Study of liver differentiation in vitro.

Area of Science:

• Cell Biology
• Virology
• Hepatology

Background:

• Primary hepatocytes have limited lifespan and are difficult to culture.
• Transformation of normal cells can create immortalized cell lines for research.
• Simian virus 40 (SV40) is a well-characterized oncogenic virus used for cell transformation.

Purpose of the Study:

• To establish a clonal rat fetal liver cell line with controllable differentiated functions.
• To investigate the temperature-sensitive regulation of transformed phenotype and liver-specific gene expression.
• To characterize the retained hepatocyte functions in the immortalized cell line.

Main Methods:

• Transformation of normal rat fetal liver cells using a temperature-sensitive simian virus 40 tsA mutant (tsA209).
• Culture of the transformed cell line (RLA209-15) at permissive (33°C) and restrictive (40°C) temperatures.
• Analysis of cell proliferation, saturation density, cloning efficiency, and synthesis of liver proteins (alpha-fetoprotein, albumin, transferrin).
• Assessment of cellular response to glucagon stimulation.

Main Results:

• RLA209-15 cells exhibited indefinite proliferation and cloning ability at 33°C.
• At 40°C, cells lost transformed characteristics and showed increased synthesis of alpha-fetoprotein, albumin, and transferrin.
• Synthesized liver proteins were immunologically identical to authentic proteins.
• Cells retained glucagon receptors, indicated by elevated cyclic AMP levels.

Conclusions:

• A temperature-inducible, immortalized rat fetal liver cell line (RLA209-15) was successfully established.
• This cell line provides a controllable model for studying differentiated liver cell functions.
• The retained expression of liver-specific proteins and functional receptors makes RLA209-15 valuable for hepatology research.