The article "CRISPR-Mediated Modular RNA-Guided Regulation of Transcription in Eukaryotes" by Gilbert et al. (2013) presents a method for precise and robust targeting of genes for expression or repression in eukaryotic cells using the CRISPR-associated catalytically inactive dCas9 protein. The authors demonstrate that fusing dCas9 to effector domains with distinct regulatory functions, such as transcriptional repressors or activators, enables stable and efficient transcriptional repression or activation in human and yeast cells. The site of delivery is determined by co-expressed short guide (sg)RNAs, which target the DNA sequence of interest. The study shows that CRISPR interference (CRISPRi) mediated by dCas9 can be highly specific, as indicated by RNA-seq analysis. The authors also show that CRISPRi can be used for multiplexed control of endogenous genes and can stably repress genes with similar efficiency to RNA interference (RNAi). The modular nature of the dCas9 system allows for the recruitment of different protein effectors to specific DNA sequences, making it a versatile tool for studying transcription, epigenetic regulation, and DNA replication and repair. The article highlights the potential of CRISPRi as a general method for precise regulation of gene expression in eukaryotic cells.The article "CRISPR-Mediated Modular RNA-Guided Regulation of Transcription in Eukaryotes" by Gilbert et al. (2013) presents a method for precise and robust targeting of genes for expression or repression in eukaryotic cells using the CRISPR-associated catalytically inactive dCas9 protein. The authors demonstrate that fusing dCas9 to effector domains with distinct regulatory functions, such as transcriptional repressors or activators, enables stable and efficient transcriptional repression or activation in human and yeast cells. The site of delivery is determined by co-expressed short guide (sg)RNAs, which target the DNA sequence of interest. The study shows that CRISPR interference (CRISPRi) mediated by dCas9 can be highly specific, as indicated by RNA-seq analysis. The authors also show that CRISPRi can be used for multiplexed control of endogenous genes and can stably repress genes with similar efficiency to RNA interference (RNAi). The modular nature of the dCas9 system allows for the recruitment of different protein effectors to specific DNA sequences, making it a versatile tool for studying transcription, epigenetic regulation, and DNA replication and repair. The article highlights the potential of CRISPRi as a general method for precise regulation of gene expression in eukaryotic cells.