Category:Team Heterozygoats

CtIP interacts with Brca1 to help promote the start of resection during NHEJ. Figure 2 shows slow DSB repair through CTIP function.

Rad50 is part of the Mre11-Rad50-Nbs1 complex which plays a role in DNA repair processes including DNA damage checkpoint and recruitment of telomerase. Rad50 is responsible for stimulating ATP dependent DNA unwinding.

Fig. 4. Efficient NHEJ requires Ku70, DNA ligase 4 and MRN. (Mre11-Rad50-Nbs1=MRN)

ZNF281 is thought to play a role in DNA repair. When cells were subjected to stress through DNA damage, the levels of ZNF281 were increased. Figure 4 shows that ZNF281 is a substrate of the ATM/ATR complex which is involved in NHEJ.

XLF directly interacts with the XRCC4-LIgase IV complex during NHEJ. Downregulated XLF leads to increased radiosensitivity as well as impaired NHEJ. Figure 3 part shows cells with XLF downregulation were more susceptible to damage from radiation.

As shown in Figure 3, ATM is required for the repair of DSB breaks. In parts D and E of Figure 3, when the ATM levels were depleted in the xenopus egg extracts, the repair levels were significantly decreased in proportion to the controls. This was confirmed by immunoblotting.

Human cells with a deletion in Smarcal1 have less frequent double stranded break repair events. This is seen in Figure 5B where cells with the Smarcal1 deletion show a 4fold decrease in DSB repair events compared to wild type.

Figure 4 shows that the survival of Caulobacter crescentus with a deletion in the AlkB gene is compensated 100fold under .01% methyl methane sulfonate conditions. This shows that AlkB plays a role in the cells defense against alkylation.

Dps plays an important role in oxidative stress response. Figure 4 shows that cells with a deletion of the Dps gene had significantly less growth under 400 uM conditions compared to wild-type.

Figure 4C shows how XRCC4 quickly accumulates at the sites of double-stranded breaks in the DNA since the merged image of XRCC4 localization and antibody detection of γH2AX, a marker of DSBs, indicates that XRCC4 is heavily present at the site of DSBs. The regulation of XRCC4 localizations might play a key role in regulating NHEJ activity since the XRCC4/DNA Ligase IV complex is crucial for the final ligation of DSBs through NHEJ.

Figure 2B shows how DNA -PKcs is required for efficient non homologous end repair activity, as evidenced with the assay on repair activity with or without DNA-PKcs inhibitor NU7441. When DNA-PKcs was inhibited, the activity of repair of double stranded breaks via NHEJ was significantly decreased. Xenopus laevis.

In figure 1B and 1C, anti-XRCC4 antibodies were stained in order to show the localization of XRCC4. When overlaid with the images of stained nuclei, the merged image showed that XRCC4 is located within the nuclei.

In figure E1, a multitude of overhang types were tested with and without the inhibition of DNA-PKcs. In all cases, the inhibition of DNA-PKcs significantly reduced the repair activity of the egg extract as compared to the control.

Mre11, a protein required for double stranded break repair via non homologous end joining, forms a dimer to bridge the gap between the two broken ends of the double-stranded DNA. Figure 6 proves how dimerization of mre11 ( or rad32 in S. pombe) needs to occur for efficient non homologous end joining since the introduced mutations in the Mre11 dimerization domain, but not the nuclease domain, reduce NHEJ. This data is represented by the drastic decrease in PCR products since the bands for PCR products would indicate successful repair by non homologous end-joining. Therefore, mre11 dimerization is essential for NHEJ since there were no excision products from PCR.