The present disclosure relates to compositions and methods for modulating gene expression and in particular to compositions and methods for increasing expression of Klotho. For example, the present disclosure provides methods for increasing expression of a Klotho gene in a human cell comprising introducing into the cell a CRISPR enzyme and a guide RNA comprising a guide sequence that is substantially complementary to a target sequence within or near the Klotho gene, wherein the guide RNA or the CRISPR enzyme associates with a transcriptional activation domain.