Sfxn1 is essential for erythrocyte maturation via facilitating hemoglobin production in zebrafish

A High-Throughput Search for SFXN1 Physical Partners Led to the Identification of ATAD3, HSD10 and TIM50

Simple Summary

Mitochondria are central players in cell fate and cell death. Indeed, mitochondrial dysfunction has been observed in many diseases, including neurodegenerative diseases. The activity of these organelles relies on numerous mitochondrial transporters, among which the sideroflexins have received little attention to date despite their emerging importance in human health. To better understand the cellular functions of these transporters and their associations with diseases, we herein investigated the molecular partners of one human sideroflexin, SFXN1. Several proteins capable of interacting with SFXN1 were identified, including ATAD3 and HSD10, two mitochondrial proteins linked to neuronal disorders.

Abstract

Sideroflexins (SFXN, SLC56) are a family of evolutionarily conserved mitochondrial carriers potentially involved in iron homeostasis. One member of the SFXN family is SFXN1, recently identified as a human mitochondrial serine transporter. However, little is known about the SFXN1 interactome, necessitating a high-throughput search to better characterize SFXN1 mitochondrial functions. Via co-immunoprecipitation followed by shotgun mass spectrometry (coIP-MS), we identified 96 putative SFXN1 interactors in the MCF7 human cell line. Our in silico analysis of the SFXN1 interactome highlights biological processes linked to mitochondrial organization, electron transport chains and transmembrane transport. Among the potential physical partners, ATAD3A and 17β-HSD10, two proteins associated with neurological disorders, were confirmed using different human cell lines. Nevertheless, further work will be needed to investigate the significance of these interactions.

Overexpression of SFXN1 indicates poor prognosis and promotes tumor progression in lung adenocarcinoma

Sideroflexin 1 (SFXN1) functions as a mitochondrial serine transporter in one-carbon metabolism. The association between SFXN1 and tumorigenesis remains to be elucidated. This study illustrated the functional role of SFXN1 in lung adenocarcinoma (LUAD). SFXN1 expression in LUAD specimens was examined using western blotting and quantitative real-time PCR (qRT-PCR), and the prognostic value between SFXN1 and clinicopathological parameters was investigated. Subsequently, the effects of SFXN1 on cellular proliferation, migration, and apoptosis were assessed by using Transwell assays and flow cytometry in A549 and H1299 cell lines. Western blotting was also employed to explore the mechanism of tumor progression. SFXN1 was significantly elevated in the LUAD samples compared with the para-carcinoma tissues. Furthermore, SFXN1 expression was an independent prognostic predictor for patients with LUAD. The expression of SFXN1 was altered in A549 and H1299 cell lines and this showed that SFXN1 promoted cell proliferation, migration, and invasion and inhibited apoptosis. SFXN1, at least partially, influenced LUAD progression via the mTOR signaling pathway. Collectively, the findings from this study demonstrated that SFXN1 promotes LUAD progression via the mTOR pathway and that SFXN1 expression is associated with clinicopathological features of LUAD. SFXN1 significantly contributes to the development of LUAD and might have potential, not only as an independent prognostic marker of LAUD but also as a promising target for LUAD therapy.

Regulation of Heme Synthesis by Mitochondrial Homeostasis Proteins

Heme plays a central role in diverse, life-essential processes that range from ubiquitous, housekeeping pathways such as respiration, to highly cell-specific ones such as oxygen transport by hemoglobin. The regulation of heme synthesis and its utilization is highly regulated and cell-specific. In this review, we have attempted to describe how the heme synthesis machinery is regulated by mitochondrial homeostasis as a means of coupling heme synthesis to its utilization and to the metabolic requirements of the cell. We have focused on discussing the regulation of mitochondrial heme synthesis enzymes by housekeeping proteins, transport of heme intermediates, and regulation of heme synthesis by macromolecular complex formation and mitochondrial metabolism. Recently discovered mechanisms are discussed in the context of the model organisms in which they were identified, while more established work is discussed in light of technological advancements.