Compact engineered Cas12m enables multiplexed CRISPR gene activation in mice

Researchers have engineered a compact CRISPR-based system that can switch on multiple genes at once in living animals, packaged within a single adeno-associated virus (AAV) vector. The work, published in Nature Biotechnology, centres on the Cas12m protein family, a naturally nuclease-dead CRISPR system that carries intrinsic self-processing activity for its precursor crRNA, meaning it can cut its own guide RNA transcript into individual functional guides inside a target cell.

From this protein family the team developed an optimized variant, denCas12m, and built it into a platform called smCRISPRa. Because the genetic elements required for conventional CRISPR-based transactivation (CRISPRa) often exceed the packaging capacity of AAV vectors, coordinated gene activation in vivo has remained difficult. The new system addresses this by allowing a single transcriptional unit encoding a multi-gRNA array to be processed into individual functional guides within the cell, enabling efficient synergistic activation of a single gene through multiple sites or simultaneous activation of distinct endogenous genes from one all-in-one AAV vector.

The platform was tested in mouse models of two diseases. In models of Duchenne muscular dystrophy and of Scn1a haploinsufficiency, the researchers reported phenotypic rescue. In the Duchenne model, persistent smCRISPRa-mediated utrophin expression was shown to rescue the dystrophic phenotype in a humanized DMD mouse model, according to the study’s figures.

The system also demonstrated high-order multiplexing in mice: a single all-in-one AAV vector supported simultaneous activation of multiple distinct endogenous genes, delivering up to eight crRNAs for the activation of six different genes. The findings suggest that a compact, self-processing CRISPRa system could broaden the reach of gene activation therapies where AAV payload limits have constrained multiplexed approaches, although the reported results are preclinical and derive from the published study’s abstract and figure descriptions.

Subject of Research: Engineering of a compact nuclease-dead Cas12m CRISPRa system for multiplexed gene activation in vivo

Article Title: An engineered, compact Cas12m variant for multiplexed gene activation in vivo

Article References: Zhang, H., Yang, L., Liu, Y., Han, D., Li, Y., Lin, J., Wang, B., Hu, J., Zhang, Y., Zhang, Y., Li, J., Wei, S., Liu, S., Li, T., Zhong, N., Zhang, G., Zhou, X., Shi, L., Huang, J., … Li, G. (2026). An engineered, compact Cas12m variant for multiplexed gene activation in vivo. Nature Biotechnology. https://doi.org/10.1038/s41587-026-03352-5

Image Credits: AI Generated

DOI: 10.1038/s41587-026-03352-5

Keywords: CRISPRa, Cas12m, denCas12m, AAV vector, gene activation, multiplexing, Duchenne muscular dystrophy, Scn1a haploinsufficiency, crRNA processing, gene therapy, utrophin, mouse models