Ostermeyer-Fay, A. G. | bioRxiv Science

bioRxiv2025

A Critical Role for Neutral Sphingomyelinase-2 in Doxorubicin-induced Cardiotoxicity

Cardiotoxicity is a major side effect of Doxorubicin (Dox) that has hampered its clinical utility, and strategies to mitigate this cardiotoxicity are limited. Sphingolipids (SL) are central to the chemotherapy response in cancer but their role in normal tissue is less clear. Here, we identified the SL enzyme neutral sphingomyelinase-2 (nSMase2) as a critical mediator of chronic Dox-induced cardiotoxicity, establishing nSMase2 as a key downstream effector of Dox in cardiomyocytes (CM) and showing that in vivo loss of nSMase2 activity is protecting against chronic Dox-induced cardiac damage and dysfunction. Biologically, these studies link nSMase2 with Dox-induced CM senescence both in vitro and in vivo and identify the dual specificity phosphatase DUSP4 as a novel effector of nSMase2 in the Dox response. In addition to cementing a role for SL metabolism in Dox effects in normal tissue, this study advances nSMase2 as a target of interest for cardioprotection.

cell biology↗

bioRxiv2025

Critical Evaluation of Sphingolipids Detection by MALDI-MSI

The increasing interest in the role of sphingolipids in (patho)physiology has led to the demand for visualization of these lipids within tissue samples (both from animal models and patient specimens) using techniques such as matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). While increasingly adopted, detection of sphingolipids with MALDI-MSI is challenging due to: i) the significant structural variations of sphingolipid molecules, ii) the potential breakdown of the more complex molecules into structurally simpler species which may confound the analysis, and iii) the great difference in levels among sphingolipid classes and subspecies, with the low-abundant ones often being close to the detection limit. In this study, we adopted a multi-pronged approach to establish a robust pipeline for the detection of sphingolipids by MALDI-MSI and to establish best practices and limitations of this technology. First, we evaluated the more commonly adopted methods [2,5-Dihydroxyacetophenon (DHA) or 2,5-Dihydroxybenzoic acid (DHB) matrix in positive ion mode and 1,5-Diaminonaphthalene (DAN) matrix in negative ion mode] using MALDI-MS on reference standards. These standards were used at ratios similar to their relative levels in biological samples to evaluate signal artifacts originating from fragmentation of more complex sphingolipids and impacting low level species. Next, by applying the most appropriate protocol for each sphingolipid class, MALDI-MSI signals were validated in cell culture by modulating specific sphingolipid species using sphingolipid enzymes and inhibitors. Finally, the optimized parameters were utilized on breast cancer tissue from the PyMT mouse model. We report the optimal signal for sphingomyelin (SM) and, for the first time, Sph in DHB positive ion mode (in cells and PyMT tissue), and the validated detection of ceramides and glycosphingolipids in DAN negative ion mode. We document the extensive fragmentation of SM into sphingosine-1-phosphate (S1P) and even more so into ceramide-1-phosphate (C1P) using DAN in negative ion mode and its effect in generating an artifactual C1P tissue signal; we also report the lack of detectable signal for S1P and C1P in biological samples (cells and tissue) using the more suitable DHB positive ion mode protocol.

cell biology↗