Biology subjects

Ruchhoeft, M. L.

Publications and source records attributed to Ruchhoeft, M. L..

3 recordsLinked to original sources

bioRxiv2026

Metabolic Salvage and Acyl-chain Remodeling Support Glycosphingolipid Synthesis with the PDAC Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy where metabolic homeostasis is maintained by tumor and stromal cells within the tumor microenvironment (TME). To better assess pathways supporting macromolecule biosynthesis in PDAC tumors, we apply 13C metabolic flux analysis (MFA) to slice cultures of treatment-naive human tumors and mouse models that retain the native TME. Glycans, lipid headgroups, and very long-chain fatty acids are the most dynamic metabolic pools, while long chain fatty acids, purines, and pyrimidines are predominantly salvaged locally in situ. We use targeted pharmacological modulators to highlight the importance of recycling pathways and metabolic redundancies which mitigate changes in lipid abundances. Finally, we leverage targeted lipid fluxomics and the distinct ganglioside and globoside profiles of tumor and stromal cells, respectively, to demonstrate the role of the lipid kinase PIKfyve in supporting ganglioside homeostasis via sialic acid and ceramide salvage. These data establish application of MFA to slice cultures of PDAC tumors as an effective approach for assessing metabolic mechanisms and therapeutic responses within an intact TME.

cancer biology↗

bioRxiv2025

Targeting serine dehydratase supports amino acid homeostasis and skin repair

Serine and glycine are altered in patients with metabolic disorders, and this dysregulation can lead to diverse pathologies1-6. Modulation of serine levels via diet can influence relevant phenotypes in mouse models of metabolic syndrome7,8. Here we identify serine dehydratase (Sds), a gluconeogenic hepatic enzyme involved in serine and threonine catabolism, as a key regulator of systemic serine and sphingolipid metabolism. We show that SDS is expressed and active in human liver tissue. Furthermore, Sds abundance strongly correlates with hepatic serine. This enzyme is highly active in BKS-db/db mice, which show amino acid alterations reminiscent of type 2 diabetes. Hepatic Sds overexpression increases serine and threonine degradation and promotes the accumulation of toxic 1-deoxysphingolipids (doxSLs). Conversely, Sds deletion dramatically increases systemic serine, glycine, and threonine while altering canonical and non-canonical sphingolipids. Finally, Sds deletion in BKS-db/db mice reduces skin doxSLs and accelerates wound healing. Our results demonstrate that Sds constrains serine levels in circulation and suggest therapeutic approaches for targeting this enzyme to improve chronic disorders.

physiology↗

bioRxiv2024

Modeling Compound Lipid Homeostasis Using Stable Isotope Tracing

Lipids represent the most diverse pool of metabolites found in cells, facilitating compartmentation, signaling, and other functions. Dysregulation of lipid metabolism is linked to disease states such as cancer and neurodegeneration. However, limited tools are available for quantifying metabolic fluxes across the lipidome. To directly measure reaction fluxes encompassing compound lipid homeostasis, we applied stable isotope tracing, liquid chromatography-high-resolution mass spectrometry, and network-based isotopologue modeling to non-small cell lung cancer (NSCLC) models. Compound lipid metabolic flux analysis (CL-MFA) enables the concurrent quantitation of fatty acid synthesis, elongation, headgroup assembly, and salvage reactions within virtually any biological system. Here, we resolve liver kinase B1 (LKB1)-mediated regulation of sphingolipid recycling in NSCLC cells and precision-cut lung slice cultures. We also demonstrate that widely used tissue culture conditions drive cells to upregulate fatty acid synthase flux to supraphysiological levels. Finally, we identify previously uncharacterized isozyme specificity of ceramide synthase inhibitors. These results highlight the ability of CL-MFA to quantify lipid cycling in biological systems to discover biological function and elucidate molecular mechanisms in membrane lipid metabolism.

cell biology↗