We have learned genetic information in our cells was considered to be four letters (A,G,C,T) for DNA and four (A,G,C,U) for RNA. It turns out a new study published in Nature by a team of Tel Aviv University, Sheba Medical Center, and University of Chicago scientists finds that RNA, considered the DNA template for protein translation, often appears with an extra letter -- and this letter is the regulatory key for control of gene expression. The discovery of a novel letter marking thousands of mRNA transcripts will offer insight into different RNA functions in cellular processes and contributions to the development of disease.
Researchers have recently developed a mathematical model that explains the underlining process of gene expression in cells. After more than 50 years of knowing the primary players in gene expression (DNA, mRNA, ribosomes, etc) the way they interact is still unknown. Previously researchers thought that the rate of transcription was limited by the amount of DNA and mRNA available in the cell, but new studies of the mathematical model have proven that the ribosomes and polymerase are the core factors that control the levels of proteins and mRNA in the cell.
As we've learned, mRNA is the end product of transcription. But did you know mRNA antibody delivery could prevent respiratory syncytial virus (RSV)? According to new research, there's a new way to deliver antibodies directly to the lungs could help children ward off this respiratory illness. RSV sends 57,000 children younger than 5 to the hospital each year. There’s no vaccine for the virus, which usually only causes cold-like symptoms and medications doctors sometimes use to prevent it in high-risk children aren’t always effective. In the study, researchers used synthetic mRNA to deliver antibodies directly to the lungs of mice via aerosol, which the study shows protected them from RSV infection. They mentioned that if these antibodies were administered into newborn children right away, when they're most vulnerable, it'll be the most effective. Using mRNA is an effective and safe delivery option, especially crucial in a pediatric population!
Researchers have developed a mathematical model that can help explain gene expression and the processes behind it. In the past, researchers believed that the rate of transcription and translation was limited by the amount of DNA and mRNA in the cell. However, with a new model and with more experimental data, they now believe that ribosomes and polymerases control level of proteins and mRNA in the cell, and thus those are the limiting factors for gene expression.
mRNA display is a technique that can identify proteins which bind to specific regions in DNA. This method has several advantages over other methods, such as yeast-to-hybrid, phage display and others. mRNA display method can be used to select and evolve new proteins and enzymes from a large library of potential sequences. One method that has been recently proposed is to use mRNA display method to select for Diels-Alderase enzymes. Another method has also been proposed to employ this method to select for novel protein-ligand pairs by interaction-dependent reverse transcription.
Stop codons are essential for the termination of the translation process. They do not code for any amino acid instead they are the hotspot for the Release factors to bind. If there is no stop codon in the mRNA, then there is the possibility that the Ribosome would synthesise mRNA until the 3′ end of the mRNA is not encountered. At the 3′ end, there is no codon and thus, the ribosome cannot proceed further. The consequence of this situation is that the ribosome will be trapped with mRNA forever as there is no codon for tRNA or Release Factors on the mRNA to terminate the translation and begin a new ribosome cycle.
Researchers has paid particular attention to long non-coding RNAs that can enhance the production of specific mRNAs, and hence proteins, in breast cancer cells. They show that the expression of long non-coding RNAs can result in particularly high expression levels of specific proteins with involvement in cancer. Research show that the long non-coding RNA called A-ROD (Activating Regulator Of DKK1 expression) is only functional the moment it is released from chromatin into the nucleoplasm. At this transient phase, it can bring transcription factors to specific sites in DNA to enhance gene expression. After its complete release from chromatin, A-ROD is no longer active as an enhancing long non-coding RNA. In a way, A-ROD functions as a lasso that can be thrown from DNA to catch proteins.
Researchers have found that RNA polymerase II which is the enzyme that transcribes DNA to RNA, frequently stops/pauses after reading a few dozen base pairs. When RNA polymerase II pauses, it affects the rate of gene expression though researchers haven’t been able to find a large impact. Very little new transcription goes on while the enzyme is stalled. Julia Zeitlinger and Wanqing Shao of the Stowers Institute for Medical Research in Kansas City used a drug to freeze the enzyme and other transcription factors in Drosphilia cells. They then analyzed the positions of the polymerases and “could clearly see minimal initiation in the presence of paused polymerase”. Craig Kaplan said that pausing can occur for different lengths and it helps give cells a “buffet of choices in how expression may happen”.
Neurodegenerative diseases are exactly what they sound like - when brain and nerve cells are damaged over time. One in particular, called Spinocerebellar ataxia type 7 (SCA7), where the attaxin-7 gene repeats over and over (in this case, CAG). This leads to blindness, difficulty walking, speaking and balancing. One way to prevent the disease protein from ever being produced is to destroy the mRNA before it is translated into a protein. Researchers have been working on different techniques to destroy RNAs. One has proven to be effective, and relies upon a short segment of DNA that is synthesized in the lab and known as an antisense oligonucleotide, or ASO. An ASO is a short stretch of DNA that is synthesized with a sequence that perfectly matches the target RNA. In the cell the ASO binds to the target mRNA and forms a duplex, a DNA-RNA hybrid molecule, which is recognized as potentially foreign and destroyed. The advent of ASOs and related therapies suggest that medical research may create powerful new treatments for many neurodegenerative diseases within the next decade or two. As estimates predict that more than 20 million people will suffer from such diseases in the USA alone by 2050, these efforts are desperately needed.
This website explained the processes of transcription and translation in detail. It was a good wrap up of all the stuff that we learned in class, and how DNA is replicated and then turned into protein.
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