CRISPR Based Rescue of Glaucoma in Lowe Syndrome

ABSTRACT Oculocerebrorenal syndrome of Lowe is a rare X-linked disorder characterized by bilateral congenital cataracts and glaucoma, renal tubular dysfunction, and mental retardation. Mutations in OCRL1, an inositol polyphosphate 5-phosphatase, cause Lowe syndrome. Despite the identification of OCRL1 as the causal gene underlying this rare disease, there is currently no therapy for Lowe syndrome. Children with Lowe syndrome often go blind due to glaucomatous optic neuropathy. We have developed a novel CRISPR-based approach to transcriptionally regulate the inositol enzymes that control the substrate of OCRL. We have developed a nuclease-deficient Cas protein that allows activation or inactivation of endogenous genes. Our preliminary data shows a novel hypercompact CasMINI for gene editing in a single viral package that allows “Plug-and-Play” delivery. We also established a nuclease-deficient CRISPR-CasMINI (dCasMINI) for gene transcriptional activation of protein expression, with functional rescue in vivo. We also established human Lowe syndrome-based human iPS stem cells, mouse and zebrafish models, and viral delivery approaches for in vivo therapies. We hypothesize that CRISPR-Cas based rescue strategies for inositol 5-phosphatases will restore the imbalance due to the loss of OCRL in Lowe syndrome. Our aims are to (1) transcriptionally activate a compensatory 5-phosphatase that degrades PI(4,5)P2, (2) generate exon-skipping transcripts to reduce OCRL loss phenotypes in human iPS models of Lowe syndrome, (3) use CRISPR-Pass strategy with both adenosine base editors and prime editors to correct OCRL gene mutations in Lowe patient derived cells. We anticipate this work will provide critical insights into how CRISPR-Cas can be used to rescue the loss of OCRL and provide important translation approaches for Lowe syndrome and then expanded to treat other forms of inherited genetic eye diseases.