HIV-1 Tat-induced VAPB disruption initiates a cascade of organellar failures culminating in neuronal lipid accumulation

People living with HIV develop persistent neurocognitive impairment despite viral suppression through incompletely defined mechanisms. HIV-1 Tat disrupts VAPB-PTPIP51 coupling at mitochondria-associated ER membranes via PTPIP51 tyrosine phosphorylation, causing VAPB relocalization away from MAMs, a causal mechanism established in our prior work. Here, we define the downstream metabolic consequences and establish VAPB as the critical determinant of neuronal lipid pathology. Lipidomic profiling identified triglycerides as the dominant altered species, comprising polyunsaturated forms normally destined for membrane synthesis or mitochondrial oxidation, consistent with membrane catabolism rather than de novo lipogenesis. Targeted metabolomics revealed bioenergetic collapse consistent with impaired mitochondrial oxidative function. The resulting lipid imbalance, including lipid droplet accumulation, produced secondary organellar dysfunction, including Golgi dispersal and ER stress. Critically, Tat failed to induce lipid droplet accumulation in shRNA-VAPB cells, while PTPIP51 silencing had no such protective effect, establishing that VAPB relocalization is the obligate trigger. Guanosine supplementation reduced lipid droplet accumulation, suggesting a link to bioenergetic failure that warrants further investigation. In postmortem HIV-infected frontal cortex, VAPB was paradoxically elevated yet correlated with worsening dementia severity, consistent with transcriptional upregulation that cannot overcome posttranslational blockade of VAPB-MAM localization. The polyunsaturated triglycerides, depleted plasmalogens, and elevated ceramides documented here closely parallel lipid signatures reported in PLWH with cerebrovascular complications, implicating Tat-driven lipid dysregulation as a candidate mechanism for the incompletely explained elevation in stroke risk in this population.