[Expression of ORIGIN-like sequence in mammalian cells].

Area of Science:

• Molecular Biology
• Radiation Biology
• Hepatocyte Research

Background:

• Gene expression changes occur in hepatocytes following whole-body X-irradiation.
• Some radiation-responsive genes may be involved in regulating cell division.
• The autonomously replicating sequence pDARC1 was previously cloned and shown to be transcribed in irradiated hepatocytes.

Purpose of the Study:

• To investigate the expression of the autonomously replicating sequence pDARC1 in normal, irradiated, and dividing rat hepatocytes.
• To determine if pDARC1 expression is linked to cell proliferation and radiation exposure.

Main Methods:

• Analysis of pDARC1 sequence expression using hybridization techniques.
• Studying hepatocytes from rats subjected to whole-body X-irradiation.
• Comparing gene expression in normal, irradiated, and dividing hepatocytes.

Main Results:

• A 4.0 kb mRNA transcript from pDARC1 was detected in non-proliferating rat hepatocytes after X-irradiation, but not in normal hepatocytes.
• The induction of this 4.0 kb mRNA is dose-dependent and peaks 6-24 hours post-irradiation (6 Gy).
• The 4.0 kb mRNA was also observed in dividing rat hepatocytes during the pre-replicative phase.

Conclusions:

• X-irradiation induces the expression of a specific 4.0 kb mRNA from the pDARC1 sequence in rat hepatocytes.
• The presence of this mRNA in both irradiated and dividing hepatocytes suggests a potential role for pDARC1 in cell division regulation.
• Further research is warranted to elucidate the precise function of pDARC1 in cellular responses to radiation and proliferation.