Isolation And Functional Analysis Of Mouse PDIP1 Gene

Polymerase delta-interacting protein 1 (PDIP1) gene was cloned in human HepG2 cells. The interaction of PDIPl with the small subunit (p50) of DNA polymerase δ ( pol δ ) and the proliferating cell nuclear antigen(PCNA) was confirmed, suggesting that PDIPl may partly assist or participate in the DNA replication and/or repair. Homology searches using BLAST with the amino acid sequence revealed that PDIPl shares a high degree of homology (70% identity) with the TNF-α induced protein B12. So PDIPl may have similar biological function as B12. TNF- α , a cell cytokine produced by the macrophage cells has a function of inducing apoptosis, especially for the tumor cells. This finding suggests that PDIPl may play a partial role in apoptosis, because B12 also has this function. Another important function of THF-α is to initiate liver regeneration after the liver was damaged. Therefore, the PDIPl gene may also play a role in liver regeneration.To further study the function of PDIPl in apoptosis and liver regeneration, we cloned the full length cDNA of mouse PDIPl by RACE PCR. The full length cDNA has 1677 bp and encodes a polypeptide of 329 amino acids. Through bioinformatic analysis, we know that the PDIPl gene was mapped to mouse chromosome 7 at F3. PDIP1 may be a transcription factor functioning in the cell nucleus. We also found that there is a PDIPl gene family including at least 3 genes. We named them as PDIPl- α ,PDIPl- β ,PDIPl-γ . We designed a suitable probe in the experiment and used Ribonuclease protection assay technology to detect the expression of PDIPl gene in mouse liver at different time points after partial hepatectomy. We found that the expression of PDIPl gene was increased. It reached the highest level after 12 hours and then decreased. Our data suggest that PDIPl gene may play a role in the repair and regeneration of damaged livers.