The function of mRNA

The function of mRNA (messenger RNA) determines many aspects of molecular biology, considering that it plays an essential role in protein synthesis. As the intermediary messenger between DNA and proteins, mRNA carries the genetic information necessary for protein production.

In this article, we will provide a comprehensive definition of mRNA. Furthermore, we will take a look at its structure and its function in biochemical mechanisms it is involved in.

mRNA Definition

mRNA (messenger RNA) functions as a means to transfer genetic information encoded by the DNA in a cell’s nucleus to protein-building machinery in the cytoplasm, which is an indispensable step in the protein production process. This single-stranded type of RNA is generated during DNA transcription, where it functions as a template for the information encoded in a specific DNA segment. Consequently, it exits the nucleus and carries the genetic code to ribosomes, where it is encoded and processed for gene expression.¹ 

Structure and types of mRNA

mRNA (messenger RNA) is a type of RNA (ribonucleic acid) that consists of a linear sequence of nucleotides, including adenine (A), guanine (G), cytosine (C), and uracil (U). In general, one can distinguish between eukaryotic mRNA (found in organisms with nucleus) and prokaryotic mRNA (prokaryotes are organisms without nucleus).

RNA exists in different types, with one of the notable types of nucleic acids being ribosomal RNA (rRNA) and transfer RNA (tRNA) – along with mRNA.

The structure of mRNA includes a coding sequence that carries the genetic information necessary for protein synthesis. The coding sequence is preceded by a promoter region, which initiates the process of transcription. These principles also need to be taken into consideration in mRNA template design, being the first step of in vitro mrna production.

mRNA functions

What does mRNA do?

The functions of mRNA are integral to the process of protein synthesis and have significant implications in medicine. Transcription, the initial step, converts DNA information into mRNA, with RNA polymerase II synthesizing pre-mRNA from the DNA template. Following transcription, mRNA undergoes processing, involving the removal of introns and addition of a 5' cap and poly(A) tail for stability and transport. Translation, the subsequent step, occurs in ribosomes, where mRNA is decoded to synthesize proteins. In medicine, mRNA plays a pivotal role in vaccines and therapies. mRNA vaccines, exemplified by COVID-19 vaccines, utilize synthetic mRNA to trigger immune responses.

Transcription – from DNA to mRNA

Transcription is a vital process that converts the information encoded in DNA into mRNA, enabling protein synthesis. The process of transcription involves several key components, including pre-mRNA and RNA polymerase II.

During transcription, RNA polymerase II, an essential enzyme, binds to the DNA molecule at a specific region called the promoter. The RNA polymerase II unwinds the DNA double helix and initiates the synthesis of a complementary RNA molecule, known as pre-mRNA. This pre-mRNA molecule is an initial transcript of a genome sequence that contains both coding and non-coding regions, including introns and exons.

As RNA polymerase II moves along the DNA template strand, it adds nucleotides to the growing pre-mRNA chain in a sequence complementary to the DNA coding strand. Adenine (A), guanine (G), cytosine (C), and uracil (U) are the nucleotides involved in this process. The process continues until the RNA polymerase II reaches a specific DNA sequence called the terminator, which regulates the end of transcription.

mRNA processing and splicing

Following transcription, the pre-mRNA molecule undergoes a process called RNA processing or RNA splicing. During RNA splicing, the non-coding introns are removed from the pre-mRNA molecule, and the remaining exons are joined together to form the mature mRNA transcript.

The modifications executed during this step also include the addition of a 5' cap and a poly(A) tail, which provide stability and facilitate the transport of mRNA from the nucleus to the cytoplasm.

Translation: Protein synthesis from mRNA

Translation of mRNA is the process of protein synthesis from mRNA. It involves ribosomal RNA (rRNA), decoding subunits on RNA molecules, like stop codons or the translation initiation factor.

During translation, ribosomes read the mRNA sequence, recruiting tRNA molecules that carry specific amino acids. The ribosome catalyzes the formation of peptide bonds between amino acids, building a polypeptide chain. The process continues until a stop codon is reached, signaling the end of translation.

Translation occurs in organelles called ribosomes, either in the cytoplasm or attached to the endoplasmic reticulum. It ensures the correct folding and functionality of proteins.

Functions of mRNA in medicine

mRNA vaccines and therapies have revolutionized medicine. They use synthetic mRNA to trigger immune responses and treat diseases. mRNA vaccines, for instance, introduce mRNA that encodes proteins of specific pathogens, stimulating the immune system to respond. They offer advantages like fast development and adaptability to variants, which is also why mRNA technology has gained major public attention for its use in COVID-19 vaccines.

mRNA therapies deliver modified mRNA to influence protein production and cellular functions. They hold promise to treat genetic disorders and cancer.

Manufacturing mRNA-based therapies and vaccines, however, requires optimizing processes, ensuring quality control, and establishing robust supply chains. Overcoming stability and scalability issues is crucial.

Overcoming challenges in mRNA manufacturing

One important aspect to be considered in mRNA manufacturing and subsequent logistic steps is its vulnerability towards thermal or physical stress. mRNA must be protected from harmful variations in temperature and requires specialized cold chain management. This, on the other side, raises the need for dedicated machines and processes to provide maximum product quality and safety.

Furthermore, sterile fluid management is vital in the manufacturing of mRNA-based products, with a minimized risk for product loss, human error and other process inconsistencies.

Therefore, Single Use Support has developed an entire product line-up that facilitates the entire process of mRNA manufacturing, storage and transport – from aseptic fluid management solutions to plate freezers and ultra-cold storage freezers. Being easily scalable, these platform solutions are suited for various different applications and provide a reliable framework for biopharmaceutical processes involving mRNA.