Alternative titles; symbols
HGNC Approved Gene Symbol: TNP1
Cytogenetic location: 2q35 Genomic coordinates (GRCh38): 2:216,859,458-216,860,064 (from NCBI)
Transition protein-1 is a spermatid-specific product of the haploid genome which replaces histone and is itself replaced in the mature sperm by the protamines (see PRM1, 182880; PRM2, 182890) (Luerssen et al., 1990).
Yelick et al. (1991) isolated and sequenced the mouse Tnp1 gene.
Luerssen et al. (1990) reported that the human TNP1 gene is 1.2 kb long with 1 intron of 200 bases.
By somatic cell hybridization and in situ hybridization, Luerssen et al. (1990) mapped the TNP1 gene to chromosome 2q35-q36.
Yelick et al. (1991) mapped the mouse Tnp1 gene to chromosome 1 by analysis of restriction fragment length variants (RFLVs) in an interspecific backcross. They found that it was located telomeric of Myl1 (myosin fast skeletal muscle light chain; 160780) and centromeric of Vil (villin; 193040).
By analyzing human spermatogenesis single-cell RNA sequencing data, Salehi et al. (2021) showed that differential expression of SPACDR (619782) and TNP1 could differentiate 2 round spermatid subcellules.
Yu et al. (2000) generated mice lacking the major transition nuclear protein, TP1, by targeted deletion of the Tnp1 gene in mouse embryonic stem cells. Surprisingly, testis weights and sperm production were normal in the mutant mice, and only subtle abnormalities were detected in sperm morphology. Electron microscopy showed large rod-like structures in the chromatin of mutant step 13 spermatids, in contrast to the fine chromatin fibrils observed in wildtype. Steps 12-13 spermatid nuclei from the testis of Tnp1-null mice contained, in place of TP1, elevated levels of TP2 (TNP2; 190232) and some PRM2 precursor. Most of the precursor was processed to mature PRM2, but high levels of incompletely processed forms remained in epididymal spermatozoa. Sperm motility was severely reduced, and approximately 60% of Tnp1-null males were infertile. Yu et al. (2000) concluded that TP1 is not essential for histone displacement or chromatin condensation. The absence of TP1 may partially be compensated for by TP2 and PRM2 precursor, but this dysregulation of nucleoprotein replacement results in an abnormal pattern of chromatin condensation and in reduced fertility.
Okada et al. (2007) used a loss-of-function approach to demonstrate that the mouse H3K9me2/1-specific demethylase Jhdm2a (611512) is essential for spermatogenesis. They showed that Jhdm2a-deficient mice exhibit postmeiotic chromatin condensation defects, and that Jhdm2a directly binds to and controls the expression of Tnp1 and protamine-1 (PRM1; 182880) genes, the products of which are required for packaging and condensation of sperm chromatin. Okada et al. (2007) concluded that their work uncovered a role for JHDM2A in spermatogenesis and revealed transition nuclear protein and protamine genes as direct targets of JHDM2A.
Luerssen, H., Mattei, M.-G., Schroter, M., Grzeschik, K.-H., Adham, I. M., Engel, W. Nucleotide sequence of the gene for human transition protein 1 and its chromosomal localization on chromosome 2. Genomics 8: 324-330, 1990. [PubMed: 2249851] [Full Text: https://doi.org/10.1016/0888-7543(90)90289-7]
Okada, Y., Scott, G., Ray, M. K., Mishina, Y., Zhang, Y. Histone demethylase JHDM2A is critical for Tnp1 and Prm1 transcription and spermatogenesis. Nature 450: 119-123, 2007. [PubMed: 17943087] [Full Text: https://doi.org/10.1038/nature06236]
Salehi, N., Karimi-Jafari, M. H., Totonchi, M., Amiri-Yekta, A. Integration and gene co-expression network analysis of scRNA-seq transcriptomes reveal heterogeneity and key functional genes in human spermatogenesis. Sci. Rep. 11: 19089, 2021. [PubMed: 34580317] [Full Text: https://doi.org/10.1038/s41598-021-98267-3]
Yelick, P. C., Kozak, C., Kwon, Y. K., Seldin, M. F., Hecht, N. B. The mouse transition protein 1 gene contains a B1 repetitive element and is located on chromosome 1. Genomics 11: 687-694, 1991. [PubMed: 1685480] [Full Text: https://doi.org/10.1016/0888-7543(91)90076-q]
Yu, Y. E., Zhang, Y., Unni, E., Shirley, C. R., Deng, J. M., Russell, L. D., Weil, M. M., Behringer, R. R., Meistrich, M. L. Abnormal spermatogenesis and reduced fertility in transition nuclear protein 1-deficient mice. Proc. Nat. Acad. Sci. 97: 4683-4688, 2000. [PubMed: 10781074] [Full Text: https://doi.org/10.1073/pnas.97.9.4683]