RESUMO
Glutathione S-transferase P1-1 (GSTP1-1) is a multifunctional enzyme which protects the cell from the influence of genotoxic factors and apoptosis. Contemporary knowledge about the GSTP1 molecule structure and the enzyme functions are summarized in this review. Also P1 isoform is compared to other glutathione S-transferases and structure-function relationships are emphasized. Novel functions of GSTP1 in cell signaling modulation, NO storage and metabolism are highlighted in this paper.
Assuntos
Glutationa S-Transferase pi/química , Glutationa S-Transferase pi/fisiologia , Animais , Apoptose/fisiologia , Catálise , Humanos , Modelos Moleculares , Óxido Nítrico/metabolismo , Transdução de Sinais/fisiologiaRESUMO
Glutathione S-transferase P1 is a major phase II detoxification enzyme in most cell types. Aberrant expression of GSTP1 is associated with carcinogenesis and development of multidrug resistance. GSTP1 gene transcription is regulated by promoter methylation and by transcription factors. To elucidate the mechanisms responsible for the different levels of GSTP1 expression observed in Hbl-100 and BeWo cells we utilized truncated promoter constructs to compare the functional role of different promoter elements. We also identified transcription factors binding the responsive elements by electrophoretic mobility shift assay. The applied approaches provided the evidence that binding of transcription factors to ARE, CRE and NF-kappaB sites are responsible for the cell specific levels of GSTP1 expression in Hbl-100 and BeWo cells. It was also indicated that partial promoter methylation occurs in BeWo cells.
Assuntos
Neoplasias da Mama/genética , Coriocarcinoma/genética , Regulação Enzimológica da Expressão Gênica , Glutationa S-Transferase pi/genética , Transcrição Gênica , Neoplasias Uterinas/genética , Western Blotting , Linhagem Celular Tumoral , Metilação de DNA , Ensaio de Desvio de Mobilidade Eletroforética , Feminino , Humanos , Reação em Cadeia da Polimerase , Gravidez , Regiões Promotoras Genéticas , Ligação Proteica , Fatores de Transcrição/metabolismoRESUMO
Glutathione S-transferase P1-1 is the main phase II xenobiotic metabolism enzyme in human placenta. Low level of its gene expression and corresponding ineffective protection of fetus from toxic compounds is associated with pregnancy disorders such as preeclampsia and abnormalities of fetus development. It was previously reported that environmental radioactive contamination caused down-regulation of GSTP1 transcription in human placenta, but mechanisms responsible for such changes were unclear. In the present study we have found that observed changes in transcription of this gene are not caused by promoter methylation because GSTP1 promoter was not methylated in any of analyzed 91 placental samples. Regulation of GSTP1 by methylation or transcription factors was not previously studied in human placenta. Using "Gene Expression Atlas" online software the placental expression profile of transcription factors known to interact with GSTP1 promoter in other cell types, was identified. According to computer analysis the genes coding for GATA2, GATA3, Fos-B, Nrf3 and MafK transcription factors are highly expressed in human placenta, while genes coding for c-Fos, Juns, Mafs, ERbeta, RARalpha and NF-kappaB factors have moderate level of expression. Competitive EMSA provided the evidence that ARE and NF-kappaB-like sites specifically interacted with placental nuclear proteins. Among these proteins transcription factors AP-1 and NF-kappaB were identified using corresponding consensus oligonucleotides as competitors in EMSA.