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Glutathione Transferases Responses Induced by Microcystin-LR in the Gills and Hepatopancreas of the Clam Venerupis philippinarum.

Carneiro M, Reis B, Azevedo J, Campos A, Osório H, Vasconcelos V, Martins JC - Toxins (Basel) (2015)

Bottom Line: No significant changes were found in PPP2 activity, the main target of MCs, for both organs.Using proteomics, qualitative and quantitative differences were found between the basal and inducible cGSTs.Overall, results suggest a distinct role of GST system in counteracting MCs toxicity between the gills and the hepatopancreas of V. philippinarum, revealing different roles between GST isoforms within and among both organs.

View Article: PubMed Central - PubMed

Affiliation: CIIMAR/CIMAR-Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, Porto 4050-123, Portugal. marianarcarneiro@gmail.com.

ABSTRACT
A multi-method approach was employed to compare the responses of Glutatione Transferases (GSTs) in the gills and hepatopancreas of Venerupis philippinarum to microcystins (MCs) toxicity. In this way, using the cytosolic fraction, the enzymatic activity of GSTs, superoxide dismutase (SOD), serine/threonine protein phosphatases (PPP2) along with the gene expression levels of four GST isoforms (pi, mu, sigma1, sigma2) were investigated in both organs of the clams exposed for 24 h to 10, 50 and 100 μg L(-1) of MC-LR. Cytosolic GSTs (cGSTs) from both organs of the high dose exposed clams were purified by glutathione-agarose affinity chromatography, characterized kinetically and the changes in the expression of cGSTs of the gills identified using a proteomic approach. MC-LR caused an increase in GST enzyme activity, involved in conjugation reactions, in both gills and hepatopancreas (100 μg L(-1) exposure). SOD activity, an indicator of oxidative stress, showed significantly elevated levels in the hepatopancreas only (50 and 100 μg L(-1) exposure). No significant changes were found in PPP2 activity, the main target of MCs, for both organs. Transcription responses revealed an up-regulation of sigma2 in the hepatopancreas at the high dose, but no significant changes were detected in the gills. Kinetic analysis evidenced differences between gills of exposed and non-exposed extracts. Using proteomics, qualitative and quantitative differences were found between the basal and inducible cGSTs. Overall, results suggest a distinct role of GST system in counteracting MCs toxicity between the gills and the hepatopancreas of V. philippinarum, revealing different roles between GST isoforms within and among both organs.

No MeSH data available.


Related in: MedlinePlus

Gill and hepatopancreas temporal changes of GSTs transcripts of V. philippinarum after exposure to three different concentrations of purified MC-LR and the respective controls. Data are expressed as mean ± SD (n = 3). Differences between treatments are considered among each gene and are represented as lowercase letters. Differences between genes are represented as capital letters depicted below each gene’s name. Treatments and genes that do not share a letter are significantly different (p < 0.05).
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toxins-07-02096-f004: Gill and hepatopancreas temporal changes of GSTs transcripts of V. philippinarum after exposure to three different concentrations of purified MC-LR and the respective controls. Data are expressed as mean ± SD (n = 3). Differences between treatments are considered among each gene and are represented as lowercase letters. Differences between genes are represented as capital letters depicted below each gene’s name. Treatments and genes that do not share a letter are significantly different (p < 0.05).

Mentions: In this study, the relative changes of the mRNA abundance of mu, pi, sigma1 and sigma2 GST isoforms were evaluated in both gills and hepatopancreas of V. philippinarum (Figure 4). In the gills, no significant changes were found for the transcription of all GST isoforms between the treatments and the control group. However, almost all GST isoforms (mu, pi, sigma1) in this organ presented a similar transcription trend in relation to the control group. Such was characterized by no changes for the 10 and 50 μg L−1 exposures and a slight increase for the highest exposure group, which in the case of pi and sigma1 isoforms is superior to 2.5-fold. On the other hand, the transcription of GST sigma2 decreased in relation to the control group upon the 10 and 50 μg L−1 MC-LR exposure (1.2- and 2.3-fold, respectively). Still, and in the same way as for the other GST isoforms, sigma2 transcription also increased after 100 μg L−1 treatment (1.7-fold). For sigma2 GST isoform, a significant change was found between the 50 and 100 μg L−1 treatment with MC-LR (p < 0.05). Our results indicate that among the four GST isoforms, sigma2 is the most abundantly expressed in the gills (p < 0.05) in non-exposed clams. In the hepatopancreas, the transcription of GST sigma2 significantly (p < 0.05) increased (2.2-fold) in relation to control for the highest exposure group (100 μg L−1). Similarly to the gills, this GST isoform also presents the same significant change between the 50 and 100 μg L−1 MC-LR exposure (p < 0.05). In this organ, no significant changes were found for the transcription of mu, pi and sigma1 GST isoforms between the treatments and the control groups. Nonetheless, a slight increase in transcription of the high dose group can be perceived (1.8-fold) for the mu GST isoform when compared to the control. In addition, a decrease of pi GST transcription in relation to control is perceived upon the 50 (2.4-fold) and 100 (1.6-fold) μg L−1 exposure. In fact, for this last isoform, a significant decrease was found between the 10 and 50 μg L−1 treatment (p < 0.05). Our data also shows that in gills no significant changes were found for the transcription of all the tested GST isoforms, although a noticeable increase of the transcription levels is found for all genes in the high dose group, with special relevance for pi and sigma1 GST isoforms. In the hepatopancreas, the transcripts of sigma2 were also dominantly expressed in relation to mu and sigma1 isoforms (p < 0.05) in non-exposed clams.


Glutathione Transferases Responses Induced by Microcystin-LR in the Gills and Hepatopancreas of the Clam Venerupis philippinarum.

Carneiro M, Reis B, Azevedo J, Campos A, Osório H, Vasconcelos V, Martins JC - Toxins (Basel) (2015)

Gill and hepatopancreas temporal changes of GSTs transcripts of V. philippinarum after exposure to three different concentrations of purified MC-LR and the respective controls. Data are expressed as mean ± SD (n = 3). Differences between treatments are considered among each gene and are represented as lowercase letters. Differences between genes are represented as capital letters depicted below each gene’s name. Treatments and genes that do not share a letter are significantly different (p < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4488691&req=5

toxins-07-02096-f004: Gill and hepatopancreas temporal changes of GSTs transcripts of V. philippinarum after exposure to three different concentrations of purified MC-LR and the respective controls. Data are expressed as mean ± SD (n = 3). Differences between treatments are considered among each gene and are represented as lowercase letters. Differences between genes are represented as capital letters depicted below each gene’s name. Treatments and genes that do not share a letter are significantly different (p < 0.05).
Mentions: In this study, the relative changes of the mRNA abundance of mu, pi, sigma1 and sigma2 GST isoforms were evaluated in both gills and hepatopancreas of V. philippinarum (Figure 4). In the gills, no significant changes were found for the transcription of all GST isoforms between the treatments and the control group. However, almost all GST isoforms (mu, pi, sigma1) in this organ presented a similar transcription trend in relation to the control group. Such was characterized by no changes for the 10 and 50 μg L−1 exposures and a slight increase for the highest exposure group, which in the case of pi and sigma1 isoforms is superior to 2.5-fold. On the other hand, the transcription of GST sigma2 decreased in relation to the control group upon the 10 and 50 μg L−1 MC-LR exposure (1.2- and 2.3-fold, respectively). Still, and in the same way as for the other GST isoforms, sigma2 transcription also increased after 100 μg L−1 treatment (1.7-fold). For sigma2 GST isoform, a significant change was found between the 50 and 100 μg L−1 treatment with MC-LR (p < 0.05). Our results indicate that among the four GST isoforms, sigma2 is the most abundantly expressed in the gills (p < 0.05) in non-exposed clams. In the hepatopancreas, the transcription of GST sigma2 significantly (p < 0.05) increased (2.2-fold) in relation to control for the highest exposure group (100 μg L−1). Similarly to the gills, this GST isoform also presents the same significant change between the 50 and 100 μg L−1 MC-LR exposure (p < 0.05). In this organ, no significant changes were found for the transcription of mu, pi and sigma1 GST isoforms between the treatments and the control groups. Nonetheless, a slight increase in transcription of the high dose group can be perceived (1.8-fold) for the mu GST isoform when compared to the control. In addition, a decrease of pi GST transcription in relation to control is perceived upon the 50 (2.4-fold) and 100 (1.6-fold) μg L−1 exposure. In fact, for this last isoform, a significant decrease was found between the 10 and 50 μg L−1 treatment (p < 0.05). Our data also shows that in gills no significant changes were found for the transcription of all the tested GST isoforms, although a noticeable increase of the transcription levels is found for all genes in the high dose group, with special relevance for pi and sigma1 GST isoforms. In the hepatopancreas, the transcripts of sigma2 were also dominantly expressed in relation to mu and sigma1 isoforms (p < 0.05) in non-exposed clams.

Bottom Line: No significant changes were found in PPP2 activity, the main target of MCs, for both organs.Using proteomics, qualitative and quantitative differences were found between the basal and inducible cGSTs.Overall, results suggest a distinct role of GST system in counteracting MCs toxicity between the gills and the hepatopancreas of V. philippinarum, revealing different roles between GST isoforms within and among both organs.

View Article: PubMed Central - PubMed

Affiliation: CIIMAR/CIMAR-Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, Porto 4050-123, Portugal. marianarcarneiro@gmail.com.

ABSTRACT
A multi-method approach was employed to compare the responses of Glutatione Transferases (GSTs) in the gills and hepatopancreas of Venerupis philippinarum to microcystins (MCs) toxicity. In this way, using the cytosolic fraction, the enzymatic activity of GSTs, superoxide dismutase (SOD), serine/threonine protein phosphatases (PPP2) along with the gene expression levels of four GST isoforms (pi, mu, sigma1, sigma2) were investigated in both organs of the clams exposed for 24 h to 10, 50 and 100 μg L(-1) of MC-LR. Cytosolic GSTs (cGSTs) from both organs of the high dose exposed clams were purified by glutathione-agarose affinity chromatography, characterized kinetically and the changes in the expression of cGSTs of the gills identified using a proteomic approach. MC-LR caused an increase in GST enzyme activity, involved in conjugation reactions, in both gills and hepatopancreas (100 μg L(-1) exposure). SOD activity, an indicator of oxidative stress, showed significantly elevated levels in the hepatopancreas only (50 and 100 μg L(-1) exposure). No significant changes were found in PPP2 activity, the main target of MCs, for both organs. Transcription responses revealed an up-regulation of sigma2 in the hepatopancreas at the high dose, but no significant changes were detected in the gills. Kinetic analysis evidenced differences between gills of exposed and non-exposed extracts. Using proteomics, qualitative and quantitative differences were found between the basal and inducible cGSTs. Overall, results suggest a distinct role of GST system in counteracting MCs toxicity between the gills and the hepatopancreas of V. philippinarum, revealing different roles between GST isoforms within and among both organs.

No MeSH data available.


Related in: MedlinePlus