Hormonal and Chemical Influences on the Expression of Class 2 Aldehyde Dehydrogenases in Rat H4IIEC3 and Human HuH7 Hepatoma Cells

Abstract

We studied the effect a variety of hormones and chemical stimuli on the activity of low Km aldehyde dehydrogenase (ALDH) in rat H4IIEC3 hepatoma cells and ALDH activity in human HuH7 hepatoma cells. The low Km enzyme in H4IIEC3 cells reflects ALDH2 activity, and the ALDH activity in HuH7 likely represents ALDH5. Of the steroid hormone family, thyroid hormone, progesterone, and dihydrotestosterone increased low Km ALDH activity approximately 50%, whereas dexamethasone and estradiol had little effect. Insulin decreased the activity of low Km ALDH. None of these hormones affected the activity of ALDH in HuH7 cells. Among second messengers, 8-bromo-cAMP and A23187 increased low Km ALDH activity; HuH7 ALDH activity again was unchanged. Exposure of the cells to 22 mM ethanol reduced low Km activity by approximately 20%, whereas hydrogen peroxide, tumor necrosis factor-alpha, and interleukin-1 beta had little effect. Ultraviolet light increased the HuH7 ALDH activity. Retinaldehyde or retinolc acid reduced the HuH7 ALDH activity, but had no effect on low Km ALDH activity. These data suggest that low Km ALDH2 can be regulated by hormones and may not be constitutive as previously thought, and that the HuH7 ALDH is regulated differently.

Ethanol Impairs Differentiation of Human Adipocyte Stromal Cells in Culture

“…Furthermore, ethanol reduced expression of C ⁄ EBPa and b mRNA, but did not affect the expression of ADH. The expression of ALDH2 in hepatoma cells was insensitive to dexamethasone, but was reduced by exposure to insulin (Crabb et al, 1995). The ALDH2 promoter is activated by HNF4, but this is antagonized by cAMP (You et al, 2002).…”

“…Propionaldehyde was then added to 7 mM to determine total ALDH activity. High K m activity was total activity with 7 mM propionaldehyde minus activity with 40 lm propionaldehyde (Crabb et al, 1995). Triglyceride was determined using the method of Eggstein and Kuhlmann (1974) as described (Fischer et al, 2003).…”

Ethanol Induces Fatty Acid Synthesis Pathways by Activation of Sterol Regulatory Element-binding Protein (SREBP)

“…We chose two rat hepatoma cell lines and a non-hepatic cell line for study. Previous studies from our laboratory have shown that H4IIEC3 expresses moderately high levels of class I (low K m ) ADH and ALDH2 protein and enzyme activity (33). This line also expresses SREBP-1 and -2 (data not shown).…”

An A/G Polymorphism in the Promoter of Mitochondrial Aldehyde Dehydrogenase (ALDH2): Effects of the Sequence Variant on Transcription Factor Binding and Promoter Strength

“…Of considerably more interest was the behavior of the reporters in the hepatoma cells. These cells express the endogenous ALDH2 gene and protein (Crabb et al, 1995), and are a good model for the control of hepatic gene expression. The reporter containing the A allele was significantly less active than the control plasmid, whereas the reporter with the G allele was significantly more active.…”