Biology subjects

Judson, R.

Publications and source records attributed to Judson, R..

4 recordsLinked to original sources

bioRxiv2026

Minimal social context decouples affective response modalities

Emotions often occur within social interactions where affective cues are partly accessible or inferable by others. This raises questions regarding how and to which degree social context modulates subjective, physiological and behavioural affective responses, as well as their coherence, questions which remain points of tension in emotion research. To investigate this, we measured subjective affective ratings, autonomic sympathetic and parasympathetic activity, and facial behaviour while participants completed an emotion-induction task. In the social-context condition (but not control), participants believed that their video feed was accessible to a potential future interaction partner. Results show that even such "minimal social context" selectively and differentially modulated affective response modalities, characterised by both intensification of autonomic responses and dampening of overt facial and subjective affect. Multivariate dimensionality analysis further identified a cross-modal affective dimension. Notably, social context reduced participants coupling with this shared affective response structure, indicating weaker cross-modal coherence. These findings suggest that emotional responding relies on a flexible, rather than rigid, configuration of affective features, likely recruited to meet the socioemotional demands of a given context. This has important implications for understanding the structure and function of emotion, as well as typical and atypical socioemotional responding.

neuroscience↗

bioRxiv2020

Loop Extrusion Mediates Physiological Locus Contraction for V(D)J Recombination

Immunoglobulin heavy chain locus (Igh) VH, D, and JH gene segments are developmentally assembled into V(D)J exons. RAG endonuclease initiates V(D)J recombination by binding a JH-recombination signal sequence (RSS) within a chromatin-based recombination center (RC) and then, in an orientation-dependent process, scans upstream D-containing chromatin presented by cohesin-mediated loop extrusion for convergent D-RSSs to initiate DJH-RC formation1,2. In primary pro-B cells, 100s of upstream VH-associated RSSs, embedded in convergent orientation to the DJH-RC-RSS, gain proximity to the DJH-RC for VH-to-DJH joining via a mechanistically-undefined VH-locus contraction process3-7. Here, we report that a 2.4 mega-base VH locus inversion in primary pro-B cells nearly abrogates rearrangements of normally convergent VH-RSSs and cryptic RSSs, even though locus contraction per se is maintained. Moreover, this inversion activated rearrangement of both cryptic VH-locus RSSs normally in the opposite orientation and, unexpectedly, of normally-oriented cryptic RSSs within multiple, sequential upstream convergent-CBE domains. Primary pro-B cells had significantly reduced transcription of Wapl8, a cohesin-unloading factor, versus levels in v-Abl pro-B lines that lack marked locus contraction or distal VH rearrangements2,9-11. Correspondingly, Wapl depletion in v-Abl lines activated VH-locus contraction and orientation-specific RAG-scanning across the VH-locus. Our findings indicate that locus contraction and physiological VH-to-DJH joining both are regulated via circumvention of CBE scanning impediments.Competing Interest StatementThe authors have declared no competing interest.View Full Text

immunology↗

bioRxiv2020

EHBP1 and EHD2 regulate Dll4 caveolin-mediated endocytosis during blood vessel development

Despite the absolute requirement of Delta/Notch signaling to activate lateral inhibition during early blood vessel development, many mechanisms remain unclear. Here, we identify EHD2 and EHBP1 as novel regulators of Notch activation in endothelial cells through controlling endocytosis of Delta-like ligand 4 (Dll4). Knockout of EHBP1 and EHD2 in zebrafish produced a significant increase in ectopic sprouts in zebrafish intersomitic vessels during development and a reduction in downstream Notch signaling. In vitro, EHBP1 and EHD2 localized to plasma membrane-bound Dll4 and actin independently of clathrin. Disruption of caveolin endocytosis resulted in EHBP1 and EHD2 failing to organize around Dll4 as well as loss of Dll4 internalization in endothelial cells. Overall, we demonstrate that EHBP1 and EHD2 regulate Dll4 endocytosis by anchoring caveolar endocytic pits to the actin cytoskeleton.

cell biology↗

bioRxiv2020

Conditional Antibody Expression to Avoid Central B Cell Deletion in a Humanized HIV-1 Vaccine Mouse Models

HIV-1 vaccine development aims to elicit broadly neutralizing antibodies (bnAbs) against diverse viral strains. In some HIV-1 infected individuals, bnAbs evolve from precursor antibodies through affinity maturation. To induce bnAbs, a vaccine must mediate a similar process of antibody maturation. One way to test vaccination strategies is to immunize mouse models that express human bnAb precursors. Such immunization experiments can assess whether the vaccine can convert precursor antibody into bnAb. A major problem with such mouse models is that bnAb expression often hinders B cell development in the bone marrow. Such developmental blocks may be attributed to unusual properties of bnAb variable regions, such as poly-reactivity and long antigen-binding loops, which are often under negative selection during primary B cell development. To address this problem, we devised a method to circumvent B cell developmental block by expressing bnAbs conditionally in mature B cells. We validated this method by expressing the unmutated common ancestor (UCA) of the human VRC26 bnAb in transgenic mice. Constitutive expression of combined immunoglobulin heavy and light chains of VRC26UCA led to developmental arrest of B cell progenitors in the bone marrow; poly-reactivity of VRC26UCA and poor pairing of VRC26UCA IgH chain with mouse surrogate light chain may contribute to the phenotype. The conditional expression strategy circumvented this developmental impediment, allowing the VRC26UCA to be expressed in mature peripheral B cells. This method should be generally applicable for expressing other antibodies that are under negative selection during B cell development. Significance statementMouse models can provide fast and cost-effective systems to test HIV-1 vaccine candidates at the pre-clinical stage. To serve this purpose, mouse models are engineered to express the precursors of human bnAbs against diverse HIV-1 strains. Immunization of such mouse models can evaluate the ability of vaccines to mature the precursor antibodies into bnAbs. However, due to unusual properties of bnAbs, mouse models expressing their precursors often have B cell developmental defects. In this study, we devised and validated a strategy to address this problem. This method could also facilitate the expression of other clinically relevant antibodies in mature B cells in transgenic mice; immunization of such mice could be used to generate novel antibodies with desirable properties.

immunology↗