1
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Fan R, Liu F, Gong Q, Liu D, Tang S, Shen D. KHDRBS1 as a novel prognostic signaling biomarker influencing hepatocellular carcinoma cell proliferation, migration, immune microenvironment, and drug sensitivity. Front Immunol 2024; 15:1393801. [PMID: 38660302 PMCID: PMC11041018 DOI: 10.3389/fimmu.2024.1393801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 03/27/2024] [Indexed: 04/26/2024] Open
Abstract
Background Human tumors pose significant challenges, with targeted therapy against specific molecular targets or signaling pathways being a mainstay alongside surgical resection. Previous studies have implicated KHDRBS1 in the oncogenesis of certain human tumors such as colorectal and prostate cancers, underscoring its potential as a therapeutic target. However, the comprehensive expression pattern of KHDRBS1 in hepatocellular carcinoma (HCC) warrants further exploration. Methods Integrating and analyzing multi-omics, multi-cohort data from public databases, coupled with clinical samples and molecular biology validation, we elucidate the oncogenic role of KHDRBS1 in HCC progression. Additionally, leveraging HCC single-cell sequencing data, we segregate malignant cells into KHDRBS1-positive and negative subsets, uncovering significant differences in their expression profiles and functional roles. Results Our study identifies KHDRBS1 as a tumor-promoting factor in HCC, with its positivity correlating with tumor progression. Furthermore, we highlight the clinical significance of KHDRBS1-positive malignant cells, aiming to further propel its clinical utility. Conclusion KHDRBS1 plays a key role in HCC development. This study provides crucial insights for further investigation into KHDRBS1 as a therapeutic target in HCC.
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MESH Headings
- Humans
- Carcinoma, Hepatocellular/immunology
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/pathology
- Carcinoma, Hepatocellular/metabolism
- Liver Neoplasms/immunology
- Liver Neoplasms/genetics
- Liver Neoplasms/pathology
- Liver Neoplasms/metabolism
- Tumor Microenvironment/immunology
- Cell Proliferation
- Biomarkers, Tumor
- Cell Movement
- Prognosis
- Signal Transduction
- Cell Line, Tumor
- Gene Expression Regulation, Neoplastic
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Drug Resistance, Neoplasm/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Adaptor Proteins, Signal Transducing/genetics
- Male
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Affiliation(s)
- Rui Fan
- Xiamen Cell Therapy Research Center, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Fahui Liu
- Xiamen Cell Therapy Research Center, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Qiming Gong
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
- Baise Key Laboratory for Metabolic Diseases (Youjiang Medical University for Nationalities), Education Department of Guangxi Zhuang Autonomous Region, Baise, China
| | - Donghua Liu
- Xiamen Cell Therapy Research Center, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Shihang Tang
- Xiamen Cell Therapy Research Center, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Dongyan Shen
- Xiamen Cell Therapy Research Center, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
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2
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Frączyk T, Bonna A, Stefaniak E, Wezynfeld NE, Bal W. Peptide Bond Cleavage by Ni(II) Ions within the Nuclear Localization Signal Sequence. Chem Biodivers 2019; 17:e1900652. [PMID: 31869504 DOI: 10.1002/cbdv.201900652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/20/2019] [Indexed: 12/30/2022]
Abstract
Nickel is harmful to humans, being both carcinogenic and allergenic. However, the mechanisms of this toxicity are still unresolved. We propose that Ni(II) ions disintegrate proteins by hydrolysis of peptide bonds preceding the Ser/Thr-Xaa-His sequences. Such sequences occur in nuclear localization signals (NLSs) of human phospholipid scramblase 1, Sam68-like mammalian protein 2, and CLK3 kinase. We performed spectroscopic experiments showing that model nonapeptides derived from these NLSs bind Ni(II) at physiological pH. We also proved that these sequences are prone to Ni(II) hydrolysis. Thus, the aforementioned NLSs may be targets for nickel toxicity. This implies that Ni(II) ions disrupt the transport of some proteins from cytoplasm to cell nucleus.
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Affiliation(s)
- Tomasz Frączyk
- Department of Immunology, Transplantology and Internal Medicine, Medical University of Warsaw, Nowogrodzka 59, 02-006, Warsaw, Poland.,Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Arkadiusz Bonna
- Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QW, Cambridge, United Kingdom
| | - Ewelina Stefaniak
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Nina E Wezynfeld
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland.,Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland
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3
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Sernbo S, Borrebaeck CAK, Uhlén M, Jirström K, Ek S. Nuclear T-STAR protein expression correlates with HER2 status, hormone receptor negativity and prolonged recurrence free survival in primary breast cancer and decreased cancer cell growth in vitro. PLoS One 2013; 8:e70596. [PMID: 23923007 PMCID: PMC3726654 DOI: 10.1371/journal.pone.0070596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 06/24/2013] [Indexed: 01/08/2023] Open
Abstract
T-STAR (testis-signal transduction and activation of RNA) is an RNA binding protein, containing an SH3-binding domain and thus potentially playing a role in integration of cell signaling and RNA metabolism. The specific function of T-STAR is unknown and its implication in cancer is poorly characterized. Expression of T-STAR has been reported in human testis, muscle and brain tissues, and is associated with a growth-inhibitory role in immortalized fibroblasts. The aim of this paper was to investigate the functional role of T-STAR through (i) survival analysis of patients with primary invasive breast cancer and (ii) experimental evaluation of the effect of T-STAR on breast cancer cell growth. T-STAR protein expression was analysed by immunohistochemistry (IHC) in tissue microarrays with tumors from 289 patients with primary invasive breast cancer, and correlations to clinicopathological characteristics, recurrence-free and overall survival (RFS and OS) and established tumor markers such as HER2 and ER status were evaluated. In addition, the function of T-STAR was investigated using siRNA-mediated knock-down and overexpression of the gene in six breast cancer cell lines. Of the tumors analysed, 86% showed nuclear T-STAR expression, which was significantly associated with an improved RFS and strongly associated with positive HER2 status and negative hormone receptor status. Furthermore, experimental data showed that overexpression of T-STAR decreased cellular growth while knock-down increased it, as shown both by thymidine incorporation and metabolic activity. In summary, we demonstrate that T-STAR protein expression correlates with an improved RFS in primary breast cancer. This is supported by functional data, indicating that T-STAR regulation is of importance both for breast cancer biology and clinical outcome but future studies are needed to determine a potential role in patient stratification.
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Affiliation(s)
- Sandra Sernbo
- Department of Immunotechnology, CREATE Health, Lund University, Lund, Sweden
| | | | - Mathias Uhlén
- Department of Biotechnology, AlbaNova University Center, Royal Institute of Technology, Stockholm, Sweden
| | - Karin Jirström
- Department of Clinical Sciences, Division of Pathology, Lund University, Skåne University Hospital, Lund, Sweden
| | - Sara Ek
- Department of Immunotechnology, CREATE Health, Lund University, Lund, Sweden
- * E-mail:
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4
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Expression and functions of the star proteins Sam68 and T-STAR in mammalian spermatogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 693:67-81. [PMID: 21189686 DOI: 10.1007/978-1-4419-7005-3_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Spermatogenesis is one of the few major developmental pathways which are still ongoing in the adult. In this chapter we review the properties of Sam68 and T-STAR, which are the STAR proteins functionally implicated in mammalian spermatogenesis. Sam68 is a ubiquitously expressed member of the STAR family, but has an essential role in spermatogenesis. Sam68 null mice are male infertile and at least in part this is due to a failure in important translational controls that operate during and after meiosis. The homologous T-STAR protein has a much more restricted anatomic expression pattern than Sam68, with highest levels seen in the testis and the developing brain. The focus of this chapter is the functional role of Sam68 and T-STAR proteins in male germ cell development. Since these proteins are known to have many cellular functions we extrapolate from other cell types and tissues to speculate on each of their likely functions within male germ cells, including control of alternative pre-mRNA splicing patterns in male germ cells.
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5
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Abd El-Aziz MM, Patel RJ, El-Ashry MF, Barragan I, Marcos I, Borrego S, Antiñolo G, Bhattacharya SS. Exclusion of Four Candidate Genes, KHDRBS2, PTP4A1, KIAA1411 and OGFRL1, as Causative of Autosomal Recessive Retinitis Pigmentosa. Ophthalmic Res 2005; 38:19-23. [PMID: 16192744 DOI: 10.1159/000088493] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 05/26/2005] [Indexed: 11/19/2022]
Abstract
To identify the disease gene in 6 Spanish families with autosomal recessive retinitis pigmentosa linked to the RP25 locus, mutation screening of 4 candidate genes, KHDRBS2, PTP4A1, KIAA1411 and OGFRL1, was undertaken based on their expression or functional relevance to the retina. Twenty-six single nucleotide polymorphisms were identified, of which 14 were novel. Even though no pathological mutations were detected, these genes however remain as good candidates for other retinal degenerations mapping to the same chromosomal region.
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Affiliation(s)
- Mai M Abd El-Aziz
- Department of Molecular Genetics, Institute of Ophthalmology, London, UK.
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6
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Cohen CD, Doran PP, Blattner SM, Merkle M, Wang GQ, Schmid H, Mathieson PW, Saleem MA, Henger A, Rastaldi MP, Kretzler M. Sam68-like mammalian protein 2, identified by digital differential display as expressed by podocytes, is induced in proteinuria and involved in splice site selection of vascular endothelial growth factor. J Am Soc Nephrol 2005; 16:1958-65. [PMID: 15901763 DOI: 10.1681/asn.2005020204] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Podocytes, the glomerular epithelial cells of the kidney, share important features with neuronal cells. In addition to phenotypical and functional similarities, a number of gene products have been found to be expressed exclusively or predominantly by both cell types. With the hypothesis of a common transcriptome shared by podocytes and neurons, digital differential display was used to identify novel podocyte-expressed gene products. Comparison of brain and kidney cDNA libraries with those of other organs identified Sam68-like mammalian protein 2 (SLM-2), a member of the STAR family of RNA processing proteins, as expressed by podocytes. SLM-2 expression was found to be restricted in the kidney to podocytes. In proteinuric diseases, SLM-2, a known regulator of neuronal mRNA splice site selection, was found significantly upregulated on mRNA and protein levels. Knockdown of SLM-2 by short interfering RNA in podocytes was performed to evaluate its biologic role. RNA splicing of vascular endothelial growth factor (VEGF), a key regulator of the filtration barrier and expressed as functionally distinct splice isoforms, was evaluated. VEGF(165) expression was found to be reduced by 25% after SLM-2 knockdown. In vivo, the glomerular expression of SLM-2 correlated with the mRNA levels of VEGF(165). This study demonstrates the power of digital differential display to predict cell type-specific gene expression by hypothesis-driven analysis of tissue cDNA libraries. SLM-2-dependent VEGF splicing indicates the importance of mRNA splice site selection for glomerular filtration barrier function.
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Affiliation(s)
- Clemens D Cohen
- Medizinische Poliklinik, Ludwig-Maximilians-University, Pettenkoferstrasse 8A, Munich, 80336, Germany.
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7
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Elliott DJ. The role of potential splicing factors including RBMY, RBMX, hnRNPG-T and STAR proteins in spermatogenesis. ACTA ACUST UNITED AC 2005; 27:328-34. [PMID: 15595951 DOI: 10.1111/j.1365-2605.2004.00496.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Investigations into the RBM gene family are uncovering networks of protein interactions which regulate RNA processing, and which might operate downstream of signal transduction pathways. Similar pathways likely operate in germ cells and somatic cells, with RBMY, hnRNPGT and T-STAR proteins providing germ cell-specific components. These pathways may be important for normal germ cell development, and might be compromised in men with Y chromosome deletions affecting RBMY gene expression. The STAR proteins have multiple functions in pre-mRNA splicing, signalling and cell cycle control. These processes might have to be very finely regulated during germ cell development, which involves both two sequential meiotic divisions (meiosis I and II) as well as mitotic (spermatogonial) cell divisions, and which is controlled by paracrine signalling within the testis from Sertoli cells.
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Affiliation(s)
- David J Elliott
- Institute of Human Genetics, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 3BZ, UK.
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8
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Haegebarth A, Heap D, Bie W, Derry JJ, Richard S, Tyner AL. The nuclear tyrosine kinase BRK/Sik phosphorylates and inhibits the RNA-binding activities of the Sam68-like mammalian proteins SLM-1 and SLM-2. J Biol Chem 2004; 279:54398-404. [PMID: 15471878 DOI: 10.1074/jbc.m409579200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Expression of the intracellular tyrosine kinase BRK/Sik is epithelial-specific and regulated during differentiation. Only a few substrates have been identified for BRK/Sik, including the KH domain containing RNA-binding protein Sam68 and the novel adaptor protein BKS. Although the physiological role of Sam68 is unknown, it has been shown to regulate mRNA transport, pre-mRNA splicing, and polyadenylation. Here we demonstrate that the Sam68-like mammalian proteins SLM-1 and SLM-2 but not the related KH domain containing heterogeneous nuclear ribonucleoprotein K are novel substrates of BRK/Sik. The expression of active BRK/Sik results in increased SLM-1 and SLM-2 phosphorylation and increased retention of BRK/Sik within the nucleus. The phosphorylation of SLM-1 and SLM-2 has functional relevance and leads to inhibition of their RNA-binding abilities. We show that SLM-1, SLM-2, and BRK/Sik have restricted patterns of expression unlike the ubiquitously expressed Sam68. Moreover, BRK/Sik, SLM-1, and Sam68 transcripts were coexpressed in the mouse gastrointestinal tract and skin, suggesting that SLM-1 and Sam68 could be physiologically relevant BRK/Sik targets in vivo. The ability of BRK/Sik to negatively regulate the RNA-binding activities of the KH domain RNA binding proteins SLM-1 and Sam68 may have an impact on the posttranscriptional regulation of epithelial cell gene expression.
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Affiliation(s)
- Andrea Haegebarth
- Departments of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607, USA
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9
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Venables JP, Dalgliesh C, Paronetto MP, Skitt L, Thornton JK, Saunders PT, Sette C, Jones KT, Elliott DJ. SIAH1 targets the alternative splicing factor T-STAR for degradation by the proteasome. Hum Mol Genet 2004; 13:1525-34. [PMID: 15163637 DOI: 10.1093/hmg/ddh165] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
T-STAR is one of three members of the SAM68 family of RNA-binding proteins that have been shown to be involved in various gene expression pathways including the control of pre-mRNA splicing. We employed a two-hybrid screen to identify proteins that interact with human T-STAR. The predominant interacting proteins were the E3 ubiquitin ligases SIAH1 and SIAH2. We found that SIAH1 bound to an octapeptide sequence in T-STAR targeting it for proteasome-dependent degradation. Rodent T-STAR orthologues (also known as etoile or SLM2) were not targeted for degradation by SIAH1. However a double amino acid substitution of mouse T-STAR that mimics the human SIAH1-binding site brought mouse T-STAR under in vivo control of SIAH1. Using a minigene transfection assay for alternative splicing activity we showed that human T-STAR, like its rodent orthologues can influence splice site choice and that human, but not mouse, T-STAR-dependent alternative splicing is modulated by SIAH1. Western blots of protein from purified germ cells indicated that SIAH1 protein expression peaks in meiosis. In mouse, T-STAR is co-expressed with SIAH1 during meiosis but, in humans, T-STAR is only strongly expressed after meiosis. Comparative sequence analysis showed SIAH-mediated proteasomal degradation of T-STAR has evolved in the primate lineage. Collectively these data suggest that SIAH-mediated down regulation of alternative splicing may be an important developmental difference between otherwise highly conserved T-STAR proteins.
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Affiliation(s)
- Julian P Venables
- Institute of Human Genetics, International Centre for Life, Newcastle upon Tyne, UK
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10
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Hyslop LA, Nixon VL, Levasseur M, Chapman F, Chiba K, McDougall A, Venables JP, Elliott DJ, Jones KT. Ca2+-promoted cyclin B1 degradation in mouse oocytes requires the establishment of a metaphase arrest. Dev Biol 2004; 269:206-19. [PMID: 15081368 DOI: 10.1016/j.ydbio.2004.01.030] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2003] [Revised: 01/22/2004] [Accepted: 01/27/2004] [Indexed: 02/05/2023]
Abstract
CDK1-cyclin B1 is a universal cell cycle kinase required for mitotic/meiotic cell cycle entry and its activity needs to decline for mitotic/meiotic exit. During their maturation, mouse oocytes proceed through meiosis I and arrest at second meiotic metaphase with high CDK1-cyclin B1 activity. Meiotic arrest is achieved by the action of a cytostatic factor (CSF), which reduces cyclin B1 degradation. Meiotic arrest is broken by a Ca2+ signal from the sperm that accelerates it. Here we visualised degradation of cyclin B1::GFP in oocytes and found that its degradation rate was the same for both meiotic divisions. Ca2+ was the necessary and sufficient trigger for cyclin B1 destruction during meiosis II; but it played no role during meiosis I and furthermore could not accelerate cyclin B1 destruction during this time. The ability of Ca2+ to trigger cyclin B1 destruction developed in oocytes following a restabilisation of cyclin B1 levels at about 12 h of culture. This was independent of actual first polar body extrusion. Thus, in metaphase I arrested oocytes, Ca2+ would induce cyclin B1 destruction and the first polar body would be extruded. In contrast to some reports in lower species, we found no evidence that oocyte activation was associated with an increase in 26S proteasome activity. We therefore conclude that Ca2+ mediates cyclin B1 degradation by increasing the activity of an E3 ubiquitin ligase. However, this stimulation occurs only in the presence of the ubiquitin ligase inhibitor CSF. We propose a model in which Ca2+ directly stimulates destruction of CSF during mammalian fertilisation.
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Affiliation(s)
- Louise A Hyslop
- Cell and Developmental Physiology Research Group, School of Cell and Molecular Biosciences, The Medical School, University of Newcastle, Newcastle NE2 4HH, UK
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11
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Kao LC, Germeyer A, Tulac S, Lobo S, Yang JP, Taylor RN, Osteen K, Lessey BA, Giudice LC. Expression profiling of endometrium from women with endometriosis reveals candidate genes for disease-based implantation failure and infertility. Endocrinology 2003; 144:2870-81. [PMID: 12810542 DOI: 10.1210/en.2003-0043] [Citation(s) in RCA: 473] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Endometriosis is clinically associated with pelvic pain and infertility, with implantation failure strongly suggested as an underlying cause for the observed infertility. Eutopic endometrium of women with endometriosis provides a unique experimental paradigm for investigation into molecular mechanisms of reproductive dysfunction and an opportunity to identify specific markers for this disease. We applied paralleled gene expression profiling using high-density oligonucleotide microarrays to investigate differentially regulated genes in endometrium from women with vs. without endometriosis. Fifteen endometrial biopsy samples (obtained during the window of implantation from eight subjects with and seven subjects without endometriosis) were processed for expression profiling on Affymetrix Hu95A microarrays. Data analysis was conducted with GeneChip Analysis Suite, version 4.01, and GeneSpring version 4.0.4. Nonparametric testing was applied, using a P value of 0.05, to assess statistical significance. Of the 12,686 genes analyzed, 91 genes were significantly increased more than 2-fold in their expression, and 115 genes were decreased more than 2-fold. Unsupervised clustering demonstrated down-regulation of several known cell adhesion molecules, endometrial epithelial secreted proteins, and proteins not previously known to be involved in the pathogenesis of endometriosis, as well as up-regulated genes. Selected dysregulated genes were randomly chosen and validated with RT-PCR and/or Northern/dot-blot analyses, and confirmed up-regulation of collagen alpha2 type I, 2.6-fold; bile salt export pump, 2.0-fold; and down-regulation of N-acetylglucosamine-6-O-sulfotransferase (important in synthesis of L-selectin ligands), 1.7-fold; glycodelin, 51.5-fold; integrin alpha2, 1.8-fold; and B61 (Ephrin A1), 4.5-fold. Two-way overlapping layer analysis used to compare endometrial genes in the window of implantation from women with and without endometriosis further identified three unique groups of target genes, which differ with respect to the implantation window and the presence of disease. Group 1 target genes are up-regulated during the normal window of implantation but significantly decreased in women with endometriosis: IL-15, proline-rich protein, B61, Dickkopf-1, glycodelin, N-acetylglucosamine-6-O-sulfotransferase, G0S2 protein, and purine nucleoside phosphorylase. Group 2 genes are normally down-regulated during the window of implantation but are significantly increased with endometriosis: semaphorin E, neuronal olfactomedin-related endoplasmic reticulum localized protein mRNA and Sam68-like phosphotyrosine protein alpha. Group 3 consists of a single gene, neuronal pentraxin II, normally down-regulated during the window of implantation and further decreased in endometrium from women with endometriosis. The data support dysregulation of select genes leading to an inhospitable environment for implantation, including genes involved in embryonic attachment, embryo toxicity, immune dysfunction, and apoptotic responses, as well as genes likely contributing to the pathogenesis of endometriosis, including aromatase, progesterone receptor, angiogenic factors, and others. Identification and validation of selected genes and their functions will contribute to uncovering previously unknown mechanism(s) underlying implantation failure in women with endometriosis and infertility, mechanisms underlying the pathogenesis of endometriosis and providing potential new targets for diagnostic screening and intervention.
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Affiliation(s)
- L C Kao
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Stanford University, Stanford, CA 94305-5317, USA
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12
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Itoh M, Haga I, Li QH, Fujisawa JI. Identification of cellular mRNA targets for RNA-binding protein Sam68. Nucleic Acids Res 2002; 30:5452-64. [PMID: 12490714 PMCID: PMC140046 DOI: 10.1093/nar/gkf673] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Sam68 (Src-associated in mitosis, 68 kDa), a nuclear RNA-binding protein, has been postulated to play a role in cell-growth control as a modulator of signal transduction and activation of RNA metabolism. Although Sam68 was demonstrated to bind to the UAAA sequences in synthetic oligoribonucleotides and poly(U) homopolymers in vitro, the legitimate cellular mRNA target remained unclear. By using the differential display and cDNA-representational difference analysis techniques, followed by reverse transcription polymerase chain reaction of RNAs co-immunoprecipitated with Sam68 from a HeLa cell lysate, we identified 10 mRNA species that bind in vivo to Sam68 in an RNA-binding domain-dependent manner. Among them, the mRNA species for hnRNP A2/B1 and beta-actin were found to bind prominently in vivo as well as in vitro, suggesting the possible involvement of Sam68 in the post- transcriptional regulation of these genes. Mapping of the Sam68-binding sequence revealed that Sam68 associates with these mRNAs through different nucleotide motifs, UAAA for hnRNP A2/B1 mRNA and UUUUUU for beta-actin mRNA, and that both binding sequences must reside in a loop structure for recognition by Sam68. The results indicated that Sam68 recognizes both the UAAA motif and poly(U) sequences in vivo for binding to cellular target mRNAs.
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Affiliation(s)
- Michiyasu Itoh
- Department of Microbiology, Kansai Medical University, 10-15 Fumizono-cho, Moriguchi, Osaka 570-8506, Japan
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Wang L, Xu J, Zeng L, Ye X, Wu Q, Dai J, Ji C, Gu S, Zhao C, Xie Y, Mao Y. Cloning and characterization of a novel human STAR domain containing cDNA KHDRBS2. Mol Biol Rep 2002; 29:369-75. [PMID: 12549823 DOI: 10.1023/a:1021246109101] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
KHDRBS2, KH domain containing, RNA binding, signal transduction associated 2, is an RNA-binding protein that is tyrosine phosphorylated by Src during mitosis. It contains a KH domain,which is embedded in a larger conserved domain called the STAR domain. This protein has a 99% sequence identity with rat SLM-1 (the Sam68-like mammalian protein 1) and 98% sequence identity with mouse SLM-1 in its STAR domain. KHDRBS2 has the characteristic Sam68 SH2 and SH3 domain binding sites. RT-PCR analysis showed its transcript is ubiquitously expressed. The characterization of KHDRBS2 indicates it may link tyrosine kinase signaling cascades with some aspect of RNA metabolism.
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Affiliation(s)
- Liu Wang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, People's Republic of China
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14
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Hawkins J, Marcy A. Characterization of Itk tyrosine kinase: contribution of noncatalytic domains to enzymatic activity. Protein Expr Purif 2001; 22:211-9. [PMID: 11437596 DOI: 10.1006/prep.2001.1447] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Itk is a Tec family tyrosine kinase found in T cells that is activated upon ligation of the T cell receptor (TCR/CD3), CD2, or CD28. Itk contains five domains in addition to the catalytic domain: pleckstrin homology, Tec homology which contains a proline-rich region, Src homology 3, and Src homology 2. To provide a basis for understanding the contribution of these various domains to catalysis, recombinant Itk was purified and its substrate specificity determined by steady-state kinetic methods. Measurements of the rates of phosphorylation of various protein substrates, including Src associated in mitosis 68K protein (SAM68), CD28, linker for activation of T cells, and CD3 zeta, at a fixed concentration indicated that SAM68 was phosphorylated most rapidly. Wild-type Itk and three Itk mutants were characterized by comparing their activity (k(cat)) using the SAM68 substrate. A deletion mutant removing the pleckstrin homology domain and part of the Tec homology domain (Itk(Delta152)) had approximately 10-fold less activity than wild type, a mutant with an altered proline-rich domain (P158A,P159A) had a more dramatic 100-fold loss of activity, and the catalytic domain alone was essentially inactive. Itk(Delta152) had K(m) values for ATP and SAM68 nearly identical to those of the wild-type enzyme, while Itk(P158A,P159A) had approximately 3-fold higher K(m) values for each substrate. SAM68 phosphorylation by the wild-type and mutant enzymes in the presence of several tyrosine kinase inhibitors were compared using a homogeneous time-resolved fluorescence assay. Both the Itk(Delta152) deletion mutant and the Itk(P158A,P159A) mutant had IC(50) values similar to those of the wild-type enzyme for staurosporine, PP1, and damnacanthal. These comparisons, taken together with the similar K(m) values for ATP and SAM68 substrate between the wild-type and the mutant enzymes, indicate that the amino acids in the N-terminal 152 residues and proline-rich domains enhance catalysis by affecting turnover rate rather than substrate binding.
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Affiliation(s)
- J Hawkins
- Department of High Throughput Screening and Automation, Merck Research Laboratories, Rahway, New Jersey 07065, USA
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Stoss O, Olbrich M, Hartmann AM, Konig H, Memmott J, Andreadis A, Stamm S. The STAR/GSG family protein rSLM-2 regulates the selection of alternative splice sites. J Biol Chem 2001; 276:8665-73. [PMID: 11118435 DOI: 10.1074/jbc.m006851200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We identified the rat Sam68-like mammalian protein (rSLM-2), a member of the STAR (signal transduction and activation of RNA) protein family as a novel splicing regulatory protein. Using the yeast two-hybrid system, coimmunoprecipitations, and pull-down assays, we demonstrate that rSLM-2 interacts with various proteins involved in the regulation of alternative splicing, among them the serine/arginine-rich protein SRp30c, the splicing-associated factor YT521-B and the scaffold attachment factor B. rSLM-2 can influence the splicing pattern of the CD44v5, human transformer-2beta and tau minigenes in cotransfection experiments. This effect can be reversed by rSLM-2-interacting proteins. Employing rSLM-2 deletion variants, gel mobility shift assays, and linker scan mutations of the CD44 minigene, we show that the rSLM-2-dependent inclusion of exon v5 of the CD44 pre-mRNA is dependent on a short purine-rich sequence. Because the related protein of rSLM-2, Sam68, is believed to play a role as an adapter protein during signal transduction, we postulate that rSLM-2 is a link between signal transduction pathways and pre-mRNA processing.
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Affiliation(s)
- O Stoss
- Max-Planck Institute of Neurobiology, Am Klopferspitz 18a, D-82152 Martinsried, the Forschungszentrum Karlsruhe, Institut für Genetik, Postfach 3640, D-76021 Karlsruhe, Germany
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