Dilruba's Blog

Category: Genetic Engineering

TRANSGENIC ANIMALS IN EFFECTIVE PRODUCTION OF RECOMBINANT PROTEINS

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On 28 November 2023

In Genetic Engineering

Transgenic Animals

Transgenic animals are those whose genetic makeup is altered through technology. The genes of the organism are modified and manipulated according to the desire.  

20 years ago, the first transgenic mammal was created by microinjecting genetically engineered constructs into the pronucleus of mouse zygote (Hammer et al., 1985).  

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The methods used to create transgenic animals are microinjection (MI) and somatic cell nuclear transfer (NT). MI is the most used method today (Kues & Niemann, 2011) and is used to produce transgenic mice, rabbits, and pigs.

What is Recombinant Protein?

Proteins which are encoded by recombinant DNA are called recombinant proteins (RP). 

Recombinant DNAs are referred to DNA molecules made in lab by genetically combining genetic material from various sources together. 

RP has a wide range of application such as:   

  • Treatment therapies for various diseases such as cancer, hemophilia, diabetes and much more  
  • Biomedical Research  
  • Understanding of Health and Disease   

RPs could now be produced through transgenic animals. In 2006 antithrombin, the first ever produced RP from the milk of transgenic goat was approved by European Medicines Evaluation Agency. 

Pronucleus Microinjection

Transgenic Animals in RP production

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Coagulation factors are used in treating long hereditary diseases and other therapeutic agents are known to cause an immune response in patients. This led to the creation of recombinant coagulation factors in the milk of transgenic animals being of great medical importance . 

Albumin is used in biotechnology as a great stabilizer of other proteins apart from medicine. Due to the excessive cost of recombinant albumin production, we now use transgenic cows for its production. GTC Biotherapeutics (USA) produced TA cows which can produce 1–5 mg/ml of recombinant human albumin in its milk (Echelard et al., 2009).  

RP production in transgenic animals is an effective method. Thus, it is highly likely that in coming years the use of transgenic animals in RP production will expand. 

References

Echelard, Y., Williams, J. L., Destrempes, M. M., Koster, J. A., Overton, S. A., Pollock, D. P., Rapiejko, K. T., Behboodi, E., Masiello, N. C., Gavin, W. G., Pommer, J., Van Patten, S. M., Faber, D. C., Cibelli, J. B., & Meade, H. M. (2009). Production of recombinant albumin by a herd of cloned transgenic cattle. Transgenic Research, 18(3), 361-376. 

Hammer, R. E., Brinster, R. L., Rosenfeld, M. G., Evans, R. M., & Mayo, K. E. (1985). Expression of human growth hormone-releasing factor in transgenic mice results in increased somatic growth. Nature, 315(6018), 413-416. 

Kues, W. A., & Niemann, H. (2011). Advances in farm animal transgenesis. Preventive Veterinary Medicine, 102(2), 146-156. 

CRISPR Cas-9: One of the Greatest Discoveries in Biology

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On 28 November 2023

In Genetic Engineering

Discovery of CRISPR

In 2011 Jennifer Doudna and Emmanuelle Charpentier discovered CRISPR Cas-9, an amazing gene editing tool which could be used to cut DNA accurately at targeted areas. They received the Nobel Prize in Chemistry in 2020. This discovery is regarded as one of the important discoveries in the field of Biology.

How CRISPR works?

How CRISPR let us edit our DNA ?

Clustered Regularly Interspaced Short Palindromic Repeat are DNA sequences found in 50% of bacterial genome and 90% archaea (Hille et al., 2018). Cas 9 is an enzyme which uses CRISPR as a guide to go and cut DNA at targeted areas. These prokaryotes use them as an immune defense mechanism to destroy bacteriophages (Barrangou et al., 2007; Hale et al., 2009).

The scientist discovered this mechanism found in prokaryotic organisms and made it into molecular scissors, which helps in editing the genes in DNA accurately. This technology could be used to insert, delete or replace specific genes accurately in many species less tediously.

The power of CRISPR

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In 2018, a Chinese biophysicist He Jiankui announced the successful use of CRISPR Cas-9 tool on human editing. He used this technology to cleanse HIV genes in HIV positive father’s sperm cells.  

Twin girls, fictionally known as Lulu and Nana were born as HIV negative children in October 2018.  

He Jiankui was sentenced to three years imprisonment for illegal medical practices. 

CRISPR – The Future

This discovery opened a wide area of opportunities such as treatment of genetic diseases, production of biotechnology products, basic biotechnology research and more. It also gave hope to the functionality of gene drive technology. Finally in 2023, CRISPR gene therapy for blood disorders were approved by the government of the UK.

UK First to approve CRISPR treatment for diseases.

https://www.nature.com/articles/d41586-023-03590-6#:~:text=In%20a%20world%20first%2C%20the,the%20decade%20since%20its%20discovery.

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References

Barrangou, R., Fremaux, C., Deveau, H., Richards, M., Boyaval, P., Moineau, S., Romero, D. A., & Horvath, P. (2007). CRISPR provides acquired resistance against viruses in prokaryotes. Science, 315(5819), 1709–1712.

Hale, C. R., Zhao, P., Olson, S., Duff, M. O., Graveley, B. R., Wells, L., Terns, R. M., & Terns, M. P. (2009). RNA-guided RNA cleavage by a CRISPR RNA-Cas protein complex. Cell, 139(5), 945–956.

Hille, F., Richter, H., Wong, S. P., Bratovič, M., Ressel, S., & Charpentier, E. (March 2018). The Biology of CRISPR-Cas: Backward and Forward. Cell, 172(6), 1239–1259.

COULD GENE DRIVE BE A KEY TO ELIMINATING MALARIA?

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On 28 November 2023

In Genetic Engineering

Malaria

According to the World Health Organization, there were 627,000 deaths reported due to malarial infection in the year 2020. Malaria is caused by a parasite called plasmodium. Due to its great adaptable power, it is of great challenge for researchers to completely eliminate the disease. 

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What is Gene Drive ?

According to Mendel 50% of the genes gets passed to the next progeny. The idea of gene drive technology was to pass genes greater than 50% into the next generation. In 2003, Burt put forward an idea of using self-gene elements (Hom endonuclease gene) for this purpose (Burt, 2003). Selfish gene elements break the chromosome which does not have them, and when cell repairs the damage, it copies itself to it. This could now enhance the percentage of organisms in the second generation to have much more of the desired gene than predicted by Mendel.

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Researchers carried out experiments on how to use a variety of selfish gene elements for the development of gene drives (Adelman et al., 2007). The next challenge faced by them was the lack of accurate tools required to cleave and insert these elements into the DNA. Then came the CRISPR technology (Cong et al., 2013). With this gene editing tool, they could now delete, insert or modify genes at targeted areas with great accuracy hence paving the way for the complete establishment of gene drive technology. 

Gene Drive & Malaria

In late 2015, two different research one by Anthony James and other by Austin Burt and Andrea Crisanti, developed gene drive modified mosquitos. Advanced knowledge in selfish gene elements and discovery of highly accurate tools like CRISPR led to an amazing breakthrough in less than four years in the area which was studied by scientists for more than 50 years. 

References

Adelman, Z. N., Jasinskiene, N., Onal, S., Juhn, J., Ashikyan, A., Salampessy, M., MacCauley, T., James, A.A. (2007). nanos gene control DNA mediates developmentally regulated transposition in the yellow fever mosquito Aedes aegypti. Proceedings of the National Academy of Sciences, 104(24), 9970–9975.

Burt, A. (2003). Site-specific selfish genes as tools for the control and genetic engineering of natural populations. Proceedings of the Royal Society B: Biological Sciences, 270(1518), 921–928.

Cong, L., Ran, F. A., Cox, D., Lin, S., Barretto, R., Habib, N., Hsu, P. D., Wu, X., Jiang, W., Marraffini, LA., Zhang, F. (2013). Multiplex genome engineering using CRISPR/Cas systems. Science, 339(6121), 819–823.

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