Uytengsu-Hamilton 22q11 Neuropsychiatry Research Awards Program

Our goal is to advance gene therapeutics for 22q11.2 Deletion Syndrome (DS). A major limitation has been the development of adenoassociated viral vectors (AAV) that can efficiently transverse the blood-brain barrier (BBB) and disseminate throughout the cells in the brain. Patients with 22q11.2 DS produce less Claudin 5, a key protein in maintaining the structure and function of the BBB. We plan to develop BBB models of 22q11.2 DS patients, screen our AAV library and select novel vectors that provide enhanced gene transfer into cells that maintain the BBB. We will use these vectors to normalize Claudin 5 protein and restore BBB function.

A recent important finding in 22q11.2DS is that neurons derived from patient cells show a reduction in the strength of the electrical field across the neuron’s membrane. Our lab specializes in the development of methods for measuring neuronal electrical fields with a microscope, rather than with an electrode. We developed a fluorescent voltage indicator named ASAP3 that can measure the electrical field with high accuracy by changing the amount of light it emits. We will apply ASAP3 to confirm the abnormal transmembrane field in neurons derived from 22q11.2DS patient cells, and from a mouse model of 22q11.2DS. We will then perform screens of known neurologically active drugs to find those that can reverse the abnormality.

Proper cellular energy production by mitochondria is critical during human brain development. The 22q11.2 chromosomal region contains mitochondrial genes. Their deletion is suspected to induce energy production deficits in individuals with 22q11.2 deletion syndrome and contribute to functional alterations and increased risk for neuropsychiatric diseases. We will perform in-depth metabolomic profiling of developing brain cells carrying the 22q11.2 deletion, using human brain organoids and cutting-edge metabolomic assays. Through comparisons with normal cells, we aim to identify differences in energy production, which would point towards therapeutic targets as early as the fetal period and eventually decrease the risk for neuropsychiatric diseases.

There is a lack of knowledge which genes in the deleted region of chromosome 22 contribute to the disease phenotype in 22q11DS, or how to restore the genes to the physiological relevant levels to remedy the disease. Here we will use cutting-edge CRISPR tools to uncover gene contributions to the neuropsychiatric phenotypes associated with 22q11DS. We will further apply precision gene editing to restore expression of affected genes to physiological relevance and rescue the disease phenotype. This will help us identify more specific and effective treatments.

Patients with 22q11DS and comorbid psychosis have been found to be less responsive to dopamine-targeting antipsychotics and more prone to their potential adverse effects. There is a need for novel therapeutics targeting other neurotransmitters to reduce psychotic and cognitive symptoms in these patients. The aim of this study is to examine the efficacy of riluzole, a FDA-approved glutamate and γ-aminobutyric acid (GABA) modulating compound, for treatment of psychotic symptoms and cognitive impairment in 22q11.2DS patients. In addition, the effects of riluzole on the glutamate/GABA-balance will be examined to increase insight in the neurobiological underpinnings of psychotic and cognitive symptoms.

We recently discovered that in people with 22q11DS and mouse models, the cerebellar paraflocculus and flocculus (PF/F) are reduced in size, and that mouse models of 22q11DS are deficient in adjusting eye movements. Cerebellar dysfunction has long-been related to the development of psychiatric symptoms and abnormal cognition, but we still do not know which cerebellar structures or molecular mechanisms are involved. We will identify the gene(s) within the 22q11DS region that causes the PF/F reduction by screening mouse models. We will then test if 22q11DS patients carrying a deletion of this gene have smaller PF/F and are deficient in controlling their eye movements. Second, we will identify the cellular processes that lead to the smaller PF/F.

Our overarching goal is to develop a data-driven computational framework for robust identification of early biomarkers of risk for psychosis in 22q11 DS patients/children. We will do so by using a novel “Big Data” science approach combining exciting recent advances in deep learning neural networks (DNN) and our recent work on quantitative dynamic brain circuit analyses with a wealth of newly available large-scale open-source cross-sectional and longitudinal brain imaging and phenotypic data from consortia and repositories around the world.

The 22q11 deletion renders a large number of genes heterozygous. Although multiple systems-level experiments on mouse models of the 22q11 deletion were performed, no analyses of the effects of the 22q11 deletion on fundamental neuronal properties, especially synaptic properties, were performed. Moreover, little is known about the identity of the key genes whose heterozygous deletion drives neuronal impairments. The overall goal of the proposed project is to determine the fundamental phenotypes produced by the 22q11 deletion in neurons, and to identify the genes whose heterozygous deletion drives the development of these phenotypes.

We will establish a novel genome analysis methodology that will make it possible, for the first time, to resolve the currently impenetrable Segmental Duplication regions (SegDups, also Low-Copy-Repeats, LCRs) that are flanking almost all 22q11 deletions, and thus to determine the extent of the 22q11 deletion in 22q11DS patients at base-pair resolution.