Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2011 Aug 12;6(8):e23432. doi: 10.1371/journal.pone.0023432

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Atsumi et al.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.

PMC Copyright notice

A. Growth curves of MEFs cultured under the standard 3T3 protocol (Std-3T3) or the T3 protocol with temporary serum deprivation (tSD-3T3) as schematically shown. MEFs under Std-3T3 conditions were immortalized, whereas MEFs cultured under tSD-3T3 conditions were not. B Genomic instability developed in immortalized MEFs (IP2) under Std-3T3 conditions. C. Genomic status was determined by flow-cytometry at the indicated conditions and passages. Representative images are shown. Tetraploidy development was blocked under tSD-3T3 conditions, while tetraploidy had already developed in growth-arrested MEFs at P9 under Std-3T3 conditions (see increasing 4N and 8N peaks). D. DNA lesions identified by γH2AX foci spontaneously accumulated in MEFs developing tetraploidy and immortality (P9) under Std-3T3 conditions as well as in immortal cells (IP2), while MEFs that maintained quiescent status with genomic stability under tSD-3T3 conditions contained no foci. E. DNA lesion-carryover into the G2-M phases was determined for lesions that spontaneously accumulated in senescent MEFs under Std-3T3 conditions. DNA lesions in senescing MEFs are also observed in the G2-M phases determined by phosphorylated H3. F. Chromosome bridge formation (Left panel) is observed in association with DNA lesion-carryover into the G2-M phases under Std-3T3 conditions with the resulting accumulation of bi-nucleated tetraploidy (Right panel: red arrow heads). Representative images are shown. G. The total H2AX level at P9 under each condition was determined. Whereas a significant reduction in H2AX expression was observed in MEFs with genomic stability under tSD-3T3 conditions, MEFs that developed immortality and genomic instability under Std-3T3 conditions did not show a significant decrease in H2AX expression. H. A model of the life-cycle of MEFs undergoing quiescence or developing immortality. While quiescent MEFs preserve diploidy and show diminished H2AX levels, MEFs developing immortality exhibited γH2AX foci accumulation.