Phosphates

Downregulation of protein phosphatase Cdc25^Twine activity is linked to remodelling of the cell cycle during the Drosophila maternal-to-zygotic transition (MZT). Here, we present a structure-function analysis of Cdc25^Twine. We use chimeras to show that the N-terminus regions of Cdc25^Twine and Cdc25^String control their differential degradation dynamics. Deletion of different regions of Cdc25^Twine reveals a putative domain involved in and required for its rapid degradation during the MZT. Notably, a very similar domain is present in Cdc25^String and deletion of the DNA replication checkpoint results in similar dynamics of degradation of both Cdc25^String and Cdc25^Twine. Finally, we show that Cdc25^Twine degradation is delayed in embryos lacking the left arm of chromosome III. Thus, we propose a model for the differential regulation of Cdc25 at the Drosophila MZT.

LRRK2 is a highly phosphorylated multidomain protein and mutations in the gene encoding LRRK2 are a major genetic determinant of Parkinson's disease (PD). Dephosphorylation at LRRK2's S910/S935/S955/S973 phosphosite cluster is observed in several conditions including in sporadic PD brain, in several disease mutant forms of LRRK2 and after pharmacological LRRK2 kinase inhibition. However, the mechanism of LRRK2 dephosphorylation is poorly understood. We performed a phosphatome-wide reverse genetics screen to identify phosphatases involved in the dephosphorylation of the LRRK2 phosphosite S935. Candidate phosphatases selected from the primary screen were tested in mammalian cells, Xenopus oocytes and in vitro. Effects of PP2A on endogenous LRRK2 phosphorylation were examined via expression modulation with CRISPR/dCas9. Our screening revealed LRRK2 phosphorylation regulators linked to the PP1 and PP2A holoenzyme complexes as well as CDC25 phosphatases. We showed that dephosphorylation induced by different kinase inhibitor triggered relocalisation of phosphatases PP1 and PP2A in LRRK2 subcellular compartments in HEK-293 T cells. We also demonstrated that LRRK2 is an authentic substrate of PP2A both in vitro and in Xenopus oocytes. We singled out the PP2A holoenzyme PPP2CA:PPP2R2 as a powerful phosphoregulator of pS935-LRRK2. Furthermore, we demonstrated that this specific PP2A holoenzyme induces LRRK2 relocalization and triggers LRRK2 ubiquitination, suggesting its involvement in LRRK2 clearance. The identification of the PPP2CA:PPP2R2 complex regulating LRRK2 S910/S935/S955/S973 phosphorylation paves the way for studies refining PD therapeutic strategies that impact LRRK2 phosphorylation.

Thiazolopyrimidine analogues are versatile synthetic scaffold possessing wide spectrum of biological interests involving potential anticancer activity.

To report the synthesis of novel bromothiazolopyrimidine derivatives and the study of both molecular modeling and in-vitro anticancer activity.

Novel bromothiazolopyrimidine derivatives 5-18 have been prepared from 2-bromo-3-(4- chlorophenyl)-1-(3,4-dimethylphenyl)-propenone 3 as a key starting compound. The anti-cancer activities of the new compounds were evaluated against HepG2, MCF-7, A549 and HCT116 cell lines.

The compounds 16, 17 and 18 showed cytotoxic and growth inhibitory activities on both colon and lung cells. The cytotoxic activities of the novel synthetic compounds 8, 9, 11, 16, 17 and 18 were due to CDC25 phosphatases inhibition as shown by the enzymatic binding assay. Although compounds 8, 9 and 11 have only demonstrated CDC25B phosphatases inhibition.

The novel bromothiazolopyrimidine derivatives showed promising in vitro anticancer activities against colon cancer HCT116 and lung cancer A549 cell lines comparable to the anticancer drug doxorubicin.