Heterogeneity of ferrous iron‐containing endolysosomes and effects of endolysosome iron on endolysosome numbers, sizes, and localization patterns. Issue 1 (23rd February 2022)

• Record Type: Journal Article
• Authors: Halcrow, Peter W.; Kumar, Nirmal; Afghah, Zahra; Fischer, Jalyn P.; Khan, Nabab; Chen, Xuesong; Meucci, Olimpia; Geiger, Jonathan D.
• Is Part Of: Journal of neurochemistry. Volume 161:Issue 1(2022)
• Page Start: 69
• Page End: 83
• Publication Date: 2022-02-23
• Subjects: Deferoxamine -- Endolysosomes -- FeRhoNox‐1 -- ferric ammonium citrate -- Golgi -- iron; Neurochemistry -- Periodicals; 616.8042
• DOI: 10.1111/jnc.15583
• Languages: English
• ISSNs: 0022-3042

Abstract

Abstract: Endolysosomes are key regulators of iron metabolism and are central to iron trafficking and redox signaling. Iron homeostasis is linked to endolysosome acidity and inhibition of endolysosome acidity triggers iron dysregulation. Because of the physiological importance and pathological relevance of ferrous iron (Fe 2+ ), we determined levels of Fe 2+ specifically and quantitatively in endolysosomes as well as the effects of Fe 2+ on endolysosome morphology, distribution patterns, and function. The fluorescence dye FeRhoNox‐1 was specific for Fe 2+ and localized to endolysosomes in U87MG astrocytoma cells and primary rat cortical neurons; in U87MG cells the endolysosome concentration of Fe 2+ ([Fe 2+ ]el ) was 50.4 μM in control cells, 73.6 μM in ferric ammonium citrate (FAC) treated cells, and 12.4 μM in cells treated with the iron chelator deferoxamine (DFO). Under control conditions, in primary rat cortical neurons, [Fe 2+ ]el was 32.7 μM. Endolysosomes containing the highest levels of Fe 2+ were located perinuclearly. Treatment of cells with FAC resulted in endolysosomes that were less acidic, increased in numbers and sizes, and located further from the nucleus; opposite effects were observed for treatments with DFO. Thus, FeRhoNox‐1 is a useful probe for the study of endolysosome Fe 2+, and much more work is needed to understand better the physiological significance and pathological relevance of endolysosomes classified according to their heterogeneous iron content Cover Image for this issue: https://doi.org/10.1111/jnc.15396 Abstract : Endolysosomes are central to iron trafficking and redox signaling. Iron homeostasis is linked to endolysosome acidity and inhibition of endolysosome acidity triggers iron dysregulation. With a view towards the physiological and pathological relevance of ferrous iron (Fe 2+ ), we determined effects of Fe 2+ on endolysosome morphology, distribution patterns, and function. The fluorescence dye FeRhoNox‐1 was specific for Fe 2+ and localized to endolysosomes in U87MG astrocytoma cells and primary rat cortical neurons; in U87MG cells the endolysosome concentration of Fe 2+ ([Fe 2+ ]el ) was 50.4 µM in control cells, 73.6 µM in ferric ammonium citrate (FAC) treated cells, and 12.4 µM in cells treated with the iron chelator deferoxamine (DFO). Endolysosomes containing the highest levels of Fe 2+ were located perinuclearly. Treatment of cells with FAC resulted in endolysosomes that were less acidic, increased in numbers and size, and located further from the nucleus; opposite effects were observed for treatments with DFO. Thus, FeRhoNox‐1 is a useful probe for the study of endolysosome Fe 2+ . Primary neuron demonstrating FeRhoNox‐1‐positive ferrous iron in LysoTracker‐positive endolysosomes (yellow puncta) concentrated perinuclearly (DAPI‐positive nucleus, blue). Cover Image for this issue: https://doi.org/10.1111/jnc.15396