Craspase: nauja saugesnė „CRISPR – Cas sistema“, kuri redaguoja ir genus, ir baltymus  

“CRISPR-Cas systems” in bacteria and viruses identify and destroy invading viral sequences. It is bacterial and archaeal immune system for protection against viral infections. In 2012, CRISPR-Cas system was recognised as a genomas editing tool. Since then, wide range of CRISPR-Cas systems have been developed and have found applications in areas such as in gene therapy, diagnostics, research and crop improvement. However, currently available CRISPR-Cas systems have limited clinical use due to frequent occurrences of off-target editing, unexpected DNA mutations and inheritable problems. Researchers have recently reported a novel CRISPR-Cas system that can target and destroy mRNA and baltymai associated with different genetic diseases more accurately without off-target impact and inheritable problems. Named Craspase, it is the first CRISPR-Cas system that shows baltymų editing function. It is also the first system that can edit both RNA and baltymų. Because Craspase overcomes many limitations of existing CRISPR-Cas systems, it has potential to revolutionise gene therapy, diagnostics and monitoring, biomedical research, and crop improvement. 

“CRISPR-Cas system” is natural immune system of bacteria and archaea against viral infections that identifies, binds and degrades the sequences in the viral gene to protect. It consists of two parts – bacterial RNA transcribed from the viral gene incorporated in the bacterial genome after first infection (called CRISPR, this identifies the target sequences of the invading viral genes) and an associated destroyer baltymų called “CRISPR associated baltymų (Cas)” which binds and degrades the identified sequences in the viral gene to protect the bacteria against viruses.  

CRISPER stands for “clustered regularly interspaced short palindromic repeats”. It is transcribed bacterial RNA characterised by palindromic repeats.  

Palindrominiai pasikartojimai (CRISPR) pirmą kartą buvo aptikti sekose E. coli in 1987. In 1995, Francisco Mojica observed similar structures in archaea, and it was he who first thought of these as a part of the immune system of bacteria and archaea. In 2008, it was experimentally demonstrated for the first time that the target of the immune system of bacteria and archaea was foreign DNA and not mRNA. The mechanism of identification and degradation viral sequences suggested that such systems could be used as a tool for genomo redagavimas. Since its recognition as a genome editing tool in 2012, CRISPR–Cas system has come a very long way as a firmly established standard genų redagavimas system and has found a wide range of applications in biomedicine, agriculture, pharmaceutical industries including in clinical gene therapy^1,2.  

Platus pasirinkimas CRISPR-Cas systems are already identified and currently available for monitoring and editing DNA/RNA sequences for research, drug screening, diagnostics and treatments. The current CRISPR/Cas systems are divided into 2 classes (Class 1 and 2) and six types (Type I to XI). Class 1 systems have multiple Cas baltymai which need to form a functional complex to bind and act on their targets. On the other hand, Class 2 systems have only one large Cas baltymų for binding and degrading target sequences which makes Class 2 systems easier to use. Commonly used Class 2 systems are Cas 9 Type II, Cas13 Type VI, and Cas12 Type V. These systems may have undesired collateral effects I.e., off-target impact and cytotoxicity^3,5.  

Gene therapies based on current CRISPR- Cas systems have limited clinical use because of frequent occurrences of off-target editing, unexpected DNA mutations, including big DNA fragment deletions and large DNA structural variants at both on-target and off-target sites that leads to cell deaths and other inheritable problems.  

Craspase (arba CRISPR valdoma kaspazė)  

Researchers have recently reported a novel CRISPER-Cas system which is a Class 2 Type III-E Cas7-11 system associated with a caspase-like baltymų hence named Craspase arba CRISPR valdoma kaspazė ⁵ (Caspases are cysteine proteases that play key role in apoptosis in breaking down cellular structures). It has potential applications in areas like gene therapy and diagnostics. Craspase is RNA-guided and RNA-targeted and do not get involved with the DNA sequences. It can target and destroy mRNA and baltymai associated with different genetic diseases more accurately without off-target impact. Thus, elimination of genes associated with diseases is possible by cleavage at mRNA or protein level. Also, when linked with specific enzyme, Craspase can also be used to modify functions of proteins. When its RNase and protease functions are removed, Craspase becomes deactivated (dCraspase). It has no cutting function but binds with RNA and protein sequences. Therefore, dCraspase can be used in diagnostics and imaging to monitor and diagnose diseases or viruses.  

Craspase is the first CRISPR-Cas system that shows protein editing function. It is also the first system that can edit both RNA and protein. Its genų redagavimas function comes at minimal off-target effects and no inheritable problems. Hence, Craspase is likely to be safer in clinical use and therapeutics than other currently available CRISPR- Cas systems ^4,5.    

Kadangi Craspase įveikia daugybę esamų CRISPR-Cas sistemų apribojimų, ji gali pakeisti genų terapiją, diagnostiką ir stebėjimą, biomedicininius tyrimus ir pasėlių gerinimą. Reikia daugiau tyrimų, kad būtų sukurta patikima tiekimo sistema, skirta tiksliai nukreipti ligą sukeliančius genus ląstelėse, prieš įrodant saugumą ir veiksmingumą klinikiniuose tyrimuose.   

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Nuorodos:  

1. Gostimskaya, I. CRISPR–Cas9: Jo atradimo istorija ir etiniai svarstymai apie jo naudojimą genomo redagavimui. Biochemistry Moscow 87, 777–788 (2022). https://doi.org/10.1134/S0006297922080090  

2. Chao Li et al 2022. Skaičiavimo įrankiai ir ištekliai CRISPR/Cas genomo redagavimui. Genomika, proteomika ir bioinformatika. Prieiga internete 24 m. kovo 2022 d. DOI: https://doi.org/10.1016/j.gpb.2022.02.006 

3. van Beljouw, SPB, Sanders, J., Rodríguez-Molina, A. ir kt. Į RNR nukreiptos CRISPR-Cas sistemos. Nat Rev Microbiol 21, 21–34 (2023). https://doi.org/10.1038/s41579-022-00793-y 

4. Chunyi Hu et al 2022. Craspase yra CRISPR RNR valdoma, RNR aktyvuota proteazė. Mokslas. 25 m. rugpjūčio 2022 d. 377 tomas, 6612 leidimas. 1278–1285 p. DOI: https://doi.org/10.1126/science.add5064  

5. Huo, G., Shepherd, J. & Pan, X. Craspase: naujas CRISPR / Cas dviejų genų redaktorius. Functional & Integrative Genomics 23, 98 (2023). Paskelbta: 23 m. kovo 2023 d. DOI: https://doi.org/10.1007/s10142-023-01024-0 

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