[Analysis of EGFR gene transcription in rat embryo and adult tissues]

EGFR gene transcription in rat embryo and adult tissues were analysed by RNA Northern and Dot hybridization using 2.4 Kb human EGFR cDNA pE 7 as probe. In Northern hybridization (Fig. 1), the normal rat liver RNA showed a major 5.6 Kb RNA band which was a common EGFR mRNA present in human normal and cancer cells. For the comparison of EGFR gene transcription in embryo of different stages and different tissues, the density scanning data of dot hybridization signals are shown as bars in accompanying figures. The results indicated that the highest level of EGFR transcription was seen in rat embryo at 10th to 12th day during neonatal development (Fig. 2 and Fig. 3). In adult rat tissues, EGFR gene was commonly expressed with some variation in different tissues, for example, much more expressed in kidney than in liver, heart, brain and spleen, and moderately expressed in testis and lung (Fig. 4). The EGFR gene transcription could be induced in liver by hepatectomy. Fig. 5 showed the increase of EGFR gene transcripts at the 2-8 th hour of liver regeneration and the decrease after the 8th hour, even reaching a value lower than that of normal liver after the 24th hour. The results suggest that EGFR gene transcripts are commonly present in a wide range of normal tissues and may be involved in the control of proliferation and differentiation in embryo and adult tissues.