eLife

Neuroimaging based pain decoding faces two underappreciated challenges: between subject variability that prevents classifiers from generalizing across patients, and within session cross validation designs that inflate reported accuracy by conflating within person and between person variance. Here we address both using portable functional near infrared spectroscopy (fNIRS) during pharmacologically verified local nerve anesthesia. Twentyfive patients with clinically painful teeth underwent 36 channel bilateral fNIRS during percussion before ("Pre") and after ("Post") local nerve anesthesia. In 13 block-success patients, a paired Pre versus Post comparison with healthy tooth control identified three temporal hemodynamic response function (HRF) features (late slope, mean first derivative, and baseline normalized amplitude) whose analgesia interaction effects (d = 0.63 to 0.79) exceeded that of raw general linear model (GLM) amplitude (d = 0.56), with a significant difference-in-differences interaction (p = 0.011). Per-patient calibration with these features yielded leave one subject out (LOSO) AUC = 0.68 to 0.76 for nonlinear classifiers (permutation p = 0.002), with HbO-specific feature selection achieving the best performance (RF AUC = 0.760); a healthy tooth negative control was non-significant. End to end deep learning on raw time series (CNN LSTM AUC = 0.719) was competitive with feature based classifiers, while linear models did not reach significance. Critically, head to head comparison of within-session CV and LOSO on the same data revealed mean inflation of +0.13 AUC across all model types, including deep learning, demonstrating that high within session accuracy alone does not establish subject-independent validity. Exploratory analyses suggested complementary roles for oxyhemoglobin (HbO; within patient analgesia detection) and deoxyhemoglobin (HbR; cross patient information), and that trial to trial response variability may complement amplitude for cross patient pain detection. These results show that per patient calibration with temporal HRF features supports subject independent analgesic-state detection under strict LOSO evaluation, and that within-session validation (standard in the fNIRS pain- decoding literature) can substantially overestimate performance.

Allostery--regulation of a proteins activity by binding to an effector--is an essential functional feature of many proteins. Its structural basis is complex: a protein must bind effector at one site--an interaction that typically involves many complementary residues--and this binding event must change the proteins conformation at the distant active site. How allosteric proteins evolved this architecture is unknown because there are no cases in which the historical mechanisms by which allostery was acquired from nonallosteric precursors have been identified. Vertebrate hemoglobin (Hb) is a tetrameric protein whose oxygen affinity is reduced by binding organic phosphates. We used ancestral protein reconstruction, biochemical experiments, and in silico studies of protein structure and dynamics to identify the changes in protein sequence and structure that caused allosteric Hb to evolve from its non-allosteric dimeric precursor. We found that just two historical substitutions were sufficient to confer positive allostery on the ancestor--one that caused the dimer to tetramerize, and another that created an effector binding site in the tetramers central cavity. Two additional substitutions changed the effectors position and conferred the modern form of negative allostery. This short evolutionary path to allostery was possible because most of the key requirements for allostery already existed as by-products of the proteins structure: the tertiary transition between oxygenated and deoxygenated conformations is an ancient and intrinsic property of the globin fold. It affects the surface patch that ultimately mediated tetramer assembly, so as soon as tetramerization evolved because of one substitution on that surface, tertiary heterogeneity propagated to large-scale quaternary heterogeneity. The other substitution(s) conferred effector binding at a site within the tetramer that is preferentially accessible in the deoxygenated state. One of the most complex and essential protein phenomena therefore evolved via simple and intelligible mechanisms.

Purkinje cells (PCs), the sole outputs of the cerebellar cortex, transform granule cell firing patterns into appropriate outputs to drive learning and behavior. Two major PC classes (typically defined by Aldoc expression) can be further subdivided into nine molecularly distinct PC subtypes, suggesting that each subtype might be specialized for distinct categories of cerebellar processing. This has been difficult to test due to limited tools to target PC subtypes. We therefore developed intersectional tools to target PC subtypes, specifically Kcng4+ PCs (primarily Aldoc-) and Gpr176+ PCs (Aldoc1). We mapped their distributions within the cerebellar cortex and quantitatively characterized their outputs onto different types of cerebellar nuclei (CbN) neurons. Although projections by PC subtypes defined by Kcng4 and Gpr176 are regionally segregated within the CbN, each PC subtype synapses onto many types of CbN neurons, and individual CbN neurons often receive convergent inputs from multiple PC subtypes. We also selectively silenced PC subtype outputs and found that silencing Kcng4+ PC outputs impaired motor behaviors while sparing emotional and social behaviors, whereas silencing Gpr176+ PC outputs selectively increased exploratory behavior and reduced anxiety without affecting motor and social behaviors. These findings demonstrate that molecularly defined PC subtypes differentially regulate specific behaviors and establish a versatile framework for uncovering how cerebellar circuits are specialized to control diverse behaviors.

Learning on both fast and slow timescales is required to enable us to adapt to a dynamic environment. Whether the mechanisms mediating fast and slow learning are implemented by the same, or different, circuit elements remains an important open question. Learning involving the cerebellum is known to be driven primarily by instructive climbing fiber inputs to Purkinje cells, but the dynamics of climbing fibers across learning on fast and slow timescales are not known. It is unclear if climbing fibers encode the same or different instructive signals at different stages of learning, and whether learning-related changes in climbing fiber encoding properties across timescales are driven by the same or distinct mechanisms. We addressed this problem using longitudinal 2-photon calcium imaging of climbing fiber activity across multiple cerebellar lobules as mice learned to execute a visuomotor integration task - slow learning - and then rapidly adapted to a new sensorimotor coupling - fast learning. Instructive signals are spatially segregated in trained mice: Lobule V preferentially encodes movement predictively, while Lobule simplex preferentially receives reward-related feedback. Moreover, the encoding of sensorimotor and reward-related instructive signals is dynamic on both slow and fast timescales: movement-related activity emerges over the course of training, while reward-related activity progressively diminishes as mice become experts but re-emerges specifically in Lobule simplex when rewards become scarce. Finally, while the same climbing fiber inputs can change on both timescales, the magnitude and spatial organization of slow changes are not related to fast changes. Thus, climbing fiber input can carry distinct instructive signals on different timescales - a multiplexing of teaching signals that may underlie the cerebellums capacity to both acquire and refine motor behaviour.

Studies of visual discrimination in rodents can confound the effects of cue salience with reward value, making it difficult to determine which factor guides choice behavior. We examined this issue by testing how changes in relative salience affect decision dynamics in rats performing a two-alternative forced-choice task in which rats chose between visual cues associated with high or low sucrose rewards. After initial training with high and low luminance cues, we introduced a novel cue of intermediate luminance as a "luminance shift" test. The intermediate luminance cue substituted for either the brighter or dimmer cue and had the same reward value as the cue that it replaced. We found that while rats maintained a preference for the higher-value option, the introduction of a perceptually more similar cue consistently reduced choice preference and eliminated latency differences compared to baseline. Using drift diffusion modeling, we determined that the luminance shifts primarily caused a reduction in the drift rate (the speed of evidence accumulation), reflecting increased difficulty in cue discrimination. This finding suggests that the relative salience of the options determines the efficiency of evidence accumulation in value-based decisions. Furthermore, this effect on drift rate shows a dissociation from our previous work (Palmer et al., 2024), where prefrontal cortex inactivation specifically affected only the decision threshold. Our results demonstrate that relative salience influences deliberation, with low-level perceptual features shaping the computational dynamics of value-based choice. Our findings clarify the distinct contributions of sensory input and prefrontal function in the decision process. Significance StatementThis study reveals that changes in the relative salience of visual stimuli shape the computational dynamics of value-based decisions. We trained rats to make visually guided choices and found that relative differences in the brightness of the stimuli affect how quickly the rats made decisions and how often they chose a higher-value option. Our findings, together with a recent study on the role of the prefrontal cortex in value-guided decisions (Palmer et al., 2024), suggest that separate factors influence choice dynamics in rodents: visual salience affects the speed of deliberation, while prefrontal activity regulates caution. This study helps clarify how sensory and higher cognitive variables relate to the distinct computational components of the decision process.

The neuropeptide signaling pathway is vital for the physiology and behavior of multicellular organisms. This pathway is mediated by ligand-receptor binding, wherein neuropeptides (NPs) are often released from neurons, while their receptors (NPRs) are ubiquitously expressed in both neuronal and non-neuronal cell types. To elucidate the underlying mechanisms of this expression pattern divergence, here we dissect the genomic and epigenomic architectures of these two distinct gene classes. We first characterized the genomic architecture of NP and NPR genes to compare their total gene length, exon and intron lengths, exon counts, and number of alternatively spliced transcripts per gene. We also profiled their regulatory genomic elements including CpG islands, TATA boxes, and their overlapping antisense transcripts. These analyses were then expanded to non-human model organisms to evaluate the evolutionary conservation of the underlying mechanisms. We found that NPRs encompass larger genomic loci and encode longer transcripts than NPs. Furthermore, the increased length of NPR transcripts was driven by longer exons rather than higher exon counts. Consistently, the number of spliced variants per gene was similar between NPs and NPRs, suggesting that alternative splicing events are a minor contributor to their distinct expression patterns. At the RNA level, NPR mRNAs possess significantly longer 3'UTRs compared to NPs, indicating a greater potential for post-transcriptional gene regulation. This complexity is also mirrored at the chromatin level, where NPR loci exhibit a higher density of epigenetic marks than NPs. Together, these findings highlight the multi-layered nature of gene regulation prioritizing control at the receptor level.

Skilled action requires expressing motor memories as appropriate for the current context, but context is often uncertain. Theoretical models make conflicting proposals about memory expression under contextual uncertainty, predicting belief-weighted combination of memories versus the selection of the most probable memory. We tested these predictions by training human participants to reach in two opposing force fields cued by the direction of a random dot motion stimulus whose coherence varied. When participants moved before reporting dot direction, adaptation scaled with coherence: low-reliability cues produced partial expression of both memories. Fitting Bayesian observer models to behavior favored belief-weighted memory combination. In contrast, when participants reported their choice before moving, adaptation was independent of coherence and model fits favored categorical memory selection. Thus, sensorimotor memories are expressed as either a probabilistic combination or categorical selection, depending on whether participants contextual inference remains implicit or is made explicit at the time of memory expression.

High hydrostatic pressure (HHP) perturbs protein assemblies by shifting conformational equilibria toward lower-volume states and by reorganizing hydration at cavities, interfaces, and solvent-exposed surfaces (Heremans 1982; Akasaka 2006; Roche et al. 2012; Hata, Nishiyama, and Kitao 2020). Here, we integrate pressure-dependent molecular dynamics descriptors, pressure-temperature interpretation, structure-based epitope prediction, and face-resolved intersubunit metrics to examine how pressure and pressure-cooling treatment remodel the tobacco mosaic virus coat protein (TMVcp) assembly. The pressure response is not adequately explained as uniform shrinkage. Instead, the data support a hierarchical transition from a broad, native-like conformational ensemble at low pressure, through a cooperative compacting regime around 1000- 1750 bar, toward a high-pressure compact state with reduced configurational diversity, suppressed global mobility, and localized residual fragility. A representative TMVcp face composed of A2, A3, A4, A19, A20, A21, A35, A36, and A37 behaves as a mechanically partitioned network: A3 behaves as a principal deformation hub, A20-A21-A35-A37 forms a lateral/diagonal compression corridor, A21 behaves as a bridge node, A36 acts as an anisotropic relay, and A2, A4, and A19 behave as stabilizing or adaptive anchors. Pairwise minimum-distance profiles, per-subunit radius of gyration, and post-fit RMSD converge around a late trajectory interval near 358-365 ns, suggesting a coordinated face-level breathing event rather than independent stochastic noise. These local dynamics provide a conservative structural explanation for predicted pressure-dependent epitope remodeling: HHP may mask canonical solvent-exposed epitopes by reducing loop mobility and closing intersubunit grooves, whereas pressure followed by low-temperature trapping may selectively preserve only protrusions compatible with the compact, hydration-trapped lattice. Because DiscoTope and ElliPro are computational predictors, these results should be interpreted as structural hypotheses requiring experimental validation by antibody binding assays, mutagenesis, HDX-MS, or high-pressure structural approaches.

Reaching and grasping are essential goal-directed behaviors that require the integration of visual, olfactory, and somatosensory inputs. Although the loss of vision can profoundly disrupt sensory-guided behaviors, mammals often exhibit compensatory cross-modal plasticity allowing them to reach and grasp with ease. To examine how early sensory loss shapes reaching behavior, we performed bilateral enucleations in short-tailed opossums (Monodelphis domestica) at postnatal day 4, before retino-thalamic and thalamocortical connections have formed. We assessed performance in early blind (EB) and sighted control (SC) animals using a semi-naturalistic reach-to-grasp task requiring precise unilateral limb targeting to retrieve a dead cricket. To isolate the contributions of specific sensory modalities to this task, we selectively disrupted olfactory and mystacial vibrissae inputs and manipulated lighting conditions during task performance. EB opossums were capable of accurate reaching and grasping, although SC animals outperformed EB opossums under light conditions, but not in the absence of light. Both groups relied strongly on tactile input, as whisker trimming significantly increased targeting error. Removal of olfactory input also impaired performance, with a disproportionately greater effect in EB animals. These findings demonstrate that short-tailed opossums retain functional reach-to-grasp behavior after early vision loss and that accurate forelimb movements are generated by the enhancement of the spared sensory systems. Significance StatementCongenital sensory loss in humans alters the landscape used to navigate the world, making compensatory strategies mediated by the spared sensory systems essential for goal-directed behaviors such as reaching and grasping. Although these behaviors have been widely studied across species, the extent to which spared senses support their execution after congenital vision loss remains unclear. Here, we use the short-tailed opossum as a model of congenital blindness to quantify the contributions of whisker-mediated touch and olfaction to reaching performance. We show that both early blind and sighted opossums rely on whisker touch for reaching and grasping, but that olfaction plays a profound role in task performance in early blind opossums.

Previous research suggests that humans are extremely sensitive to object-directed eye gaze, which effectively guides their attention toward objects of shared interest. This contrasts with non-human primates, who typically require much more salient eye-gaze cues to achieve comparable attentional orienting. However, it remains unclear whether cross-species differences in ocular morphology account for this performance gap. To address this question, we examined humans covert shifts of spatial attention in response to eye-gaze cues provided by either realistic human or rhesus monkey head avatars. Target detection was reliably enhanced on gaze-congruent compared to gaze-incongruent trials, with comparable gaze-cueing effects for both avatar types, despite the fact that monkey eyes lack many of the conspicuous features characteristic of human eyes. Hence, eye morphology alone does not substantially modulate gaze-driven attentional orienting in humans, whereas humans reliable use of monkey eye-gaze cues highlights a clear species difference in perceptual sensitivity to eye gaze signals. Significance StatementEye-gaze-mediated attentional orienting is a conserved ability across primates, yet sensitivity to subtle eye-gaze cues may differ between species. Here, we provide empirical evidence that humans exhibit a quantitatively greater capacity than non-human primates to follow subtle eye-gaze cues. Importantly, we showed that this difference cannot be attributed to species-specific ocular morphology as human participants showed robust and comparable reflexive attentional orienting to both human and rhesus monkey eye-gaze cues. This is striking given the pronounced differences in ocular morphology and coloration/contrast between the two species. These findings suggest that cross-species diversity in extracting spatial information from eye-gaze cues likely reflects differences in perceptual sensitivity rather than bottom-up constraints imposed by species-specific ocular morphology.

An object on immediate collision course generates a rapidly expanding visual stimulus on the retina, which will typically trigger a fast, evasive behavior. In hoverflies, for example, such visual looming stimuli may be generated if the insect is about to collide with a stationary object in the surround, by an approaching predator, or by conspecifics during territorial interactions. Thus, similar looming cues can evoke distinct behavioral outputs depending on their source. Supporting this diverse range of appropriate behavioral responses are a multitude of different looming sensitive descending neurons that project information from the head to the thoracic ganglia. We here show that the looming receptive fields of looming sensitive descending neurons are predominantly located in the ventral visual field. To investigate if this is matched by behavior, we recorded how tethered hoverflies responded to looming stimuli displayed either in the dorsal or ventral part of a visual monitor, at four different speeds (l/|v| of 10 - 667 ms), covering a naturalistic range. We found that ventral stimuli, especially at intermediate speeds (l/|v| = 50 - 200 ms), triggered much stronger behavioral responses than dorsally displayed stimuli. The behavioral data thus not only match the receptive fields of the neurons likely to support the behavior, but also highlight that behavioral output is not entirely reflexive but is strongly modulated by stimulus speed and elevation. Significance StatementIf someone throws a ball at you, this generates a rapidly expanding object across your visual field, which will make you react before you have even had time to think. You may for example duck, dip or dive to avoid the ball, or bring your hands up to grab it. Similarly, many insects respond to rapidly approaching objects. We here show that hoverfly reactions to such looming stimuli depend on stimulus speed and elevation, with the strongest reaction to stimuli approaching from below. We further demonstrate that the neurons likely supporting these behaviors show highest sensitivity in the ventral visual field, suggesting a close match between neural tuning and behavioral output.

Elucidating the mechanisms that control the formation of the mammalian neocortex is crucial for understanding brain functions. Synaptic activity of thalamocortical axons (TCAs), mediated by glutamate, exerts a major extrinsic influence on the maturation of their target layer 4 neurons in postnatal primary sensory cortex. However, TCAs reach the sensory cortex during mid-embryonic stages in mice, when neurons of future superficial layers, including layer 4, are still being generated from radial glia (RGs) or intermediate progenitor cells (IPCs), well before the formation of direct synapses. We previously showed that TCAs are required for the production and specification of the proper number of layer 4 neurons in sensory areas, and that part of these area-specific roles is played by the thalamus-derived molecule VGF. However, the role of TCA-derived glutamate prior to synapse formation has remained unclear. In this study, we used mutant mice lacking vGluT2, a vesicular glutamate transporter expressed in the embryonic thalamus, and found that vesicular release of thalamus-derived glutamate is required for the proper production and specification of layer 4 neurons in the sensory cortex by the neonatal stage, through mechanism distinct from those involving VGF. Our findings reveal that multiple molecular cues produced by incoming TCAs play distinct roles in the production and specification of layer 4 neurons in the sensory cortex.

Cytochrome bc1 is one of the key enzymes of biological energy-conserving systems. In its catalytic Q cycle, the central reaction is the oxidation of quinol (QH2), upon which electrons are directed to two separate cofactor chains. The molecular mechanism of this reaction remains elusive. The canonical model, assuming a sequence of reactions dictated by the equilibrium redox midpoint potentials of cofactors (the 2Fe2S cluster and heme bL), has recently been challenged by a new model of EB derived from quantum mechanical (QM) calculations - EMET (EMergent Electron Transfer) (https://doi.org/10.1021/acsomega.5c13233). These two models predict fundamentally different microstates of the enzyme in which semiquinone (SQ) is formed in the catalytic site (Q o) and also predict different lowest-energy configurations. Here, we test these predictions using EPR spectroscopy on highly concentrated preparations of isolated bacterial cytochrome bc1. We detect SQ spin-coupled to the reduced 2Fe2S cluster (2Fe2Sred), whose population markedly exceeds that of reduced heme bL and forms exclusively in sites containing oxidized heme. We also identify that the lowest-energy configuration corresponds to the state with reduced heme bH (adjacent to heme bL), oxidized heme bL and SQ-2Fe2Sred. These two features are precluded by the canonical model but are consistent with EMET. We conclude that EMET, unlike the canonical EB model, satisfactorily describes the occurrence of stochastic, spin-selective processes that result in electron stoichiometry among hemes b, the 2Fe2S cluster, and SQ at Qo that are observed spectroscopically.

Photoreceptor degeneration drives electrophysiological remodeling in downstream retinal neurons, including hyperactive firing of retinal ganglion cells (RGCs) that degrades residual vision. Although Retinoic Acid (RA) and its receptor (RAR) are known to upregulate ion channel genes associated with RGC hyperactivity, these genes lack canonical RAR binding sites required for direct transcriptional regulation. Here, we identify P2X7 receptor (P2X7R) as a key intermediary in RA-induced remodeling in the rd1 mouse model of retinitis pigmentosa. Genetic deletion of P2X7R prevents the upregulation of RA-responsive genes and abolishes RGC hyperactivity. Loss of P2X7R also eliminates RGC hyperpermeability, as measured by uptake of an otherwise membrane-impermeant dye. Acute pharmacological inhibition of P2X7R suppresses hyperpermeability without affecting hyperactivity, supporting an indirect signaling mechanism rather than a direct electrophysiological role. Notably, elevation of resting Ca{superscript 2} is absent in P2X7R-deficient cells, implicating Ca{superscript 2}-dependent gene expression as a link between P2X7R-mediated hyperpermeability and RGC hyperactivity. Together, these findings establish P2X7R as a critical intermediate in retinal remodeling and a potential therapeutic target for preserving vision in retinitis pigmentosa. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/728267v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@7745d4org.highwire.dtl.DTLVardef@89a01corg.highwire.dtl.DTLVardef@16ea51borg.highwire.dtl.DTLVardef@119d0f9_HPS_FORMAT_FIGEXP M_FIG C_FIG

The atypical receptor ACKR3 works together with the canonical chemokine receptor CXCR4 to drive cell migration along gradients of their shared agonist CXCL12. CXCR4 promotes chemotaxis by activating canonical G protein pathways and recruiting {beta}-arrestins. ACKR3 indirectly regulates CXCR4-mediated chemotaxis by scavenging CXCL12. Unlike canonical chemokine receptors, ACKR3 does not couple to G proteins and instead is 100% biased towards {beta}-arrestins. CXCR4 activation by CXCL12 is exquisitely sensitive to subtle changes in both receptor and ligand. By contrast, ACKR3 is activation-prone: it recruits {beta}-arrestins in response to many ligands and is much less sensitive to mutations, suggesting distinct activation mechanisms compared to CXCR4. To explore the basis of these differences, we compared the dynamics of ACKR3 and CXCR4 complexes with chemokines using molecular dynamic (MD) simulations. Ten-microsecond atomistic MD simulations revealed that CXCR4 adopts a stable active state when bound to WT CXCL12 but transitions to an inactive state when in complex with the antagonist variant, [P2G]CXCL12. By comparison, ACKR3 exhibits a variable transmembrane (TM) 6 state distribution and persistently "active" TM7 when complexed with either WT CXCL12 or [P2G]CXCL12, the latter retaining substantial agonistic activity at ACKR3. We further identified ligand-mediated residue interaction networks in the TM core that regulate TM6 and TM7 activation in CXCR4 but are absent or disrupted in ACKR3, resulting in less constrained receptor dynamics. These findings were validated by BRET-based assays with CXCL12 and ACKR3 mutants. Together, the data suggests that the unique conformational dynamics of ACKR3 govern its activation propensity, its ligand promiscuity, and its atypical effector coupling.

Mammalian diet and feeding ecology are often reflected by craniofacial skeleton specializations, but feeding requires skeletal actuation by a complex suite of muscles with varying sizes, lines of action, and mechanical function. While muscles play a critical role in feeding mechanics, and hence diet, it remains unclear how well variation in jaw muscle morphology predicts diet in mammals. We quantified the evolutionary interplay between mammalian muscle morphology and diet using a large and taxonomically broad sample. We measured the relative proportions and putative force production capacity, quantified as muscle physiological cross-sectional area (PCSA), for the major adductor complexes, along with a key jaw depressor, in 91 mammalian species (30 chiropterans, 33 primates, and 28 ungulates, carnivorans, rodents, and marsupials). We recovered clear dietary signals for several muscle complexes, with the medial pterygoid (larger in herbivores) and temporalis (larger in carnivores) performing best as dietary predictors. The medial pterygoid is particularly relevant for the mechanical innovation in mammals of moving the mandible along non-orthal, medio-lateral trajectories during mastication. Our findings underscore the intuitive, yet previously unquantified, importance of muscles in the evolution of mandibular roll, yaw, and lateral translation, all mammalian hallmarks of processing diverse types of food.

The basal ganglia (BG) form anatomically and functionally segregated yet integrative parallel circuits, but the molecular mechanisms specifying them remain unclear. We immunohistochemically mapped the expression of three {delta}2-protocadherin ({delta}2-PCDH) cell adhesion molecules--PCDH10, PCDH17, and PCDH19--in the BG of macaques. Within the striatum, each PCDH exhibited regional gradients of expression along the rostro-caudal and ventromedial-dorsolateral axes. The three PCDHs showed complementary distributions that continuously delineated molecular boundaries corresponding to functional subdivisions in a graded fashion. Such complementary distributions were also observed in the BG output nuclei. Given that neurons expressing the same {delta}2-PCDH in distinct BG structures preferentially connect with each other, the three {delta}2-PCDH expression patterns could define functional territories within parallel BG circuits. Together, the complementary expression of PCDH10, PCDH17, and PCDH19 broadly align with the distinct BG circuits, respectively, suggesting molecular codes underlying the segregated yet integrative parallel organization of the primate BG.

Hearts change their wall thickness (concentric growth) and chamber size (eccentric growth) as they adapt to circulatory demands and the intrinsic function of their contractile cells. Factors associated with wall thickening include variants of sarcomeric proteins that enhance contractility, mitochondrial dysfunction, and hypertension. Chambers can dilate due to many factors including sarcomeric variants that depress contractility and aortic and / or mitral valve insufficiency. Despite intensive study, the mechanisms that regulate cardiac growth remain unclear. It is also uncertain whether inherited variants induce growth via the same mechanisms as more common clinical pathologies, such as hypertension. Here we show that computer simulations of a beating left ventricle reproduce both variant and non-variant-related growth patterns when myocytes grow concentrically to regulate intracellular ATP concentration and eccentrically to maintain titin-based intracellular stress. The simulations support the hypothesis that cardiac growth reflects homeostatic feedback through three interacting systems whereby myocytes add or remove mitochondria and sarcomeres (1) in parallel to match ATP generation to myocardial energy demand, and (2) in series to regulate passive tension, while (3) the autonomic nervous system regulates cardiac power, and thus myocardial ATPase, via baroreflex control. The new framework provides a mechanistic basis for the patterns of eccentric and concentric growth induced by a wide range of clinically-relevant conditions and could facilitate in silico testing of potential therapies for cardiac disease. Significance statementHearts grow in response to both physiological and pathological stimuli. The patterns of concentric (wall thickening / thinning) and eccentric (chamber dilation / constriction) induced by different challenges are well recognized but the underlying mechanisms remain unclear. This work presents simulations of a beating left ventricle where (1) concentric growth is regulated by myocytes attempting to stabilize the intracellular ATP concentration and (2) eccentric growth is regulated by titin-mediated stress. The calculations reproduce the growth associated with inherited variants of sarcomeric proteins, mitochondrial dysfunction, hypertension, and both mitral and aortic valve insufficiency. The new ability to predict cardiac growth and its potential modification by treatments, including myotropes, brings the field closer to in silico optimization of therapy for cardiovascular disease.

Many biomolecular condensates are thought to form through phase separation driven by weak and multivalent, non-stoichiometric interactions between intrinsically disordered protein regions (IDRs). IDRs are abundant in the transcription-related proteome. In vitro, different transcription-related IDRs coalesce into the same droplets, providing support for this IDR-centric paradigm of protein enrichment in transcription condensates in the cell nucleus. But our experiments show that IDRs are not sufficient to account for the degree of enrichment observed for full-length proteins in endogenous transcription condensates. Instead, we find a pattern in which IDRs facilitate engagement of structured interaction domains with a binding substrate. Instead, we find a pattern in which IDRs facilitate engagement of structured interaction domains with a binding substrate. Our results indicate that the role of IDRs in transcription condensates requires further investigation with tools that assess their mode of action in situ. Understanding the role of different protein domains and their interplay will also be important for interpreting biotechnological assays that utilize parts of condensate forming proteins.

The neurotransmitter dopamine (DA) is central to synaptic regulation that support diverse behavioral functions, including both learning and forgetting. This multi-functional role of DA is due to receptor specific signaling in specific subcellular environments that remain uncharacterized. Here we utilized proximity labelling proteomics in human cells to characterize the proximal environments of two Drosophila D1-like DA receptors (Dop1R1 and Dop1R2) in basal and DA activation environments. While DA drives both receptors to recruit Beta-Arrestin 2, Dop1R1 alone showed ligand driven recruitment of G-protein Receptor Kinase 2/3, proximity to clathrin mediated endocytosis, and WASH complex mediated endosomal trafficking. Additionally, we show evidence that Dop1R1 and Dop1R2 reside in distinct domains at the cell surface. In vivo disruption of Drosophila orthologs of Dop1R proximal proteins revealed three trafficking proteins, Sec24AB, Krz, and CG13887, that regulate R1-mediated learning, starvation induced attraction to odors, and DA-mediated cAMP responses in memory circuits. In addition to revealing DA receptor trafficking proteins that support learning, our comparative characterization of the cellular environments D1-like receptors offers insights into how DA differentially regulates diverse behavioral and synaptic functions. For TOC only O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/728438v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@656e56org.highwire.dtl.DTLVardef@12f0084org.highwire.dtl.DTLVardef@cb05cdorg.highwire.dtl.DTLVardef@e9d623_HPS_FORMAT_FIGEXP M_FIG C_FIG