PMID- 10383892
OWN - NLM
STAT- MEDLINE
DCOM- 19990824
LR  - 20190513
IS  - 0143-3334 (Print)
IS  - 0143-3334 (Linking)
VI  - 20
IP  - 7
DP  - 1999 Jul
TI  - cDNA cloning, expression and activity of a second human aflatoxin B1-metabolizing
      member of the aldo-keto reductase superfamily, AKR7A3.
PG  - 1215-23
AB  - The aflatoxin B1 (AFB1) aldehyde metabolite of AFB1 may contribute to the
      cytotoxicity of this hepatocarcinogen via protein adduction. Aflatoxin B1
      aldehyde reductases, specifically the NADPH-dependent aldo-keto reductases of rat
      (AKR7A1) and human (AKR7A2), are known to metabolize the AFB1 dihydrodiol by
      forming AFB1 dialcohol. Using a rat AKR7A1 cDNA, we isolated and characterized a 
      distinct aldo-keto reductase (AKR7A3) from an adult human liver cDNA library. The
      deduced amino acid sequence of AKR7A3 shares 80 and 88% identity with rat AKR7A1 
      and human AKR7A2, respectively. Recombinant rat AKR7A1 and human AKR7A3 were
      expressed and purified from Escherichia coli as hexa-histidine tagged fusion
      proteins. These proteins catalyzed the reduction of several model
      carbonyl-containing substrates. The NADPH-dependent formation of AFB1 dialcohol
      by recombinant human AKR7A3 was confirmed by liquid chromatography coupled to
      electrospray ionization mass spectrometry. Rabbit polyclonal antibodies produced 
      using recombinant rat AKR7A1 protein were shown to detect nanogram amounts of rat
      and human AKR7A protein. The amount of AKR7A-related protein in hepatic cytosols 
      of 1, 2-dithiole-3-thione-treated rats was 18-fold greater than in cytosols from 
      untreated animals. These antibodies detected AKR7A-related protein in normal
      human liver samples ranging from 0.3 to 0.8 microg/mg cytosolic protein. Northern
      blot analysis showed varying levels of expression of AKR7A RNA in human liver and
      in several extrahepatic tissues, with relatively high levels in the stomach,
      pancreas, kidney and liver. Based on the kinetic parameters determined using
      recombinant human AKR7A3 and AFB1 dihydrodiol at pH 7.4, the catalytic efficiency
      of this reaction (k2/K, per M/s) equals or exceeds those reported for other
      enzymes, for example cytochrome P450s and glutathione S-transferases, known to
      metabolize AFB1 in vivo. These findings indicate that, depending on the extent of
      AFB1 dihydrodiol formation, AKR7A may contribute to the protection against
      AFB1-induced hepatotoxicity.
FAU - Knight, L P
AU  - Knight LP
AD  - Department of Environmental Health Sciences, Johns Hopkins School of Hygiene and 
      Public Health, Baltimore, MD 21205, USA.
FAU - Primiano, T
AU  - Primiano T
FAU - Groopman, J D
AU  - Groopman JD
FAU - Kensler, T W
AU  - Kensler TW
FAU - Sutter, T R
AU  - Sutter TR
LA  - eng
SI  - GENBANK/AF040639
GR  - CA39416/CA/NCI NIH HHS/United States
GR  - CA63922/CA/NCI NIH HHS/United States
GR  - ES08148/ES/NIEHS NIH HHS/United States
GR  - etc.
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - Carcinogenesis
JT  - Carcinogenesis
JID - 8008055
RN  - 0 (Benzaldehydes)
RN  - 0 (DNA, Complementary)
RN  - 0 (Phenanthrenes)
RN  - 0 (RNA, Messenger)
RN  - 42L7BZ8H74 (9,10-phenanthrenequinone)
RN  - 555-16-8 (4-nitrobenzaldehyde)
RN  - 9N2N2Y55MH (Aflatoxin B1)
RN  - EC 1.1.1.- (Aldo-Keto Reductases)
RN  - EC 1.1.1.21 (AKR7A3 protein, human)
RN  - EC 1.1.1.21 (Aldehyde Reductase)
SB  - IM
MH  - Aflatoxin B1/analogs & derivatives/*metabolism
MH  - Aldehyde Reductase/*biosynthesis/*genetics/isolation & purification/metabolism
MH  - Aldo-Keto Reductases
MH  - Amino Acid Sequence
MH  - Animals
MH  - Base Sequence
MH  - Benzaldehydes/metabolism
MH  - Cloning, Molecular
MH  - DNA, Complementary/genetics
MH  - Humans
MH  - Immunoblotting
MH  - Liver/enzymology
MH  - Molecular Sequence Data
MH  - Multigene Family/genetics
MH  - Phenanthrenes/metabolism
MH  - RNA, Messenger/metabolism
MH  - Rats
MH  - Sequence Homology, Amino Acid
MH  - Tissue Distribution
EDAT- 1999/06/29 00:00
MHDA- 1999/06/29 00:01
CRDT- 1999/06/29 00:00
PHST- 1999/06/29 00:00 [pubmed]
PHST- 1999/06/29 00:01 [medline]
PHST- 1999/06/29 00:00 [entrez]
AID - 10.1093/carcin/20.7.1215 [doi]
PST - ppublish
SO  - Carcinogenesis. 1999 Jul;20(7):1215-23. doi: 10.1093/carcin/20.7.1215.