| 1. |
- Bonczek, Ondrej, et al.
(författare)
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DNA and RNA Binding Proteins : From Motifs to Roles in Cancer
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 23:16
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Forskningsöversikt (refereegranskat)abstract
- DNA and RNA binding proteins (DRBPs) are a broad class of molecules that regulate numerous cellular processes across all living organisms, creating intricate dynamic multilevel networks to control nucleotide metabolism and gene expression. These interactions are highly regulated, and dysregulation contributes to the development of a variety of diseases, including cancer. An increasing number of proteins with DNA and/or RNA binding activities have been identified in recent years, and it is important to understand how their activities are related to the molecular mechanisms of cancer. In addition, many of these proteins have overlapping functions, and it is therefore essential to analyze not only the loss of function of individual factors, but also to group abnormalities into specific types of activities in regard to particular cancer types. In this review, we summarize the classes of DNA-binding, RNA-binding, and DRBPs, drawing particular attention to the similarities and differences between these protein classes. We also perform a cross-search analysis of relevant protein databases, together with our own pipeline, to identify DRBPs involved in cancer. We discuss the most common DRBPs and how they are related to specific cancers, reviewing their biochemical, molecular biological, and cellular properties to highlight their functions and potential as targets for treatment.
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| 2. |
- Chen, Sa, 1967-
(författare)
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Expression and function of Suppressor of zeste 12 in Drosophila melanogaster
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of animals and plants needs a higher order of regulation of gene expression to maintain proper cell state. The mechanisms that control what, when and where a gene should (or should not) be expressed are essential for correct organism development. The Polycomb group (PcG) is a family of genes responsible for maintaining gene silencing and Suppressor of zeste 12 (Su(z)12) is one of the core components in the PcG. The gene is highly conserved in organisms ranging from plants to humans, however, the specific function is not well known. The main tasks of this thesis was to investigate the function of Su(z)12 and its expression at different stages of Drosophila development. In polytene chromosomes of larval salivary glands, Su(z)12 binds to about 90 specific euchromatic sites. The binding along the chromosome arms is mostly in interbands, which are the most DNA de-condensed regions. The binding sites of Su(z)12 in polytene chromosomes correlate precisely with those of the Enhancer-of-zeste (E(z)) protein, indicating that Su(z)12 mainly exists within the Polycomb Repressive Complex 2 (PRC2). However, the binding pattern does not overlap well with Histone 3 lysine 27 tri-methylations (H3K27me3), the specific chromatin mark created by PRC2. The Su(z)12 binding to chromatin is dynamically regulated during mitotic and meiotic cell division. The two different Su(z)12 isoforms: Su(z)12-A and Su(z)12-B (resulting from alternative RNA splicing), have very different expression patterns during development. Functional analyses indicate that they also have different functions he Su(z)12-B form is the main mediator of silencing. Furthermore, a neuron specific localization pattern in larval brain and a giant larval phenotype in transgenic lines reveal a potential function of Su(z)12-A in neuron development. In some aspects the isoforms seem to be able to substitute for each other. The histone methyltransferase activity of PRC2 is due to the E(z) protein. However, Su(z)12 is also necessary for H3K27me3 methylation in vivo, and it is thus a core component of PRC2. Clonal over-expression of Su(z)12 in imaginal wing discs results in an increased H3K27me3 activity, indicating that Su(z)12 is a limiting factor for silencing. When PcG function is lost, target genes normally become de-repressed. The segment polarity gene engrailed, encoding a transcription factor, is a target for PRC2 silencing. However, we found that it was not activated when PRC2 function was deleted. We show that the Ultrabithorax protein, encoded by another PcG target gene, also acts as an inhibitor of engrailed and that de-regulation of this gene causes a continued repression of engrailed. The conclusion is that a gene can have several negative regulators working in parallel and that secondary effects have to be taken into consideration, when analyzing effects of mutants. PcG silencing affects very many cellular processes and a large quantity of knowledge is gathered on the overall mechanisms of PcG regulation. However, little is known about how individual genes are silenced and how cells “remember” their fate through cell generations.
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| 3. |
- Chen, Sa, 1967-, et al.
(författare)
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In vivo analysis of Suppressor of zeste 12´s different isoforms
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Polycomb Group (PcG) genes are known to encode a large chromatin-associated family of proteins which are involved in genomic regulation of many cellular processes. Su(z)12 is a key component in PcG silencing. It is needed for three levels of methylation of histone 3 lysine 27 in vivo in Drosophila. Here, we report that Su(z)12 may exist in different isoforms and that these isoforms are spatially and temporally regulated. The biological function of the Su(z)12-A and -B isoforms seems to be very different. For instance the transgenic Su(z)12-B and the human homolog SUZ12, but not Su(z)12-A, rescue Su(z)12 mutants. Furthermore, transgenic flies over-expressing Su(z)12-B show typical homeotic transformation phenotypes, while over-expression of Su(z)12-A does not. However, the two isoforms appears to be able to substitute for each other in some aspects. During larval and pupal stages, Su(z)12-A seems to play the main role.
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| 4. |
- Chen, Sa, 1967-, et al.
(författare)
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Regulation of the Drosophila engrailed gene by Polycomb repressor complex 2
- 2009
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Ingår i: Mechanisms of Development. - Amsterdam : Elsevier. - 0925-4773 .- 1872-6356. ; 126:5-6, s. 443-448
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Tidskriftsartikel (refereegranskat)abstract
- Suppressor-of-zeste-12 (Su(z)12) is a core component of the Polycomb repressive complex 2 (PRC2), which has a methyltransferase activity directed towards lysine residues of histone 3. Mutations in Polycomb group (PcG) genes cause de-repression of homeotic genes and subsequent homeotic transformations. Another target for Polycomb silencing is the engrailed gene, which encodes a key regulator of segmentation in the early Drosophila embryo. In close proximity to the en gene is a Polycomb Response Element, but whether en is regulated by Su(z)12 is not known. In this report, we show that en is not de-repressed in Su(z)12 or Enhancer-of-zeste mutant clones in the anterior compartment of wing discs. Instead, we find that en expression is down-regulated in the posterior portion of wing discs, indicating that the PRC2 complex acts as an activator of en. Our results indicate that this is due to secondary effects, probably caused by ectopic expression of Ubx and Abd-B.
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| 5. |
- Chen, Sa, 1967-, et al.
(författare)
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The role of Suppressor of zeste 12 in cell cycle regulation
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Polycomb group (PcG) proteins control a large amount of target genes and are essential for genomic programming and differentiation. Many members in the PcG family have been shown to be upregulated in different types of cancers. Suppressor of zeste 12 (Su(z)12) is an essential component in PcG silencing and is necessary for histone 3 lysine 27 tri-methylation in vivo. To unravel a possible role of Su(z)12 in cell cycle regulation, we first investigate the localization pattern of Su(z)12 in Drosophila wildtype testes and embryos by immunohistochemical staining. We found that Su(z)12 was dynamically regulated during cell division. Further investigation of the function of Su(z)12 in cell division was done by cell number counting, apoptosis and proliferation marker staining in Su(z)12 somatic knockout clones in wing discs. The conclusion from the small wing phenotype in Su(z)12 knockout wing discs is that Su(z)12 may increase apoptosis and decrease cell proliferation rate.
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| 6. |
- Chen, Xi, et al.
(författare)
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Type-I interferon signatures in SARS-CoV-2 infected Huh7 cells
- 2021
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Ingår i: Cell Death Discovery. - : Springer Nature. - 2058-7716. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes Coronavirus disease 2019 (COVID-19) has caused a global health emergency. A key feature of COVID-19 is dysregulated interferon-response. Type-I interferon (IFN-I) is one of the earliest antiviral innate immune responses following viral infection and plays a significant role in the pathogenesis of SARS-CoV-2. In this study, using a proteomics-based approach, we identified that SARS-CoV-2 infection induces delayed and dysregulated IFN-I signaling in Huh7 cells. We demonstrate that SARS-CoV-2 is able to inhibit RIG-I mediated IFN-β production. Our results also confirm the recent findings that IFN-I pretreatment is able to reduce the susceptibility of Huh7 cells to SARS-CoV-2, but not post-treatment. Moreover, senescent Huh7 cells, in spite of showing accentuated IFN-I response were more susceptible to SARS-CoV-2 infection, and the virus effectively inhibited IFIT1 in these cells. Finally, proteomic comparison between SARS-CoV-2, SARS-CoV, and MERS-CoV revealed a distinct differential regulatory signature of interferon-related proteins emphasizing that therapeutic strategies based on observations in SARS-CoV and MERS-CoV should be used with caution. Our findings provide a better understanding of SARS-CoV-2 regulation of cellular interferon response and a perspective on its use as a treatment. Investigation of different interferon-stimulated genes and their role in the inhibition of SARS-CoV-2 pathogenesis may direct novel antiviral strategies.
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| 7. |
- Flodbring Larsson, Per, et al.
(författare)
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FcγRIIIa receptor interacts with androgen receptor and PIP5K1α to promote growth and metastasis of prostate cancer
- 2022
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Ingår i: Molecular Oncology. - : John Wiley & Sons. - 1574-7891 .- 1878-0261.
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Tidskriftsartikel (refereegranskat)abstract
- Low-affinity immunoglobulin gamma Fc region receptor III-A (FcγRIIIa) is a cell surface protein that belongs to a family of Fc receptors that facilitate the protective function of the immune system against pathogens. However, the role of FcγRIIIa in prostate cancer (PCa) progression remained unknown. In this study, we found that FcγRIIIa expression was present in PCa cells and its level was significantly higher in metastatic lesions than in primary tumors from the PCa cohort (P = 0.006). PCa patients with an elevated level of FcγRIIIa expression had poorer biochemical recurrence (BCR)-free survival compared with those with lower FcγRIIIa expression, suggesting that FcγRIIIa is of clinical importance in PCa. We demonstrated that overexpression of FcγRIIIa increased the proliferative ability of PCa cell line C4-2 cells, which was accompanied by the upregulation of androgen receptor (AR) and phosphatidylinositol-4-phosphate 5-kinase alpha (PIP5Kα), which are the key players in controlling PCa progression. Conversely, targeted inhibition of FcγRIIIa via siRNA-mediated knockdown or using its inhibitory antibody suppressed growth of xenograft PC-3 and PC-3M prostate tumors and reduced distant metastasis in xenograft mouse models. We further showed that elevated expression of AR enhanced FcγRIIIa expression, whereas inhibition of AR activity using enzalutamide led to a significant downregulation of FcγRIIIa protein expression. Similarly, inhibition of PIP5K1α decreased FcγRIIIa expression in PCa cells. FcγRIIIa physically interacted with PIP5K1α and AR via formation of protein-protein complexes, suggesting that FcγRIIIa is functionally associated with AR and PIP5K1α in PCa cells. Our study identified FcγRIIIa as an important factor in promoting PCa growth and invasion. Further, the elevated activation of FcγRIII and AR and PIP5K1α pathways may cooperatively promote PCa growth and invasion. Thus, FcγRIIIa may serve as a potential new target for improved treatment of metastatic and castration-resistant PCa.
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| 8. |
- Fusée, Leila, et al.
(författare)
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The p53 endoplasmic reticulum stress-response pathway evolved in humans but not in mice via PERK-regulated p53 mRNA structures
- 2023
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Ingår i: Cell Death and Differentiation. - : Springer Nature. - 1350-9047 .- 1476-5403. ; 30, s. 1072-1081
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Tidskriftsartikel (refereegranskat)abstract
- Cellular stress conditions activate p53-dependent pathways to counteract the inflicted damage. To achieve the required functional diversity, p53 is subjected to numerous post-translational modifications and the expression of isoforms. Little is yet known how p53 has evolved to respond to different stress pathways. The p53 isoform p53/47 (p47 or ΔNp53) is linked to aging and neural degeneration and is expressed in human cells via an alternative cap-independent translation initiation from the 2nd in-frame AUG at codon 40 (+118) during endoplasmic reticulum (ER) stress. Despite an AUG codon in the same location, the mouse p53 mRNA does not express the corresponding isoform in either human or mouse-derived cells. High-throughput in-cell RNA structure probing shows that p47 expression is attributed to PERK kinase-dependent structural alterations in the human p53 mRNA, independently of eIF2α. These structural changes do not take place in murine p53 mRNA. Surprisingly, PERK response elements required for the p47 expression are located downstream of the 2nd AUG. The data show that the human p53 mRNA has evolved to respond to PERK-mediated regulation of mRNA structures in order to control p47 expression. The findings highlight how p53 mRNA co-evolved with the function of the encoded protein to specify p53-activities under different cellular conditions.
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| 9. |
- Gnanasundram, Sivakumar Vadivel, et al.
(författare)
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MDM2's dual mRNA binding domains co-ordinate its oncogenic and tumour suppressor activities
- 2020
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Ingår i: Nucleic Acids Research. - : Oxford University Press. - 0305-1048 .- 1362-4962. ; 48:12, s. 6775-6787
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Tidskriftsartikel (refereegranskat)abstract
- Cell growth requires a high level of protein synthesis and oncogenic pathways stimulate cell proliferation and ribosome biogenesis. Less is known about how cells respond to dysfunctional mRNA translation and how this feeds back into growth regulatory pathways. The Epstein-Barr virus (EBV)-encoded EBNA1 causes mRNA translation stress in cis that activates PI3Kδ. This leads to the stabilization of MDM2, induces MDM2’s binding to the E2F1 mRNA and promotes E2F1 translation. The MDM2 serine 166 regulates the interaction with the E2F1 mRNA and deletion of MDM2 C-terminal RING domain results in a constitutive E2F1 mRNA binding. Phosphorylation on serine 395 following DNA damage instead regulates p53 mRNA binding to its RING domain and prevents the E2F1 mRNA interaction. The p14Arf tumour suppressor binds MDM2 and in addition to preventing degradation of the p53 protein it also prevents the E2F1 mRNA interaction. The data illustrate how two MDM2 domains selectively bind specific mRNAs in response to cellular conditions to promote, or suppress, cell growth and how p14Arf coordinates MDM2’s activity towards p53 and E2F1. The data also show how EBV via EBNA1-induced mRNA translation stress targets the E2F1 and the MDM2 - p53 pathway.
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| 10. |
- Gnanasundram, Sivakumar Vadivel, et al.
(författare)
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P53 mRNA metabolism links with the DNA damage response
- 2021
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Ingår i: Genes. - : MDPI. - 2073-4425. ; 12:9
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Forskningsöversikt (refereegranskat)abstract
- Human cells are subjected to continuous challenges by different genotoxic stress attacks. DNA damage leads to erroneous mutations, which can alter the function of oncogenes or tumor suppressors, resulting in cancer development. To circumvent this, cells activate the DNA damage response (DDR), which mainly involves cell cycle regulation and DNA repair processes. The tumor suppressor p53 plays a pivotal role in the DDR by halting the cell cycle and facilitating the DNA repair processes. Various pathways and factors participating in the detection and repair of DNA have been described, including scores of RNA-binding proteins (RBPs) and RNAs. It has become increasingly clear that p53’s role is multitasking, and p53 mRNA regulation plays a prominent part in the DDR. This review is aimed at covering the p53 RNA metabolism linked to the DDR and highlights the recent findings.
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