The present invention relates to engineered chimeric guide RNAs and their uses in systems and methods for gene expression perturbation in eukaryotic cells. Furthermore, the invention also relates to methods for generating a modified T cell using the engineered chimeric guide RNAs of the present application, and to the obtained modified T cell. Also included are methods and pharmaceutical compositions comprising the modified T cell for adoptive therapy and treating a condition, such as cancer, infections or autoimmune diseases.