{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Gametogenetin (GGN) is a germ cell‐specific protein encoded by a gene that generates several isoforms (GGN1, GGN2, and GGN3) via alternative splicing. These isoforms are predominantly expressed in testicular germ cells from the late pachytene spermatocyte stage through round spermatids, a period coinciding with critical events in meiotic progression."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Detailed studies indicate that the isoforms differ in their subcellular distributions: for example, GGN1 localizes along the nuclear envelope and later becomes incorporated into the sperm tail, GGN2 is largely cytoplasmic and associates with intracellular membranes—possibly implicating it in acrosome biogenesis and cell trafficking—and GGN3 is detected in the nucleus and nucleoli."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "2", "end_ref": "4"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Functional analyses using yeast two‐hybrid and colocalization approaches have revealed that GGN isoforms interact with several proteins that are critical for germ cell development. For example, GGN1 interacts with gametogenetin‐binding proteins GGNBP1 and GGNBP2 as well as the testis‐specific antizyme OAZ3, suggesting that these proteins may form a complex that is important for the regulation of spermatogenesis."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}, {"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Moreover, interactions of GGN1 (and its isoforms) with proteins such as POG/FANCL—which is involved in DNA repair—and CRISP2, have been observed. The GGN1–CRISP2 interaction, for instance, suggests a role in sperm tail development and motility, while the association with FANCL/POG and experimental evidence linking GGN with repair of DNA double‐strand breaks point to a contribution in meiotic recombination and chromatin remodeling."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}, {"type": "fg_fs", "start_ref": "6", "end_ref": "8"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In humans, localization of GGN1 in testicular pachytene spermatocytes and spermatids as well as in ovarian granulosa cells suggests that the protein may have roles in both male and female germ cell differentiation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Finally, clinical genetic studies have identified frameshift mutations in GGN in patients with globozoospermia—a severe form of male infertility marked by aberrant acrosome formation—highlighting the significance of GGN in ensuring proper sperm head development and acrosomal integrity."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Overall, the available evidence supports a model in which GGN and its isoforms function as integral components of a testis‐specific protein network that governs meiotic progression, DNA repair, cellular trafficking, and the terminal differentiation of germ cells, thereby ensuring the generation of functional spermatozoa.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Jin Zhang, Yan Wang, Yu Zhou, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Yeast two-hybrid screens imply that GGNBP1, GGNBP2 and OAZ3 are potential interaction partners of testicular germ cell-specific protein GGN1."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "FEBS Lett (2005)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.febslet.2004.10.112"}], "href": "https://doi.org/10.1016/j.febslet.2004.10.112"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15642376"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15642376"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Baisong Lu, Colin E Bishop "}, {"type": "b", "children": [{"type": "t", "text": "Mouse GGN1 and GGN3, two germ cell-specific proteins from the single gene Ggn, interact with mouse POG and play a role in spermatogenesis."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2003)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M211023200"}], "href": "https://doi.org/10.1074/jbc.M211023200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "12574169"}], "href": "https://pubmed.ncbi.nlm.nih.gov/12574169"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "D Jamsai, M A Sarraj, D J Merriner, et al. "}, {"type": "b", "children": [{"type": "t", "text": "GGN1 in the testis and ovary and its variance within the Australian fertile and infertile male population."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Int J Androl (2011)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/j.1365-2605.2010.01127.x"}], "href": "https://doi.org/10.1111/j.1365-2605.2010.01127.x"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "21114676"}], "href": "https://pubmed.ncbi.nlm.nih.gov/21114676"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Qingguo Zhao, Yu Zhou, Zhiguo Cao, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Germ-cell specific protein gametogenetin protein 2 (GGN2), expression in the testis, and association with intracellular membrane."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Mol Reprod Dev (2005)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1002/mrd.20313"}], "href": "https://doi.org/10.1002/mrd.20313"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15892049"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15892049"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Yu Zhou, Qingguo Zhao, Colin E Bishop, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Identification and characterization of a novel testicular germ cell-specific gene Ggnbp1."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Mol Reprod Dev (2005)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1002/mrd.20214"}], "href": "https://doi.org/10.1002/mrd.20214"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15625700"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15625700"}]}, {"type": "r", "ref": 6, "children": [{"type": "t", "text": "Kaimin Guo, Yan He, Lingyun Liu, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Ablation of Ggnbp2 impairs meiotic DNA double-strand break repair during spermatogenesis in mice."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Cell Mol Med (2018)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/jcmm.13751"}], "href": "https://doi.org/10.1111/jcmm.13751"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "30055035"}], "href": "https://pubmed.ncbi.nlm.nih.gov/30055035"}]}, {"type": "r", "ref": 7, "children": [{"type": "t", "text": "Duangporn Jamsai, Deborah M Bianco, Stephanie J Smith, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Characterization of gametogenetin 1 (GGN1) and its potential role in male fertility through the interaction with the ion channel regulator, cysteine-rich secretory protein 2 (CRISP2) in the sperm tail."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Reproduction (2008)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1530/REP-07-0485"}], "href": "https://doi.org/10.1530/REP-07-0485"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "18502891"}], "href": "https://pubmed.ncbi.nlm.nih.gov/18502891"}]}, {"type": "r", "ref": 8, "children": [{"type": "t", "text": "Qing-Guo Zhao, Bai-Song Lu, Pei-Tang Huang "}, {"type": "b", "children": [{"type": "t", "text": "[Functions of FANCL in primordial germ cell formation and Fanconi anemia]."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Yi Chuan Xue Bao (2005)"}]}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "16201245"}], "href": "https://pubmed.ncbi.nlm.nih.gov/16201245"}]}, {"type": "r", "ref": 9, "children": [{"type": "t", "text": "M S Oud, Ö Okutman, L A J Hendricks, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Exome sequencing reveals novel causes as well as new candidate genes for human globozoospermia."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Hum Reprod (2020)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1093/humrep/dez246"}], "href": "https://doi.org/10.1093/humrep/dez246"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "31985809"}], "href": "https://pubmed.ncbi.nlm.nih.gov/31985809"}]}]}]}