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Microarray analysis of altered gene expression in the TM4 Sertoli-like cell line exposed to chromium(III) chloride
Robert Y S Cheng1, W Gregory Alvord, Douglas Powell
1Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, National Institutes of Health, Box B, Building 538, Fort Detrick, Frederick, MD 21702, USA. rcheng@ncicrf.gov
Abstract:
Chromium(III) chloride is a common human exposure metal that is a preconceptional carcinogen in mice, although it enters cells poorly, and is non-toxic and non-carcinogenic in most biologic systems. An indirect effect on sperm is postulated, and this effect might be mediated through the testicular Sertoli cells that influence spermatogenesis. To test this possibility, we exposed mouse TM4 Sertoli-like cultured cells to 1mM CrCl(3) x 6H(2)O, a non-toxic dose, for 7 days and then extracted mRNA for microarray analysis. The chromium(III) chloride had modest effects on the expression of many genes, in the range of 1.5-2.3-fold. These effects provided an opportunity for development of statistical approaches for sifting microarray data in a situation where differences were small. Data were winnowed by screening for those ratios that fell outside the 99% confidence limits and/or represented a > or = 50% change in expression in the three comparison pairs. Fifty-two genes/clones were significant after the Bonferroni adjustment for multiple comparisons. The largest average increase was observed for the transcription factor Bach2, and this increase was confirmed by RT-PCR. The results show that Cr(III) has significant effects on gene expression in a Sertoli-like cell line.
Insights
Chromium(III) chloride exposure alters gene expression in mouse Sertoli cells, potentially impacting sperm development. This study identified significant changes in 52 genes, including Bach2, using microarray analysis.
Area of Science:
- Reproductive Toxicology
- Environmental Health
- Molecular Biology
Background:
- Chromium(III) chloride (CrCl3) is a common environmental metal.
- While generally considered non-toxic and poorly cell-penetrant, Cr(III) is a preconceptional carcinogen in mice.
- An indirect effect on sperm via Sertoli cells is hypothesized.
Purpose of the Study:
- To investigate the effects of chromium(III) chloride on gene expression in a mouse Sertoli cell line.
- To identify specific genes affected by Cr(III) exposure in these crucial cells for spermatogenesis.
Main Methods:
- Exposure of mouse TM4 Sertoli-like cells to a non-toxic dose (1mM) of CrCl3 x 6H2O for 7 days.
- Utilized microarray analysis to assess global gene expression changes.
- Applied statistical methods, including Bonferroni adjustment, to identify significant alterations.
Main Results:
- CrCl3 exposure resulted in modest, yet significant, changes in the expression of numerous genes (1.5-2.3-fold).
- Fifty-two genes/clones showed significant expression changes after statistical filtering (99% confidence limits, >50% change).
- The transcription factor Bach2 exhibited the largest average increase, confirmed by RT-PCR.
Conclusions:
- Chromium(III) chloride significantly impacts gene expression in Sertoli-like cells.
- These findings support the hypothesis of an indirect mechanism for Cr(III) toxicity on spermatogenesis.
- Further research is warranted to elucidate the downstream consequences of these gene expression changes.