1. |
- Cai, Huan, et al.
(författare)
-
Critical role of Lama4 for hematopoiesis regeneration and acute myeloid leukemia progression
- 2022
-
Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 139:20, s. 3040-3057
-
Tidskriftsartikel (refereegranskat)abstract
- Impairment of normal hematopoiesis and leukemia progression are 2 well-linked processes during leukemia development and are controlled by the bone marrow (BM) niche. Extracellular matrix proteins, including laminin, are important BM niche components. However, their role in hematopoiesis regeneration and leukemia is unknown. Laminin α4 (Lama4), a major receptor-binding chain of several laminins, is altered in BM niches in mice with acute myeloid leukemia (AML). So far, the impact of Lama4 on leukemia progression remains unknown. We here report that Lama4 deletion in mice resulted in impaired hematopoiesis regeneration following irradiation-induced stress, which is accompanied by altered BM niche composition and inflammation. Importantly, in a transplantation-induced MLL-AF9 AML mouse model, we demonstrate accelerated AML progression and relapse in Lama4−/− mice. Upon AML exposure, Lama4−/− mesenchymal stem cells (MSCs) exhibited dramatic molecular alterations, including upregulation of inflammatory cytokines that favor AML growth. Lama4−/− MSCs displayed increased antioxidant activities and promoted AML stem cell proliferation and chemoresistance to cytarabine, which was accompanied by increased mitochondrial transfer from the MSCs to AML cells and reduced reactive oxygen species in AML cells in vitro. Similarly, we detected lower levels of reactive oxygen species in AML cells from Lama4−/− mice post–cytarabine treatment. Notably, LAMA4 inhibition or knockdown in human MSCs promoted human AML cell proliferation and chemoprotection. Together, our study for the first time demonstrates the critical role of Lama4 in impeding AML progression and chemoresistance. Targeting Lama4 signaling pathways may offer potential new therapeutic options for AML.
|
|
2. |
- Herold, Nikolas, et al.
(författare)
-
Targeting SAMHD1 with the Vpx protein to improve cytarabine therapy for hematological malignancies
- 2017
-
Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 23:2, s. 256-263
-
Tidskriftsartikel (refereegranskat)abstract
- The cytostatic deoxycytidine analog cytarabine (ara-C) is the most active agent available against acute myelogenous leukemia (AML). Together with anthracyclines, ara-C forms the backbone of AML treatment for children and adults'. In AML, both the cytotoxicity of ara-C in vitro and the clinical response to ara-C therapy are correlated with the ability of AML blasts to accumulate the active metabolite ara-C triphosphate (ara-CTP)(2-5), which causes DNA damage through perturbation of DNA synthesis(6). Differences in expression levels of known transporters or metabolic enzymes relevant to ara-C only partially account for patient-specific differential ara-CTP accumulation in AML blasts and response to ara-C treatment(7-9). Here we demonstrate that the deoxynucleoside triphosphate (dNTP) triphosphohydrolase SAM domain and HD domain 1 (SAMHD1) promotes the detoxification of intracellular ara-CTP pools. Recombinant SAMHD1 exhibited ara-CTPase activity in vitro, and cells in which SAMHD1 expression was transiently reduced by treatment with the simian immunodeficiency virus (SIV) protein Vpx were dramatically more sensitive to ara-C-induced cytotoxicity. CRISPR-Cas9-mediated disruption of the gene encoding SAMHD1 sensitized cells to ara-C, and this sensitivity could be abrogated by ectopic expression of wild-type (WT), but not dNTPase-deficient, SAMHD1. Mouse models of AML lacking SAMHD1 were hypersensitive to ara-C, and treatment ex vivo with Vpx sensitized primary patient derived AML blasts to ara-C. Finally, we identified SAMHD1 as a risk factor in cohorts of both pediatric and adult patients with de novo AML who received ara-C treatment. Thus, SAMHD1 expression levels dictate patient sensitivity to ara-C, providing proof-of-concept that the targeting of SAMHD1 by Vpx could be an attractive therapeutic strategy for potentiating ara-C efficacy in hematological malignancies.
|
|
3. |
- Isaac, Sara, et al.
(författare)
-
Interaction of Epe1 with the heterochromatin assembly pathway in Schizosaccharomyces pombe
- 2007
-
Ingår i: Genetics. - : Oxford University Press (OUP). - 0016-6731 .- 1943-2631. ; 175:4, s. 1549-1560
-
Tidskriftsartikel (refereegranskat)abstract
- Epe1 is a JmjC domain protein that antagonizes heterochromatization in Schizosaccharomyces pombe. Related JmjC domain proteins catalyze a histone demethylation reaction that depends on Fe(II) and alpha-ketoglutarate. However, no detectable demethylase activity is associated with Epe1, and its JmjC domain lacks conservation of Fe(II)-binding residues. We report that Swi6 recruits Epe1 to heterochromatin and that overexpression of epe1(+), like mutations in silencing genes or overexpression of swi6(+), upregulates expression of certain genes. A significant overlap was observed between the lists of genes that are upregulated by overexpression of epe1(+) and those that are upregulated by mutations in histone deacetylase genes. However, most of the common genes are not regulated by Clr4 histone methyltransferase. This suggests that Epe1 interacts with the heterochromatin assembly pathway at the stage of histone deacetylation. Mutational inactivation of Epe1 downregulates similar to 12% of S. pombe genes, and the list of these genes overlaps significantly with the lists of genes that are upregulated by mutations in silencing genes and genes that are hyperacetylated at their promoter regions in clr6-1 mutants. We propose that an interplay between the repressive HDACs activity and Epe1 helps to regulate gene expression in S. pombe.
|
|
4. |
- Johard, Helena, et al.
(författare)
-
HCN Channel Activity Balances Quiescence and Proliferation in Neural Stem Cells and Is a Selective Target for Neuroprotection During Cancer Treatment
- 2020
-
Ingår i: Molecular Cancer Research. - 1541-7786 .- 1557-3125. ; 18:10, s. 1522-1533
-
Tidskriftsartikel (refereegranskat)abstract
- Children suffering from neurologic cancers undergoing chemotherapy and radiotherapy are at high risk of reduced neurocognitive abilities likely via damage to proliferating neural stem cells (NSC). Therefore, strategies to protect NSCs are needed. We argue that induced cell-cycle arrest/quiescence in NSCs during cancer treatment can represent such a strategy. Here, we show that hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels are dynamically expressed over the cell cycle in NSCs, depolarize the membrane potential, underlie spontaneous calcium oscillations and are required to maintain NSCs in the actively proliferating pool. Hyperpolarizing pharmacologic inhibition of HCN channels during exposure to ionizing radiation protects NSCs cells in neurogenic brain regions of young mice. In contrast, brain tumor-initiating cells, which also express HCN channels, remain proliferative during HCN inhibition.
|
|
5. |
- Khalkar, Prajakta, et al.
(författare)
-
Selenite and methylseleninic acid epigenetically affects distinct gene sets in myeloid leukemia : A genome wide epigenetic analysis
- 2018
-
Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 117, s. 247-257
-
Tidskriftsartikel (refereegranskat)abstract
- Selenium compounds have emerged as promising chemotherapeutic agents with proposed epigenetic effects, however the mechanisms and downstream effects are yet to be studied. Here we assessed the effects of the inorganic selenium compound selenite and the organic form methylseleninic acid (MSA) in a leukemic cell line K562, on active (histone H3 lysine 9 acetylation, H3K9ac and histone H3 lysine 4 tri-methylation, H3K4me3) and repressive (histone H3 lysine 9 tri-methylation, H3K9me3) histone marks by Chromatin immunoprecipitation followed by DNA sequencing (ChIP-Seq). Both selenite and MSA had major effects on histone marks but the effects of MSA were more pronounced. Gene ontology analysis revealed that selenite affected genes involved in response to oxygen and hypoxia, whereas MSA affected distinct gene sets associated with cell adhesion and glucocorticoid receptors, also apparent by global gene expression analysis using RNA sequencing. The correlation to adhesion was functionally confirmed by a significantly weakened ability of MSA treated cells to attach to fibronectin and linked to decreased expression of integrin beta 1. A striking loss of cellular adhesion was also confirmed in primary patient AML cells. Recent strategies to enhance the cytotoxicity of chemotherapeutic drugs by disrupting the interaction between leukemic and stromal cells in the bone marrow are of increasing interest; and organic selenium compounds like MSA might be promising candidates. In conclusion, these results provide new insight on the mechanism of action of selenium compounds, and will be of value for the understanding, usage, and development of new selenium compounds as anticancer agents.
|
|
6. |
|
|
7. |
- Kitambi, Satish Srinivas, et al.
(författare)
-
Vulnerability of Glioblastoma Cells to Catastrophic Vacuolization and Death Induced by a Small Molecule
- 2014
-
Ingår i: Cell. - : Elsevier BV. - 0092-8674 .- 1097-4172. ; 157:2, s. 313-328
-
Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma multiforme (GBM) is the most aggressive form of brain cancer with marginal life expectancy. Based on the assumption that GBM cells gain functions not necessarily involved in the cancerous process, patient-derived glioblastoma cells (GCs) were screened to identify cellular processes amenable for development of targeted treatments. The quinine-derivative NSC13316 reliably and selectively compromised viability. Synthetic chemical expansion reveals delicate structure-activity relationship and analogs with increased potency, termed Vacquinols. Vacquinols stimulate death by membrane ruffling, cell rounding, massive macropinocytic vacuole accumulation, ATP depletion, and cytoplasmic membrane rupture of GCs. The MAP kinase MKK4, identified by a shRNA screen, represents a critical signaling node. Vacquinol-1 displays excellent in vivo pharmacokinetics and brain exposure, attenuates disease progression, and prolongs survival in a GBM animal model. These results identify a vulnerability to massive vacuolization that can be targeted by small molecules and point to the possible exploitation of this process in the design of anticancer therapies.
|
|
8. |
- Opel, Michael, et al.
(författare)
-
Genome-Wide Studies of Histone Demethylation Catalysed by the Fission Yeast Homologues of Mammalian LSD1
- 2007
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 2:4
-
Tidskriftsartikel (refereegranskat)abstract
- In order to gain a more global view of the activity of histone demethylases, we report here genome-wide studies of the fission yeast SWIRM and polyamine oxidase (PAO) domain homologues of mammalian LSD1. Consistent with previous work we find that the two S. pombe proteins, which we name Swm1 and Swm2 (after SWIRM1 and SWIRM2), associate together in a complex. However, we find that this complex specifically demethylates lysine 9 in histone H3 (H3K9) and both up-and down-regulates expression of different groups of genes. Using chromatin-immunoprecipitation, to isolate fragments of chromatin containing either H3K4me2 or H3K9me2, and DNA microarray analysis (ChIP-chip), we have studied genome-wide changes in patterns of histone methylation, and their correlation with gene expression, upon deletion of the swm1(+) gene. Using hyper-geometric probability comparisons we uncover genetic links between lysine-specific demethylases, the histone deacetylase Clr6, and the chromatin remodeller Hrp1. The data presented here demonstrate that in fission yeast the SWIRM/PAO domain proteins Swm1 and Swm2 are associated in complexes that can remove methyl groups from lysine 9 methylated histone H3. In vitro, we show that bacterially expressed Swm1 also possesses lysine 9 demethylase activity. In vivo, loss of Swm1 increases the global levels of both H3K9me2 and H3K4me2. A significant accumulation of H3K4me2 is observed at genes that are up-regulated in a swm1 deletion strain. In addition, H3K9me2 accumulates at some genes known to be direct Swm1/2 targets that are down-regulated in the swm1 Delta strain. The in vivo data indicate that Swm1 acts in concert with the HDAC Clr6 and the chromatin remodeller Hrp1 to repress gene expression. In addition, our in vitro analyses suggest that the H3K9 demethylase activity requires an unidentified post-translational modification to allow it to act. Thus, our results highlight complex interactions between histone demethylase, deacetylase and chromatin remodelling activities in the regulation of gene expression.
|
|
9. |
- Pena-Perez, Lucia, et al.
(författare)
-
FOXO Dictates Initiation of B Cell Development and Myeloid Restriction in Common Lymphoid Progenitors
- 2022
-
Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- The development of B cells relies on an intricate network of transcription factors critical for developmental progression and lineage commitment. In the B cell developmental trajectory, a temporal switch from predominant Foxo3 to Foxo1 expression occurs at the CLP stage. Utilizing VAV-iCre mediated conditional deletion, we found that the loss of FOXO3 impaired B cell development from LMPP down to B cell precursors, while the loss of FOXO1 impaired B cell commitment and resulted in a complete developmental block at the CD25 negative proB cell stage. Strikingly, the combined loss of FOXO1 and FOXO3 resulted in the failure to restrict the myeloid potential of CLPs and the complete loss of the B cell lineage. This is underpinned by the failure to enforce the early B-lineage gene regulatory circuitry upon a predominantly pre-established open chromatin landscape. Altogether, this demonstrates that FOXO3 and FOXO1 cooperatively govern early lineage restriction and initiation of B-lineage commitment in CLPs.
|
|
10. |
- Provost, P, et al.
(författare)
-
Dicer is required for chromosome segregation and gene silencing in fission yeast cells
- 2002
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 99:26, s. 16648-16653
-
Tidskriftsartikel (refereegranskat)abstract
- RNA interference is a form of gene silencing in which the nuclease Dicer cleaves double-stranded RNA into small interfering RNAs. Here we report a role for Dicer in chromosome segregation of fission yeast. Deletion of the Dicer (dcr1(+)) gene caused slow growth, sensitivity to thiabendazole, lagging chromosomes during anaphase, and abrogated silencing of centromeric repeats. As Dicer in other species, Dcr1p degraded double-stranded RNA into approximate to23 nucleotide fragments in vitro, and dcr1Delta cells were partially rescued by expression of human Dicer, indicating evolutionarily conserved functions. Expression profiling demonstrated that dcr1(+) was required for silencing of two genes containing a conserved motif.
|
|
11. |
- Rudd, Sean, et al.
(författare)
-
Ribonucleotide reductase inhibitors suppress SAMHD1 ara-CTPase activity enhancing cytarabine efficacy
- 2020
-
Ingår i: EMBO Molecular Medicine. - : Blackwell Publishing Ltd. - 1757-4676 .- 1757-4684.
-
Tidskriftsartikel (refereegranskat)abstract
- The deoxycytidine analogue cytarabine (ara-C) remains the backbone treatment of acute myeloid leukaemia (AML) as well as other haematological and lymphoid malignancies, but must be combined with other chemotherapeutics to achieve cure. Yet, the underlying mechanism dictating synergistic efficacy of combination chemotherapy remains largely unknown. The dNTPase SAMHD1, which regulates dNTP homoeostasis antagonistically to ribonucleotide reductase (RNR), limits ara-C efficacy by hydrolysing the active triphosphate metabolite ara-CTP. Here, we report that clinically used inhibitors of RNR, such as gemcitabine and hydroxyurea, overcome the SAMHD1-mediated barrier to ara-C efficacy in primary blasts and mouse models of AML, displaying SAMHD1-dependent synergy with ara-C. We present evidence that this is mediated by dNTP pool imbalances leading to allosteric reduction of SAMHD1 ara-CTPase activity. Thus, SAMHD1 constitutes a novel biomarker for combination therapies of ara-C and RNR inhibitors with immediate consequences for clinical practice to improve treatment of AML. © 2020 The Authors. Published under the terms of the CC BY 4.0 license
|
|
12. |
- Sanjiv, Kumar, et al.
(författare)
-
MTH1 Inhibitor TH1579 Induces Oxidative DNA Damage and Mitotic Arrest in Acute Myeloid Leukemia
- 2021
-
Ingår i: Cancer Research. - : American Association For Cancer Research (AACR). - 0008-5472 .- 1538-7445. ; 81:22, s. 5733-5744
-
Tidskriftsartikel (refereegranskat)abstract
- Acute myeloid leukemia (AML) is an aggressive hematologic malignancy, exhibiting high levels of reactive oxygen species (ROS). ROS levels have been suggested to drive leukemogenesis and is thus a potential novel target for treating AML. MTH1 prevents incorporation of oxidized nucleotides into the DNA to maintain genome integrity and is upregulated in many cancers. Here we demonstrate that hematologic cancers are highly sensitive to MTH1 inhibitor TH1579 (karonudib). A functional precision medicine ex vivo screen in primary AML bone marrow samples demonstrated a broad response profile of TH1579, independent of the genomic alteration of AML, resembling the response profile of the standard-of-care treatments cytarabine and doxorubicin. Furthermore, TH1579 killed primary human AML blast cells (CD45+) as well as chemotherapy resistance leukemic stem cells (CD45+Lin−CD34+CD38−), which are often responsible for AML progression. TH1579 killed AML cells by causing mitotic arrest, elevating intracellular ROS levels, and enhancing oxidative DNA damage. TH1579 showed a significant therapeutic window, was well tolerated in animals, and could be combined with standard-of-care treatments to further improve efficacy. TH1579 significantly improved survival in two different AML disease models in vivo. In conclusion, the preclinical data presented here support that TH1579 is a promising novel anticancer agent for AML, providing a rationale to investigate the clinical usefulness of TH1579 in AML in an ongoing clinical phase I trial.
|
|
13. |
- Strålfors, Annelie, et al.
(författare)
-
The FUN30 Chromatin Remodeler, Fft3, Protects Centromeric and Subtelomeric Domains from Euchromatin Formation
- 2011
-
Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 7:3
-
Tidskriftsartikel (refereegranskat)abstract
- The chromosomes of eukaryotes are organized into structurally and functionally discrete domains. This implies the presence of insulator elements that separate adjacent domains, allowing them to maintain different chromatin structures. We show that the Fun30 chromatin remodeler, Fft3, is essential for maintaining a proper chromatin structure at centromeres and subtelomeres. Fft3 is localized to insulator elements and inhibits euchromatin assembly in silent chromatin domains. In its absence, euchromatic histone modifications and histone variants invade centromeres and subtelomeres, causing a mis-regulation of gene expression and severe chromosome segregation defects. Our data strongly suggest that Fft3 controls the identity of chromatin domains by protecting these regions from euchromatin assembly.
|
|
14. |
|
|
15. |
- Walfridsson, Julian, et al.
(författare)
-
A genome-wide role for CHD remodelling factors and Nap1 in nucleosome disassembly
- 2007
-
Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 26:12, s. 2868-2879
-
Tidskriftsartikel (refereegranskat)abstract
- Chromatin remodelling factors and histone chaperones were previously shown to cooperatively affect nucleosome assembly and disassembly processes in vitro. Here, we show that Schizosaccharomyces pombe CHD remodellers, the Hrp1 and Hrp3 paralogs physically interact with the histone chaperone Nap1. Genome- wide analysis of Hrp1, Hrp3 and Nap1 occupancy, combined with nucleosome density measurements revealed that the CHD factors and Nap1 colocalized in particular to promoter regions where they remove nucleosomes near the transcriptional start site. Hrp1 and Hrp3 also regulate nucleosome density in coding regions, where they have redundant roles to stimulate transcription. Previously, DNA replication-dependent and -independent nucleosome disassembly processes have been described. We found that nucleosome density increased in the hrp1 mutant in the absence of DNA replication. Finally, regions where nucleosome density increased in hrp1, hrp3 and nap1 mutants also showed nucleosome density and histone modification changes in HDAC and HAT mutants. Thus, this study revealed an important in vivo role for CHD remodellers and Nap1 in nucleosome disassembly at promoters and coding regions, which are linked to changes in histone acetylation.
|
|
16. |
- Walfridsson, Julian
(författare)
-
The CHD chromatin remodeling factors in schizosaccharomyces pombe
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Regulation of chromatin structure is essential in a wide variety of processes including transcriptional regulation, recombination, replication, chromosome segregation, development and differentiation. The enzymes that are central in regulating chromatin structure can be classified into two major groups. The first group of proteins consists of the histone modifying enzymes that catalyse the addition or removal of posttranslational modifications of histones. The second group of proteins is the highly conserved ATP-dependent remodeling factors that modify the nucleosome structure. Evidence is emerging that these two groups of proteins are intimately linked in chromatin function. This thesis describes the roles of the S. pombe Hrp1 and Hrp3 CHD remodeling factors in chromatin regulation, which have been shown to be important in centromere function and transcriptional regulation. The Hrp remodeling factors are functionally linked to the histone chaperone Nap1 as well as acetylation and methylation activities. We have demonstrated that Hrp1 has both independent and overlapping roles with Hrp3 in regulating centromere assembly and function. Both hrp1 and hrp3 deficient cells are disrupted in centromere silencing and display various chromosome segregation defects indicative of functions at both the outer repeats and the central core of the centromere. These phenotypes are likely to originate from the requirement of Hrp1 in keeping the centromeres hypoacetylated and for maintaining the histone H3 variant CENP-A at the central core of the centromere. Genetic interactions combined with chromatin immunoprecipitation and fluorescent in situ hybridisation indicate that Hrp1 stimulates CENP-A assembly during DNA replication. In addition to their centromere functions, the Hrp remodeling factors contribute to transcriptional regulation by promoting histone removal. Biochemical purifications identified a physical interaction between Hrp1 and Hrp3 and with the histone chaperone Nap1. Consistent with the physical interaction data, genome wide analysis showed that the CHD remodeling factors together with Nap1 have a common function in removing histones particularly at promoter regions. Interestingly, we found that histone disassembly in coding regions by both Hrp1 and Hrp3 promote transcriptional activation. Cell synchronisation studies revealed that the Hrp1 dependent histone disassembly occurs in a DNA replication independent manner. A functional interaction between acetylation and remodeling activity was established based on the high degree of overlap between the Hrp ATPases, regions affected by Nap1 histone density, and corresponding histone deacetylase and histone acetylase targets. Finally, we discovered that regions with upregulated genes and altered levels of histone modifications in the HDAC clr6-1 mutant were significantly similar to equivalent lists for the histone demethyl transferase swm1 mutant. In addition, the same regions with upregulated genes and effects on histone modification levels in the swm1 and clr6 mutant overlapped with Hrp1 and Hrp3 binding targets. Thus, it is likely that Swm1 act in concert with Clr6 and Hrp1 to mediate transcriptional silencing. Thus, HDACs, HATs, and HMTs are intimately linked in vivo to CHD nucleosome remodeling factors as well as histone chaperones in centromere assembly and transcriptional regulation.
|
|
17. |
|
|
18. |
- Wiren, Marianna, et al.
(författare)
-
Genomewide analysis of nucleosome density histone acetylation and HDAC function in fission yeast
- 2005
-
Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 24:16, s. 2906-2918
-
Tidskriftsartikel (refereegranskat)abstract
- We have conducted a genomewide investigation into the enzymatic specificity, expression profiles, and binding locations of four histone deacetylases (HDACs), representing the three different phylogenetic classes in fission yeast ( Schizosaccharomyces pombe). By directly comparing nucleosome density, histone acetylation patterns and HDAC binding in both intergenic and coding regions with gene expression profiles, we found that Sir2 ( class III) and Hos2 ( class I) have a role in preventing histone loss; Clr6 ( class I) is the principal enzyme in promoter-localized repression. Hos2 has an unexpected role in promoting high expression of growth-related genes by deacetylating H4K16Ac in their open reading frames. Clr3 ( class II) acts cooperatively with Sir2 throughout the genome, including the silent regions: rDNA, centromeres, mat2/3 and telomeres. The most significant acetylation sites are H3K14Ac for Clr3 and H3K9Ac for Sir2 at their genomic targets. Clr3 also affects subtelomeric regions which contain clustered stress- and meiosis-induced genes. Thus, this combined genomic approach has uncovered different roles for fission yeast HDACs at the silent regions in repression and activation of gene expression.
|
|