TY - JOUR
T1 - Sphingosine kinase 1 expression is downregulated during differentiation of friend cells due to decreased c-MYB
AU - Mizutani, N.
AU - Kobayashi, M.
AU - Sobue, S.
AU - Ichihara, M.
AU - Ito, H.
AU - Tanaka, K.
AU - Iwaki, S.
AU - Fujii, S.
AU - Ito, Y.
AU - Tamiya-Koizumi, K.
AU - Takagi, A.
AU - Kojima, T.
AU - Naoe, T.
AU - Suzuki, M.
AU - Nakamura, M.
AU - Banno, Y.
AU - Nozawa, Y.
AU - Murate, T.
N1 - Funding Information:
The authors are grateful to Dr. F. Moreau-Gachelin (Inserm U528, Paris, France), Dr. T. Yoshimoto (Tokyo Medical University, Tokyo, Japan), Dr. A. Katsumi (Hamamatsu University School of Medicine, Hamamatsu, Japan), and Dr. A. Tomita (Nagoya University Graduate School of Medicine, Nagoya, Japan) for their vectors. This work was supported in part by JSPS Kakenhi 23590667 and the Medical Science Promotion Fund . Supplementary information is available at BBA Molecular Cell Research's website.
PY - 2013/5
Y1 - 2013/5
N2 - Sphingosine kinase 1 (SPHK1) overexpression in malignant cells has been reported. Mouse Friend cells showed higher SPHK1 but not SPHK2 expression compared with other mouse cell lines. A Sphk1 promoter analysis demonstrated the region between -. 53. bp and the first exon as the minimal promoter. Further promoter truncation revealed the importance of a MYB-binding site. EMSA using this region as the probe demonstrated one band containing c-MYB protein, and its intensity decreased during erythroid differentiation with hexamethylane bisacetamide (HMBA), a potent inducer of erythroid differentiation of Friend cells. ChIP assay also revealed in vivo binding of c-MYB. c-MYB overexpression and siRNA for c-Myb affected SPHK1 expression, confirming the important regulatory role of c-MYB in SPHK1 expression. HMBA reduced c-MYB expression rapidly. Induced differentiation by HMBA caused a marked and rapid reduction of SPHK1 mRNA, protein and enzyme activity leading to the rapid decrease of cellular sphingosine 1-phosphate level. Moreover, terminally differentiated cells did not resume SPHK1 expression. Compared with original Friend cells, stable overexpression of wild-type SPHK1 showed higher cell proliferation, resistance to cell death by serum depletion. Interestingly, HMBA-induced differentiation of these cells was delayed but not completely suppressed. In contrast, SPHK inhibitor and its siRNA inhibited cell growth and enhanced HMBA-induced differentiation significantly, suggesting that SPHK1 delayed HMBA-induced differentiation by its cell proliferation-promoting activity. Effects of pertussis toxin, a G-protein-coupled receptor inhibitor, and S1P receptor antagonist on Friend cell growth and differentiation were negligible, suggesting the importance of the intracellular SPHK1/S1P signaling in Friend cells.
AB - Sphingosine kinase 1 (SPHK1) overexpression in malignant cells has been reported. Mouse Friend cells showed higher SPHK1 but not SPHK2 expression compared with other mouse cell lines. A Sphk1 promoter analysis demonstrated the region between -. 53. bp and the first exon as the minimal promoter. Further promoter truncation revealed the importance of a MYB-binding site. EMSA using this region as the probe demonstrated one band containing c-MYB protein, and its intensity decreased during erythroid differentiation with hexamethylane bisacetamide (HMBA), a potent inducer of erythroid differentiation of Friend cells. ChIP assay also revealed in vivo binding of c-MYB. c-MYB overexpression and siRNA for c-Myb affected SPHK1 expression, confirming the important regulatory role of c-MYB in SPHK1 expression. HMBA reduced c-MYB expression rapidly. Induced differentiation by HMBA caused a marked and rapid reduction of SPHK1 mRNA, protein and enzyme activity leading to the rapid decrease of cellular sphingosine 1-phosphate level. Moreover, terminally differentiated cells did not resume SPHK1 expression. Compared with original Friend cells, stable overexpression of wild-type SPHK1 showed higher cell proliferation, resistance to cell death by serum depletion. Interestingly, HMBA-induced differentiation of these cells was delayed but not completely suppressed. In contrast, SPHK inhibitor and its siRNA inhibited cell growth and enhanced HMBA-induced differentiation significantly, suggesting that SPHK1 delayed HMBA-induced differentiation by its cell proliferation-promoting activity. Effects of pertussis toxin, a G-protein-coupled receptor inhibitor, and S1P receptor antagonist on Friend cell growth and differentiation were negligible, suggesting the importance of the intracellular SPHK1/S1P signaling in Friend cells.
KW - C-MYB
KW - ChIP
KW - Friend cell
KW - HMBA-induced differentiation
KW - Promoter analysis
KW - SPHK1
UR - https://www.scopus.com/pages/publications/84874344879
UR - https://www.scopus.com/pages/publications/84874344879#tab=citedBy
U2 - 10.1016/j.bbamcr.2013.01.001
DO - 10.1016/j.bbamcr.2013.01.001
M3 - Article
C2 - 23328083
AN - SCOPUS:84874344879
SN - 0167-4889
VL - 1833
SP - 1006
EP - 1016
JO - Biochimica et Biophysica Acta - Molecular Cell Research
JF - Biochimica et Biophysica Acta - Molecular Cell Research
IS - 5
ER -