Biology subjects

Stafford, A. M.

Publications and source records attributed to Stafford, A. M..

8 recordsLinked to original sources

bioRxiv2025

Transplantation of GABAergic Interneuron Progenitors Restores Cortical Circuit Function in an Alzheimer's Disease Mouse Model

In addition to dementia, Alzheimers patients suffer from sleep impairments and aberrations in sleep-dependent brain rhythms. Deficits in inhibitory GABAergic interneuron function disrupt one of those rhythms, slow oscillation in particular, and actively contribute to Alzheimers progression. We tested the degree to which transplantation of healthy donor interneuron progenitors would restore slow oscillation rhythm in young APP mice. We harvested medial ganglionic eminence (MGE) progenitors from mouse embryos and transplanted them into host APP mutant cortices. 3D light-sheet and structured illumination microscopy revealed that transplanted MGE progenitors survived and matured into healthy interneurons. In vivo multiphoton calcium imaging and voltage-sensitive dye imaging showed functional integration and slow oscillation rescue in absence or presence of optogenetic stimulation. Our work provides proof-of-concept evidence that stem cell therapy may serve as a viable strategy to rescue functional impairments in cortical circuits of APP mice and potentially those of Alzheimers patients.

neuroscience↗

bioRxiv2024

Complimentary vertebrate Wac models exhibit phenotypes relevant to DeSanto-Shinawi Syndrome

Monogenic syndromes are associated with neurodevelopmental changes that result in cognitive impairments and neurobehavioral phenotypes including autism and seizures. Limited studies and resources are available to make meaningful headway into the underlying molecular mechanisms that result in these symptoms. One such example is DeSanto-Shinawi Syndrome (DESSH), a rare disorder caused by pathogenic variants in the WAC gene. Individuals with DESSH syndrome exhibit a recognizable craniofacial gestalt, developmental delay/intellectual disability, neurobehavioral symptoms that include autism, ADHD, behavioral difficulties and seizures. However, no thorough studies from a vertebrate model exist to understand how these changes occur. To overcome this, we developed both murine and zebrafish Wac/wac deletion mutants and studied whether their phenotypes recapitulate those described in individuals with DESSH syndrome. We first show that the two Wac models exhibit craniofacial and behavioral changes, reminiscent of abnormalities found in DESSH syndrome. In addition, each model revealed impacts to GABAergic neurons and further studies showed that the mouse mutants are susceptible to seizures, changes in brain volumes that are different between sexes and relevant behaviors. Finally, we uncovered transcriptional impacts of Wac loss of function in mice that will pave the way for future molecular studies into DESSH. These studies present two new animals that begin to uncover some biological underpinnings of DESSH syndrome and elucidate the biology of Wac.

neuroscience↗

bioRxiv2022

Distinct hyperactive RAS/MAPK alleles converge on common GABAergic interneuron core programs

RAS/MAPK gene dysfunction underlies various cancers and neurocognitive disorders. While the role of RAS/MAPK genes have been well studied in cancer, less is known about their function during neurodevelopment. There are many genes that work in concert to regulate RAS/MAPK signaling, suggesting that if common brain phenotypes could be discovered they could have a broad impact on the many other disorders caused by distinct RAS/MAPK genes. We assessed the cellular and molecular consequences of hyperactivating the RAS/MAPK pathway using two distinct genes in a cell type previously implicated in RAS/MAPK-mediated cognitive changes, cortical GABAergic interneurons. We uncovered some GABAergic core programs that are commonly altered in each of the mutants. Notably, hyperactive RAS/MAPK mutants bias developing cortical interneurons towards those that are somatostatin+. The increase in somatostatin+ interneurons could also be induced by elevated neural activity and we show the core RAS/MAPK signaling pathway is one mechanism by which this occurs. Overall, these findings present new insights into how different RAS/MAPK mutations can converge on GABAergic interneurons, which may be important for other RAS/MAPK genes/disorders.

neuroscience↗

bioRxiv2022

Multifunctional requirements for ERK1/2 signaling in the development of ganglionic eminence derived glia and cortical inhibitory neurons

The RAS/RAF/MEK/ERK1/2 intracellular signaling pathway is activated by numerous cues during brain development and dysregulated in neurodevelopmental syndromes, particularly the RASopathies and certain forms of autism. Cortical excitatory/inhibitory imbalance is thought to be critical in the neuropathogenesis of these conditions. However, the developmental functions of ERK1/2 signaling in cortical inhibitory neurons (CINs) and other medial ganglionic eminence (MGE)-derived non-neuronal cells are poorly understood. Here, we genetically modulated ERK1/2 signaling in mouse MGE neural progenitors or GABAergic neurons in vivo. We find that MEK-ERK1/2 signaling is essential for regulating MGE-derived oligodendrocyte number in the anterior commissure. While Erk1/2 inactivation does not alter CIN number, we discovered a significant and persistent reduction in somatostatin, but not parvalbumin, expression in a subset of CINs. ERK1/2 signaling is also necessary for chemogenetic activity-dependent FOSB expression in CINs in vivo. Interestingly, one week of chronic chemogenetic stimulation in juvenile or adult animals partially rescues the decrease in somatostatin expression in Erk1/2 mutant CINs. Our data demonstrate ERK1/2 signaling is required for the establishment of MGE-derived glia, whereas in CINs, ERK1/2 drives activity dependent-responses and the expression of somatostatin in a subset of neurons.

neuroscience↗

bioRxiv2022

A murine Wac model exhibits phenotypes relevant to DeSanto-Shinawi Syndrome

Several monogenic syndromes are associated with neurodevelopmental changes that result in cognitive impairments, including autism, attention deficit hyperactivity disorder (ADHD) and seizures. Limited studies and resources are available to make meaningful headway into the underlying mechanisms that result in these symptoms. One such example, DeSanto-Shinawi Syndrome (DESSH), is a rare disorder caused by mutations in the WAC gene. Those diagnosed with DESSH experience craniofacial alterations as well as cognitive symptoms that include autism, ADHD and seizures. However, no thorough studies from a mammalian model exist to understand how these changes occur. To overcome this, we generated constitutive murine Wac mutants and assessed phenotypes that are relevant to humans diagnosed with DESSH. Wac mutants have craniofacial, anatomical, behavioral and seizure susceptibility that are relevant to DESSH; this new model is suited to study some of the core symptoms of DESSH and the biology of Wac.

neuroscience↗

bioRxiv2020

A human TSC1 mutation screening platform in GABAergic cortical interneurons for Genotype to Phenotype assessments

Tuberous Sclerosis Complex is a complex syndrome that affects multiple organs and is caused by dysfunction of either the TSC1 or TSC2 genes. One of the least understood features of TSC is the impact of TSC1&2 variants on brain phenotypes, including elevated rates of autism spectrum disorder and seizures. Moreover, while a great deal of work has uncovered how loss of either gene can alter various neural cell types, the impact of many variants in TSC and on these cell types is poorly understood. In particular, missense variants that cause minor changes in the proteins are expected to cause functional changes that differ from a complete loss of the protein. Herein, we examined how some missense variants in TSC1 impacted the development of cortical inhibitory interneurons, a cell type whose molecular, cellular and physiological properties are known to be altered after loss of mouse Tsc1. Importantly, we found that most missense variants complemented phenotypes caused by loss of Tsc1 and resulting in elevated MTOR activity as well as several cell intrinsic physiological properties. However, distinct variants showed deficits in complementing an increase in parvalbumin levels, which is observed after loss of Tsc1 and demonstrated smaller amplitudes of after hyperpolarizations. These data suggest subtle but sensitive phenotypes can be detected by some TSC1 missense variants and provide an in vivo system in which to better assess TSC variants.

neuroscience↗

bioRxiv2019

Nf1 deletion results in depletion of the Lhx6 transcription factor and a specific loss of parvalbumin+ cortical interneurons

Neurofibromatosis-1 (NF-1) is a monogenic disorder caused by mutations in the NF1 gene, which encodes the protein, Neurofibromin, an inhibitor of Ras GTPase activity. While NF-1 is often characterized by cafe-au-lait skin spots and benign tumors, the mechanisms underlying cognitive changes in NF-1 are poorly understood. Cortical GABAergic interneurons (CINs) are implicated in NF-1 pathology but cellular and molecular changes to CINs are poorly understood. We deleted Nf1 from the medial ganglionic eminence (MGE), which gives rise to both oligodendrocytes and CINs that express somatostatin and parvalbumin. Loss of Nf1 led to a persistence of immature oligodendrocytes that prevented later born oligodendrocytes from occupying the cortex. Moreover, PV+ CINs were uniquely lost, without changes in SST+ CINs. We discovered that loss of Nf1 results in a graded decrease in Lhx6 expression, the transcription factor necessary to establish SST+ and PV+ CINs, revealing a mechanism whereby Nf1 regulates a critical CIN developmental milestone.

neuroscience↗

bioRxiv2019

The Tuberous Sclerosis gene, Tsc1, represses parvalbumin+/fast-spiking properties in somatostatin-lineage cortical interneurons

Medial ganglionic eminence (MGE)-derived somatostatin (SST)+ and parvalbumin (PV)+ cortical interneurons (CINs), have characteristic molecular, anatomical and physiological properties. However, mechanisms regulating their diversity remain poorly understood. Here, we show that conditional loss of the Tuberous Sclerosis (TS) gene, Tsc1, which inhibits mammalian target of rapamycin (MTOR), causes a subset of SST+ CINs, to express PV and adopt fast-spiking (FS) properties, characteristic of PV+ CINs. These changes also occur when only one allele of Tsc1 is deleted, making these findings relevant to individuals with TS. Notably, treatment with rapamycin, which inhibits MTOR, reverses these changes in adult mice. These data reveal novel functions of MTOR signaling in regulating PV expression and FS properties, which may contribute to some neuropsychiatric symptoms observed in TS. Moreover, they suggest that CINs can exhibit properties intermediate between those classically associated with PV+ or SST+ CINs, which may be dynamically regulated by the MTOR signaling.

neuroscience↗