Toll and Toll-like receptor signalling in development

Abstract

The membrane receptor Toll and the related Toll-like receptors (TLRs) are best known for their universal function in innate immunity. However, Toll/TLRs were initially discovered in a developmental context, and recent studies have revealed that Toll/TLRs carry out previously unanticipated functions in development, regulating cell fate, cell number, neural circuit connectivity and synaptogenesis. Furthermore, knowledge of their molecular mechanisms of action is expanding and has highlighted that Toll/TLRs function beyond the canonical NF-κB pathway to regulate cell-to-cell communication and signalling at the synapse. Here, we provide an overview of Toll/TLR signalling and discuss how this signalling pathway regulates various aspects of development across species.

Potential of <i>TLR</i>-gene diversity in Czech indigenous cattle for resistance breeding as revealed by hybrid sequencing

“…For example, the well-known mutation 9787C > T (c.2021) in the TLR4 product is associated with a change in polarity in the crucial transmembrane part of the molecule, thereby affecting signal transfer (White et al, 2003). In accordance with expectations, this predicted functional change led to a shift in somatic cell count in cattle populations (Sharma et al, 2006;Beecher et al, 2010).…”

“…The effects of the mutation 5087A > G seem to be multilateral since an association with keratoconjunctivitis and calving ease has been reported (Mullen et al, 2018). This observation is not surprising in view of the range of known non-immune functions of toll-like receptors (Anthoney et al, 2018). In the particular case of calving ease, the effect of TLR4 variation might reflect a role in the inflammatory response and myometrial signalling before parturition, which is mediated by the MyD88/TRAF6/NF-κB pathway (Lim et al, 2017).…”

“…The change 9787C > T (c.2021, T674I), which is located in the transmembrane region of the receptor, is well known for its effect on susceptibility to PTB (Fisher et al, 2011) and its positive effect on milk protein and fat contents (Beecher et al, 2010); however, the CRP population was found to be already monomorphic for the favourable C allele, although variation still persists.…”

Effects of lipopolysaccharide and juvenile hormone III treatments on cell growth and gene expression in the Ceratitis capitata (Diptera: Tephritidae) CCE/CC128 cell line

“…The toll pathway is one of the signaling pathways present in insect species involved in immune responses and is activated via the Toll‐like receptors (Boutros, Agaisse, & Perrimon, ; Valanne, Wang, & Rämet, ). Besides the immune system, toll‐like receptors can play different roles and some have been proven to be related to embryonic development (Anthoney, Foldi, & Hidalgo, ; Espín‐Palazón, & Traver, ; Halfon, Hashimoto, & Keshishian, ).…”

Transcriptional profiling of macrophages infected with Fonsecaea monophora

“…But in antifungal immunity, it is TLRs and CLRs that play a major role . TLRs, belonging to type I transmembrane proteins, are mainly expressed on the cell membrane of macrophages and dendritic cells, and capable of inducing a great numbers of inflammatory cytokines through classical MyD88‐dependent or other pathways . CLRs, a kind of type II transmembrane proteins, mainly contain dectin‐1, dectin‐2, mincle, mannose receptor (MR) and DC‐SIGN, which can activate NF‐κB, AP‐1, NFAT and other transcription factors through Syk‐CARD9 or other signalling pathways, thus inducing the synthesis of cytokines .…”