Biology subjects

Zhou, J. Y.

Publications and source records attributed to Zhou, J. Y..

4 recordsLinked to original sources

bioRxiv2022

Plasma ST6Gal1 is Dispensable for IgG Sialylation

The glycosylation of IgG has attracted increased attention due to the impact of N-glycan modifications at N297 on IgG function, acting primarily through modulation of Fc domain conformation and Fc{gamma} receptor binding affinities and signaling. However, the mechanisms regulating IgG glycosylation and especially 2,6-sialylation of its N-glycan remain poorly understood. We observed previously that IgG is normally sialylated in mice with B cells lacking the sialyltransferase ST6Gal1. This supported the hypothesis that IgG may be sialylated outside of B cells, perhaps through the action of hepatocyte-released plasma ST6Gal1. Here we demonstrate that this model is incorrect. Animals lacking hepatocyte expressed ST6Gal1 retain normal IgG 2,6-sialylation, despite the lack of detectable ST6Gal1 in plasma. Moreover, we confirmed that B cells were not a redundant source of IgG sialylation. Thus, while 2,6-sialylation is lacking in IgG from mice with germline ablation of ST6Gal1, IgG 2,6-sialylation is normal in mice lacking ST6Gal1 in either hepatocytes or B cells. These results indicate that IgG 2,6-sialylation arises after release from a B cell, but is not dependent on plasma-localized ST6Gal1 activity.

immunology↗

bioRxiv2022

Divergent Golgi Trafficking Limits B cell-Mediated IgG Sialylation

The degree of 2,6-linked sialylation on IgG glycans is associated with a variety of inflammatory conditions and is thought to drive IgG anti-inflammatory activity. Previous findings revealed that ablation of {beta}-galactoside 2,6-sialyltransferase 1 (ST6Gal1) in B cells failed to alter IgG sialylation in vivo, yet resulted in the loss of B cell surface 2,6 sialylation, suggesting divergent pathways for IgG and cell surface glycoprotein glycosylation and trafficking. Employing both B cell hybridomas and ex vivo murine B cells, we discovered that IgG was poorly sialylated by ST6Gal1 and highly core fucosylated by 1,6-fucosyltransferase 8 (Fut8) in cell culture. In contrast, IgG-producing cells showed the opposite pattern by flow cytometry, with high cell surface 2,6 sialylation and low 1,6 fucosylation. Paired studies further revealed that ex vivo B cell-produced IgG carried significantly less sialylation compared to IgG isolated from the plasma of matched animals, providing evidence that sialylation increases after release in vivo. Finally, confocal analyses demonstrated that IgG poorly localized to subcellular compartments rich in sialylation and ST6Gal1, and strongly to regions rich in fucosylation and Fut8. These findings support a model in which IgG subcellular trafficking diverges from the canonical secretory pathway by promoting Fut8-mediated core fucosylation and limiting exposure to and modification by ST6Gal1, providing a mechanism for why B cell-expressed ST6Gal1 is dispensable for IgG sialylation in vivo.

immunology↗

bioRxiv2020

Single-cell characterization of transcriptomic heterogeneity in lymphoblastoid cell lines

Lymphoblastoid Cell Lines (LCLs) are generated by transforming primary B cells with Epstein-Barr Virus (EBV) and are used extensively as model systems in viral oncology, immunology, and human genetics research. In this study, we characterized single-cell transcriptomic profiles of five LCLs and present a simple discrete-time simulation to explore the influence of stochasticity on LCL clonal evolution. Single-cell RNA sequencing revealed substantial phenotypic heterogeneity within and across LCLs with respect to immunoglobulin isotype; virus-modulated host pathways involved in survival, proliferation, and differentiation; viral replication state; and oxidative stress. This heterogeneity is likely attributable to intrinsic variance in primary B cells and host-pathogen dynamics. Stochastic simulations demonstrate that initial primary cell heterogeneity, random sampling, time in culture, and even mild differences in phenotype-specific fitness can contribute substantially to dynamic diversity in populations of nominally clonal cells.

immunology↗

bioRxiv2020

Integration of IL-2 and IL-4 Signals Coordinates Divergent Regulatory T cell Responses and Drives Therapeutic Efficacy

Cells exist within complex milieus of communicating factors, such as cytokines, that combine to generate context-specific responses, yet nearly all knowledge about the function of each cytokine and the signaling propagated downstream of their recognition is based upon the response to individual cytokines. Here, we found that regulatory T cells (Tregs) integrate concurrent signaling initiated by IL-2 and IL-4 to generate a response divergent from the sum of the two pathways in isolation. IL-4 stimulation of STAT6 phosphorylation was blocked by IL-2, while IL-2 and IL-4 synergized to enhance STAT5 phosphorylation, IL-10 production, and the selective proliferation of IL-10-producing Tregs, leading to increased inhibition of conventional T cell activation and the reversal of asthma and multiple sclerosis in mice. These data define a mechanism of combinatorial cytokine signaling and lay the foundation upon which to better understand the origins of cytokine pleiotropy while informing improved the clinical use of cytokines. Impact StatementSimultaneous cytokine signaling results in unexpected transcription factor changes that fuel a cellular response divergent from the sum of each cytokine alone.

biochemistry↗