In vivo treatment of tyrosinaemia with hypercompact Cas12f1.
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ABSTRACT:
SUBMITTER: Guo R
PROVIDER: S-EPMC10352374 | biostudies-literature | 2023 Jul
REPOSITORIES: biostudies-literature
Publications
In vivo treatment of tyrosinaemia with hypercompact Cas12f1.
Guo Ruochen R Li Zhifang Z Li Guoling G Zhang Hainan H Zhang Chang C Huo Xiaona X Zhang Xiaoyin X Yang Xiali X Yang Rongrong R Liu Yuanhua Y Sun Xiaozhi X Liu Xinyu X Yang Hui H Zhou Yingsi Y Xu Chunlong C
Cell discovery 20230718 1
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Project description:Gene therapy would benefit from a miniature CRISPR system that fits into the small adeno-associated virus (AAV) genome and has high cleavage activity and specificity in eukaryotic cells. One of the most compact CRISPR-associated nucleases yet discovered is the archaeal Un1Cas12f1. However, Un1Cas12f1 and its variants have very low activity in eukaryotic cells. In the present study, we redesigned the natural guide RNA of Un1Cas12f1 at five sites: the 5' terminus of the trans-activating CRISPR RNA (tracrRNA), the tracrRNA-crRNA complementary region, a penta(uridinylate) sequence, the 3' terminus of the crRNA and a disordered stem 2 region in the tracrRNA. These optimizations synergistically increased the average indel frequency by 867-fold. The optimized Un1Cas12f1 system enabled efficient, specific genome editing in human cells when delivered by plasmid vectors, PCR amplicons and AAV. As Un1Cas12f1 cleaves outside the protospacer, it can be used to create large deletions efficiently. The engineered Un1Cas12f1 system showed efficiency comparable to that of SpCas9 and specificity similar to that of AsCas12a.
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Project description:A 19 year old woman with tyrosinaemia type 1 gave birth to a healthy girl after 41 weeks of gestation. Nitisinone was continued throughout the pregnancy (maternal levels 68-96 μmol/l, target level 30-60 μmol/l). Tyrosine levels during pregnancy were between 500 and 693 μmol/l (normal values 20-120 μmol/l) and phenylalanine levels between 8 and 39 μmol/l (normal values 30-100 μmol/l). Nitisinone was measurable in neonatal blood immediately after birth, at a level comparable to the simultaneous level in the mother. Nitisinone half-life in the neonate was estimated to be 90 h. Tyrosine levels in the neonate decreased from 1,157 μmol/l at birth (cord blood) to normal levels within 4 weeks. Phenylalanine levels in the neonate were normal from birth on. The child had a normal psychomotor development as assessed throughout the first year of life.This is the first report worldwide of a pregnancy during treatment with nitisinone.In this case, no adverse effects of nitisinone, maternal high tyrosine or low phenylalanine were detected in the child, so far. Long-term results in a larger cohort of pregnancies and births are needed to determine whether nitisinone can be administered safely during pregnancy.
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Project description:Many metabolic liver disorders are refractory to drug therapy and require orthotopic liver transplantation. Here we demonstrate a new strategy, which we call metabolic pathway reprogramming, to treat hereditary tyrosinaemia type I in mice; rather than edit the disease-causing gene, we delete a gene in a disease-associated pathway to render the phenotype benign. Using CRISPR/Cas9 in vivo, we convert hepatocytes from tyrosinaemia type I into the benign tyrosinaemia type III by deleting Hpd (hydroxyphenylpyruvate dioxigenase). Edited hepatocytes (Fah(-/-)/Hpd(-/-)) display a growth advantage over non-edited hepatocytes (Fah(-/-)/Hpd(+/+)) and, in some mice, almost completely replace them within 8 weeks. Hpd excision successfully reroutes tyrosine catabolism, leaving treated mice healthy and asymptomatic. Metabolic pathway reprogramming sidesteps potential difficulties associated with editing a critical disease-causing gene and can be explored as an option for treating other diseases.
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Project description:Nitisinone (NIT) produces inevitable but varying degree of tyrosinaemia. However, the understanding of the dynamic adaptive relationships within the tyrosine catabolic pathway has not been investigated fully. The objective of the study was to assess the contribution of protein intake, serum NIT (sNIT) and tyrosine pathway metabolites to nitisinone-induced tyrosinaemia in alkaptonuria (AKU). Samples of serum and 24-h urine collected during SONIA 2 (Suitability Of Nitisinone In Alkaptonuria 2) at months 3 (V2), 12 (V3), 24 (V4), 36 (V5) and 48 (V6) were included in these analyses. Homogentisic acid (HGA), tyrosine (TYR), phenylalanine (PHE), hydroxyphenylpyruvate (HPPA), hydroxyphenyllactate (HPLA) and sNIT were analysed at all time-points in serum and urine. Total body water (TBW) metabolites were derived using 60% body weight. 24-h urine and TBW metabolites were summed to obtain combined values. All statistical analyses were post-hoc. 307 serum and 24-h urine sampling points were analysed. Serum TYR from V2 to V6, ranging from 478 to 1983 µmol/L were stratified (number of sampling points in brackets) into groups < 701 (47), 701-900 (105), 901-1100 (96) and > 1100 (59) µmol/L. The majority of sampling points had values greater than 900 µmol/L. sPHE increased with increasing sTYR (p < 0.001). Tyrosine, HPPA and HPLA in serum and TBW all increased with rising sTYR (p < 0.001), while HPLA/TYR ratio decreased (p < 0.0001). During NIT therapy, adaptive response to minimise TYR formation was demonstrated. Decreased conversion of HPPA to HPLA, relative to TYR, seems to be most influential in determining the degree of tyrosinaemia.
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Project description:CRISPR-CasΦ, a small RNA-guided enzyme found uniquely in bacteriophages, achieves programmable DNA cutting as well as genome editing. To investigate how the hypercompact enzyme recognizes and cleaves double-stranded DNA, we determined cryo-EM structures of CasΦ (Cas12j) in pre- and post-DNA-binding states. The structures reveal a streamlined protein architecture that tightly encircles the CRISPR RNA and DNA target to capture, unwind and cleave DNA. Comparison of the pre- and post-DNA-binding states reveals how the protein rearranges for DNA cleavage upon target recognition. On the basis of these structures, we created and tested mutant forms of CasΦ that cut DNA up to 20-fold faster relative to wild type, showing how this system may be naturally attenuated to improve the fidelity of DNA interference. The structural and mechanistic insights into how CasΦ binds and cleaves DNA should allow for protein engineering for both in vitro diagnostics and genome editing.
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Project description:In contrast to traditional CRISPR-Cas9 homology-directed repair, base editing can correct point mutations without supplying a DNA-repair template. Here we show in a mouse model of tyrosinaemia that hydrodynamic tail-vein injection of plasmid DNA encoding the adenine base editor (ABE) and a single-guide RNA (sgRNA) can correct an A>G splice-site mutation. ABE treatment partially restored splicing, generated fumarylacetoacetate hydrolase (FAH)-positive hepatocytes in the liver, and rescued weight loss in mice. We also generated FAH+ hepatocytes in the liver via lipid-nanoparticle-mediated delivery of a chemically modified sgRNA and an mRNA of a codon-optimized base editor that displayed higher base-editing efficiency than the standard ABEs. Our findings suggest that adenine base editing can be used for the correction of genetic diseases in adult animals.
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| S-EPMC10663539 | biostudies-literature
Project description:CRISPR-Cas systems are found widely in prokaryotes, where they provide adaptive immunity against virus infection and plasmid transformation. We describe a minimal functional CRISPR-Cas system, comprising a single ~70-kilodalton protein, CasΦ, and a CRISPR array, encoded exclusively in the genomes of huge bacteriophages. CasΦ uses a single active site for both CRISPR RNA (crRNA) processing and crRNA-guided DNA cutting to target foreign nucleic acids. This hypercompact system is active in vitro and in human and plant cells with expanded target recognition capabilities relative to other CRISPR-Cas proteins. Useful for genome editing and DNA detection but with a molecular weight half that of Cas9 and Cas12a genome-editing enzymes, CasΦ offers advantages for cellular delivery that expand the genome editing toolbox.
| S-EPMC8207990 | biostudies-literature
Project description:BackgroundSynthetic CRISPR-Cas9 gene drive has been developed to control harmful species. However, resistance to Cas9 gene drive can be acquired easily when DNA repair mechanisms patch up the genetic insults introduced by Cas9 and incorporate mutations to the sgRNA target. Although many strategies to reduce the occurrence of resistance have been developed so far, they are difficult to implement and not always effective.ResultsHere, Cas12f1, a recently developed CRISPR-Cas system with minimal potential for causing mutations within target sequences, has been explored as a potential platform for yielding low-resistance in gene drives. We construct Cas9 and Cas12f1 gene drives in a fast-replicating DNA virus, HSV1. Cas9 and Cas12f1 gene drives are able to spread among the HSV1 population with specificity towards their target sites, and their transmission among HSV1 viruses is not significantly affected by the reduced fitness incurred by the viral carriers. Cas12f1 gene drives spread similarly as Cas9 gene drives at high introduction frequency but transmit more slowly than Cas9 gene drives at low introduction frequency. However, Cas12f1 gene drives outperform Cas9 gene drives because they reach higher penetration and induce lower resistance than Cas9 gene drives in all cases.ConclusionsDue to lower resistance and higher penetration, Cas12f1 gene drives could potentially supplant Cas9 gene drives for population control.
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