Temperature-dependent transmembrane potential changes in cells infected with a temperature-sensitive Moloney sarcoma...

Area of Science:

• Cell biology
• Virology
• Membrane biophysics

Background:

• Moloney murine sarcoma virus (MMSV) is a retrovirus known to induce tumors.
• Temperature-sensitive (ts) mutants of MMSV allow for the study of viral transformation under controlled conditions.
• Transmembrane potential (Em) is a critical indicator of cell membrane function and integrity.

Purpose of the Study:

• To investigate the role of transmembrane potential (Em) changes during viral transformation.
• To characterize the temporal relationship between Em alterations and morphological changes in virus-transformed cells.
• To determine if Em changes are an early event in the transformation process.

Main Methods:

• Utilized a temperature-sensitive mutant of Moloney murine sarcoma virus to infect normal rat kidney (NRK) cells, generating a transformable cell line (6m2).
• Measured transmembrane potential (Em) using the cyanine dye diS-C3-(5) and fluorometry, correlating fluorescence intensity with Em.
• Shifted cell cultures between permissive (33°C) and non-permissive (39°C) temperatures to induce and reverse morphological transformation and monitored Em changes.

Main Results:

• The 6m2 cell line exhibited a transformed morphology at 33°C and a normal morphology at 39°C.
• Transmembrane potential (Em) was lower in transformed cells (33°C) compared to normal cells (39°C).
• Significant Em changes occurred within 15 minutes of temperature shifts, preceding other transformation-specific morphological changes.

Conclusions:

• Alterations in transmembrane potential (Em) are an early event in Moloney murine sarcoma virus-induced cell transformation.
• The study provides evidence that changes in Em are a critical early indicator of viral transformation.
• These findings contribute to understanding the biophysical mechanisms underlying viral oncogenesis.