Apoptosis is associated with numerous phenotypical characteristics, and is thus studied with many tools. In this study, we compared two broadly used apoptotic assays: TUNEL and staining with an antibody targeting the activated form of an effector caspase. To compare them, we developed a protocol based on commonly used tools such as filters, zprojection and thresholding. Even though it is commonly used in imageprocessing protocols, thresholding remains a recurring problem. Here we analyzed the impact of processing parameters and readout choice on the accuracy of apoptotic signal quantification. Our results show that TUNEL is quite robust, even if image processing parameters can allow or not to detect subtle differences of the apoptotic rate. On the contrary, images from anticleaved caspase staining are more sensitive to handle and proved to necessitate to be processed more carefully. We then developed an open source Fiji macro automatizing most steps of the image processing and quantification protocol. It is noteworthy that the field of application of this macro is wider than apoptosis as it can perfectly be used to treat and quantify other kind of images.

Sideroflexins (SFXN) are evolutionarily conserved mitochondrial carriers belonging to the SCL56 family. Until recently, the metabolites transported by SFXN were unknown and they were thought to be transporters of a metabolite involved in iron homeostasis. SFXN1 is now known as the mitochondrial serine transporter. Because little is known about SFXN1 interactome, we launched a high-throughput search of SFXN1 binding partners with the aim to better understand its mitochondrial functions. Using a large-scale identification of SFXN1 physical partners based on co-immunoprecipitation followed by shotgun mass spectrometry (coIP-MS), we identified 96 putative SFXN1 interactants in the MCF7 human cell line. Our in-silico analysis of the SFXN1 interactome highlights biological processes linked to mitochondrial organization, electron transport chain and transmembrane transport. Among SFXN1 potential physical partners, ATAD3A and 17-HSD10, two proteins associated with neurological disorders and neurodegeneration, were further confirmed as interactants using different human cell lines. Further work will be needed to investigate the significance of these interactions in neurological disorders.