Biology subjects

Lowenstein, E. D.

Publications and source records attributed to Lowenstein, E. D..

9 recordsLinked to original sources

bioRxiv2025

A hypothalamic circuit for anticipating future changes in energy balance.

AgRP neurons cause hunger, the drive to seek and consume food. Their activation by fasting is key for survival and is thought to be triggered by feedback when energy stores are low. However, we know that environmental cues can also regulate AgRP neurons, since cues that predict future food intake rapidly inhibit AgRP neurons. But is the converse true: can the prediction of future fasting rapidly activate AgRP neurons? Here we show that such rapid fasting activation of AgRP neurons does occur. This fasting response is driven by excitatory input from paraventricular hypothalamic neurons expressing Sim2, which are bidirectionally sensitive to predictions of future energy state. In this way, cognitively-processed contextual information conveyed by PVHSim2 neurons strongly activates AgRP neurons. Lastly, chronic silencing of PVHSim2 neurons causes persistent hypophagia. This PVHSim2 to AgRP neuron circuit, by anticipating and preventing negative energy balance, provides an important new dimension of hunger regulation.

neuroscience↗

bioRxiv2025

Identification of V0g propriospinal neurons and their role in locomotor control

Propriospinal neurons relay sensory and motor information across the spinal cord and are critical components of the circuits coordinating body movements. Their diversity and roles in motor control are not clearly defined yet. In this study, by combining anatomical, molecular, and functional analyses in mice, we identified and characterized an ascending subtype of propriospinal neurons belonging to the Pitx2+ V0 family of spinal neurons. We found that Pitx2+ ascending neurons are integrated in spinal sensorimotor circuits and their function is important for the execution of precise limb movements required for effectively moving in challenging environments, like walking on a horizontal ladder or a balance beam. This work advances our understanding of the functional organization of propriospinal and V0 neurons, highlighting a previously unappreciated role in adjusting body movements to the more demanding needs of skilled locomotor tasks.

neuroscience↗

bioRxiv2023

Molecular characterization of nodose ganglia development reveals a novel population of Phox2b+ glial progenitors in mice

The vagal ganglia, comprised of the superior (jugular) and inferior (nodose) ganglia of the vagus nerve, receive somatosensory information from the head and neck, or viscerosensory information from the inner organs, respectively. Developmentally, the cranial neural crest gives rise to all vagal glial cells and to neurons of the jugular ganglia, while the epibranchial placode gives rise to neurons of the nodose ganglia. Crest-derived nodose glial progenitors can additionally generate autonomic neurons in the peripheral nervous system, but how these progenitors generate neurons is unknown. Here, we found that some Sox10+ neural crest-derived cells in, and surrounding, the nodose ganglion transiently expressed Phox2b, a master regulator of autonomic nervous system development, during early embryonic life. Our genetic lineage tracing analysis revealed that despite their common developmental origin and extreme spatial proximity a substantial proportion of glial cells in the nodose, but not in the neighboring jugular ganglia, have a history of Phox2b expression. Lastly, we used single cell RNA-sequencing (scRNA-seq) to demonstrate that these progenitors give rise to all major glial subtypes in the nodose ganglia, including Schwann cells, satellite glia and glial precursors, and mapped their spatial distribution by in situ hybridization. Our work demonstrates that these crest- derived nodose glial progenitors transiently express Phox2b, give rise to the entire complement of nodose glial cells and display a transcriptional program that may underlie their bipotent nature. Significance statementThe nodose ganglia contain sensory neurons that innervate many inner organs and play key roles in homeostatic behaviors such as digestion, regulation of blood pressure and heart rate, and breathing. Nodose sensory neurons are supported by nodose glial cells, which are understudied compared to their neuronal neighbors. Specifically, the genetic program governing their development is not fully understood. Here, we uncover a transcriptional program unique to nodose glial cells (transient expression of Phox2b) that resolves the 40-year-old finding that nodose glial progenitors can also give rise to autonomic neurons (whose development depends on Phox2b expression). Lastly, we leveraged single cell RNA-sequencing to identify the four major subtypes of nodose glial cells and used subtype specific marker genes to map their spatial distribution.

neuroscience↗

bioRxiv2023

Genetic identification of novel medullary neurons underlying congenital central hypoventilation syndrome

Congenital Central Hypoventilation Syndrome (CCHS) is a rare, but life-threatening, respiratory disorder that is classically diagnosed in children. This disease is characterized by pronounced alveolar hypoventilation and diminished chemoreflexes, particularly to abnormally high levels of arterial pCO2. Mutations in the transcription factors PHOX2B and LBX1 have been identified in CCHS patients, but the dysfunctional circuit responsible for this disease remains unknown. Here, we show that distinct sets of medullary neurons co-expressing both transcription factors (dB2 neurons) account for specific respiratory functions and phenotypes seen in CCHS. By combining murine intersectional chemogenetics, intersectional labeling, and the selective targeting of the CCHS disease-causing Lbx1FS mutation to specific subgroups of dB2 neurons, we uncovered novel sets of these cells key for i) respiratory tidal volumes and the hypercarbic reflex, ii) neonatal respiratory stability and iii) neonatal survival. These data provide functional evidence for the essential role of dB2 neurons in neonatal respiratory physiology and will be instrumental for the development of therapeutic strategies for the management of CCHS. In summary, our work uncovers new neural components of the central circuit regulating breathing and establishes dB2 neuron dysfunction to be causative of CCHS.

neuroscience↗

bioRxiv2022

The molecular foundation of proprioceptor muscle-type identity

The precise execution of coordinated movements depends on proprioception, the sense of body position in space. However, the molecular underpinnings of proprioceptive neuron subtype identities are not clear yet. In this study, we searched for molecular correlates of proprioceptor subtypes defined according to the identity of the muscle they innervate. We identified and validated signatures for subtypes monitoring the activity of back, abdominal, and hindlimb muscles. We found that proprioceptor muscle identity is acquired early in development and comprise programs controlling wiring specificity. Altogether this work paves the way for defining the mechanisms underlying the development of proprioceptor subtypes to the single muscle level and dissect their contributions to motor control.

neuroscience↗

bioRxiv2022

Prox2+ and Runx3+ neurons regulate esophageal motility

Sensory neurons of the vagus nerve monitor distention and stretch in the gastrointestinal tract. Major efforts are underway to assign physiological functions to the many distinct subtypes of vagal sensory neurons. Here, we used genetically guided anatomical tracing, optogenetics and electrophysiology to identify and characterize three vagal sensory neuronal subtypes expressing Prox2 and Runx3. We show that these neuronal subtypes innervate the esophagus and stomach where they display regionalized innervation patterns. Their electrophysiological analysis showed that they are all low threshold mechanoreceptors, but possess different adaptation properties. Lastly, genetic ablation of Prox2+ and Runx3+ neurons demonstrated their essential roles for esophageal peristalsis and swallowing in freely behaving animals. Our work reveals the identity and function of the vagal neurons that provide mechanosensory feedback from the esophagus to the brain, and could lead to better understanding and treatment of esophageal motility disorders.

neuroscience↗

bioRxiv2022

The IgCAM BT-IgSF (IgSF11) is essential for connexin43-mediated astrocyte-astrocyte and ependymal cell-cell coupling

The type I transmembrane protein BT-IgSF is predominantly localized in the brain and testes. It belongs to the CAR subgroup of Ig cell adhesion proteins, which have been hypothesized to regulate connexin expression or localization. Here, we studied the putative link between BT-IgSF and connexins in astrocytes, ependymal cells and neurons of the mouse. Global knockout of BT-IgSF caused an increase in the clustering of connexin43 (Gja1), but not of connexin30 (Gjb6), on astrocytes and ependymal cells. Additionally, knockout animals displayed reduced expression levels of connexin43 protein in the cortex and hippocampus. Importantly, analysis of biocytin spread in hippocampal or cortical slices from mature mice of either sex revealed a decrease in astrocytic cell-cell coupling in the absence of BT-IgSF. Blocking either protein biosynthesis or proteolysis showed that the lysosomal pathway increased connexin43 degradation. Localization of connexin43 in subcellular compartments was not impaired in the mutant. In contrast to connexin43 the localization and expression of connexin36 (Gjd2) on neurons was not affected by the absence of BT-IgSF. Overall, our data indicate that the IgCAM BT-IgSF is essential for correct gap junction-mediated astrocyte-to-astrocyte and ependymal cell-to-ependymal cell communication. Significance StatementAstrocytes regulate a variety of physiological processes in the developing and adult brain that are essential for proper brain function. Astrocytes form extensive networks in the brain and communicate via gap junctions. Disruptions of gap junction coupling are found in several diseases such as neurodegeneration or epilepsy. Here, we demonstrate that the cell adhesion protein BT-IgSF is essential for gap junction mediated coupling between astrocytes in the cortex and hippocampus.

cell biology↗

bioRxiv2020

Olig3 acts as a master regulator of cerebellar development

The mature cerebellum controls motor skill precision and participates in other sophisticated brain functions that include learning, cognition and speech. Different types of GABAergic and glutamatergic cerebellar neurons originate in temporal order from two progenitor niches, the ventricular zone and rhombic lip, which express the transcription factors Ptf1a and Atoh1, respectively. However, the molecular machinery required to specify the distinct neuronal types emanating from these progenitor zones is still unclear. Here, we uncover the transcription factor Olig3 as a major determinant in generating the earliest neuronal derivatives emanating from both progenitor zones. In the rhombic lip, Olig3 regulates progenitor cell proliferation. In the ventricular zone, Olig3 safeguards Purkinje cell specification by curtailing the expression of Pax2, a transcription factor that we found to impose an inhibitory interneuron identity. Our work thus defines Olig3 as a key factor in cerebellar development.

neuroscience↗

bioRxiv2017

Predominant Patterns of Splicing Evolution on Human, Chimpanzee, and Macaque Evolutionary Lineages

Although splicing is widespread and evolves rapidly among species, the mechanisms driving this evolution, as well as its functional implications, are not yet fully understood. We analyzed the evolution of splicing patterns based on transcriptome data from five tissues of humans, chimpanzees, rhesus macaques, and mice. In total, 1,526 exons and exon sets from 1,236 genes showed significant splicing differences among primates. More than 60% of these differences represent constitutive-to-alternative exon transitions while an additional 25% represent changes in exon inclusion frequency. These two dominant evolutionary patterns have contrasting conservation, regulation, and functional features. The sum of these features indicates that, despite their prevalence, constitutive-to-alternative exon transitions do not substantially contribute to long-term functional transcriptome changes. Conversely, changes in exon inclusion frequency appear to be functionally relevant, especially for changes taking place in the brain on the human evolutionary lineage.

evolutionary biology↗