2. Academic Validation
  3. Multiple N-linked glycosylation sites critically modulate the synaptic abundance of Neuroligin isoforms

Multiple N-linked glycosylation sites critically modulate the synaptic abundance of Neuroligin isoforms

  • J Biol Chem. 2023 Oct 19:105361. doi: 10.1016/j.jbc.2023.105361.
Orion Benner 1,  Thomas P Cast 1,  Laurie S Minamide 1,  Zephyr Lenninger 2,  James R Bamburg 3,  Soham Chanda 4
Affiliations

Affiliations

  • 1 Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
  • 2 Molecular, Cellular & Integrated Neurosciences, Colorado State University, Fort Collins, CO 80523, USA.
  • 3 Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; Molecular, Cellular & Integrated Neurosciences, Colorado State University, Fort Collins, CO 80523, USA; Cell & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
  • 4 Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; Molecular, Cellular & Integrated Neurosciences, Colorado State University, Fort Collins, CO 80523, USA; Cell & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA. Electronic address: [email protected].
PMID: 37865312 DOI: 10.1016/j.jbc.2023.105361
Abstract

In recent years, elegant glycomic and glycoproteomic approaches have revealed an intricate glycosylation profile of mammalian brain with enormous spatial and temporal diversities. Nevertheless, at a cellular level, it is unclear how these post-translational modifications (PTMs) affect various proteins to influence crucial neuronal properties. Here, we have investigated the impact of N-linked glycosylation on Neuroligins (NLGNs), a class of cell-adhesion molecules (CAMs) that play instructive roles in synapse organization. We found that endogenous NLGN proteins are differentially glycosylated across several regions of murine brain in a sex-independent but isoform-dependent manner. In both rodent primary neurons derived from brain sections and human neurons differentiated from stem cells, all NLGN variants were highly enriched with multiple N-glycan subtypes, which cumulatively ensured their efficient trafficking to the cell-surface. Removal of these N-glycosylation residues only had a moderate effect on NLGNs' stability or expression levels, but particularly enhanced their retention at the endoplasmic reticulum (ER). As a result, glycosylation-deficient NLGNs exhibited considerable impairments in their dendritic distribution and postsynaptic accumulation, which virtually eliminated their ability to recruit presynaptic terminals and significantly reduced NLGN overexpression -induced assemblies of both Glutamatergic and GABAergic synapse structures. Therefore, our results highlight an essential mechanistic contribution of N-linked glycosylations in facilitating the appropriate secretory transport of a major synaptic CAM and promoting its cellular function in neurons.

Keywords

N-linked glycosylation; Neuroligins; Post-translational modification; Protein trafficking; Synaptic cell-adhesion.

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