Abstract
Background: Human class I alcohol dehydrogenase 2 isoenzymes (encoded by the ADH1B locus) have large differences in kinetic properties; however, individuals inheriting the alleles for the different isoenzymes exhibit only small differences in alcohol elimination rates. This suggests that other cellular factors must regulate the activity of the isoenzymes.Methods: The activity of the isoenzymes expressed from ADH1B*1, ADH1B*2, and ADH1B*3 cDNAs was examined in stably transduced HeLa cell lines, including lines which expressed human low Km aldehyde dehydrogenase (ALDH2). The ability of the cells to metabolize ethanol was compared with that of HeLa cells expressing rat class I alcohol dehydrogenase (ADH) (HeLa-rat ADH cells), rat hepatoma (H4IIEC3) cells, and rat hepatocytes.Results: The isoenzymes had similar protein half-lives in the HeLa cells. Rat hepatocytes, H4IIEC3 cells, and HeLa-rat ADH cells oxidized ethanol much faster than the cells expressing the ADH1B isoenzymes. This was not explained by high cellular NADH levels or endogenous inhibitors; but rather because the activity of the β1 and β2 ADHs was constrained by the accumulation of acetaldehyde, as shown by the increased rate of ethanol oxidation by cell lines expressing β2 ADH plus ALDH2.Conclusion: The activity of the human β2 ADH isoenzyme is sensitive to inhibition by acetaldehyde, which likely limits its activity in vivo. This study emphasizes the importance of maintaining a low steady-state acetaldehyde concentration in hepatocytes during ethanol metabolism.
| Original language | English |
|---|---|
| Pages (from-to) | 28-38 |
| Number of pages | 11 |
| Journal | Alcoholism: Clinical and Experimental Research |
| Volume | 35 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2011 |
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Keywords
- Acetaldehyde
- Enzyme Kinetics
- Ethanol Elimination
- Product Inhibition
- Protein Half-Life
ASJC Scopus subject areas
- Medicine (miscellaneous)
- Psychiatry and Mental health
- Toxicology
Cite this
Ethanol Metabolism by HeLa Cells Transduced With Human Alcohol Dehydrogenase Isoenzymes : Control of the Pathway by Acetaldehyde Concentration. / Matsumoto, Michinaga; Cyganek, Izabela; Sanghani, Paresh C.; Cho, Won Kyoo; Liangpunsakul, Suthat; Crabb, David.
In: Alcoholism: Clinical and Experimental Research, Vol. 35, No. 1, 01.2011, p. 28-38.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Ethanol Metabolism by HeLa Cells Transduced With Human Alcohol Dehydrogenase Isoenzymes
T2 - Control of the Pathway by Acetaldehyde Concentration
AU - Matsumoto, Michinaga
AU - Cyganek, Izabela
AU - Sanghani, Paresh C.
AU - Cho, Won Kyoo
AU - Liangpunsakul, Suthat
AU - Crabb, David
PY - 2011/1
Y1 - 2011/1
N2 - Background: Human class I alcohol dehydrogenase 2 isoenzymes (encoded by the ADH1B locus) have large differences in kinetic properties; however, individuals inheriting the alleles for the different isoenzymes exhibit only small differences in alcohol elimination rates. This suggests that other cellular factors must regulate the activity of the isoenzymes.Methods: The activity of the isoenzymes expressed from ADH1B*1, ADH1B*2, and ADH1B*3 cDNAs was examined in stably transduced HeLa cell lines, including lines which expressed human low Km aldehyde dehydrogenase (ALDH2). The ability of the cells to metabolize ethanol was compared with that of HeLa cells expressing rat class I alcohol dehydrogenase (ADH) (HeLa-rat ADH cells), rat hepatoma (H4IIEC3) cells, and rat hepatocytes.Results: The isoenzymes had similar protein half-lives in the HeLa cells. Rat hepatocytes, H4IIEC3 cells, and HeLa-rat ADH cells oxidized ethanol much faster than the cells expressing the ADH1B isoenzymes. This was not explained by high cellular NADH levels or endogenous inhibitors; but rather because the activity of the β1 and β2 ADHs was constrained by the accumulation of acetaldehyde, as shown by the increased rate of ethanol oxidation by cell lines expressing β2 ADH plus ALDH2.Conclusion: The activity of the human β2 ADH isoenzyme is sensitive to inhibition by acetaldehyde, which likely limits its activity in vivo. This study emphasizes the importance of maintaining a low steady-state acetaldehyde concentration in hepatocytes during ethanol metabolism.
AB - Background: Human class I alcohol dehydrogenase 2 isoenzymes (encoded by the ADH1B locus) have large differences in kinetic properties; however, individuals inheriting the alleles for the different isoenzymes exhibit only small differences in alcohol elimination rates. This suggests that other cellular factors must regulate the activity of the isoenzymes.Methods: The activity of the isoenzymes expressed from ADH1B*1, ADH1B*2, and ADH1B*3 cDNAs was examined in stably transduced HeLa cell lines, including lines which expressed human low Km aldehyde dehydrogenase (ALDH2). The ability of the cells to metabolize ethanol was compared with that of HeLa cells expressing rat class I alcohol dehydrogenase (ADH) (HeLa-rat ADH cells), rat hepatoma (H4IIEC3) cells, and rat hepatocytes.Results: The isoenzymes had similar protein half-lives in the HeLa cells. Rat hepatocytes, H4IIEC3 cells, and HeLa-rat ADH cells oxidized ethanol much faster than the cells expressing the ADH1B isoenzymes. This was not explained by high cellular NADH levels or endogenous inhibitors; but rather because the activity of the β1 and β2 ADHs was constrained by the accumulation of acetaldehyde, as shown by the increased rate of ethanol oxidation by cell lines expressing β2 ADH plus ALDH2.Conclusion: The activity of the human β2 ADH isoenzyme is sensitive to inhibition by acetaldehyde, which likely limits its activity in vivo. This study emphasizes the importance of maintaining a low steady-state acetaldehyde concentration in hepatocytes during ethanol metabolism.
KW - Acetaldehyde
KW - Enzyme Kinetics
KW - Ethanol Elimination
KW - Product Inhibition
KW - Protein Half-Life
UR - http://www.scopus.com/inward/record.url?scp=78650329574&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78650329574&partnerID=8YFLogxK
U2 - 10.1111/j.1530-0277.2010.01319.x
DO - 10.1111/j.1530-0277.2010.01319.x
M3 - Article
C2 - 21166830
AN - SCOPUS:78650329574
VL - 35
SP - 28
EP - 38
JO - Alcoholism: Clinical and Experimental Research
JF - Alcoholism: Clinical and Experimental Research
SN - 0145-6008
IS - 1
ER -