| 1. |
- Alao, John Patrick, 1973, et al.
(författare)
-
Caffeine stabilises fission yeast Wee1 in a Rad24-dependent manner but attenuates Its expression in response to DNA damage.
- 2020
-
Ingår i: Microorganisms. - : MDPI AG. - 2076-2607. ; 8:10
-
Tidskriftsartikel (refereegranskat)abstract
- The widely consumed neuroactive compound caffeine has generated much interest due to its ability to override the DNA damage and replication checkpoints. Previously Rad3 and its homologues was thought to be the target of caffeine's inhibitory activity. Later findings indicate that the Target of Rapamycin Complex 1 (TORC1) is the preferred target of caffeine. Effective Cdc2 inhibition requires both the activation of the Wee1 kinase and inhibition of the Cdc25 phosphatase. The TORC1, DNA damage, and environmental stress response pathways all converge on Cdc25 and Wee1. We previously demonstrated that caffeine overrides DNA damage checkpoints by modulating Cdc25 stability. The effect of caffeine on cell cycle progression resembles that of TORC1 inhibition. Furthermore, caffeine activates the Sty1 regulated environmental stress response. Caffeine may thus modulate multiple signalling pathways that regulate Cdc25 and Wee1 levels, localisation and activity. Here we show that the activity of caffeine stabilises both Cdc25 and Wee1. The stabilising effect of caffeine and genotoxic agents on Wee1 was dependent on the Rad24 chaperone. Interestingly, caffeine inhibited the accumulation of Wee1 in response to DNA damage. Caffeine may modulate cell cycle progression through increased Cdc25 activity and Wee1 repression following DNA damage via TORC1 inhibition, as TORC1 inhibition increased DNA damage sensitivity.
|
|
| 2. |
- Johansson Sjölander, Johanna, 1980, et al.
(författare)
-
The fission yeast FHIT homolog affects checkpoint control of proliferation and is regulated by mitochondrial electron transport.
- 2020
-
Ingår i: Cell Biology International. - : Wiley. - 1095-8355 .- 1065-6995. ; 44:2, s. 412-423
-
Tidskriftsartikel (refereegranskat)abstract
- Genetic analysis has strongly implicated human FHIT (Fragile Histidine Triad) as a tumor suppressor gene, being mutated in a large proportion of early-stage cancers. The functions of the FHIT protein have, however, remained elusive. Here, we investigated aph1+ , the fission yeast homolog of FHIT, for functions related to checkpoint control and oxidative metabolism. In sublethal concentrations of DNA damaging agents, aph1Δ mutants grew with a substantially shorter lag phase. In aph1Δ mutants carrying a hypomorphic allele of cds1 (the fission yeast homolog of Chk2), in addition, increased chromosome fragmentation and missegregation were found. We also found that under hypoxia or impaired electron transport function, the Aph1 protein level was strongly depressed. Previously, FHIT has been linked to regulation of the human 9-1-1 checkpoint complex constituted by Hus1, Rad1, and Rad9. In Schizosaccharomyces pombe, the levels of all three 9-1-1 proteins are all downregulated by hypoxia in similarity with Aph1. Moreover, deletion of the aph1+ gene reduced the Rad1 protein level, indicating a direct relationship between these two proteins. We conclude that the fission yeast FHIT homolog has a role in modulating DNA damage checkpoint function, possibly through an effect on the 9-1-1 complex, and that this effect may be critical under conditions of limiting oxidative metabolism and reoxygenation.
|
|
| 3. |
- Otreba, Michal, et al.
(författare)
-
A small molecule targeting human MEK1/2 enhances ERK and p38 phosphorylation under oxidative stress or with phenothiazines.
- 2021
-
Ingår i: Life (Basel). - : MDPI AG. - 2075-1729. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- Small molecules are routinely used to inhibit protein kinases, but modulators capable of enhancing kinase activity are rare. We have previously shown that the small molecule INR119, designed as an inhibitor of MEK1/2, will enhance the activity of its fission yeast homologue, Wis1, under oxidative stress. To investigate the generality of these findings, we now study the effect of INR119 in human cells under similar conditions. Cells of the established breast cancer line MCF-7 were exposed to H2O2 or phenothiazines, alone or combined with INR119. In line with the previous results in fission yeast, the phosphorylation of the MAPKs ERK and p38 increased substantially more with the combination treatment than by H2O2 or phenothiazines, whereas INR119 alone did not affect phosphorylation. We also measured the mRNA levels of TP53 and BAX, known to be affected by ERK and p38 activity. Similarly, the combination of INR119 and phenothiazines increased both mRNAs to higher levels than for phenothiazines alone. In conclusion, the mechanism of action of INR119 on its target protein kinase may be conserved between yeast and humans.
|
|
