Genetic Disorders – Development
Kidney International (2002) 61, 396–404; doi:10.1046/j.1523-1755.2002.00152.x
L-arginine rescues decreased erythropoietin gene expression by stimulating GATA-2 with L-NMMA
Shigehiko Imagawa, Takahisa Tarumoto, Norio Suzuki, Harumi Y Mukai, Yuichi Hasegawa, Masato Higuchi, Tomohiro Neichi, Keiya Ozawa, Masayuki Yamamoto and Toshiro Nagasawa
Division of Hematology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki; Department of Hematology, Jichi Medical School, Tochigi; Center for Tsukuba Advanced Research Alliance and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki; and Chugai Pharmaceutical Co., Ltd., Tokyo, Japan
Correspondence: Shigehiko Imagawa, M.D., Ph.D., Division of Hematology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan. E-mail: simagawa@md.tsukuba.ac.jp
Received 28 March 2001; Revised 13 September 2001; Accepted 14 September 2001.
Abstract
L-arginine rescues decreased erythropoietin gene expression by stimulating GATA-2 with L-NMMA.
Background
NG-monomethyl-L-arginine (L-NMMA) decreases the expression of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) and increases the expression of GATA-2 mRNA and levels of GATA-2 binding activity, thereby inhibiting erythropoietin (Epo) promoter activity and causing a decrease in the expression of Epo protein. In the present study, we examined the effect of L-arginine on Epo gene expression in Hep3B cells and BDF1 mice.
Methods
Hep3B cells were incubated with and without different concentrations of L-NMMA and/or L-arginine. Anemic mice were injected with phosphate-buffered saline (PBS) or L-NAME and L-arginine.
Results
Incubation with L-NMMA under hypoxic conditions inhibited Epo expression, but this inhibition was recovered by the addition of L-arginine. Hypoxia induced the secretions of NO and cGMP, but the addition of L-NMMA inhibited these inductions, though these inhibitions of NO and cGMP by L-NMMA were recovered by the addition of L-arginine. Hep3B cells transfected with the Epo promoter/enhancer-luciferase gene had Epo promoter activity. This activity was inhibited by L-NMMA, but it could be recovered by the addition of L-arginine. L-NMMA induced the binding activity of GATA-2 under hypoxic conditions. This binding activity was inhibited by the addition of L-arginine. The addition of cGMP inhibited L-NMMA-induced GATA-2 binding activity in a dose-dependent manner. The results of an in vivo mouse assay revealed that L-NAME inhibited the expression of Epo, but this inhibition of Epo expression by L-NAME was rescued by pretreatment with L-arginine.
Conclusion
L-arginine rescues decreased erythropoietin gene expression by stimulating GATA-2 with NG-monomethyl-L-arginine.
Keywords:
L-NAME, L-NMMA, anemia, hypoxia, signal transduction, oxygen sensing, uremic toxin
