Uytengsu-Hamilton 22q11 Neuropsychiatry Research Awards Program

Adults with 22q11.2 deletion have a 20-fold higher risk of developing Parkinson’s Disease than healthy individuals. Clinically, these patients present with typical motor symptoms and respond well to dopamine replacement therapy, but show an earlier disease onset in their late 30s. In brain autopsies of cases with 22q11.2 deletions, loss of neurons and intracellular protein aggregates are found that are reminiscent of Parkinson’s disease. These clinical and neuropathological findings suggest overlapping pathways both for Parkinson’s disease and 22q11.2 deletion syndrome.

Our goal is to understand which specific genes in the 22q11 deletion region contribute to the neurodegenerative process. We will examine whether human induced pluripotent stem cell (iPSC)-derived neuronal networks from adults with 22q11.2 deletions show 1) changes in early oxidative stress markers, 2) altered neuronal network activity compared to control neuronal networks, and 3) test whether activation of a selected gene or groups of genes in the 22q11.2 deletion region can ameliorate phenotypes of early oxidative stress and restore neuronal network activity. Our multidisciplinary team developed a high-density neuronal network array with 16,000 electrodes to assess human iPSC-derived neuronal networks. To rescue function, we established gene engineering tools in cell lines from adults with 22q11.2 deletion to regulate gene expression within the 22q11.2 deletion region. 

The deletion in 22q11 is almost always surrounded by long stretches of DNA called SegDups (or LCRs). It is believed that these SegDups are what causes the deletion to happen in the first place. Also, we know that genes and other important sections of DNA sequence can be hiding in SegDups. Until recently it was impossible to study the DNA sequence of the SegDups on 22q11. We have developed a CRISPR-based technology (called CTLR-Seq) that now allows us to do so.

In this study, we want to build on CTLR-Seq, and look at what is happening inside the SegDups surrounding the 22q11 deletion, in stem cells and in different cell types of the brain. We think that there may be important differences between patients hiding there. We believe that the 22q11 deletion may interact with the rest of the genome through the SegDups. If we are correct, our study will give us clues as to why and how the 22q11 deletion is causing the symptoms we see in patients, and why these symptoms can be so different.

The study of brain-immune interactions has contributed to a paradigm shift in understanding of the causes of mental disorders and has provided new insights into their prevention and treatment. Notably, the brain vasculature functions to limit the influence of peripheral inflammation on the brain, so impairment of the brain vasculature could affect the development and outcome of neuropsychiatric disease.

Our team has found that weakness in the blood brain barrier (BBB) occurs in the 22q11.2DS. One 22q11.2 gene is a key component of junctions between vascular cells of the BBB, and several of the 22q11.2 deleted genes function in the mitochondria, from which much of the energy critical to BBB function is generated. In a nutshell, the BBB in 22q11.2DS appears to be leaky for circulating inflammatory mediators and immune cells, leading to an increase in neuroinflammation and behavioral deficits associated with neuropsychiatric disorders.

Here, we propose to use the 22q11.2 DS mouse model to test whether induced peripheral activation promotes neuroinflammation and related behavioral deficits in 22q11.2DS mice. Besides providing a compelling rationale to devise immune therapeutic strategies, the demonstration of a brain-immune link will be crucial for understanding the mechanisms driving disease processes in 22q11.2DS and mental illness at large.

22q11.2 Deletion Syndrome (22q11.2DS) is a genetic syndrome associated with increased risk of developmental neuropsychiatric disorders such as Autism Spectrum Disorders, schizophrenia and attention deficit hyperactivity disorder. These disorders, as well as 22q11.2DS, have been found to be associated with alterations in brain structure and function.

Brain mapping has shown that 22q11DS is characterized by asynchronous communication between brain areas. Hence, one of the keys to understanding neurobehavioral manifestations of 22q11DS, is to understand and decode the patterns of dysfunctional brain activity that characterize the genetic syndrome. Importantly, pinpointing the origin and significance of impaired brain function in 22q11.2DS can also guide the development of possible targeted therapies aimed to restore impaired circuit function.

Towards this goal, we designed a number of studies in both a mouse model and human 22q11DS patients, aimed at tracking the developmental trajectory of brain function and connectivity associated with this syndrome, before and after adolescence. Preliminary results in our laboratory have shown parallels between these trajectories in mice and human 22q11DS, corroborating the validity of our approach. A major goal of our research is to investigate the neural and genetic underpinnings of altered brain communication in 22q11DS. Here we will test the hypothesis that the cross-species dysfunction we found can be explained in terms of disruption of synaptic homeostasis. Our investigations will also provide means to identify specific genes within the 22q11.2 locus that may drive brain connectivity alterations in 22q11DS, providing opportunities for the identification of targets for novel therapies.

The 22q11.2 deletion is associated with a high risk for psychiatric disorders, such as schizophrenia and autism. However, it is largely unknown how this deletion affects human cells and their properties, and how it results in susceptibility for psychiatric disorders.

We propose to use stem cells derived from many individuals with 22q11.2 deletion to test how the deletion changes human brain cells through innovative experimental approaches. Specifically, we will examine how the deletion affects the morphology, or architecture, of brain cells (neurons), measuring several hundred morphological traits, including shape, size, texture, and many others. We will further measure the function of these cells by measuring their connections to each other, or synapses, and their electrical properties. We will thus generate rich datasets reporting on changes in cell shape and function then compare them with our existing data on gene expression changes in these cells. 

Psychosis is enormously problematic for patients, families, and caregivers and there are disappointingly only imperfect therapeutics. There are thought to be genetic aspects as well as environmental factors that drive the development of psychosis. Several epidemiologic features are known to be associated with the subsequent development of schizophrenia, the leading type of psychosis. These epidemiologic features can be conceptually tied together as early life stress and/or inflammation. People born with a deletion in 22q11.2 have an immune system that can be different, leading to increased infections, increased length of infections, and increased inflammatory disease; and the rate of psychosis in adults with 22q11.2 deletion syndrome is as high as 25%. Thus, there is a strong rationale for evaluating the immune system in more detail in people living with 22q11.2 deletion syndrome and schizophrenia. We hypothesize that the immunologic differences contribute to the high risk of schizophrenia in 22q11.2 deletion syndrome. Our study will examine inflammatory mediators in the blood and the packaging of the DNA in chromosomes. This packaging, known as epigenetics, represents a type of code separate from genetic sequence that dictates the behavior of cells and integrates environmental clues and overall health. By analyzing that epigenetic code, we can gain insight into the T cell features associated with psychosis. Successful completion of our study will lead to conceptualization of therapeutics directed at inflammation, infection, or T cell dysfunction. Our goal is risk mitigation through targeted modulation of the immune system.

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.

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.