Preclinical evaluation of antisense oligonucleotide therapy in a mouse model of <i>HNRNPH2</i>-related neurodevelopmental disorder.

Abstract

Mutations in <i>HNRNPH2</i> cause an X-linked disorder characterized by developmental delay, intellectual disability, motor and gait disturbances, and seizures. Murine models that reproduce key clinical features of <i>HNRNPH2</i>-related neurodevelopmental disorder suggest that it may result from a toxic gain of function of the mutant protein or a complex loss of normal HNRNPH2 function with impaired compensation by its paralog, HNRNPH1. In this study, we tested gapmer antisense oligonucleotides (ASOs) that target murine <i>Hnrnph2</i> in a non-allele-specific manner. The lead ASO reduced <i>Hnrnph2</i> messenger RNA (mRNA) and protein expression while inducing compensatory up-regulation of <i>Hnrnph1</i> expression in both wild-type and <i>Hnrnph2</i> mutant mouse brains. A single intracerebroventricular injection of the <i>Hnrnph2</i> ASO into neonatal mutant <i>Hnrnph2</i> mice rescued molecular and audiogenic seizure phenotypes and improved certain motor and cognitive phenotypes. ASO treatment at the juvenile stage also rescued audiogenic seizures. In contrast, <i>Hnrnph2</i> ASO administration did not alter survival, body weight, or the incidence of hydrocephalus. In human induced pluripotent stem cell-derived neurons, a human-specific <i>HNRNPH2</i> research ASO reduced <i>HNRNPH2</i> mRNA and up-regulated <i>HNRNPH1</i> mRNA. Mechanistically, we found that <i>HNRNPH1</i> expression is regulated by alternative splicing and that HNRNPH2 modulates this process. These findings provide a preclinical proof of concept for <i>HNRNPH2</i> ASO therapy and offer insights into its underlying molecular mechanism.