Biology subjects

Henley, J. M.

Publications and source records attributed to Henley, J. M..

6 recordsLinked to original sources

bioRxiv2025

PINK1 SUMOylation regulates basal mitophagy

The mitochondrial kinase PTEN-induced kinase 1 (PINK1) initiates mitophagy in response to mitochondrial damage, yet mechanisms that constrain its activation under basal conditions remain incompletely defined. Here, we identify a non-canonical SUMO-2/3 modification of PINK1 that suppresses basal mitophagy. We show that the mitochondrial E3 ligase mitochondrial-anchored protein ligase (MAPL/MUL1) promotes PINK1 SUMO-2/3 modification, while MAPL depletion reduces SUMOylation and enhances basal mitophagy. Targeted deSUMOylation increases PINK1 stabilisation and augments mitophagy. These findings reveal a novel SUMO-based checkpoint for basal PINK1 activation and mitochondrial quality control.

cell biology↗

bioRxiv2023

Coordinated interplay between palmitoylation, phosphorylation and SUMOylation regulates kainate receptor surface expression.

Kainate receptors (KARs) are key regulators of neuronal excitability and synaptic transmission. KAR surface expression is tightly controlled in part by post-translational modifications (PTMs) of the GluK2 subunit. We have shown previously that agonist activation of GluK2-containing KARs leads to phosphorylation of GluK2 at S868, which promotes subsequent SUMOylation at K886 and receptor endocytosis. Furthermore, GluK2 has been shown to be palmitoylated. However, how the interplay between palmitoylation, phosphorylation and SUMOylation orchestrate KAR trafficking remains unclear. Here, we used a library of site-specific GluK2 mutants to investigate the interrelationship between GluK2 PTMs, and their impact on KAR surface expression. We show that GluK2 is basally palmitoylated and that this is decreased by kainate stimulation. Moreover, a non-palmitoylatable GluK2 mutant (C858/C871A) shows enhanced S868 phosphorylation and K886 SUMOylation under basal conditions and is insensitive to KA-induced internalisation. These results indicate that GluK2 palmitoylation contributes to stabilising KAR surface expression and that dynamic depalmitoylation promotes downstream phosphorylation and SUMOylation to mediate activity-dependent KAR endocytosis. Significance StatementPost-translational modifications (PTMs) are biochemical switches that control substrate protein properties and interactions. In consequence, PTMs are critical regulators of essentially all cellular pathways and are vital for eukaryotic cell survival. In the brain, among other roles, PTMs influence neuronal growth, differentiation, synaptic activity and plasticity. Kainate receptors (KARs) play core roles in all these processes and previous work has shown that the GluK2 subunit of KARs is subject to multiple PTMs. Here, using GluK2 as an exemplar protein, we delineate the sequence, coordination, and consequences of the PTMs palmitoylation, phosphorylation and SUMOylation on KAR surface expression. Our data show how the complex interplay between PTMs dynamically regulates synaptic proteins and neuronal function.

neuroscience↗

bioRxiv2023

SGIP1 binding to the α-helical H9 domain of cannabinoid receptor 1 promotes axonal surface expression

Endocannabinoid signalling mediated by cannabinoid type 1 receptors (CB1Rs) is critical for homeostatic neuromodulation of both excitatory and inhibitory synapses. This requires highly polarised axonal surface expression of CB1R, but how this is achieved remains unclear. We previously reported that the H9 domain in the intracellular C-terminus of CB1R contributes to polarised surface expression by an unknown mechanism. Here we show the H9 domain binds to the endocytic adaptor protein SGIP1 to promote CB1R expression in the axonal membrane. Overexpression of SGIP1 increases CB1R axonal surface localisation but has no effect on CB1R lacking the H9 domain (CB1R{Delta}H9). Conversely, SGIP1 knockdown reduces axonal surface expression of CB1R but does not affect CB1R{Delta}H9. Furthermore, SGIP1 knockdown diminishes CB1R-mediated inhibition of presynaptic Ca2+ influx in response to neuronal activity. Together, these data advance mechanistic understanding of endocannabinoid signalling by demonstrating that SGIP1 interaction with H9 underpins axonal CB1R surface expression to regulate presynaptic responsiveness.

neuroscience↗

bioRxiv2020

Sustained postsynaptic kainate receptor activation downregulates AMPA receptor surface expression and induces hippocampal LTD

Here we report that sustained activation of GluK2 subunit-containing kainate receptors leads to AMPA receptor endocytosis and a novel form of long-term depression (KAR-LTDAMPAR) in hippocampal neurons. The KAR-evoked loss of surface AMPA receptors requires KAR channel activity and is occluded by the blockade of PKC or PKA. Moreover, in acute hippocampal slices, kainate invoked LTD of AMPA EPSCs. These data, together with our previously reported KAR-LTPAMPAR, demonstrate that KARs bidirectionally regulate synaptic AMPARs and synaptic plasticity.

neuroscience↗

bioRxiv2020

Sorting nexin-27 regulates AMPA receptor trafficking through the synaptic adhesion protein LRFN2

The endosome-associated cargo adaptor sorting nexin-27 (SNX27) is linked to various neuropathologies through sorting of integral proteins to the synaptic surface, most notably AMPA receptors. To provide a broader view of SNX27-associated pathologies we have performed unbiased proteomics to identify new neuronal SNX27-dependent cargoes, and identified proteins linked to excitotoxicity (SLC1A3, SLC4A7, SLC6A11), epilepsy, intellectual disabilities and working memory deficits (KCNT2, ADAM22, KIDINS220, LRFN2). Focusing on the synaptic adhesion molecule leucine-rich repeat and fibronectin type-III domain-containing protein 2 (LRFN2), we establish that SNX27 binds to LRFN2 and is responsible for regulating its endosomal sorting. LRFN2 associates with AMPA receptors and knockdown of LRFN2 phenocopies SNX27 depletion in decreasing surface expression of AMPA receptors, reducing synaptic activity and attenuating hippocampal long-term potentiation. Our evidence suggests that, in contrast to previous reports, SNX27 does not directly bind to AMPA receptors, and instead controls AMPA receptor-mediated synaptic transmission and plasticity indirectly through the endosomal sorting of LRFN2. Overall, our study provides new molecular insight into the perturbed function of SNX27 and LRFN2 in a range of neurological conditions.

molecular biology↗

bioRxiv2018

The C-terminal Helix 9 motif regulates cannabinoid receptor type 1 trafficking and surface expression

Cannabinoid type 1 receptor (CB1R) is only stably surface expressed in axons, where it downregulates neurotransmitter release. How this tightly regulated axonal surface polarity is established and maintained is unclear. To address this question, we used time-resolved imaging to determine the trafficking of CB1R from biosynthesis to mature polarised localisation. We show that the secretory pathway delivery of CB1R is axonally biased and that surface expressed CB1R is more stable in axons than in dendrites. This dual mechanism is mediated by the CB1R C-terminal and involves the Helix 9 (H9) domain. Removal of the H9 domain increases dendrite secretory pathway delivery and decreases in surface stability. Furthermore, CB1R{Delta}H9 is more sensitive to agonist-induced internalisation and less efficient at downstream signalling than CB1RWT. Together, these results shed new light on how polarity of CB1R is mediated and indicate that the C-terminal H9 domain plays key roles in this process.

neuroscience↗