Biology subjects

Huynh, D. T.

Publications and source records attributed to Huynh, D. T..

5 recordsLinked to original sources

bioRxiv2025

Evidence for Functional Regulation of the KLHL3/WNK Pathway by O-GlcNAcylation

The 42-member Kelch-like (KLHL) protein family are adaptors for ubiquitin E3 ligase complexes, governing the stability of a wide range of substrates. KLHL proteins are critical for maintaining proteostasis in a variety of tissues and are mutated in human diseases, including cancer, neurodegeneration, and familial hyperkalemic hypertension. However, the regulation of KLHL proteins remains incompletely understood. Previously, we reported that two KLHL family members, KEAP1 and gigaxonin, are regulated by O-linked {beta}-N-acetylglucosamine (O-GlcNAc), an intracellular form of glycosylation. Interestingly, some ubiquitination targets of KEAP1 and gigaxonin are themselves also O-GlcNAcylated, suggesting that multi-level control by this post-translational modification may influence many KLHL pathways. To test this hypothesis, we examined KLHL3, which ubiquitinates with-no-lysine (WNK) kinases to modulate downstream ion channel activity. Our biochemical and glycoproteomic data demonstrate that human KLHL3 and all four WNK kinases (WNK1-4) are O-GlcNAcylated. Moreover, our results suggest that O-GlcNAcylation affects WNK4 function in both osmolarity control and ferroptosis, with potential implications ranging from blood pressure regulation to neuronal health and survival. This work demonstrates the functional regulation of the KLHL3/WNK axis by O-GlcNAcylation and supports a broader model of O-GlcNAc serving as a general regulator of KLHL signaling and proteostasis.

cell biology↗

bioRxiv2023

O-GlcNAcylation regulates neurofilament-light assembly and function and is perturbed by Charcot-Marie-Tooth disease mutations

The neurofilament (NF) cytoskeleton is critical for neuronal morphology and function. In particular, the neurofilament-light (NF-L) subunit is required for NF assembly in vivo and is mutated in subtypes of Charcot-Marie-Tooth (CMT) disease. NFs are highly dynamic, and the regulation of NF assembly state is incompletely understood. Here, we demonstrate that human NF-L is modified in a nutrient-sensitive manner by O-linked-{beta}-N-acetylglucosamine (O-GlcNAc), a ubiquitous form of intracellular glycosylation. We identify five NF-L O-GlcNAc sites and show that they regulate NF assembly state. Interestingly, NF-L engages in O-GlcNAc-mediated protein-protein interactions with itself and with the NF component -internexin, implying that O-GlcNAc is a general regulator of NF architecture. We further show that NF-L O-GlcNAcylation is required for normal organelle trafficking in primary neurons, underlining its functional significance. Finally, several CMT-causative NF-L mutants exhibit perturbed O-GlcNAc levels and resist the effects of O-GlcNAcylation on NF assembly state, indicating a potential link between dysregulated O-GlcNAcylation and pathological NF aggregation. Our results demonstrate that site-specific glycosylation regulates NF-L assembly and function, and aberrant NF O-GlcNAcylation may contribute to CMT and other neurodegenerative disorders.

cell biology↗

bioRxiv2021

Ventral tegmental area glutamate neurons mediate the nonassociative consequences of traumatic stress

Exposure to trauma is a risk factor for the development of a number of mood disorders, and may enhance vulnerability to future adverse life events. Recent data implicate ventral tegmental area (VTA) glutamate neuronal activity as functionally important for signaling aversive or threating stimuli. However, it is unknown whether VTA glutamate neurons regulate transsituational outcomes that result from stress and whether these neurons are sensitive to stressor controllability. This work established an operant mouse paradigm to examine the impact of stressor controllability on VTA glutamate neuron function and stressor outcome. Uncontrollable (inescapable) stress, but not physically identical controllable (escapable) stress, produced social avoidance in male mice. Cell-type-specific calcium recordings showed that both controllable and uncontrollable stressors increased VTA glutamate neuronal activity. Chemogenetic reduction of VTA glutamate neuron activity prevented the behavioral sequelae of uncontrollable stress. Our results provide causal evidence that mice can be used to model stressor controllability and that VTA glutamate neurons may contribute to transsituational stressor outcomes, such as social avoidance and exaggerated fear that are observed within trauma-related disorders.

neuroscience↗

bioRxiv2020

Evidence for nutrient-dependent regulation of the COPII coat by O-GlcNAcylation

O-linked {beta}-N-acetylglucosamine (O-GlcNAc) is a dynamic form of intracellular glycosylation common in animals, plants and other organisms. O-GlcNAcylation is essential in mammalian cells and is dysregulated in myriad human diseases, such as cancer, neurodegeneration and metabolic syndrome. Despite this pathophysiological significance, key aspects of O-GlcNAc signaling remain incompletely understood, including its impact on fundamental cell biological processes. Here, we investigate the role of O-GlcNAcylation in the coat protein II complex (COPII), a system universally conserved in eukaryotes that mediates anterograde vesicle trafficking from the endoplasmic reticulum. We identify new O-GlcNAcylation sites on Sec24C, Sec24D and Sec31A, core components of the COPII system, and provide evidence for potential nutrient-sensitive pathway regulation through site-specific glycosylation. Our work suggests a new connection between metabolism and trafficking through the conduit of COPII protein O-GlcNAcylation.

cell biology↗

bioRxiv2019

Oral prescription opioid-seeking behavior in male and female mice

A significant portion of prescription opioid users self-administer orally rather than intravenously. Animal models of opioid addiction have demonstrated that intravenous cues are sufficient to cause drug-seeking. However, intravenous models may not model oral users, and the preference to self-administer orally appears to be partially influenced by the users sex. Our objectives were to determine whether oral opioid-associated cues are sufficient for relapse and whether sex differences exist in relapse susceptibility. Mice orally self-administered escalating doses of oxycodone under postprandial (prefed) or non-postprandial (no prefeeding) conditions. Both sexes demonstrated robust cue-induced reinstatement. In separate mice we found that oral oxycodone cues were sufficient to reinstate extinguished oral oxycodone-seeking behavior in the absence of postprandial or prior water self-administration training. During self-administration, we found that female mice earned significantly more mg/kg oxycodone than male mice. Follow-up studies indicated sex differences in psychomotor stimulation and plasma oxycodone/oxymorphone following oral oxycodone administration. In addition, gonadal steroid studies were performed in which we found divergent responses where ovariectomy enhanced and orchiectomy suppressed oral self-administration. While the suppressive effects of orchiectomy were identified across doses and postprandial conditions, the enhancing effects of ovariectomy were selective to non-postprandial conditions. These studies establish that 1) oral drug cues are sufficient to cause reinstatement that is independent of prandial conditions and water-seeking behavior, 2) earned oral oxycodone is larger in female mice compared with male mice potentially through differences in psychomotor stimulation and drug metabolism, and 3) gonadectomy produces divergent effects on oral oxycodone self-administration between sexes.

neuroscience↗