Extracellular vesicles (EVs) are present in biofluids and may be useful biomarkers to non-invasively monitor brain cells, but isolating cell type-specific EVs remains challenging. Here we introduce an approach to immuno-isolate EVs from neurons and glia based on protein surface markers. We first selected transmembrane proteins suitable as cell type-specific EV markers based on gene expression and EV proteomic data. We developed a high-purity EV isolation method and cataloged the proteins present on EVs in human cerebrospinal fluid and plasma. We then computationally identified cell type-specific candidate markers for isolating EVs from neurons, astrocytes, oligodendrocytes and microglia. Using ultrasensitive immunoassays against several predicted neuron-specific proteins, we confirmed one marker, NRXN3, as present on EVs in cerebrospinal fluid and plasma. Finally, we developed efficient EV immuno-isolation methods and applied them to isolate NRXN3+ EVs. Our work provides a general methodology for the isolation of cell type-specific EVs, advancing the goal of using EVs to study brain diseases. The authors developed methods to identify extracellular vesicles (EVs) in the blood that come from the brain by capturing EV surface proteins. This could be used in the future to diagnose neurological diseases.
Psychedelics produce long-lasting antidepressant effects, but their hallucinogenic properties limit clinical use. Using structure-guided design of 5-HT2AR–β-arrestin-biased agonists, we identified β-arrestin signaling as a critical driver of prolonged antidepressant-like effects in mice. Here we show that the slow-dissociation kinetics of lysergic acid diethylamide (LSD) enable progressive accumulation of 5-HT2AR engagement during repeated low-dose administration, approaching the receptor occupancy achieved by an acute high dose while avoiding its high peak concentration. This kinetic separation sustains β-arrestin signaling while limiting robust Gαq-mediated Ca2+ responses. Consistent with this framework, repeated low-dose LSD and repeated low-dose psilocybin pretreatment followed by a high-dose psychedelic challenge produced sustained antidepressant-like behavioral effects in mice. In parallel, these regimens produced no detectable psychedelic-associated behavioral disruption in mice and cynomolgus macaques. Together, these findings uncover the signaling basis of sustained psychedelic efficacy and provide a rational framework for developing nonhallucinogenic psychedelic therapies for psychiatric disorders. This study shows that the sustained antidepressant-like effect of psychedelics is driven by 5-HT2A receptor–β-arrestin signaling. Repeated low-dose LSD preserves this effect in mice without inducing hallucinogenic-like behaviors in mice or monkeys.
Somatosensation is mediated by dorsal root ganglion (DRG) neurons, which convert physical and chemical stimuli into electrical signals. However, the full repertoire of molecular components underlying somatosensation remains incompletely identified. Here we developed an efficient postnatal CRISPR–Cas9 knockout platform for interrogating DRG-expressed genes (such as Piezo2, Trpv1 and Scn9a) in mice using AAV9-mediated single-guide RNA delivery. Combining this approach with somatosensory behavioral assays, we performed a targeted screen of 20 genes and identified Creld1 as a cross-model regulator of somatosensation. Either single-guide RNA-mediated postnatal knockout or tamoxifen-induced Cre-mediated deletion of Creld1 in DRG neurons resulted in profound behavioral deficits in touch, temperature, pain and itch, whereas its overexpression enhanced touch and thermal responses. Mechanistically, CRELD1 functions as an auxiliary regulator of voltage-gated sodium channels (Nav) for controlling DRG neuron excitability. Together, this work establishes a robust postnatal screening platform for behavioral genomics and identifies Creld1 as a master regulator of somatosensory function. Jiang et al. developed a robust postnatal knockout platform for somatosensory genomics and behavioral screening, identifying Creld1 as a cross-modal regulator of somatosensation through its control of sensory neuron excitability via voltage-gated sodium channels.
Flexible cognition requires the brain to generalize across tasks while preserving task-specific information. Previous work showed that task representations are compressed in the association cortex and expanded in sensory and motor systems, but the mechanisms underlying these transformations are unclear. Here we test whether the geometry of intrinsic brain connectivity constrains how representations change between cortical regions. We analyzed functional MRI acquired during 16 diverse cognitive tasks together with activity flow modeling, finding that connectivity dimensionality predicts representational changes across the cortex. Low-dimensional connectivity compressed task representations and increased similarities across tasks, whereas high-dimensional connectivity expanded representations and supported conjunctive coding of task features. Activity flow modeling reproduced the observed compression-to-expansion pattern along the sensory–association–motor hierarchy and generated representational geometries that more closely matched targets than sources, consistent with transformation rather than transfer of information. These findings identify network geometry as a systems-level principle that shapes cortical representations and supports flexible cognition. The dimensionality of intrinsic brain connectivity systematically shapes how task representations compress and expand across the cortex, and activity flow modeling shows the active role of network geometry in generating the transformation.
Synaptic NMDA-type glutamate receptors (NMDARs) are central components of all neural computations. NMDAR levels critically vary between synapses but how the synaptic localization of NMDARs is controlled remains unclear. Here we show that SIK3, a serine–threonine protein kinase, localizes to synapses where it phosphorylates the obligatory NMDAR subunit GluN1 at a single site. This single phosphorylation event controls NMDAR recruitment to synapses. Genetic deletion of SIK3 severely and selectively decreases synaptic GluN1 levels by ~60% without altering AMPA-type glutamate receptor levels or inducing major transcriptional changes. Pharmacological inhibition of SIK3 impairs synaptic NMDAR responses within 45 minutes. Mutating the SIK3-phosphorylation site inhibits GluN1 synaptic recruitment. ‘Sleepy’, a gain-of-function mutation in SIK3 that increases sleep, selectively enhances synaptic NMDAR levels by increasing GluN1 phosphorylation. Thus, SIK3 phosphorylation of GluN1 provides a key signal for recruiting NMDARs to synapses. SIK3 kinase controls synaptic NMDA receptor recruitment by phosphorylating GluN1 at a single site. Loss or inhibition of SIK3 markedly reduces synaptic NMDARs, while a gain-of-function mutation increases GluN1 phosphorylation and NMDAR levels.
