Tena, J. | Search bioRxiv

bioRxiv2022

L-Fucose is a candidate monosaccharide neuromodulator and mitigates Alzheimer's synaptic deficits

We identified a novel signaling function of L-fucose, a structurally unique monosaccharide. We showed that L-fucose enhanced excitatory neurotransmission and long-term potentiation (LTP) in Schaffer-collateral-CA1 synapses. L-fucose was released by neurons in an activity- and store-dependent manner, and induced rapid signaling changes to enhance presynaptic release. Such effects required L-fucose metabolism through the salvage pathway driven by fucokinase (FUK). Thus, L-fucose could be the first described monosaccharide neuromodulator affecting a metabolic-signaling mechanism. Human Alzheimers disease (AD) and 5xFAD mouse brains showed signs of fucose hypometabolism with impaired L-fucose signaling. Such abnormalities could be corrected by exogenous L-fucose, exemplified by rectification of LTPdeficits in 5xFAD hippocampus. Dietary L-fucose supplement, which increased cerebral free L-fucose levels and upregulated FUK to drive the salvage pathway, mitigated synaptic and behavioral deficits of 5xFAD mice. Our data reveals a therapeutic potential of oral L-fucose for AD, which is safe and easy to comply with.

neuroscience↗

bioRxiv2021

Forkhead transcription factor FKH-8 is a master regulator of primary cilia in C. elegans

Cilia, either motile or non-motile (a.k.a primary or sensory), are complex evolutionary conserved eukaryotic structures composed of hundreds of proteins required for their assembly, structure and function that are collectively known as the ciliome. Ciliome mutations underlie a group of pleiotropic genetic diseases known as ciliopathies. Proper cilium function requires the tight coregulation of ciliome gene transcription, which is only fragmentarily understood. RFX transcription factors (TF) have an evolutionarily conserved role in the direct activation of ciliome genes both in motile and non-motile cilia cell types. In vertebrates, FoxJ1 and FoxN4 Forkhead (FKH) TFs work with RFX in the direct activation of ciliome genes, exclusively in motile cilia cell-types. No additional TFs have been described to act together with RFX in primary cilia cell-types in any organism. Here we describe FKH-8, a FKH TF, as master regulator of the primary ciliome in Caenorhabditis elegans. fkh-8 is expressed in all ciliated neurons in C. elegans, binds the regulatory regions of ciliome genes, regulates ciliome gene expression, cilium morphology and a wide range of behaviours mediated by sensory cilia. Importantly, we find FKH-8 function can be replaced by mouse FOXJ1 and FOXN4 but not by members of other mouse FKH subfamilies. In conclusion, our results show that RFX and FKH TF families act as master regulators of ciliogenesis also in sensory ciliated cell types and suggest that this regulatory logic could be an ancient trait predating functional cilia sub-specialization.

developmental biology↗