| 1. |
- Carter, Megan, et al.
(författare)
-
Human NUDT22 Is a UDP-Glucose/Galactose Hydrolase Exhibiting a Unique Structural Fold
- 2018
-
Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 26:2, s. 295-303
-
Tidskriftsartikel (refereegranskat)abstract
- Human NUDT22 belongs to the diverse NUDIX family of proteins, but has, until now, remained uncharacterized. Here we show that human NUDT22 is a Mg2+-dependent UDP-glucose and UDP-galactose hydrolase, producing UMP and glucose 1-phosphate or galactose 1-phosphate. We present the structure of human NUDT22 alone and in a complex with the substrate UDP-glucose. These structures reveal a partially conserved NUDIX fold domain preceded by a unique N-terminal domain responsible for UDP moiety binding and recognition. The NUDIX domain of NUDT22 contains a modified NUDIX box identified using structural analysis and confirmed through functional analysis of mutants. Human NUDT22's distinct structure and function as a UDP-carbohydrate hydrolase establish a unique NUDIX protein subfamily.
|
|
| 2. |
- Herr, Patrick, et al.
(författare)
-
A genome-wide IR-induced RAD51 foci RNAi screen identifies CDC73 involved in chromatin remodeling for DNA repair
- 2015
-
Ingår i: Cell discovery. - : Springer Science and Business Media LLC. - 2056-5968. ; 1
-
Tidskriftsartikel (refereegranskat)abstract
- To identify new regulators of homologous recombination repair, we carried out a genome-wide short-interfering RNA screen combined with ionizing irradiation using RAD51 foci formation as readout. All candidates were confirmed by independent short-interfering RNAs and validated in secondary assays like recombination repair activity and RPA foci formation. Network analysis of the top modifiers identified gene clusters involved in recombination repair as well as components of the ribosome, the proteasome and the spliceosome, which are known to be required for effective DNA repair. We identified and characterized the RNA polymerase II-associated protein CDC73/Parafibromin as a new player in recombination repair and show that it is critical for genomic stability. CDC73 interacts with components of the SCF/Cullin and INO80/NuA4 chromatin-remodeling complexes to promote Histone ubiquitination. Our findings indicate that CDC73 is involved in local chromatin decondensation at sites of DNA damage to promote DNA repair. This function of CDC73 is related to but independent of its role in transcriptional elongation.
|
|
| 3. |
- Valenta, Tomas, et al.
(författare)
-
Wnt Ligands Secreted by Subepithelial Mesenchymal Cells Are Essential for the Survival of Intestinal Stem Cells and Gut Homeostasis
- 2016
-
Ingår i: Cell Reports. - : Elsevier. - 2211-1247. ; 15:5, s. 911-918
-
Tidskriftsartikel (refereegranskat)abstract
- Targeting of Wnt signaling represents a promising anti-cancer therapy. However, the consequences of systemically attenuating the Wnt pathway in an adult organism are unknown. Here, we globally prevent Wnt secretion by genetically ablating Wntless. We find that preventing Wnt signaling in the entire body causes mortality due to impaired intestinal homeostasis. This is caused by the loss of intestinal stem cells. Reconstitution of Wnt/β-catenin signaling via delivery of external Wnt ligands prolongs the survival of intestinal stem cells and reveals the essential role of extra-epithelial Wnt ligands for the renewal of the intestinal epithelium. Wnt2b is a key extra-epithelial Wnt ligand capable of promoting Wnt/β-catenin signaling and intestinal homeostasis. Wnt2b is secreted by subepithelial mesenchymal cells that co-express either Gli1 or Acta2. Subepithelial mesenchymal cells expressing high levels of Wnt2b are predominantly Gli1 positive.
|
|
| 4. |
- Valerie, Nicholas C. K., et al.
(författare)
-
NUDT15 Hydrolyzes 6-Thio-DeoxyGTP to Mediate the Anticancer Efficacy of 6-Thioguanine
- 2016
-
Ingår i: Cancer Research. - 0008-5472 .- 1538-7445. ; 76:18, s. 5501-5511
-
Tidskriftsartikel (refereegranskat)abstract
- Thiopurines are a standard treatment for childhood leukemia, but like all chemotherapeutics, their use is limited by inherent or acquired resistance in patients. Recently, the nucleoside diphosphate hydrolase NUDT15 has received attention on the basis of its ability to hydrolyze the thiopurine effector metabolites 6-thio-deoxyGTP (6-thio-dGTP) and 6-thio-GTP, thereby limiting the efficacy of thiopurines. In particular, increasing evidence suggests an association between the NUDT15 missense variant, R139C, and thiopurine sensitivity. In this study, we elucidated the role of NUDT15 and NUDT15 R139C in thiopurine metabolism. In vitro and cellular results argued that 6-thio-dGTP and 6-thio-GTP are favored substrates for NUDT15, a finding supported by a crystallographic determination of NUDT15 in complex with 6-thio-GMP. We found that NUDT15 R139C mutation did not affect enzymatic activity but instead negatively influenced protein stability, likely due to a loss of supportive intramolecular bonds that caused rapid proteasomal degradation in cells. Mechanistic investigations in cells indicated that NUDT15 ablation potentiated induction of the DNA damage checkpoint and cancer cell death by 6-thioguanine. Taken together, our results defined how NUDT15 limits thiopurine efficacy and how genetic ablation via the R139C missense mutation confers sensitivity to thiopurine treatment in patients.
|
|
