Compositions, systems, and methods for reducing low-density lipoprotein through targeted gene repression

An epigenetic-modifying DNA-targeting system comprising

• (a) a fusion protein comprising:
• (i) a Clustered Regularly Interspaced Short Palindromic Repeats associated protein 9 (Cas9) that is a Streptococcus pyogenes dCas9 (dSpCas9) protein comprising at least one amino acid mutation selected from D10A and H840A, with reference to numbering of positions of SEQ ID NO:206, and
• (ii) a transcriptional repressor effector domain comprising a KRAB domain and a DNMT3A/L domain, wherein the KRAB domain is set forth in SEQ ID NO:
• 290 and the DNMT3A/L domain is set forth in SEQ ID NO:199,
• wherein the fusion protein comprises one or more nuclear localization signal (NLS), wherein an NLS is between the DNMT3A/L domain and the dSpCas9 protein, and an NLS is between the SpCas9 protein and the KRAB domain;
• and
• (b) a gRNA for targeting to a target site for PCSK9, wherein the gRNA is set forth in SEQ ID NO:129.

An epigenetic-modifying DNA-targeting system comprising

• (a) a fusion protein comprising an amino acid sequence having at least 90% sequence identity to the sequence set forth in SEQ ID NO:
• 278;
• and
• (b) a gRNA for targeting to a target site for PCSK9, wherein the gRNA comprises the sequence set forth in SEQ ID NO:66.