Viola Nawrocka

All Publications

• A dendritic guidance receptor functions in both ligand dependent and independent modes. PLoS genetics Reddy, A. R., Machera, S. J., Cook, Z. T., Deng, H., Nawrocka, W. I., Özkan, E., Shen, K. 2025; 21 (12): e1011942

  Abstract

  The formation of an appropriately shaped dendritic arbor is critical for a neuron to receive information. Dendritic morphogenesis is a dynamic process involving growth, branching, and retraction. How the growth and stabilization of dendrites are coordinated at the molecular level remains a key question in developmental neurobiology. The highly arborized and stereotyped dendritic arbors of the Caenorhabditis elegans PVD neuron are shaped by the transmembrane DMA-1 receptor through its interaction with a tripartite ligand complex consisting of SAX-7/L1CAM, MNR-1/FAM151B, and LECT-2/LECT2. However, receptor null mutants exhibit strongly reduced dendrite outgrowth, whereas ligand null mutants show disordered branch patterns, suggesting a ligand-independent function of the receptor. To test this idea, we identified point mutations in dma-1 that disrupt receptor-ligand binding and introduced corresponding mutations into the endogenous gene. We show that the ligand-free receptor is sufficient to drive robust, disordered dendritic branch formation but results in a complete loss of arbor shape. This disordered outgrowth program utilizes similar downstream effectors as the stereotyped outgrowth program, further arguing that ligand binding is not necessary for outgrowth. Finally, we demonstrate that ligand binding is required to maintain higher-order dendrites after development is complete. Taken together, our findings support a surprising model in which ligand-free and ligand-bound DMA-1 receptors have distinct functions: the ligand-free receptor promotes stochastic outgrowth and branching, whereas the ligand-bound receptor guides stereotyped dendrite morphology by stabilizing arbors at target locations.

  View details for DOI 10.1371/journal.pgen.1011942

  View details for PubMedID 41348823

• Identification of Natural Regulatory T Cell Epitopes Reveals Convergence on a Dominant Autoantigen IMMUNITY Leonard, J. D., Gilmore, D. C., Dileepan, T., Nawrocka, W. I., Chao, J. L., Schoenbach, M. H., Jenkins, M. K., Adams, E. J., Savage, P. A. 2017; 47 (1): 107-+

  Abstract

  Regulatory T (Treg) cells expressing the transcription factor Foxp3 are critical for the prevention of autoimmunity and the suppression of anti-tumor immunity. The major self-antigens recognized by Treg cells remain undefined, representing a substantial barrier to the understanding of immune regulation. Here, we have identified natural Treg cell ligands in mice. We found that two recurrent Treg cell clones, one prevalent in prostate tumors and the other associated with prostatic autoimmune lesions, recognized distinct non-overlapping MHC-class-II-restricted peptides derived from the same prostate-specific protein. Notably, this protein is frequently targeted by autoantibodies in experimental models of prostatic autoimmunity. On the basis of these findings, we propose a model in which Treg cell responses at peripheral sites converge on those self-proteins that are most susceptible to autoimmune attack, and we suggest that this link could be exploited as a generalizable strategy for identifying the Treg cell antigens relevant to human autoimmunity.

  View details for DOI 10.1016/j.immuni.2017.06.015

  View details for Web of Science ID 000405712800013

  View details for PubMedID 28709804

  View details for PubMedCentralID PMC5562039

• Phosphoantigen-induced conformational change of butyrophilin 3A1 (BTN3A1) and its implication on Vγ9Vδ2 T cell activation. Proceedings of the National Academy of Sciences of the United States of America Gu, S. n., Sachleben, J. R., Boughter, C. T., Nawrocka, W. I., Borowska, M. T., Tarrasch, J. T., Skiniotis, G. n., Roux, B. n., Adams, E. J. 2017; 114 (35): E7311–E7320

  Abstract

  Human Vγ9Vδ2 T cells respond to microbial infections as well as certain types of tumors. The key initiators of Vγ9Vδ2 activation are small, pyrophosphate-containing molecules called phosphoantigens (pAgs) that are present in infected cells or accumulate intracellularly in certain tumor cells. Recent studies demonstrate that initiation of the Vγ9Vδ2 T cell response begins with sensing of pAg via the intracellular domain of the butyrophilin 3A1 (BTN3A1) molecule. However, it is unknown how downstream events can ultimately lead to T cell activation. Here, using NMR spectrometry and molecular dynamics (MD) simulations, we characterize a global conformational change in the B30.2 intracellular domain of BTN3A1 induced by pAg binding. We also reveal by crystallography two distinct dimer interfaces in the BTN3A1 full-length intracellular domain, which are stable in MD simulations. These interfaces lie in close proximity to the pAg-binding pocket and contain clusters of residues that experience major changes of chemical environment upon pAg binding. This suggests that pAg binding disrupts a preexisting conformation of the BTN3A1 intracellular domain. Using a combination of biochemical, structural, and cellular approaches we demonstrate that the extracellular domains of BTN3A1 adopt a V-shaped conformation at rest, and that locking them in this resting conformation without perturbing their membrane reorganization properties diminishes pAg-induced T cell activation. Based on these results, we propose a model in which a conformational change in BTN3A1 is a key event of pAg sensing that ultimately leads to T cell activation.

  View details for DOI 10.1073/pnas.1707547114

  View details for PubMedID 28807997

  View details for PubMedCentralID PMC5584448

• Sensing of Pyrophosphate Metabolites by Vgamma9Vdelta2 T Cells. Frontiers in immunology Gu, S., Nawrocka, W., Adams, E. J. 2014; 5: 688

  Abstract

  The predominant population of gammadelta T cells in human blood express a T cell receptor (TCR) composed of a Vgamma9 (Vgamma2 in an alternate nomenclature) and Vdelta2 domains. These cells came into the limelight when it was discovered they can respond to certain microbial infections and tumorigenic cells through the detection of small, pyrophosphate containing organic molecules collectively called "phosphoantigens" or "pAgs." These molecules are intermediates in both eukaryotic and prokaryotic metabolic pathways. Chemical variants of these intermediates have been used in the clinic to treat a range of different cancers, however, directed optimization of these molecules requires a full understanding of their mechanism of action on target cells. We and others have identified a subclass of butyrophilin-related molecules (BTN3A1-3) that are directly involved in pAg sensing in the target cell, leading to engagement and activation of the T cell through the TCR. Our data and that of others support the pAg binding site to be the intracellular B30.2 domain of BTN3A1, which is the only isoform capable of mediating pAg-dependent stimulation of Vgamma9Vdelta2 T cells. Here, we review the data demonstrating pAg binding to the B30.2 domain and our studies of the structural conformations of the BTN3A extracellular domains. Finally, we synthesize a model linking binding of pAg to the intracellular domain with T cell detection via the extracellular domains in an "inside-out" signaling mechanism of the type characterized first for integrin molecule signaling. We also explore the role of Vgamma9Vdelta2 TCR variability in the CDR3 gamma and delta loops and how this may modulate Vgamma9Vdelta2 cells as a population in surveillance of human health and disease.

  View details for DOI 10.3389/fimmu.2014.00688

  View details for PubMedID 25657647