Progranulin upregulation by antisense oligonucleotides targeting regRNAs for treatment of FTD‐GRN

Abstract

AbstractBackgroundHeterozygous mutations in progranulin (GRN) gene leading to progranulin protein (PGRN) haploinsufficieny are the major genetic cause of GRN‐related frontotemporal dementia (FTD‐GRN)1, 2 and 3. Decreased levels of PGRN disrupt lysosome homeostasis, cause aberrant microglia activation and neuronal cell death resulting in progressive behavioral changes, language deficits and memory impairment4. We hypothesize that upregulation of PGRN in both neuronal cells and microglia would be effective for treating FTD‐GRN patients.MethodRegulatory RNAs (regRNAs) are a class of noncoding RNAs that modulate gene transcription. We have developed an RNA Actuating Platform (RAPTM) that identified regRNAs and enables tunable upregulation of genes by specific targeting of regRNAs with antisense oligonucleotides (ASOs).ResultOur platform identified shared GRN regRNAs in human iPSC‐derived neuron and microglia like cells (iMGLs). ASOs targeting shared regRNAs were screened in a human neuroblastoma cell line to identify lead ASOs that upregulate GRN at least 2‐fold. We showed that the lead ASOs upregulate GRN in both human iPSC‐derived neurons and iMGL cells. Moreover, this level of GRN upregulation was sufficient to rescue staurosporine‐induced toxicity in FTD‐GRN patient iPSC‐derived neurons.Furthermore, we identified mouse Grn regRNA‐targeting ASOs that upregulate Grn transcription 2.5‐fold in mouse neuroblastoma cell lines and primary neurons. We tested these ASOs for efficacy in an FTD‐GRN mouse model (Grn+/tm1.1Far )5 by intracerebroventricular injection. Grn upregulation is observed across disease‐relevant brain regions, including cortex in the Grn haploinsufficient mice.ConclusionHere, we describe the development of oligonucleotide drug candidates that target regRNAs to upregulate GRN expression as a therapeutic approach for FTD‐GRN. We believe that our strategy will restore secreted and lysosomal PGRN levels in both microglia and neurons thereby decreasing neuroinflammation and neurotoxicity. We are developing these oligonucleotides as a disease modifying treatment for patients with FTD‐GRN.