| 1. |
- Gad, Helge, et al.
(författare)
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MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
- 2014
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 508:7495, s. 215-221
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Tidskriftsartikel (refereegranskat)abstract
- Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bindin the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.
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| 2. |
- Bräutigam, Lars, et al.
(författare)
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Hypoxic Signaling and the Cellular Redox Tumor Environment Determine Sensitivity to MTH1 Inhibition
- 2016
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Ingår i: Cancer Research. - 0008-5472 .- 1538-7445. ; 76:8, s. 2366-2375
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Tidskriftsartikel (refereegranskat)abstract
- Cancer cells are commonly in a state of redox imbalance that drives their growth and survival. To compensate for oxidative stress induced by the tumor redox environment, cancer cells upregulate specific nononcogenic addiction enzymes, such as MTH1 (NUDT1), which detoxifies oxidized nucleotides. Here, we show that increasing oxidative stress in nonmalignant cells induced their sensitization to the effects of MTH1 inhibition, whereas decreasing oxidative pressure in cancer cells protected against inhibition. Furthermore, we purified zebrafish MTH1 and solved the crystal structure of MTH1 bound to its inhibitor, highlighting the zebrafish as a relevant tool to study MTH1 biology. Delivery of 8-oxo-dGTP and 2-OH-dATP to zebrafish embryos was highly toxic in the absence of MTH1 activity. Moreover, chemically or genetically mimicking activated hypoxia signaling in zebrafish revealed that pathologic upregulation of the HIF1 alpha response, often observed in cancer and linked to poor prognosis, sensitized embryos to MTH1 inhibition. Using a transgenic zebrafish line, in which the cellular redox status can be monitored in vivo, we detected an increase in oxidative pressure upon activation of hypoxic signaling. Pretreatment with the antioxidant N-acetyl-L-cysteine protected embryos with activated hypoxia signaling against MTH1 inhibition, suggesting that the aberrant redox environment likely causes sensitization. In summary, MTH1 inhibition may offer a general approach to treat cancers characterized by deregulated hypoxia signaling or redox imbalance.
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| 3. |
- Bräutigam, Lars, et al.
(författare)
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Localized Expression of Urocortin Genes in the Developing Zebrafish rain
- 2010
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 518:15, s. 2978-2995
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Tidskriftsartikel (refereegranskat)abstract
- The corticotropin-releasing hormone (CRH) family consists of four aralogous genes, CRH and urocortins (UCNs) 1, 2, and 3. In a previous tudy, we analyzed CRH in the teleost model organism zebrafish and its ranscript distribution in the embryonic brain. Here, we describe ull-length cDNAs encoding urotensin 1 (UTS1), the teleost UCN1 rtholog, and UCN3 of zebrafish. Major expression sites of uts1 in adult ebrafish are the caudal neurosecretory system and brain. By using T-PCR analysis, we show that uts1 mRNA is also present in ovary, aternally contributed to the embryo, and expressed throughout embryonic evelopment. Expression of ucn3 mRNA was detected in a range of adult issues and during developmental stages from 24 hours post fertilization nward. Analysis of spatial transcript distributions by whole-mount in itu hybridization revealed limited forebrain expression of uts1 and cn3 during early development. Small numbers of uts1-synthesizing eurons were found in subpallium, hypothalamus, and posterior iencephalon, whereas ucn3-positive cells were restricted to elencephalon and retina. The brainstem was the main site of uts1 and cn3 synthesis in the embryonic brain. uts1 Expression was confined to he midbrain tegmentum; distinct hindbrain cell groups, including locus oeruleus and Mauthner neurons; and the spinal cord. ucn3 Expression was ocalized to the optic tectum, serotonergic raphe, and distinct hombomeric cell clusters. The prominent expression of uts1 and ucn3 in rainstem is consistent with proposed roles of CRH-related peptides in tress-induced modulation of locomotor activity through monoaminergic rainstem neuromodulatory systems. J. Comp. Neurol. 518:2978-2995, 2010.
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| 4. |
- Bräutigam, Lars
(författare)
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Urocortins in the zebrafish brain and redox regulation of embryonic development through glutaredoxins
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The cellular redox state is a central regulator of embryonic development. Redox homeostasis and thiol redox signaling are modulated through glutaredoxins (Grxs), glutathione dependent thiol-disulfide oxidoreductases. Grxs can reduce protein disulfides and protein-glutathione mixed disulfides (de-glutathionylation) via distinct reaction mechanisms. Although it has been shown that Grxs protect cells against oxidative stress induced apoptosis, known interaction partners are rare and physiological functions of this protein family are poorly understood. This thesis represents the first investigation of dithiol Grxs during vertebrate embryonic development, and we demonstrate that vertebrate specific Grx2 is essential for the formation of a functional brain and cardiovascular system. We characterized a redox circuit, in which Grx2 modulates the activity of a newly identified interaction partner, collapsin response mediator protein 2 (CRMP2), through the reduction of an intra-molecular disulfide. Thereby, Grx2 regulates axonal outgrowth and neuronal survival. Since CRMP2 and Grx2 have already been implicated in various neurological disorders, the redox circuit based on Grx2 might be a promising target for future therapeutic strategies. Additionally, we unraveled that development of functional vessels, heart, and erythrocytes in the zebrafish embryo is dependent on the de-glutathionylation activity of Grx2. These results have high clinical relevance, as defects in the cardiovascular system are a major reason for human embryonic mortality. Moreover, we sought to characterize zebrafish Grx2 (zfGrx2) biochemically and biophysically. Mössbauer spectroscopy as well as size-exclusion chromatography demonstrated the coordination of one [2Fe2S]2+ cluster per zfGrx2 monomer. Further analysis indicated that two out of four additional cysteines, which are conserved across the infraclass of bony fish, are involved in cluster coordination. As this mode of cluster binding is different to all yet described [FeS] Grxs, zfGrx2 might represent a new class of iron-sulfur Grxs. Embryonic development is also regulated by environmental factors, and the stress axis is responsible to mediate the body’s response to those stimuli. Here we investigated the expression pattern of urocortin (UCN) genes, important regulators of the stress axis, in the embryonic zebrafish brain. The specific expression sites indicate that UCNs might modulate locomotor activity through noradrenergic and serotonergic systems.
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| 5. |
- Bräutigam, Malin, et al.
(författare)
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[Primary PTCA or thrombolysis in acute myocardial infarction?]. : Primär PTCA eller trombolys vid akut hjärtinfarkt?
- 2001
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Ingår i: Läkartidningen. - 0023-7205. ; 98:32-33, s. 3392-5
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Tidskriftsartikel (refereegranskat)abstract
- In acute ST-elevation infarction two different reperfusion strategies--thrombolytic medication and acute coronary angiography--have proved to improve the prognosis. The clinical course for patients with ST-elevation infarction is described in relation to whether they received thrombolytic medication or underwent acute coronary angiography with the aim of mechanical revascularization. The one-year mortality was high (20 percent) regardless of treatment strategy. In terms of morbidity there were no clear differences between the two treatment groups.
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| 6. |
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| 7. |
- Karsten, Stella, et al.
(författare)
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MTH1 as a target to alleviate T cell driven diseases by selective suppression of activated T cells
- 2021
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Ingår i: Cell Death & Differentiation. - Stockholm : Karolinska Institutet, Dept of Oncology-Pathology. - 1350-9047 .- 1476-5403.
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Tidskriftsartikel (refereegranskat)abstract
- T cell-driven diseases account for considerable morbidity and disability globally and there is an urgent need for new targeted therapies. Both cancer cells and activated T cells have an altered redox balance, and up-regulate the DNA repair protein MTH1 that sanitizes the oxidized nucleotide pool to avoid DNA damage and cell death. Herein we suggest that the up-regulation of MTH1 in activated T cells correlates with their redox status, but occurs before the ROS levels increase, challenging the established conception of MTH1 increasing as a direct response to an increased ROS status. We also propose a heterogeneity in MTH1 levels among activated T cells, where a smaller subset of activated T cells does not upregulate MTH1 despite activation and proliferation. The study suggests that the vast majority of activated T cells have high MTH1 levels and are sensitive to the MTH1 inhibitor TH1579 (Karonudib) via induction of DNA damage and cell cycle arrest. TH1579 further drives the surviving cells to the MTH1[superscript low] phenotype with altered redox status. TH1579 does not affect resting T cells, as opposed to the established immunosuppressor Azathioprine, and no sensitivity among other major immune cell types regarding their function can be observed. Finally, we demonstrate a therapeutic effect in a murine model of experimental autoimmune encephalomyelitis. In conclusion, we show proof of concept of the existence of MTH1[superscript high] and MTH1[superscript low] activated T cells, and that MTH1 inhibition by TH1579 selectively suppresses pro-inflammatory activated T cells. Thus, MTH1 inhibition by TH1579 may serve as a novel treatment option against autoreactive T cells in autoimmune diseases, such as multiple sclerosis.
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| 8. |
- Scaletti, Emma Rose, et al.
(författare)
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MutT homologue 1 (MTH1) removes N6-methyl-dATP from the dNTP pool
- 2020
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:15, s. 4761-4772
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Tidskriftsartikel (refereegranskat)abstract
- MutT homologue 1 (MTH1) removes oxidized nucleotides from the nucleotide pool and thereby prevents their incorporation into the genome and thereby reduces genotoxicity. We previously reported that MTH1 is an efficient catalyst of O6-methyl-dGTP hydrolysis suggesting that MTH1 may also sanitize the nucleotide pool from other methylated nucleotides. We here show that MTH1 efficiently catalyzes the hydrolysis of N6-methyl-dATP to N6-methyl-dAMP and further report that N6-methylation of dATP drastically increases the MTH1 activity. We also observed MTH1 activity with N6-methyl-ATP, albeit at a lower level. We show that N6-methyl-dATP is incorporated into DNA in vivo, as indicated by increased N6-methyl-dA DNA levels in embryos developed from MTH1 knock-out zebrafish eggs microinjected with N6-methyl-dATP compared with noninjected embryos. N6-methyl-dATP activity is present in MTH1 homologues from distantly related vertebrates, suggesting evolutionary conservation and indicating that this activity is important. Of note, N6-methyl-dATP activity is unique to MTH1 among related NUDIX hydrolases. Moreover, we present the structure of N6-methyl-dAMP?bound human MTH1, revealing that the N6-methyl group is accommodated within a hydrophobic active-site subpocket explaining why N6-methyl-dATP is a good MTH1 substrate. N6-methylation of DNA and RNA has been reported to have epigenetic roles and to affect mRNA metabolism. We propose that MTH1 acts in concert with adenosine deaminase-like protein isoform 1 (ADAL1) to prevent incorporation of N6-methyl-(d)ATP into DNA and RNA. This would hinder potential dysregulation of epigenetic control and RNA metabolism via conversion of N6-methyl-(d)ATP to N6-methyl-(d)AMP, followed by ADAL1-catalyzed deamination producing (d)IMP that can enter the nucleotide salvage pathway.
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| 9. |
- Stenström, Pernilla, et al.
(författare)
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Total colonic aganglionosis: : a multicenter study of surgical treatment and patient-reported outcomes up to adulthood
- 2020
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Ingår i: BJS Open. - : Oxford University Press (OUP). - 2474-9842. ; 4:5, s. 943-953
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Tidskriftsartikel (refereegranskat)abstract
- Background: Surgery for total colonic aganglionosis (TCA) is designed to preserve continence and achieve satisfactory quality of life. This study evaluated a comprehensive group of clinical and social outcomes.Methods: An international multicentre study from eight Nordic hospitals involving examination of case records and a patient-reported questionnaire survey of all patients born with TCA between 1987 and 2006 was undertaken.Results: Of a total of 116 patients, five (4 center dot 3 per cent) had died and 102 were traced. Over a median follow-up of 12 (range 0 center dot 3-33) years, bowel continuity was established in 75 (73 center dot 5 per cent) at a median age of 11 (0 center dot 5-156) months. Mucosectomy with a short muscular cuff and straight ileoanal anastomosis (SIAA) (29 patients) or with aJpouch (JIAA) (26) were the most common reconstructions (55 of 72, 76 per cent). Major early postoperative complications requiring surgical intervention were observed in four (6 per cent) of the 72 patients. In 57 children aged over 4 years, long-term functional bowel symptoms after reconstruction included difficulties in holding back defaecation in 22 (39 per cent), more than one faecal accident per week in nine (16 per cent), increased frequency of defaecation in 51 (89 per cent), and social restrictions due to bowel symptoms in 35 (61 per cent). Enterocolitis occurred in 35 (47 per cent) of 72 patients. Supplementary enteral and/or parenteral nutrition was required by 51 (55 per cent) of 93 patients at any time during follow-up. Of 56 responders aged 2-20 years, true low BMI for age was found in 20 (36 per cent) and 13 (23 per cent) were short for age.Conclusion: Reconstruction for TCA was associated with persistent bowel symptoms, and enterocolitis remained common. Multidisciplinary follow-up, including continuity of care in adulthood, might improve care standards in patients with TCA.
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| 10. |
- Yang, Muyi, et al.
(författare)
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Novel loss-of-function variant in DENND5A impedes melanosomal cargo transport and predisposes to familial cutaneous melanoma
- 2022
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Ingår i: Genetics in Medicine. - : Elsevier BV. - 1098-3600 .- 1530-0366. ; 24:1, s. 157-169
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: More than half of the familial cutaneous melanomas have unknown genetic predisposition. This study aims at characterizing a novel melanoma susceptibility gene. Methods: We performed exome and targeted sequencing in melanoma-prone families without any known melanoma susceptibility genes. We analyzed the expression of candidate gene DENND5A in melanoma samples in relation to pigmentation and UV signature. Functional studies were carried out using microscopic approaches and zebrafish model. Results: We identified a novel DENND5A truncating variant that segregated with melanoma in a Swedish family and 2 additional rare DENND5A variants, 1 of which segregated with the disease in an American family. We found that DENND5A is significantly enriched in pigmented melanoma tissue. Our functional studies show that loss of DENND5A function leads to decrease in melanin content in vitro and pigmentation defects in vivo. Mechanistically, harboring the truncating variant or being suppressed leads to DENND5A losing its interaction with SNX1 and its ability to transport the SNX1-associated vesicles from melanosomes. Consequently, untethered SNX1-premelanosome protein and redundant tyrosinase are redirected to lysosomal degradation by default, causing decrease in melanin content. Conclusion: Our findings provide evidence of a physiological role of DENND5A in the skin context and link its variants to melanoma susceptibility.
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