Biology subjects

Veeraraghavan, P.

Publications and source records attributed to Veeraraghavan, P..

6 recordsLinked to original sources

bioRxiv2026

Sequestration of growth cone surface proteins by cytoplasmic Lrrtm2 induces de novo amygdala innervation by cerebral cortex associative neurons

Precise establishment of distinct cerebral cortex circuits is essential for sensorimotor function, high-level cognition, and cross-modality integration and association. Although an increasing set of molecular controls over subtype-specific cortical wiring have been identified, much less is known about how molecules in growth cones (GCs) regulate precise long-range projection of axons through complex environments, or how dysregulation of GC molecular machinery disrupts precision of circuit formation. Here, we discover a generalizable mechanism for regulation of precise circuit wiring by focusing on callosal projection neurons (CPN), which link cortical hemispheres via the corpus callosum. CPN are centrally involved in associative and cognitive function, and are often disrupted in people with autism spectrum disorders (ASD) and intellectual disabilities (ID). We identify dysregulated subcellular CPN GC proteomes in vivo after CPN-specific deletion of Bcl11a/Ctip1, a transcription factor (TF) with variants that cause ASD/ID in humans, and validate localization of dysregulated proteins to CPN GCs ex vivo. We identify that disruption of Lrrtm2 - a canonically postsynaptic transmembrane protein - in CPN GCs specifically induces de novo innervation of the amygdala, an evolutionarily ancient regulator of social behavior, cognition, and anxiety that is abnormally activated in humans with ASD. Mechanistically, we identify that deletion of Bcl11a from CPN disrupts targeting of Lrrtm2 to CPN GC membranes, causing cytoplasmic sequestration of key CPN GC surface proteins, and resulting in aberrant innervation of basolateral amygdala (BLA), which is typically targeted by evolutionarily older archicortex. Together, this work connects deletion of a causal ASD/ID TF, dysregulation of a non-canonical control over GC surface protein remodeling, and formation of a de novo, subtype-specific circuit between cerebral cortex and BLA - similar mechanisms likely generalize across neuron subtypes. These results expand conceptual understanding of how diverse circuits are precisely constructed and potentially evolve, and how coordinated dysregulation of GC molecules can disrupt precise subtype-specific circuitry, contributing to diverse neurodevelopmental and neuropsychiatric disorders.

neuroscience↗

bioRxiv2025

Developmental dynamics and axonal transport of cerebral cortex projection neuron mRNAs in vivo

Appropriate development of long-range nervous system circuitry requires dynamic regulation of subcellular mRNA localization, but little is known about how specific neuron subtypes control this critical process in vivo. Here, we employ an integrated genetic and temporally controlled approach to investigate in vivo developmental mRNA dynamics in somata and axons of a prototypical cerebral cortex projection neuron subtype, callosal projection neurons (CPN), which connect the cortical hemispheres to integrate sensorimotor information, and regulate high-level associative cognition and behavior. We identify cis-regulatory elements that are associated with mRNA turnover in CPN somata, including specific 3 untranslated regions (UTRs), and elucidate distinct modes of axon transport in CPN axons for function-specific mRNA classes. Together, these findings elucidate how developing CPN control subcellular mRNA localization, and how dysregulation of these processes might lead to neurodevelopmental and/or neurodegenerative disorders. More broadly, this work identifies general mRNA localization mechanisms that likely function across projection neuron subtypes, and in other polarized cells.

neuroscience↗

bioRxiv2024

Spatiotemporal proteomic profiling of cellular responses to NLRP3 agonists

Nucleotide-binding domain and leucine-rich repeat pyrin-domain containing protein 3 (NLRP3) is an innate immune sensor that forms an inflammasome in response to various cellular stressors. Gain-of-function mutations in NLRP3 cause autoinflammatory diseases and NLRP3 signalling itself exacerbates the pathogenesis of many other human diseases. Despite considerable therapeutic interest, the primary drivers of NLRP3 activation remain controversial due to the diverse array of signals that are integrated through NLRP3. Here, we mapped subcellular proteome changes to lysosomes, mitochondrion, EEA1-positive endosomes, and Golgi caused by the NLRP3 inflammasome agonists nigericin and CL097. We identified several common disruptions to retrograde trafficking pathways, including COPI and Shiga toxin-related transport, in line with recent studies. We further characterized mouse NLRP3 trafficking throughout its activation using temporal proximity proteomics, which supports a recent model of NLRP3 recruitment to endosomes during inflammasome activation. Collectively, these findings provide additional granularity to our understanding of the molecular events driving NLRP3 activation and serve as a valuable resource for cell biological research. We have made our proteomics data accessible through an open-access Shiny browser to facilitate future research within the community, available at: https://harperlab.connect.hms.harvard.edu/inflame/. We will display anonymous peer review for this manuscript on pubpub.org (https://harperlab.pubpub.org/pub/nlrp3/) rather than a traditional journal. Moreover, we invite community feedback on the pubpub version of this manuscript, and we will address criticisms accordingly.

cell biology↗

bioRxiv2023

Dynamic subtype- and context-specific subcellular RNA regulation in growth cones of neocortical projection neurons

Molecular mechanisms that cells employ to compartmentalize function via localization of function-specific RNA and translation are only partially elucidated. We investigate long-range projection neurons of the cerebral cortex as highly polarized exemplars to elucidate dynamic regulation of RNA localization, stability, and translation within growth cones (GCs), leading tips of growing axons. Comparison of GC-localized transcriptomes between two distinct subtypes of projection neurons- interhemispheric-callosal and corticothalamic- across developmental stages identifies both distinct and shared subcellular machinery, and intriguingly highlights enrichment of genes associated with neurodevelopmental and neuropsychiatric disorders. Developmental context-specific components of GC-localized transcriptomes identify known and novel potential regulators of distinct phases of circuit formation: long-distance growth, target area innervation, and synapse formation. Further, we investigate mechanisms by which transcripts are enriched and dynamically regulated in GCs, and identify GC-enriched motifs in 3 untranslated regions. As one example, we identify cytoplasmic adenylation element binding protein 4 (CPEB4), an RNA binding protein regulating localization and translation of mRNAs encoding molecular machinery important for axonal branching and complexity. We also identify RNA binding motif single stranded interacting protein 1 (RBMS1) as a dynamically expressed regulator of RNA stabilization that enables successful callosal circuit formation. Subtly aberrant associative and integrative cortical circuitry can profoundly affect cortical function, often causing neurodevelopmental and neuropsychiatric disorders. Elucidation of context-specific subcellular RNA regulation for GC- and soma-localized molecular controls over precise circuit development, maintenance, and function offers generalizable insights for other polarized cells, and might contribute substantially to understanding neurodevelopmental and behavioral-cognitive disorders and toward targeted therapeutics.

neuroscience↗

bioRxiv2023

CaV2.1 α1 subunit motifs that control presynaptic CaV2.1 subtype abundance are distinct from CaV2.1 preference

Presynaptic voltage-gated Ca2+ channels (CaV) subtype abundance at mammalian synapses regulates synaptic transmission in health and disease. In the mammalian central nervous system, most presynaptic terminals are CaV2.1 dominant with a developmental reduction in CaV2.2 and CaV2.3 levels, and CaV2 subtype levels are altered in various diseases. However, the molecular mechanisms controlling presynaptic CaV2 subtype levels are largely unsolved. Since the CaV2 1 subunit cytoplasmic regions contain varying levels of sequence conservation, these regions are proposed to control presynaptic CaV2 subtype preference and abundance. To investigate the potential role of these regions, we expressed chimeric CaV2.1 1 subunits containing swapped motifs with the CaV2.2 and CaV2.3 1 subunit on a CaV2.1/CaV2.2 null background at the calyx of Held presynaptic terminal. We found that expression of CaV2.1 1 subunit chimeras containing the CaV2.3 loop II-III region or cytoplasmic C-terminus (CT) resulted in a large reduction of presynaptic Ca2+ currents compared to the CaV2.1 1 subunit. However, the Ca2+ current sensitivity to the CaV2.1 blocker Agatoxin-IVA, was the same between the chimeras and the CaV2.1 1 subunit. Additionally, we found no reduction in presynaptic Ca2+ currents with CaV2.1/2.2 cytoplasmic CT chimeras. We conclude that the motifs in the CaV2.1 loop II-III and CT do not individually regulate CaV2.1 preference, but these motifs control CaV2.1 levels and the CaV2.3 CT contains motifs that negatively regulate presynaptic CaV2.3 levels. We propose that the motifs controlling presynaptic CaV2.1 preference are distinct from those regulating CaV2.1 levels and may act synergistically to impact pathways regulating CaV2.1 preference and abundance. Key points summaryO_LIPresynaptic CaV2 subtype abundance regulates neuronal circuit properties, however the mechanisms regulating presynaptic CaV2 subtype abundance and preference remains enigmatic. C_LIO_LIThe CaV 1 subunit determines subtype and contains multiple motifs implicated in regulating presynaptic subtype abundance and preference. C_LIO_LIThe CaV2.1 1 subunit domain II-III loop and cytoplasmic C-terminus are positive regulators of presynaptic CaV2.1 abundance but do not regulate preference. C_LIO_LIThe CaV2.3 1 subunit cytoplasmic C-terminus negatively regulates presynaptic CaV2 subtype abundance but not preference while the CaV2.2 1 subunit cytoplasmic C-terminus is not a key regulator of presynaptic CaV2 subtype abundance or preference. C_LIO_LIThe CaV2 1 subunit motifs determining the presynaptic CaV2 preference are distinct from abundance. C_LI

neuroscience↗

bioRxiv2019

Presynaptic development is controlled by the core active zone proteins CAST/ELKS

Many presynaptic active zone proteins have multiple regulatory roles that vary during distinct stages of neuronal circuit development. However, our understanding how presynaptic active zone proteins regulate synapse development during neuronal circuit maturation is in its early stages. Although CAST/ELKS are presynaptic active zone core proteins, their roles in synapse development in the mammalian central nervous system remain enigmatic. To unravel CAST/ELKS roles in glutamatergic synapse development, we analyzed how their loss during the early stages of circuit maturation impacted the calyx of Held presynaptic terminal development and function. We found a reduction in presynaptic surface area and volume, but an increase in active zone size. Additionally, we found a reduction in all presynaptic Cav2 channel subtype currents. Surprisingly, these changes did not impair synaptic transmission. We propose that CAST/ELKS are involved in pathways regulating presynaptic morphological properties and Cav2 channel subtype levels during early stages of neuronal circuit maturation.

neuroscience↗