TY - JOUR
T1 - Involvement of SULT1A3 in elevated sulfation of 4-hydroxypropranolol in Hep G2 cells pretreated with β-naphthoflavone
AU - Miyano, Junko
AU - Yamamoto, Shigeo
AU - Hanioka, Nobumitsu
AU - Narimatsu, Shizuo
AU - Ishikawa, Tsutomu
AU - Ogura, Kenichiro
AU - Watabe, Tadashi
AU - Nishimura, Masuhiro
AU - Ueda, Nobuhiko
AU - Naito, Shinsaku
PY - 2005/3/15
Y1 - 2005/3/15
N2 - Pretreatment of Hep G2 cells with β-naphthoflavone (BNF 1-25 μM) significantly increased cytosolic sulfation activities of 4-hydroxypropranolol (4-OH-PL) racemate. The profile was similar to those of sulfations towards dopamine and triiodothyronine in the same cytosolic fractions. Kinetic studies of 4-OH-PL sulfation in Hep G2 cytosolic fractions revealed that Vmax values increased but apparent Km values remained unchanged following the BNF pretreatment. Among five recombinant human SULT isoforms (SULT1A1, -1A3, -1B1, -1E1 and -2A1) examined, only SULT2A1 did not show 4-OH-PL sulfation activities under the conditions used. SULT1A3 and -1E1 exhibited an enantioselectivity of 4-OH-R-PL sulfation > 4-OH-S-PL sulfation, which agreed with that of BNF-pretreated Hep G2 cells as well as of nontreated cells, whereas SULT1A1 and -1B1 showed a reversed enantioselectivity (R < S). In kinetic studies of 4-OH-PL sulfations by four kinds of human SULT isoforms, apparent Km values for SULT1A3 were the lowest, and the parameters were close to those of Hep G2 cytosolic fractions. Real time RT-PCR using TaqMan probes demonstrated that the mRNA levels of SULT1A3 increased following BNF pretreatment, which paralleled the results from Western blotting showing the elevated levels of SULT1A3 proteins. These results suggest that the induction of SULT1A3 is mainly responsible for the elevated 4-OH-PL sulfation activities following the pretreatment of Hep G2 cells with BNF.
AB - Pretreatment of Hep G2 cells with β-naphthoflavone (BNF 1-25 μM) significantly increased cytosolic sulfation activities of 4-hydroxypropranolol (4-OH-PL) racemate. The profile was similar to those of sulfations towards dopamine and triiodothyronine in the same cytosolic fractions. Kinetic studies of 4-OH-PL sulfation in Hep G2 cytosolic fractions revealed that Vmax values increased but apparent Km values remained unchanged following the BNF pretreatment. Among five recombinant human SULT isoforms (SULT1A1, -1A3, -1B1, -1E1 and -2A1) examined, only SULT2A1 did not show 4-OH-PL sulfation activities under the conditions used. SULT1A3 and -1E1 exhibited an enantioselectivity of 4-OH-R-PL sulfation > 4-OH-S-PL sulfation, which agreed with that of BNF-pretreated Hep G2 cells as well as of nontreated cells, whereas SULT1A1 and -1B1 showed a reversed enantioselectivity (R < S). In kinetic studies of 4-OH-PL sulfations by four kinds of human SULT isoforms, apparent Km values for SULT1A3 were the lowest, and the parameters were close to those of Hep G2 cytosolic fractions. Real time RT-PCR using TaqMan probes demonstrated that the mRNA levels of SULT1A3 increased following BNF pretreatment, which paralleled the results from Western blotting showing the elevated levels of SULT1A3 proteins. These results suggest that the induction of SULT1A3 is mainly responsible for the elevated 4-OH-PL sulfation activities following the pretreatment of Hep G2 cells with BNF.
KW - 4-Hydroxypropranolol
KW - Hep G2 cell line
KW - SULT1A3
KW - β-Naphthoflavone
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UR - http://www.scopus.com/inward/citedby.url?scp=20044362381&partnerID=8YFLogxK
U2 - 10.1016/j.bcp.2004.12.012
DO - 10.1016/j.bcp.2004.12.012
M3 - Article
C2 - 15748705
AN - SCOPUS:20044362381
SN - 0006-2952
VL - 69
SP - 941
EP - 950
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 6
ER -