What are Interrupted Genes?

An interrupted gene is a DNA sequence that has been modified in such a way that it is unable to produce a functional protein. These genes are of great interest to scientists and researchers because they can provide insight into how our genes function and how they may be related to the development of various diseases. In this blog, we will delve into the different types of interrupted genes, how they form, and their potential consequences for human health. Stay tuned for more information on this fascinating topic!

Most eukaryotic genes are interrupted by non-coding or non-translatable sequences known as introns. The coding or translatable sequences are known as exons. Such genes are called split genes or interrupted genes. Both intron and exon sequences are transcribed to produce a primary transcript, precursor RNA, or pre-RNA.

Interrupted Genes

The precursor RNA for mRNA is known as heterogeneous RNA (hnRNA). Following the transcription, the intron sequences are removed and exons are joined to form a mature or functional RNA. This process is known as RNA splicing.

For this reason, the RNA transcript in the nucleus differs from the mRNA found in the cytoplasm for translation. For each split gene, only about 25% of hnRNA takes part in splicing, leading to mRNA formation. The rest undergoes degradation.

How interrupted genes form?

Genes are the basic unit of inheritance in our bodies and are made up of DNA. DNA is a long, double-stranded molecule that contains the instructions for building and maintaining an organism. Each gene is a specific sequence of nucleotides, or building blocks of DNA, that codes for a particular protein or function.

Interrupted genes can occur due to a variety of different factors. One way that interruptions can happen is through mutations in the DNA sequence itself, which can change the way a gene is expressed or cause it to stop working altogether.

Interruptions can also be caused by modifications to the DNA molecule itself, such as DNA methylation and histone modification.

a. Role of DNA methylation

DNA methylation is a chemical process that involves the addition of a methyl group to a cytosine nucleotide in the DNA molecule. This process can silence gene expression and prevent the production of a functional protein. 

b. Role of Histone modification

Similarly, histone modification refers to the chemical modification of histones, which are proteins that help package the DNA molecule into a compact structure. These modifications can also affect gene expression and interrupt the production of functional proteins.

c. Modification and formation of Interrupted genes:

Even before transcription is completed, the hnRNA is modified by the addition of a 7-methylguanosine residue (m7G) to the 5′-end. This is called “5′-capping.” The 5′-cap of myG helps in the recognition of ribosomes. The capping is initiated by the addition of GTP to the s’-end in reverse orientation of 5′-5′ phosphodiester (not the usual 5′-3′ diester), and then a methyl group is transferred to X-7 by the methyltransferase enzyme. However, some eukaryotic mRNA like those for histone proteins, lack 5′-cap.r

The 3′ end of most eukaryotic mRNA has a long stretch of “A” residues added after transcription. This stretch of “A” residues is called poly-A-tail, and the process of its addition is called polyadenylation. The poly-A polymerase enzyme adds a poly-A tail of about 200 adenine nucleotides to the 3′-end of the primary transcript.

Some of the hnRNAs are spliced in large complexes called spliceosomes. Spliceosomes are complexes of proteins and five types of small nuclear RNAs (S RNA). These small nuclear RNAs are Ui, U2, U4, U5, and U6. Some HN RNA molecules are also autospliced without the involvement of a spliceosome.

Types of interrupted genes

There are several different types of interrupted genes that researchers study. 

a. Protein-coding genes

Protein-coding genes are perhaps the best-known type of gene, as they encode the instructions for making proteins that carry out various functions in the body. When these genes are interrupted, they are unable to produce functional proteins, which can lead to various health problems.

B. Non-coding RNA genes

Noncoding RNA (ncRNA) genes are another type of interrupted gene that do not code for proteins, but rather play a regulatory role in the expression of other genes. ncRNA genes can be divided into several different categories based on their function, such as microRNAs, which regulate the stability and translation of mRNA molecules, and long noncoding RNAs, which play a role in gene expression and regulation.

C. Pseudogenes

Pseudogenes are a type of interrupted gene that are similar to protein-coding genes, but are no longer functional due to mutations or other changes in their DNA sequence. Pseudogenes can be found in many different organisms and are thought to be remnants of functional genes that have been rendered inactive over time.

The study of interrupted genes is a diverse and complex field that involves the investigation of a variety of different types of genes and their functions. Understanding the various types of interrupted genes and how they differ from one another can provide valuable insight into the regulation of gene expression and the development of various diseases.

Consequences of interrupted genes

The consequences of interrupted genes can be wide-ranging and significant, as they can affect protein production and function in the body. When a gene is interrupted and unable to produce a functional protein, it can disrupt important biological processes and lead to various health problems.

a. Role in disease development

One of the most significant consequences of interrupted genes is their role in the development of diseases. Many diseases are caused or influenced by genetic factors, and the interruption of certain genes can contribute to the development of these conditions.

For example, the BRCA1 gene, which is involved in DNA repair and cell cycle regulation, can be interrupted and contribute to the development of breast and ovarian cancer.

b. Potential as therapeutic targets

In addition to their role in disease development, interrupted genes also have potential as therapeutic targets. By targeting and correcting the interruption of specific genes, it may be possible to treat or prevent certain diseases. For example, drugs that target the interruption of the BRCA1 gene are being developed as a potential treatment for breast and ovarian cancer.

Overall, the consequences of interrupted genes are multifaceted and complex. Understanding the impact of interrupted genes on protein production and function, as well as their role in disease development and potential as therapeutic targets, can provide valuable insight into the development and treatment of various diseases.

Case studies of interrupted genes

There are many different examples of interrupted genes that have been studied by researchers and have played a role in the development of various diseases. Here, we will examine two such case studies: BRCA1 and breast cancer, and FMR1 and fragile X syndrome.

Example 1: BRCA1 and breast cancer

BRCA1 is a protein-coding gene that plays a role in DNA repair and cell cycle regulation. When this gene is interrupted, it can increase the risk of breast and ovarian cancer. Women with a mutation in the BRCA1 gene have a higher risk of developing these types of cancer, and the interruption of this gene has also been linked to a higher risk of breast cancer in men.

Example 2: FMR1 and fragile X syndrome

FMR1 is a protein-coding gene that plays a role in the development and function of the nervous system. When this gene is interrupted, it can lead to the development of fragile X syndrome, a genetic condition that causes intellectual disability, behavioral and emotional problems, and physical abnormalities. Fragile X syndrome is the most common inherited form of intellectual disability, and the interruption of the FMR1 gene is the most common cause of this condition.

Overall, these case studies demonstrate the wide-ranging and significant consequences of interrupted genes and the important role that they play in the development of various diseases.

Understanding the mechanisms behind the interruption of specific genes and how they contribute to the development of diseases can provide valuable insights into the diagnosis, treatment, and prevention of these conditions.

Final words

In conclusion, the study of interrupted genes is a critical and rapidly advancing field that has the potential to provide valuable insights into the regulation of gene expression and the development of various diseases.

Through the investigation of different types of interrupted genes, such as protein-coding genes, noncoding RNA genes, and pseudogenes, researchers have been able to better understand the mechanisms behind gene interruption and how it can impact protein production and function.

In addition to their role in disease development, interrupted genes also have potential as therapeutic targets, and research in this area is ongoing. By targeting and correcting the interruption of specific genes, it may be possible to treat or prevent certain diseases.

Looking to the future, there are many exciting directions for research in the field of interrupted genes. Continued study of the mechanisms behind gene interruption and how it impacts protein production and function will likely lead to the development of new diagnostic and therapeutic approaches for various diseases.

Additionally, advances in technology and techniques will likely enable researchers to investigate interrupted genes at an increasingly fine-grained level, providing even more detailed insights into this complex and fascinating field.

Test your skills now with this MCQ test