Human cell variants resistant to rhodamine 6G

Area of Science:

• Cell Biology
• Mitochondrial Biology
• Genetics

Background:

• Mitochondrial-specific fluorescent dyes like rhodamine 6G and rhodamine 123 are vital tools for assessing mitochondrial membrane potential.
• Understanding mechanisms of dye resistance can reveal insights into mitochondrial function and cellular transport.

Purpose of the Study:

• To isolate and characterize human cell variants exhibiting resistance to rhodamine dyes.
• To investigate the genetic basis and functional consequences of rhodamine resistance in cultured human cells.

Main Methods:

• Isolation of rhodamine-resistant variants from the VA2-B human cell line.
• Cross-resistance and sensitivity testing with other cellular agents (ethidium bromide, colchicine, chloramphenicol).
• Analysis of dye retention in resistant versus wild-type cells and assessment of inheritance patterns through cell fusions.

Main Results:

• Two distinct rhodamine-resistant variants were isolated, showing cross-resistance to ethidium bromide but sensitivity to colchicine and chloramphenicol.
• Resistant cells displayed significantly reduced mitochondrial rhodamine fluorescence, indicating decreased dye binding and retention.
• Rhodamine resistance was gradually expressed in hybrid cell fusions, suggesting nuclear gene involvement rather than mitochondrial DNA mutation.

Conclusions:

• The isolated variants possess a reduced capacity to bind and retain rhodamine dyes, likely due to altered mitochondrial transmembrane electrical potential.
• The nuclear inheritance pattern of rhodamine resistance points to mutations in nuclear genes affecting mitochondrial dye uptake or retention.
• These findings provide a valuable model for studying mitochondrial function and the genetic basis of drug resistance.