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General Comment |
MacDonald et al. (1995) identified and purified an immunoglobulin E (IgE)-dependent histamine-releasing factor (which
they symbolized HRF) produced by lymphocytes of atopic children and present in biological fluids of allergic patients.
Amino-terminal sequencing revealed extensive homology to the mouse protein, p21, and identity to its human homolog, p23,
. Both the human and the mouse recombinant proteins caused
histamine release from human basophils of a subpopulation of donors, and this release was dependent on IgE (OMIM 147180).
NCBI Summary:
This gene encodes a protein that is a regulator of cellular growth and proliferation. Its mRNA is highly structured and contains an oligopyrimidine tract (5'-TOP) in its 5' untranslated region that functions to repress its translation under quiescent conditions. The encoded protein is involved in a variety of cellular pathways, including apoptosis, protein synthesis and cell division. It binds to and stabilizes microtubules, and removal of this protein through phosphorylation is required for progression through mitotic and meiotic cell divisions. This gene is known to play a role in carcinogenesis, and is upregulated in some cancer cells. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Aug 2017]
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Comment |
TCTP overexpression reverses age-associated telomere attrition by upregulating telomerase activity in mouse oocytes. Jeon HJ et al. (2021) A prolonged time span between ovulation and fertilization can cause postovulatory aging of oocytes, which impairs oocyte quality and subsequent embryo development. Telomere attrition has long been considered as the primary hallmark of aging or the cause of age-associated diseases. However, the status of telomere and its regulation during postovulatory oocyte aging are poorly understood. Here we found that oocytes experience telomere shortening during postovulatory aging, although they have the capacity to maintain telomere length. However, translationally controlled tumor protein (TCTP) overexpression could reverse age-associated telomere shortening by upregulating telomerase activity in mouse oocytes. Telomere length in mature oocytes gradually decreased with postovulatory aging, which was associated with a marked reduction in TRF1 expression, decreased telomerase activity, and decreased homologous combination (HR)-based alternative lengthening of telomeres (ALT) with a concomitant increase in oxidative stress. Surprisingly, however, overexpression of TCTP led to a remarkable increase in telomere length during postovulatory aging. Notably, neither TRF1 nor BRCA1 level was altered by TCTP overexpression. Moreover, TCTP-mediated telomere lengthening was not blocked by HR inhibition. In striking contrast, telomerase activity, as well as TERT and TERC levels, increased after TCTP overexpression. Importantly, unlike the chromosome-wide distribution of endogenous TCTP, overexpressed TCTP was ectopically localized at telomeres, implying that TCTP overexpression is required to increase telomerase activity. Collectively, our results demonstrate that TCTP prevents telomere attrition during postovulatory aging by upregulating telomerase activity in mouse oocytes.//////////////////
TCTP regulates spindle assembly during postovulatory aging and prevents deterioration in mouse oocyte quality. Jeon HJ et al. (2017) If no fertilization occurs for a prolonged time following ovulation, oocytes experience a time-dependent deterioration in quality both in vivo and in vitro due to processes called postovulatory aging. Because the postovulatory aging of oocytes has marked detrimental effects on embryo development and offspring, many efforts have been made to unveil the underlying mechanisms. Here we showed that translationally controlled tumor protein (TCTP) regulates spindle assembly during postovulatory aging and prevents deterioration in mouse oocyte quality. Spindle dynamics decreased with reduced TCTP level during aging of mouse oocytes. Knockdown of TCTP accelerated the reduction of spindle dynamics, accompanying with aging-related deterioration of oocyte quality. Conversely, overexpression of TCTP prevented aging-associated decline of spindle dynamics. Moreover, the aging-related abnormalities in oocytes were rescued after TCTP overexpression, thereby improving fertilization competency and subsequent embryo development. Therefore, our results demonstrate that TCTP-mediated spindle dynamics play a key role in maintaining oocyte quality during postovulatory aging and overexpression of TCTP is sufficient to prevent aging-associated abnormalities in mouse oocytes.//////////////////
TCTP regulates spindle microtubule dynamics by stabilizing polar microtubules during mouse oocyte meiosis. Jeon HJ et al. (2016) Dynamic changes in spindle structure and function are essential for maintaining genomic integrity during the cell cycle. Spindle dynamics are highly dependent on several microtubule-associated proteins that coordinate the dynamic behavior of microtubules, including microtubule assembly, stability and organization. Here, we show that translationally controlled tumor protein (TCTP) is a novel microtubule-associated protein that regulates spindle dynamics during meiotic maturation. TCTP was expressed and widely distributed in the cytoplasm with strong enrichment at the spindle microtubules during meiosis. TCTP was found to be phosphorylated during meiotic maturation, and was exclusively localized to the spindle poles. Knockdown of TCTP impaired spindle organization without affecting chromosome alignment. These spindle defects were mostly due to the destabilization of the polar microtubules. However, the stability of kinetochore microtubules attached to chromosomes was not affected by TCTP knockdown. Overexpression of a nonphosphorylable mutant of TCTP disturbed meiotic maturation, stabilizing the spindle microtubules. In addition, Plk1 was decreased by TCTP knockdown. Taken together, our results demonstrate that TCTP is a microtubule-associating protein required to regulate spindle microtubule dynamics during meiotic maturation in mouse oocytes.//////////////////
Tpt1 activates transcription of oct4 and nanog in transplanted somatic nuclei. Koziol MJ et al. Nuclear transfer to eggs or oocytes provides a potential route for cell-replacement therapies because oocytes directly reprogram transplanted mammalian somatic-cell nuclei such that they have an embryo-like pattern of gene expression. This includes a large increase in the mRNA level of the stem-cell marker gene oct4. We have developed a novel procedure to identify new proteins that greatly increase the level of oct4 mRNA upon nuclear transfer. We have isolated Xenopus oocyte proteins that bind to the regulatory region of the mouse oct4 gene and identified these by mass spectrometry. The proteins include the retinoic-acid-receptor gamma, a known repressor of oct4 transcription, and Tpt1, a cancer-associated factor. The depletion of transcripts of retinoic-acid receptor gamma from oocytes increases oct4 and nanog transcription as expected, and depletion of tpt1 transcripts in oocytes reduces oct4 and nanog transcription in injected HeLa nuclei. An elevation of tpt1 transcripts in oocytes results in an earlier activation of oct4 transcription. Therefore, we identify a novel role for tpt1 in activating pluripotency genes upon nuclear transfer. Our results help to elucidate the mechanism by which somatic-cell nuclei are reprogrammed to have an embryo-like pattern of gene expression.
Proteomic profiling of murine oocyte maturation. Vitale AM et al. In an effort to better understand oocyte function, we utilized two-dimensional (2D) electrophoresis and mass spectrometry to identify proteins that are differentially expressed during murine oocyte maturation. Proteins from 500 germinal vesicle (GV) and metaphase II-(MII) arrested oocytes were extracted, resolved on 2D electrophoretic gels, and stained with silver. Analysis of the gels indicated that 12 proteins appeared to be differentially expressed between the GV and MII stage. These proteins were then cored from the 2D gels and identified by mass spectrometry as: transforming acidic coiled-coil protein 3 (TACC3), heat shock protein 105 (HSP105), programmed cell death six-interacting protein (PDCD6IP), stress-inducible phosphoprotein (STI1), importin alpha2, adenylsuccinate synthase (ADDS), nudix, spindlin, lipocalin, lysozyme, translationally controlled tumor protein (TCTP), and nucleoplasmin 2 (NPM2). Interestingly, PDCD6IP, importin alpha2, spindlin, and NPM2 appear slightly larger in mass and more acidic on the MII oocyte gel compared to the GV oocyte gel, suggesting that they may be post-translationally modified during oocyte maturation. Given NPM2 is an oocyte-restricted protein, we chose to further investigate its properties during oocyte maturation and preimplantation development. Real-Time RT-PCR showed that NPM2 mRNA levels rapidly decline at fertilization. Indirect immunofluorescence analysis showed that, with the exception of cortical localization in MII-arrested oocytes, NPM2 is localized to the nucleus of both GV stage oocytes and all stages of preimplantation embryos. We then performed one-dimensional (1D) western blot analysis of mouse oocytes and preimplantation embryos and found that, as implicated by the 2D gel comparison, NPM2 undergoes a phosphatase-sensitive electrophoretic mobility shift during the GV to MII transition. The slower migrating NPM2 form is also present in pronuclear embryos but by the two-cell stage, the majority of NPM2 exists as the faster migrating form, which persists to the blastocyst stage. Mol. Reprod. Dev. (c) 2006 Wiley-Liss, Inc.
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