Conditional AGO Knockout Reveals Tissue-Specific Requirements of miRNA Activity in C. elegans

MicroRNAs (miRNAs) are essential for worm development, yet their roles remain unclear in most tissues. Here, we established a tissue-specific Argonaute (AGO) knockout system in Caenorhabditis elegans using conditional deletion of alg-1 in an alg-2 mutant background. Tissue-restricted loss of AGO revealed distinct developmental and tissue-specific phenotypes. AGO depletion in the intestine, pharynx, and hypodermis caused developmental arrest and tissue-specific defects, whereas neuronal and muscle-specific AGO depletion impaired locomotion and affected neuronal or muscle-associated phenotypes. Moreover, combined loss of selected tissue-expressed miRNAs only partially recapitulated the corresponding AGO-depletion phenotypes. Muscle-specific re-expression of selected miRNAs rescued the locomotion defect of the compound miRNA mutant. This study establishes a platform for dissecting tissue-specific miRNA functions during animal development.