Sorrells, J. E. | bioRxiv Science

bioRxiv2026

Impact of noise on optical redox ratio estimation

Optical redox ratio (ORR) is a commonly used metric to quantify the metabolic state of biological samples based on autofluorescence of NAD(P)H and FAD. Despite its relevance and popularity, little work has been done to quantify the estimation error of ORR, especially in low-photon count data. Here, we provide an analytical solution to determine ORR variability in the presence of shot noise and dark counts. We then validate this analytical model with simulated and experimental data. This work will enable researchers to quantify the uncertainty in their ORR measurements, aiding in more accurate and efficient experimental design and data analysis.

bioengineering↗

bioRxiv2024

Cholesterol Metabolite 27-Hydroxycholesterol Enhances the Secretion of Cancer Promoting Extracellular Vesicles by a Mitochondrial ROS-Induced Impairment of Lysosomal Function

Extracellular vesicles (EVs) serve as crucial mediators of cell-to-cell communication in normal physiology as well as in diseased states, and have been largely studied in regard to their role in cancer progression. However, the mechanisms by which their biogenesis and secretion are regulated by metabolic or endocrine factors remain unknown. Here, we delineate a mechanism by which EV secretion is regulated by a cholesterol metabolite, 27-Hydroxycholesterol (27HC), where treatment of myeloid immune cells (RAW 264.7 and J774A.1) with 27HC impairs lysosomal homeostasis, leading to shunting of multivesicular bodies (MVBs) away from lysosomal degradation, towards secretion as EVs. This impairment of lysosomal function is caused by mitochondrial dysfunction and subsequent increase in reactive oxygen species (ROS). Interestingly, cotreatment with a mitochondria-targeted antioxidant rescued the lysosomal impairment and attenuated the 27HC-mediated increase in EV secretion. Overall, our findings establish how a cholesterol metabolite regulates EV secretion and paves the way for the development of strategies to regulate cancer progression by controlling EV secretion.

cell biology↗