miRNA expression in transcriptomics studies.

Review Questions

• How do micrornas influence gene expression at the post-transcriptional level?
  • Micrornas influence gene expression at the post-transcriptional level by binding to complementary sequences in target messenger RNAs (mRNAs). This binding can lead to two main outcomes: degradation of the mRNA or inhibition of its translation into proteins. As a result, miRNAs effectively decrease the amount of protein produced from specific mRNAs, allowing for fine-tuning of gene expression and cellular functions.
• Discuss the role of micrornas in development and how they contribute to cellular differentiation.
  • Micrornas play a critical role in development by regulating the expression of genes involved in cellular differentiation and growth. During embryonic development, specific miRNAs are expressed at certain stages to guide cells toward particular fates, such as becoming muscle or nerve cells. By modulating the levels of key transcription factors and other signaling molecules through their interaction with mRNAs, miRNAs ensure that cells develop properly and acquire their distinct characteristics.
• Evaluate the potential implications of microrna dysregulation in human diseases, particularly cancer.
  • Dysregulation of micrornas has significant implications for human diseases, especially cancer. Abnormal miRNA expression can lead to enhanced cell proliferation or reduced apoptosis by either promoting oncogenes or suppressing tumor suppressor genes. This dysregulation can create an environment conducive to tumorigenesis. Understanding these relationships opens avenues for novel therapeutic strategies that target miRNAs to restore normal gene expression patterns and potentially halt or reverse disease progression.

Related terms

Gene Silencing: A process by which the expression of a specific gene is inhibited or completely shut down, often involving mechanisms such as RNA interference.

Transcription Factors: Proteins that bind to specific DNA sequences to regulate the transcription of genes, influencing cell function and identity.

Messenger RNA (mRNA): The RNA molecule that carries genetic information from DNA to the ribosome, where it serves as a template for protein synthesis.