{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nTransition protein 1 (TNP1) is a major nuclear protein that plays a critical role during spermiogenesis by replacing somatic histones with protamines to achieve the high degree of chromatin condensation necessary for mature sperm formation. Perturbations in the TNP1 gene—including mutations and altered expression levels—have been linked to male infertility, as illustrated by screening studies that evaluate clinically relevant alterations in spermatogenesis‐associated genes."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nQuantitative analysis of sperm transcripts has revealed that lower levels of TNP1 are associated with abnormal sperm quality. For instance, reduced TNP1 expression in asthenozoospermic patients points to its involvement in ensuring proper chromatin remodeling and sperm motility. Similar downregulation of TNP1 has also been observed in contexts of lifestyle-related toxic exposures such as tobacco smoke, suggesting that environmental factors may disrupt its normal expression and thus compromise sperm function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nGenetic studies have further underscored the importance of TNP1 for normal spermatogenesis. Detailed sequencing of TNP1 has identified various mutations—including a notable 15‐nucleotide deletion in its promoter region—that can reduce gene expression and are associated with conditions such as azoospermia. Haplotype analyses reinforce that specific allele combinations in the TNP1 gene may serve as risk factors for male infertility, thereby confirming its essential role in germ cell development."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond its established role in sperm chromatin remodeling, TNP1 has also been implicated as an autoantigen in systemic lupus erythematosus. Autoantibodies against TNP1 have been detected in patients with lupus nephritis, and the formation of immune complexes involving TNP1 may contribute to glomerular deposition and subsequent renal pathology, establishing an intriguing link between reproductive proteins and autoimmune disease."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nFinally, the detection of TNP1 protein in ejaculated spermatids, particularly in samples from patients with various forms of male infertility, serves as a marker for disrupted spermiogenesis. Its persistent expression in immature germ cells further emphasizes the protein’s pivotal function in the terminal differentiation of spermatozoa, highlighting that any deviation from its normal expression pattern can indicate an arrest in sperm maturation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Vincent W Aoki, Greg L Christensen, John F Atkins, et al. 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"}, {"type": "b", "children": [{"type": "t", "text": "Quantitative assessment of transition proteins 1, 2 spermatid-specific linker histone H1-like protein transcripts in spermatozoa from normozoospermic and asthenozoospermic men."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Arch Androl (2007)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1080/01485010701426430"}], "href": "https://doi.org/10.1080/01485010701426430"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "17852044"}], "href": "https://pubmed.ncbi.nlm.nih.gov/17852044"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Houda Amor, Ali Zeyad, Mohamad Eid Hammadeh "}, {"type": "b", "children": [{"type": "t", "text": "Tobacco smoking and its impact on the expression level of sperm nuclear protein genes: H2BFWT, TNP1, TNP2, PRM1 and PRM2."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Andrologia (2021)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/and.13964"}], "href": "https://doi.org/10.1111/and.13964"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "33440036"}], "href": "https://pubmed.ncbi.nlm.nih.gov/33440036"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "A Khattri, S S Bhushan, V Sireesha, et al. 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