Reece, J. M. | bioRxiv Science

bioRxiv2023

HIV viral protein R induces loss of DCT1-type renal tubules

Hyponatremia and salt wasting is a common occurance in patients with HIV/AIDS, however, the understanding of its contributing factors is limited. HIV viral protein R (Vpr) contributes to HIV-associated nephropathy. To investigate the effects of Vpr on the expression level of the Slc12a3 gene, encoding the Na-Cl cotransporter, which is responsible for sodium reabsorption in distal nephron segments, we performed single-nucleus RNA sequencing of kidney cortices from three wild-type (WT) and three Vpr-transgenic (Vpr Tg) mice. The results showed that the percentage of distal convoluted tubule (DCT) cells was significantly lower in Vpr Tg mice compared with WT mice (P < 0.05), and that in Vpr Tg mice, Slc12a3 expression was not different in DCT cell cluster. The Pvalb+ DCT1 subcluster had fewer cells in Vpr Tg mice compared with WT (P < 0.01). Immunohistochemistry demonstrated fewer Slc12a3+ Pvalb+ DCT1 segments in Vpr Tg mice. Differential gene expression analysis comparing Vpr Tg and WT in the DCT cluster showed Ier3, an inhibitor of apoptosis, to be the most downregulated gene. These observations demonstrate that the salt-wasting effect of Vpr in Vpr Tg mice is mediated by loss of Slc12a3+ Pvalb+ DCT1 segments via apoptosis dysregulation.

pathology↗

bioRxiv2020

Nutrient sensing pathways regulating adult reproductive diapause in C. elegans

Genetic and environmental manipulations, such as dietary restriction (DR), can improve both health span and lifespan in a wide range of organisms, including humans. Changes in nutrient intake trigger often overlapping metabolic pathways that can generate distinct or even opposite outputs depending on several factors, such as when DR occurs in the lifecycle of the organism or the nature of the changes in nutrients. Due to the complexity of metabolic pathways and the diversity in outputs, the underlying mechanisms regulating diet-associated pro-longevity are not yet well understood. Adult reproductive diapause (ARD) in the model organism Caenorhabditis elegans is a DR model that is associated with lengthened lifespan and reproductive potential (Angelo and Van Gilst 2009). As the metabolic pathways regulating ARD have not yet been explored in depth, we performed a candidate-based genetic screen analyzing select nutrient-sensing pathways to determine their contribution to the regulation of ARD. Focusing on the three phases of ARD (initiation, maintenance, and recovery), we find that ARD initiation is regulated by fatty acid metabolism, sirtuins, AMPK, and the O-linked N-acetyl glucosamine (O-GlcNAc) pathway. Although ARD maintenance was not significantly influenced by the nutrient sensors in our screen, we found that ARD recovery was modulated by energy sensing, stress response, insulin-like signaling, and the TOR pathway. We also discovered that fatty acid {beta}-oxidation regulates ARD initiation through a pathway involving the O-GlcNAc cycling enzyme, OGT-1, acting with the nuclear hormone receptor NHR-49. Consistent with these findings, our analysis revealed a change in levels of neutral lipids associated with ARD entry defects. Our findings thus identify novel conserved genetic pathways required for ARD entry and recovery and identify new genetic interactions that provide insight into the role of OGT and OGA.

genetics↗