Biology subjects

Sandoval, A.

Publications and source records attributed to Sandoval, A..

7 recordsLinked to original sources

bioRxiv2026

Pathogenic mutations in ATAD3A cause dysregulation of RagC/D-TFEB axis and disrupt lysosomal homeostasis

We previously discovered that a de novo variant p.R528W in ATAD3A, encoding a mitochondrial membrane-anchored protein, causes a human neurological syndrome. While ATAD3A mutations induce aberrant lysosomal expansion accompanied by undigested material in the lysosomes, how mutant ATAD3A disrupts lysosomal homeostasis and whether this contributes to neurodevelopmental defects remain unknown. Here we show that pathogenic ATAD3A p.R528W expression disrupts the mTORC1-TFEB axis as revealed by dysregulation of mTORC1 substrate phosphorylation, TFEB nuclear localization, and CLEAR gene activation associated with lysosomal biogenesis. ATAD3A binds to lysosome-localized Rag C/D GTPases, which constitute a platform for TFEB recruitment, with pathogenic variants increasing this association and thereby decreasing lysosomal localization of Rag GTPases. Importantly, overexpression of RagC or RagD restores TFEB phosphorylation in human cells expressing p.R528W, and RagC-D overexpression or TFEB/Mitf knockdown rescues lysosomal expansion and neurodevelopmental defects in Drosophila. These data indicate that disrupted Rag GTPase recruitment to lysosomes and subsequent aberrant TFEB/Mitf activation contribute to neurodevelopmental and lysosomal phenotypes caused by pathogenic mutations in ATAD3A. Our work reveals a novel role for the mitochondrial resident protein ATAD3A in modulating lysosomal homeostasis through regulation of the mTORC1-TFEB axis, providing a mechanistic link between impaired mitochondrial and lysosomal homeostasis in a neurodevelopmental disorder.

genetics↗

bioRxiv2026

Bumetanide Strengthens Residual Brain Bladder Communication After Spinal Cord Injury

Neurogenic bladder is one of the most disabling consequences of spinal cord injury (SCI), yet it remains unclear whether residual brain bladder communication persists after injury and can be therapeutically strengthened. Here, we integrated analysis of a clinical SCI cohort with studies in a mouse model that recapitulates key features of human neurogenic bladder. SCI markedly impaired both descending and ascending limbs of the spinobulbospinal micturition reflex, reducing bladder responses evoked by stimulation of the pontine micturition center (PMC) and bladder filling-induced activation of the periaqueductal gray. Despite this marked functional impairment, pseudorabies virus tracing, optogenetics, and machine learning assisted three dimensional imaging revealed persistent bladder connected neurons within the spared thoracic interlesion region. Neurons within this region remained responsive to descending PMC input, identifying the interlesion network as a candidate substrate for residual brain bladder communication. Early continuous intrathecal bumetanide improved urinary storage and emptying, enhanced descending PMC to bladder and ascending bladder to brain signaling, and increased the functional engagement of bladder-connected thoracic neurons without increasing urine production. Bumetanide also increased transsynaptic labeling between the bladder and PMC, consistent with enhanced polysynaptic brain bladder connectivity. Together, these findings indicate that brain bladder communication is not completely lost after SCI and may be supported by a functionally compromised residual spinal network that remains amenable to therapeutic reinforcement. Targeting spared autonomic circuitry may therefore provide a strategy for improving bladder function after SCI.

neuroscience↗

bioRxiv2025

Vertical transmission of chronic wasting disease in free-ranging white-tailed deer populations

Chronic wasting disease (CWD) is a fatal neurodegenerative disease affecting cervids across North America, Northern Europe, and Asia. Disease transmission among cervids has historically been attributed to direct animal-to-animal contact with secreta (saliva, blood, urine, and feces) containing the infectious agent, and indirect contact with the agent shed to the environment in these bodily components. Mounting evidence provides another mechanism of CWD transmission, that from mother-to-offspring, including during pregnancy (vertical transmission). Here we describe the detection of the infectious CWD agent and prion seeding in fetal and reproductive tissues collected from healthy-appearing free-ranging white-tailed deer (Odocoileus virginianus) from multiple U.S. states by mouse bioassay and in vitro prion amplification assays. This is the first report of the infectious agent in several in utero derived fetal and maternal-fetal reproductive tissues, providing evidence that CWD infections are propagated within gestational fetal tissues of white-tailed deer populations. This work confirms previous experimental and field findings in several cervid species supporting vertical transmission as a mechanism of CWD transmission and helps to further explain the facile dissemination of this disease among captive and free-ranging cervid populations.

neuroscience↗

bioRxiv2024

Activation of hypothalamic-pontine-spinal pathway promotes locomotor initiation and functional recovery after spinal cord injury in mice

The hypothalamus is critical for regulating behaviors essential for survival and locomotion, but how it integrates internal needs and transmits locomotion commands to the spinal cord (SC) remains unclear. We found that glutamatergic neurons in lateral hypothalamic area (LHA) are essential for regulating motivated locomotor activity. Using single-neuron projectome analysis, trans-synaptic tracing, and optogenetic manipulation, we showed that LHA facilitates motivated locomotion during food seeking via pontine oral part (PnO) projection neurons, rather than direct SC projections or indirect stress signaling via medial septum and diagonal band. Activating PnO-SC projection neurons also initiated locomotion. Importantly, LHA-PnO projection neurons were crucial for regulating locomotor recovery following mouse spinal cord injury (SCI). Closed-loop deep brain stimulation (DBS) of LHA via gating by motor cortex signals markedly promoted long-term restoration of hindlimb motor functions after SCI. Thus, we have identified a hypothalamic-pontine- spinal pathway and the stimulation paradigm for potential therapeutic intervention after SCI.

neuroscience↗

bioRxiv2023

Precision Targeting of Na-K-2Cl cotransporter (NKCC1) RNA In Vitro with RfxCas13d

The Na-K-2Cl cotransporter (NKCC1) is considered an attractive drug target in the Central nervous system (CNS) for treating various CNS disorders. However, the specific role of NKCC1 in different types following injury within the CNS is not well understood due to its expression in multiple cell types. Additionally, there is a lack of a robust method for knocking down NKCC1 transcripts. In this study, we utilized Cas13 nucleases, a type of programmable RNA-targeting CRISPR enzyme, to effectively degrade NKCC1 mRNA in cultured cells. We developed a versatile pipeline for crRNA screening and validation in vitro and demonstrated the successful knockdown of NKCC1 using RfxCas13d. Our findings establish RfxCas13d as a powerful tool for targeting specific transcripts in vitro. By demonstrating the successful in vitro application of RfxCas13d-mediated NKCC1 RNA knockdown, we have laid the groundwork for future investigations into the therapeutic potential of NKCC1 modulation in CNS disorders.

cell biology↗

bioRxiv2023

A leaky integrate-and-fire computational model based on the connectome of the entire adult Drosophila brain reveals insights into sensorimotor processing

The forthcoming assembly of the adult Drosophila melanogaster central brain connectome, containing over 125,000 neurons and 50 million synaptic connections, provides a template for examining sensory processing throughout the brain. Here, we create a leaky integrate-and-fire computational model of the entire Drosophila brain, based on neural connectivity and neurotransmitter identity, to study circuit properties of feeding and grooming behaviors. We show that activation of sugar-sensing or water-sensing gustatory neurons in the computational model accurately predicts neurons that respond to tastes and are required for feeding initiation. Computational activation of neurons in the feeding region of the Drosophila brain predicts those that elicit motor neuron firing, a testable hypothesis that we validate by optogenetic activation and behavioral studies. Moreover, computational activation of different classes of gustatory neurons makes accurate predictions of how multiple taste modalities interact, providing circuit-level insight into aversive and appetitive taste processing. Our computational model predicts that the sugar and water pathways form a partially shared appetitive feeding initiation pathway, which our calcium imaging and behavioral experiments confirm. Additionally, we applied this model to mechanosensory circuits and found that computational activation of mechanosensory neurons predicts activation of a small set of neurons comprising the antennal grooming circuit that do not overlap with gustatory circuits, and accurately describes the circuit response upon activation of different mechanosensory subtypes. Our results demonstrate that modeling brain circuits purely from connectivity and predicted neurotransmitter identity generates experimentally testable hypotheses and can accurately describe complete sensorimotor transformations.

neuroscience↗

bioRxiv2019

Increasing Synaptic GluN2B levels within the Basal and Lateral Amygdala Enables the Modification of Strong Reconsolidation Resistant Fear Memories

Reconsolidation disruption has been proposed as a method to attenuate pathological memories in disorders such as PTSD. However, studies from our group and others indicate that strong memories are resistant to becoming destabilized following reactivation, rendering them impervious to agents that disrupt the re-stabilization phase of reconsolidation. Thus, therapies designed to attenuate maladaptive memories by disrupting reconsolidation updating have not been adequately developed. We previously determined that animals possessing strong auditory fear memories, compared to animals with weaker fear memories, are associated with an enduring increase in the synaptic GluN2A/GluN2B ratio in neurons of the mouse basal and lateral amygdala (BLA). In this study, we determined whether increasing GluN2B levels within BLA excitatory neuronal synapses is sufficient to enable modification of strong fear memories via reconsolidation. To accomplish this, we utilized a combinatorial genetic strategy to express GluN2B or GluN2B(E1479Q) in excitatory neurons of the mouse BLA before or after fear memory consolidation. GluN2B(E1479Q) contains a point mutation that increases synaptic expression of the subunit by interfering with phosphorylation-driven endocytosis. At the time of memory retrieval, increasing synaptic GluN2B levels by expression of GluN2B(E1479Q), but not GluN2B(WT), enhanced the induction of reconsolidation rendering the strong fear memory modifiable. GluN2B(WT) or GluN2B(E1479Q) expression did not influence fear memory maintenance or extinction. Fear memory consolidation, however, was enhanced when GluN2B(E1479Q) was expressed in the BLA at the time of training. These findings indicate that enhancing GluN2B synaptic trafficking may provide a novel therapeutic strategy to enhance modification of pathological memories.

neuroscience↗