Biology subjects

Moncrieffe, M. C.

Publications and source records attributed to Moncrieffe, M. C..

3 recordsLinked to original sources

bioRxiv2022

Anterograde Trafficking of Toll-Like Receptors Requires the Cargo Sorting Adaptors TMED-2 and 7 and specific N-glycans

Toll-Like Receptors (TLRs) play a pivotal role in immunity by recognizing conserved structural features of pathogens and initiating the innate immune response. TLR signaling is subject to complex regulation that remains poorly understood. Here we show that two small type I transmembrane receptors, TMED2 and 7, that function as cargo sorting adaptors in the early secretory pathway are required for transport of TLRs from the ER to Golgi. Protein interaction studies reveal that TMED7 interacts with TLR2, TLR4, and TLR5 but not with TLR3 and TLR9. On the other hand, TMED2 interacts with TLR2, TLR4 and TLR3. Dominant negative forms of TMED7 suppress the export of cell surface TLRs from the ER to the Golgi. By contrast TMED2 is required for the ER-export of both plasma membrane and endosomal TLRs. We also find that a specific N-linked glycan of TLR2 is required for anterograde trafficking and may be directly recognised by TMEDs. Together, these findings suggest that association of TMED2 and TMED7 with TLRs facilitates anterograde transport from the ER to the Golgi.

cell biology↗

bioRxiv2021

Viral tolerance in Aedes aegypti relies on the negative cooperativity between Toll5A and the cytokine ligand Spz1C

Aedes aegypti has evolved to become an efficient vector for arboviruses but the mechanisms of host-pathogen tolerance are unknown. Immunoreceptor Toll and its ligand Spaetzle have undergone duplication which may allow neofunctionalization and adaptation. Here we present cryo-EM structures and biophysical characterisation of low affinity Toll5A complexes that display transient but specific interactions with Spaetzle1C, forming asymmetric complexes, with only one ligand clearly resolved. Loop structures of Spaetzle1C and Toll5A intercalate, temporarily bridging the receptor C-termini to promote signalling. By contrast unbound receptors form head-to-head homodimers that keep the juxtamembrane regions far apart in an inactive conformation. Interestingly the transcriptional signature of Spaetzle1C differs from other Spaetzle cytokines and controls genes involved in innate immunity, metabolism and tissue regeneration. Taken together our results explain how upregulation of Spaetzle1C in the midgut and Toll5A in the salivary gland shape the concomitant immune response.

immunology↗

bioRxiv2020

Differential host response to a herpesvirus: Mareks disease virus peptides on chicken MHC class II molecules are derived from only a few genes and illustrate a new mode of peptide binding

Viral diseases pose major threats to humans and other animals, including the billions of chickens that are an important food source as well as a public health concern due to zoonotic pathogens. Unlike humans and other typical mammals, the major histocompatibility complex (MHC) of chickens can confer decisive resistance or susceptibility to many viral diseases. An iconic example is Mareks disease, caused by an oncogenic herpesvirus with over 100 genes. Classical MHC class I and class II molecules present antigenic peptides to T lymphocytes, and it has been hard to understand how such MHC molecules could be involved in susceptibility to Mareks disease, given the potential number of peptides from over 100 genes. We used a new in vitro infection system and immunopeptidomics to determine peptide motifs for the two class II molecules expressed by the MHC haplotype B2, which is known to confer resistance to Mareks disease. Surprisingly, we found that the vast majority of viral peptide epitopes presented by chicken class II molecules arise from only four viral genes, nearly all having the peptide motif for BL2, the dominantly-expressed class II molecule in chickens. We expressed BL2 linked to several MDV peptides, and determined one X-ray crystal structure, showing how a single small amino acid in the binding site causes a crinkle in the peptide, leading to core binding peptide of ten amino acids, compared to the nine amino acids in all other reported class II molecules. The limited number of potential T cell epitopes from such a complex virus can explain the differential MHC-determined resistance to MDV, but raises questions of mechanism and opportunities for vaccine targets in this important food species, as well as providing a basis for understanding class II molecules in other species including humans.

immunology↗