A cytoskeleton-membrane interaction conserved in fast-spiking neurons controls movement, emotion, and memory

The pathogenesis of schizophrenia is believed to involve combined dysfunctions of many proteins including microtubule-associated protein 6 (MAP6) and Kv3.1 voltage-gated K+ (Kv) channel, but their relationship and functions in behavioral regulation are often not known. Here we report that MAP6 stabilizes Kv3.1 channels in parvalbumin-positive (PV+ ) fast-spiking GABAergic interneurons, regulating behavior. MAP6-/- and Kv3.1-/- mice display similar hyperactivity and avoidance reduction. Their proteins colocalize in PV+ interneurons and MAP6 deletion markedly reduces Kv3.1 protein level. We further show that two microtubule-binding modules of MAP6 bind the Kv3.1 tetramerization domain with high affinity, maintaining the channel level in both neuronal soma and axons. MAP6 knockdown by AAV-shRNA in the amygdala or the hippocampus reduces avoidance or causes hyperactivity and recognition memory deficit, respectively, through elevating projection neuron activity. Finally, knocking down Kv3.1 or disrupting the MAP6-Kv3.1 binding in these brain regions causes avoidance reduction and hyperactivity, consistent with the effects of MAP6 knockdown. Thus, disrupting this conserved cytoskeleton-membrane interaction in fast-spiking neurons causes different degrees of functional vulnerability in various neural circuits.

Determinant roles of dendritic cell-expressed Notch Delta-like and Jagged ligands on anti-tumor T cell immunity

Background

Notch intercellular communication instructs tissue-specific T-cell development and function. In this study, we explored the roles of dendritic cell (DC)-expressed Notch ligands in the regulation of T-cell effector function.

Methods

We generated mice with CD11c lineage-specific deletion of Notch Delta-like ligand (Dll)1 and Jagged (Jag)2. Using these genetically-ablated mice and engineered pharmacological Notch ligand constructs, the roles of various Delta-like and Jagged ligands in the regulation of T-cell-mediated immunity were investigated. We assessed tumor growth, mouse survival, cytokine production, immunophenotyping of myeloid and lymphoid populations infiltrating the tumors, expression of checkpoint molecules and T-cell function in the experimental settings of murine lung and pancreatic tumors and cardiac allograft rejection. Correlative studies were also performed for the expression of NOTCH ligands, NOTCH receptors and PD-1 on various subsets of myeloid and lymphoid cells in tumor-infiltrating immune cells analyzed from primary human lung cancers.

Results

Mice with CD11c lineage-specific deletion of Notch ligand gene Dll1, but not Jag2, exhibited accelerated growth of lung and pancreatic tumors concomitant with decreased antigen-specific CD8⁺T-cell functions and effector-memory (Tem) differentiation. Increased IL-4 but decreased IFN-γ production and elevated populations of T-regulatory and myeloid-derived suppressor cells were observed in Dll1-ablated mice. Multivalent clustered DLL1-triggered Notch signaling overcame DC Dll1 deficiency and improved anti-tumor T-cell responses, whereas the pharmacological interference by monomeric soluble DLL1 construct suppressed the rejection of mouse tumors and cardiac allograft. Moreover, monomeric soluble JAG1 treatment reduced T-regulatory cells and improved anti-tumor immune responses by decreasing the expression of PD-1 on CD8⁺Tem cells. A significant correlation was observed between DC-expressed Jagged and Delta-like ligands with Tem-expressed PD-1 and Notch receptors, respectively, in human lung tumor-infiltrates.

Conclusion

Our data show the importance of specific expression of Notch ligands on DCs in the regulation of T-cell effector function. Thus, strategies incorporating selectively engineered Notch ligands could provide a novel approach of therapeutics for modulating immunity in various immunosuppressive conditions including cancer.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0566-4) contains supplementary material, which is available to authorized users.

Abstract 1624: NOTCH ligand-based therapeutics for immunomodulation in cancer and organ transplantation

We demonstrated in human and mouse studies that tumor-induced modulation of Notch ligand expression and Notch signaling in hematopoietic compartment contributes to tumor immune escape. Down-regulation of delta-like ligands (DLL) leads to defects in T cell development and T helper (Th1) cell differentiation with the prevalence of regulatory T cell (Treg) generation.

To determine the roles of Notch ligands in antigen-presenting dendritic cells in regulation of antitumor immune responses we generated a set of lineage-specific knock-out mice lacking one of the Notch ligands in CD11c+ dendritic cells (DC). We are developing and testing a set of reagents for clinical application for ligand-specific activation or inhibition of Notch signaling to stimulate or inhibit, respectively, various types of immune responses for applications in oncology and immune diseases.

Mice with DLL1 insufficiency in DC demonstrated remarkably accelerated growth of Lewis lung carcinoma (LLC) tumor, and reduced survival compared to wild type animals. This associated with impaired anti-tumor immune responses indicated by the decreased tumor infiltration by IFNγ-producing T cells. Jagged2 knockout did not cause any significant alterations. Notch ligand expression in antigen-presenting cells was identified as a “checkpoint” regulating the type of immune response. Data reveal that expression of Notch ligands by antigen-presenting cells is an important immune response specifying mechanism and that ligand-specific Notch signaling could be a valuable therapeutic target.

Reagents for the pharmacological modulation of immune responses based on Notch ligand constructs is proposed. Our cell-based study showed that pharmacological activation of Notch ligands required multivalent receptor-ligand interaction, whereas soluble ligands acted as competitive Notch inhibitors. We have generated reagents that comprise specific domains of the DLL1 in multivalent or monovalent form. Therapeutic inhibition of Notch by monovalent DLL1-based reagent accelerated LLC tumor growth and attenuated T cell-mediated anti-tumor immune response. In a heart transplantation mouse model, monovalent DLL1 reagent significantly prolonged allograft survival by inhibiting Th1 effector and memory T cell differentiation. Multivalent forms of DLL1 effectively stimulated Notch signaling in T cell cultures and enhanced IFNγ production, whereas monovalent reagent had opposite effects.

Pharmacological up-regulation of DLL1-mediated Notch signaling with multivalent forms of ligand represents an efficient strategy for the enhancement of anti-tumor immunity and targeting multiple mechanisms of tumor growth. Monovalent DLL1 forms could be utilized for therapeutic inhibition of Th1 responses in autoimmune diseases and organ transplantation. Reagents based on the mono- and multivalent forms of Notch ligands can be efficiently utilized for therapeutic modulation of Notch signaling.

Note: This abstract was not presented at the meeting.

Citation Format: Elena I. Tchekneva, Anneliese E. Antonucci, Irina Chekneva, Nicholas Long, Jason V. Evans, Anwari Akhter, David P. Carbone, Thomas Magliery, Mikhail M. Dikov. NOTCH ligand-based therapeutics for immunomodulation in cancer and organ transplantation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1624. doi:10.1158/1538-7445.AM2017-1624

Understanding the sequence requirements of protein families: insights from the BioVis 2013 contests

Introduction

In 2011, the BioVis symposium of the IEEE VisWeek conferences inaugurated a new variety of data analysis contest. Aimed at fostering collaborations between computational scientists and biologists, the BioVis contest provided real data from biological domains with emerging visualization needs, in the hope that novel approaches would result in powerful new tools for the community. In 2011 and 2012 the theme of these contests was expression Quantitative Trait Locus analysis, within and across tissues respectively. In 2013 the topic was updated to protein sequence and mutation visualization.

Methods

The contest was framed in the context of a real protein with numerous mutations that had lost function, and the question posed "what minimal set of changes would you propose to rescue function, or how could you support a biologist attempting to answer that question?". The data was grounded in actual experimental results in triosephosphate isomerase(TIM) enzymes. Seven teams composed of 36 individuals submitted entries with proposed solutions and approaches to the challenge. Their contributions ranged from careful analysis of the visualization and analytical requirements for the problem through integration of existing tools for analyzing the context and consequences of protein mutations, to completely new tools addressing the problem.

Results

Judges found valuable and novel contributions in each of the entries, including interesting ways to hierarchicalize the protein into domains of informational interaction, tools for simultaneously understanding both sequential and spatial order, and approaches for conveying some types of inter-residue dependencies. In this manuscript we document the problem presented to the contestants, summarize the biological contributions of their entries, and suggest opportunities that this work has highlighted for even more improved tools in the future.