LINGO family receptors are differentially expressed in the mouse brain and form native multimeric complexes

Abstract

Leucine‐rich repeat and immunoglobin‐domain containing (LRRIG) proteins that are commonly involved in protein‐protein interactions play important roles in nervous system development and maintenance. LINGO‐1, one of this family members, is characterized as a negative regulator of neuronal survival, axonal regeneration, and oligodendrocyte precursor cell (OPC) differentiation into mature myelinating oligodendrocytes. Three LINGO‐1 homologs named LINGO‐2, LINGO‐3, and LINGO‐4 have been described. However, their relative expression and functions remain unexplored. Here, we show by in situ hybridization and quantitative polymerase chain reaction that the transcripts of LINGO homologs are differentially expressed in the central nervous system. The immunostaining of brain slices confirmed this observation and showed the co‐expression of LINGO‐1 with its homologs. Using BRET (bioluminescence resonance energy transfer) analysis, we demonstrate that LINGO proteins can physically interact with each of the other ones with comparable affinities and thus form the oligomeric states. Furthermore, co‐immunoprecipitation experiments indicate that LINGO proteins form heterocomplexes in both heterologous systems and cortical neurons. Since LINGO‐1 is a promising target for the treatment of demyelinating diseases, its ability to form heteromeric complexes reveals a new level of complexity in its functioning and opens the way for new strategies to achieve diverse and nuanced LINGO‐1 regulation.

Chemical Synthesis of TFF3 Reveals Novel Mechanistic Insights and a Gut-Stable Metabolite

“…( 38 ) Neither TFF3 nor TFF3 homodimer displayed any effect on LINGO2 dimerization, which was assessed by BRET ( Figure 3 E). 59 Due to the limited availability of functional LINGO2 bioassays, we cannot fully exclude that TFF3 does not signal through LINGO2 and we can only state that TFF3 does not interfere with LINGO2 dimerization.…”

“…No ligand able to alter LINGO2 dimerization is known; therefore, no positive control could be used. 59 Results are expressed as mean ± SEM for n = 4. One-way ANOVA followed by Dunnett correction was performed to assess differences between treated and nontreated cells.…”

“… 3 However, no systematic gut stability studies have been carried out and some reports indicate that TFF3 is not fully resistant to proteases. For example, only 15% of intravenously injected iodine-labeled TFF3 homodimer in rats was recovered from urine after 24 h. 26 TFF3 homodimer was also degraded in the terminal parts of the large intestine 27 and truncated at the C-terminal Phe 59 in human saliva. 28 It was thus important to characterize TFF3’s gastrointestinal stability in more detail, particularly considering that studies often rely on the use of sodium dodecyl sulfate (SDS) gels and antibodies to identify and characterize TFF3, where truncations can easily be missed.…”

“…We observed a strong BRET signal under basal condition, demonstrating the capacity of LINGO2 to form dimers, as already described. 59 We then evaluated whether the TFF3 constructs could promote changes of this basal BRET signal by inducing conformational change within the dimers and/or change the dimerization state of LINGO2. However, no statistically significant (p > 0.05) modification of BRET signal was observed following stimulation of HEK-293 cells coexpressing LINGO2-YFP and LINGO2-Rluc with TFF3(C 57 Acm) or TFF3 homodimer For agonistic evaluation, all compounds were used individually for stimulation in the given concentration range.…”

Histone methyltransferase Ezh2 coordinates mammalian axon regeneration via epigenetic regulation of key regenerative pathways

“…Lingo1 loss-of-function promotes axon regeneration and neuronal survival in various CNS injury and disease models (Fu et al, 2008; Inoue et al, 2007; Ji et al, 2006). A recent study showed that Lingo family receptors could form heteromers with one another in the mouse brain (Guillemain et al, 2020), suggesting potential functional overlap between the paralogs. Tenascin-R is an extracellular matrix molecule that was shown in previous studies to be a repulsive guidance cue in zebrafish during development (Becker et al, 2003) and an inhibitor of mouse optic nerve regeneration (Becker et al, 2000).…”