Hemin control of heme biosynthesis in mouse Friend virus-transformed erythroleukemia cells in culture

J.L Granick,S Sassa

doi:10.1016/s0021-9258(17)30385-x

Abstract

Hemin treatment of mouse Friend virus-transformed cells in cultured caused a dose-dependent increase in hemoglobin synthesis. By the addition of radioactively labeled hemin and by the analysis of the radioactive heme in hemoglobin, only 60 to 70% of heme in the newly synthesized hemoglobin was accounted for by the exogenously added hemin. In keeping with this finding, hemin treatment increased the activity of two enzymes in the heme biosynthetic activity, i.e. delta-aminolevulinate (ALA) dehydratase and uroporphyrinogen-I (URO) synthase in these cells. Incorporation of [2(-14C)]glycine, [14C]ALA, and 59Fe into heme was also significantly increased in the cells treated with hemin, suggesting that essentially all enzyme activities in the heme biosynethetic pathway were increased after hemin treatment. These results indicate that heme in the newly synthesized hemoglobin in hemin-treated Friend cells derives both from hemin added to the culture and from heme synthesized intracellularly. In addition, these results suggest that the stimulation of heme biosynthesis by hemin in Friend virus-transformed cells is in contrast to the hemin repression of heme biosynthesis in liver cells.

Highlights

[2-14C]glycine, [14C]ALA, and 5vFe into heme was significantly increased in the cells treated with hemin, suggesting that essentially all enzyme activities in the heme biosynthetic pathway were increased after hemin treatment
When the rate of ““Fe utilization for heme synthesis was calculated as the fraction of total cellular “‘Fe uptake, it was found that MezSO, and hemin or hemin plus Me2S0 caused significant increases of heme synthesis as compared with the control culture (Table V). These results indicate that hemin treatment as well as MezSO or Me2S0 plus hemin caused an increase in ferrochelatase activity, the terminal enzyme of heme biosynthesis, leading to an increased hemoglobin formation
The results of this study demonstrate that hemin treatment of Friend virus-transformed cells in culture increases hemoglobin concentration and enzymes in the heme biosynthetic pathway

Summary

Introduction

[2-14C]glycine, [14C]ALA, and 5vFe into heme was significantly increased in the cells treated with hemin, suggesting that essentially all enzyme activities in the heme biosynthetic pathway were increased after hemin treatment These results indicate that heme in the newly synthesized hemoglobin in hemin-treated Friend cells derives both from hemin added to the culture and from heme synthesized intracellularly. Several classes of apparently unrelated agents have been shown to cause cultured cell lines of mouse Friend virustransformed cells to undergo erythroid cell differentiation These include dimethylsulfoxide [1]) hexamethylenebisacetamide [2], short chain fatty acids such as butyric acid [3], and hemin [4, 5], as well as certain purines and purine analogues [6].

Methods

Results

Conclusion