Comprehensive phenotypic analysis of knockout mice deficient in cyclin G1 and cyclin G2

Abstract

Cyclin G1 (CycG1) and Cyclin G2 (CycG2) play similar roles during the DNA damage response (DDR), but their detailed roles remain elusive. To investigate their distinct roles, we generated knockout mice deficient in CycG1 (G1KO) or CycG2 (G2KO), as well as double knockout mice (DKO) deficient in both proteins. All knockouts developed normally and were fertile. Generation of mouse embryonic fibroblasts (MEFs) from these mice revealed that G2KO MEFs, but not G1KO or DKO MEFs, were resistant to DNA damage insults caused by camptothecin and ionizing radiation (IR) and underwent cell cycle arrest. CycG2, but not CycG1, co-localized with γH2AX foci in the nucleus after γ-IR, and γH2AX-mediated DNA repair and dephosphorylation of CHK2 were delayed in G2KO MEFs. H2AX associated with CycG1, CycG2, and protein phosphatase 2A (PP2A), suggesting that γH2AX affects the function of PP2A via direct interaction with its B’γ subunit. Furthermore, expression of CycG2, but not CycG1, was abnormal in various cancer cell lines. Kaplan–Meier curves based on TCGA data disclosed that head and neck cancer patients with reduced CycG2 expression have poorer clinical prognoses. Taken together, our data suggest that reduced CycG2 expression could be useful as a novel prognostic marker of cancer.

ELAS1 induces apoptotic death in adenocarcinoma DU145 and squamous-cell carcinoma SAS cancer cells, but not in normal KD cells

“…This concern was removed by showing that ELAS1 caused little apoptosis in normal KD cells (Figure 5 ). The healthy growth of CycG1- and CycG2-double-knockout mice [ 13 ] also supports the safety of ELAS1, which inhibits a function of CycG1 [ 9 ].…”

“…Moreover, apoptosis of Myc-ELAS1-expressing U2OS cells is efficiently induced by only one-hundredth (CPT) or one-fifth (irinotecan) of the amounts of drugs required to induce this effect in Myc-vector-expressing cells [ 9 ]. ELAS1, a peptide corresponding to the association domain of Cyclin G1 (CycG1) with protein phosphatase 2A (PP2A), associates with the B'γ subunit of PP2A [ 10 , 11 ] and competitively inhibits the association with CycG1 [ 12 , 13 ]. ELAS1 prevents the proper action of the PP2A holoenzyme on its dephosphorylating target p53-pS46, which is activated following DSB insults [ 9 , 14 , 15 ].…”

Characterization of gene expression profiles in the mouse brain after 35 days of spaceflight mission

“…GADD45G ( https://www.ncbi.nlm.nih.gov/gene/?term=NM_011817 ) has been found to play a role in activating checkpoints in the cell cycle following exposure of cells to irradiation 76 . CCNG2 ( https://www.ncbi.nlm.nih.gov/gene/?term=NM_007635 ) contributes to cell cycle arrest during DNA damage and is upregulated in response to diverse stimuli, including hypoxia 77 . Additionally, expression of CCNG2 is found to be significantly increased in cell cycle-arrested and terminally differentiated cells 78 .…”

Clathrin heavy chain phosphorylated at T606 plays a role in proper cell division

“…For methanol (MeOH) fixation, HeLa S3 cells plated on coverslips were treated with 100% ice-cold MeOH at −20°C for 10 min after pretreatment of the cells with microtubule-stabilizing buffer (80 mM Pipes-KOH, pH6.8, 5 mM EGTA, 1 mM MgCl 2 , 0.5% Triton X-100) for 5 min at RT, followed by washing the cells three times in PBS (-). IF staining was performed as described in our previous reports [37,53]. The signal intensity of immuneflurescence images was measured by MetaVue software (Molecular Devices) or FLUOVIEW software Ver.…”