Chromatin organization and behavior in HRAS-transformed mouse fibroblasts.

Area of Science:

• Cell Biology
• Genomics
• Cancer Research

Background:

• Higher eukaryotic cells feature irregularly folded chromatin domains where nucleosomes exhibit liquid-like local behavior.
• Chromatin dynamics are linked to DNA transactions like transcription and repair, often elevated in cancer cells.

Purpose of the Study:

• To investigate and compare chromatin behavior in cancer cells versus non-cancer cells.
• To analyze the effects of oncogenic HRAS transformation on chromatin structure and nuclear morphology.

Main Methods:

• Utilized oncogenic-HRAS (Gly12Val)-transformed mouse fibroblasts (CIRAS-3) and parental cells (10T1/2).
• Employed single-nucleosome imaging/tracking in live cells.
• Performed Hi-C analysis to examine chromatin interactions.
• Assessed heterochromatin markers like H3K27me3.

Main Results:

• HRAS transformation altered chromosome structure and nuclear morphology.
• Nucleosomes were locally more constrained in CIRAS-3 cancer cells compared to 10T1/2 cells.
• Heterochromatin (H3K27me3) and B-B compartment interactions were upregulated in CIRAS-3 cells, indicating transcriptionally inactive regions.

Conclusions:

• Increased heterochromatin in cancer cells may influence cell migration and metastasis.
• Single-nucleosome imaging offers novel insights into local chromatin organization in living cells.
• Altered chromatin dynamics are a hallmark of HRAS-induced transformation.