A fission yeast chromosome can replicate autonomously in mouse cells

Area of Science:

• * Molecular Biology
• * Genetics
• * Cell Biology

Background:

• * Investigating the functional capacity of eukaryotic chromosomes in heterologous systems is crucial for understanding genome stability and gene regulation.
• * Fission yeast (Schizosaccharomyces pombe) serves as a model organism for studying chromosome biology.

Purpose of the Study:

• * To assess the ability of a fission yeast chromosome to function within mouse cells.
• * To characterize the behavior and structure of Schizosaccharomyces pombe chromosome III after introduction into mouse C127 cells.

Main Methods:

• * Construction of a modified fission yeast strain (ED628 Int5) with a selectable marker (SV2NEO gene) on chromosome III.
• * Introduction of S. pombe chromosomes into mouse C127 cells via polyethylene glycol (PEG)-facilitated protoplast fusion.
• * Analysis of G418-resistant mouse cell lines (F1.1 and F7.1) for the presence and structure of the introduced yeast chromosome.

Main Results:

• * Two distinct G418-resistant cell lines, F1.1 and F7.1, were established.
• * F1.1 contained a rearranged fragment of S. pombe chromosome III integrated into a mouse chromosome, stably maintained without selection.
• * F7.1 harbored unstable, linear, unintegrated copies of S. pombe chromosome III, potentially due to centromere dysfunction or replication issues.

Conclusions:

• * Fission yeast chromosome III can be functionally maintained in mouse cells, either integrated or in an autonomous state.
• * The study highlights the potential for inter-species chromosome transfer and the challenges of maintaining extrachromosomal elements in mammalian cells.
• * Defective centromere function or replication errors may explain the instability of autonomously maintained yeast chromosomes in mouse cells.