{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nMGARP, also known as OSAP, was originally identified as a mitochondria‐localized protein that is prominently expressed in steroidogenic tissues. In these cells—including those from the ovary, adrenal gland, and testis—MGARP’s presence within mitochondria is critical for maintaining mitochondrial abundance and proper morphology, which in turn supports steroid hormone biosynthesis. In contrast, other mitochondrial proteins, such as HUMMR (a HIF‑1α–induced factor), regulate mitochondrial transport in neurons under hypoxic conditions, highlighting the diverse strategies cells employ to optimize mitochondrial function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn the retina, MGARP/OSAP is highly expressed in mitochondria‐rich layers—such as the inner segments of photoreceptors, outer plexiform, and ganglion cell layers—where its proper function is essential for maintaining mitochondrial morphology. Experiments have shown that overexpression of a truncated MGARP variant triggers severe mitochondrial aggregation, which suggests that MGARP may play a role in organizing mitochondrial networks and possibly assembling ion channels on the mitochondrial membrane to support retinal energetic metabolism."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nDetailed ultrastructural studies have now precisely localized MGARP to the inner and cristae membranes of mitochondria. Overexpression of full‐length MGARP induces mitochondrial remodeling—including deformation and collapse of the mitochondrial network—while loss of its transmembrane domain abolishes mitochondrial localization and function. In steroidogenic cells, these effects are linked to disruptions in mitochondrial integrity, which ultimately impair hormone biosynthesis. Together, these findings underscore MGARP’s pivotal role in preserving mitochondrial architecture and cellular metabolism."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": ""}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Tadashi Matsumoto, Kazuhiro Minegishi, Hitoshi Ishimoto, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Expression of ovary-specific acidic protein in steroidogenic tissues: a possible role in steroidogenesis."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Endocrinology (2009)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1210/en.2008-1584"}], "href": "https://doi.org/10.1210/en.2008-1584"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "19325000"}], "href": "https://pubmed.ncbi.nlm.nih.gov/19325000"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Yan Li, Seung Lim, David Hoffman, et al. "}, {"type": "b", "children": [{"type": "t", "text": "HUMMR, a hypoxia- and HIF-1alpha-inducible protein, alters mitochondrial distribution and transport."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Cell Biol (2009)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1083/jcb.200811033"}], "href": "https://doi.org/10.1083/jcb.200811033"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "19528298"}], "href": "https://pubmed.ncbi.nlm.nih.gov/19528298"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Shaoling Qi, Yifeng Wang, Mingxue Zhou, et al. "}, {"type": "b", "children": [{"type": "t", "text": "A mitochondria-localized glutamic acid-rich protein (MGARP/OSAP) is highly expressed in retina that exhibits a large area of intrinsic disorder."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Mol Biol Rep (2011)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s11033-010-9948-x"}], "href": "https://doi.org/10.1007/s11033-010-9948-x"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20107910"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20107910"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Da Jin, Rui Li, Dongxue Mao, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Mitochondria-localized glutamic acid-rich protein (MGARP) gene transcription is regulated by Sp1."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "PLoS One (2012)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1371/journal.pone.0050053"}], "href": "https://doi.org/10.1371/journal.pone.0050053"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23209644"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23209644"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Shuping Zhang "}, {"type": "b", "children": [{"type": "t", "text": "MGARP is ultrastructurally located in the inner faces of mitochondrial membranes."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochem Biophys Res Commun (2019)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.bbrc.2019.06.028"}], "href": "https://doi.org/10.1016/j.bbrc.2019.06.028"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "31202457"}], "href": "https://pubmed.ncbi.nlm.nih.gov/31202457"}]}]}]}