SUSCEPTIBLE PYRAMIDAL NEURONS IN PRIMATE DORSOLATERAL PREFRONTAL CORTEX EXPRESS AN ENRICHED CALCIUM INTERACTOME: CRITICAL ROLE OF CALBINDIN AND CAV1.2 IN HIGHER-ORDER COGNITION
Authors: Datta *Dibyadeep , Yang Shengtao , Joyce Mary Kate , Woo Elizabeth , McCarroll Steven , Gonzalez-Burgos Guillermo , Perone Isabella , Uchendu Stacy , Ling Emi , Goldman Raye , Berretta Sabrina , Murray John , Morozov Yury , Arellano Jon , Duque Alvaro , Rakic Pasko , O'dell Ryan , van Dyck Christopher H , Lewis David A , Wang Min , Krienen Fenna , Arnsten Amy 
Published: February 2025

Abstract

Background
The newly evolved dorsolateral prefrontal cortex (dlPFC) with pyramidal cell circuits in layer 3 are essential to higher cognition1,2. However, these pyramidal cells are uniquely susceptible in psychiatric disorders, where layer 3 is the focus of synapse dendritic atrophy in schizophrenia and degenerative disorders such as Alzheimer’ s disease (AD), correlating with the degree of cognitive deficits3-6. In particular, mutations in CACNA1C (L-type-calcium-channel Cav1.2) are consistently linked to increased risk of mental disorders but it is unknown why these channels are critical to cognition7-9, and whether they effect layer 3 pyramidal cells in dlPFC that are especially vulnerable in cognitive disorders. We examined the transcriptomic signatures of dlPFC layer 3 pyramidal cells, as well as additional studies of their connections and molecular regulation in macaque dlPFC, and found that they express magnified calcium signaling needed to sustain mental representations. However, higher levels, during chronic stress, caused a loss of firing and impaired cognition.

Aims & Objectives
The current study examined the molecular mechanisms expressed in layer III pyramidal cells in primate dlPFC.

Methods
The current study integrated single-nucleus RNA-sequencing in human and rhesus macaque dlPFC, multi-label immunofluorescence (MLIF), super-resolution immunoelectron microscopy (immunoEM), in vivo physiology coupled with iontophoresis of pharmacological compounds and behavior in rhesus macaque dlPFC to evaluate the calcium interactome (CACNA1C, GRIN2B, KCNN3).

Results
We showed that, in both human and macaque dlPFC, these cells have especially high expression of GRIN2B, CACNA1C and KCNN3, encoding the NMDAR-GluN2B and LTCC Cav1.2 channels that flux high levels of calcium into the neuron, and the SK3 potassium channel that whose open state is increased by calcium. Macaque studies showed that the CALB1-enriched pyramidal cells preferentially connect to the contralateral dlPFC, suggesting that increased calcium may be needed to maintain firing across the corpus callosum. ImmunoEM demonstrated that Cav1.2, SK3 channels and B1-AR are all concentrated on layer III dendritic spines, similar to NMDAR-GluN2B, with Cav1.2 on the plasma membrane near the calcium-storing spine apparatus, positioned to further increase calcium actions via internal release. Physiological recordings from cognitively engaged macaques showed that either inadequate or excessive LTCC actions, the latter driven by B1-AR stimulation, markedly reduced Delay cell firing needed for working memory via opening of SK potassium channels. Comparable effects were seen at the behavioral level, with stress-induced working memory impairment rescued by LTCC or B1-AR blockade.

Discussion & Conclusion
These data reveal a mechanism by which stress impairs dlPFC cognitive function, and suggests that either loss-of-function or gain-of-function mutations in CACNA1C would be harmful to dlPFC function and increase risk of neuropsychiatric disorders. As elevated calcium signaling is known to drive AD pathology, the data also explain why this subset of pyramidal cells with an enriched calcium interactome is especially susceptible to tau pathology and degeneration. The current findings are a rare example where transcriptomic and genomic data are related to the dysfunction of higher cortical circuits, illuminating how molecular insults give rise to symptoms of cognitive deficits.

References
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