Major erythrocyte membrane protein genes in EKLF-deficient mice.

Abstract

OBJECTIVES:

Mice deficient in the transcription factor erythroid Krüppel-like factor, KLF1 (EKLF) die approximately 14.5 days postcoitum of anemia, attributed to decreased expression of the beta-globin gene. The objectives of this study were to rescue EKLF-deficient embryos with mice expressing gamma-globin from beta-spectrin or ankyrin promoters and to characterize expression of the major erythrocyte membrane genes in EKLF-deficient cells.

METHODS:

Transgenic beta-spectrin/gamma-globin or ankyrin/gamma-globin mice were bred onto EKLF-deficient and wild-type backgrounds. Animals were genotyped, gamma-globin mRNA levels measured, and hemoglobin electrophoresis performed. Steady-state mRNA levels and transcriptional rates of the major erythrocyte membrane protein genes were assayed.

RESULTS:

beta-spectrin/gamma-globin or ankyrin/gamma-globin mice on EKLF-deficient and wild-type backgrounds had identical levels of gamma-globin mRNA, indicating EKLF-independence of these promoters. gamma-Globin expression improved globin chain imbalance, but hemolysis was not improved and no live-born EKLF-deficient/(A)gamma-globin mice were obtained. Circulating erythroid cells from EKLF-deficient/(A)gamma-globin embryos exhibited hemolysis reminiscent of that seen in patients with severe erythrocyte membrane defects. Levels of beta-spectrin, ankyrin, and band 3 mRNA, but not alpha-spectrin, were decreased in EKLF-deficient fetal liver RNA. In a run-on assay, levels of transcription of the ankyrin and band 3 genes were decreased in EKLF-deficient fetal liver nuclei.

CONCLUSIONS:

These results indicate that the EKLF-responsive regions of the ankyrin and beta-spectrin genes are outside their promoters and that EKLF is necessary for full transcriptional activity of the ankyrin and band 3 genes; the results also provide additional evidence that defects in addition to beta-globin deficiency, including an abnormal erythrocyte membrane, contribute to the anemia and embryonic lethality in EKLF-deficient mice.

• Authors: Douglas G Nilson, Denise E Sabatino, David M Bodine, Patrick G Gallagher
• Journal: Experimental hematology (Exp Hematol) Vol. 34 Issue 6 Pg. 705-12 (Jun 2006) ISSN: 0301-472X [Print] Netherlands
• PMID: 16728274 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Kruppel-Like Transcription Factors
• Membrane Proteins
• erythroid Kruppel-like factor
• Globins

Topics

• Animals
• Cell Nucleus (genetics, metabolism, pathology)
• Embryo Loss (genetics, metabolism, pathology)
• Erythrocyte Membrane (genetics, metabolism)
• Erythrocytes, Abnormal (metabolism, pathology)
• Gene Expression Regulation (genetics)
• Globins (biosynthesis, deficiency, genetics)
• Hemolysis (genetics)
• Humans
• Kruppel-Like Transcription Factors (deficiency, metabolism)
• Liver (metabolism)
• Membrane Proteins (biosynthesis, genetics)
• Mice
• Mice, Knockout
• Promoter Regions, Genetic (genetics)