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Variations within oxygen-regulated gene expression in humans.

Brooks JT, Elvidge GP, Glenny L, Gleadle JM, Liu C, Ragoussis J, Smith TG, Talbot NP, Winchester L, Maxwell PH, Robbins PA - J. Appl. Physiol. (2008)

Bottom Line: Double logarithmic transformation of these data resulted in a linear relationship that allowed the response to be parameterized through a gradient and intercept.Analysis of variance (ANOVA) on these parameters showed that the level of between-subject variation in the gradients of the responses that was common across all four HIF-regulated transcripts was significant (P = 0.008).The common nature of the variability across all four HIF-regulated genes suggests that the source of this variation resides within the HIF system itself.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Physiology, University of Oxford, Oxford OX1 3PT, UK.

ABSTRACT
The effects of hypoxia on gene transcription are mainly mediated by a transcription factor complex termed hypoxia-inducible factor (HIF). Genetic manipulation of animals and studies of humans with rare hereditary disease have shown that modifying the HIF pathway affects systems-level physiological responses to hypoxia. It is, however, an open question whether variations in systems-level responses to hypoxia between individuals could arise from variations within the HIF system. This study sought to determine whether variations in the responsiveness of the HIF system at the cellular level could be detected between normal individuals. Peripheral blood lymphocytes (PBL) were isolated on three separate occasions from each of 10 healthy volunteers. After exposure of PBL to eight different oxygen tensions ranging from 20% to 0.1%, the expression levels of four HIF-regulated transcripts involved in different biological pathways were measured. The profile of expression of all four transcripts in PBL was related to oxygen tension in a curvilinear manner. Double logarithmic transformation of these data resulted in a linear relationship that allowed the response to be parameterized through a gradient and intercept. Analysis of variance (ANOVA) on these parameters showed that the level of between-subject variation in the gradients of the responses that was common across all four HIF-regulated transcripts was significant (P = 0.008). We conclude that statistically significant variation within the cellular response to hypoxia can be detected between normal humans. The common nature of the variability across all four HIF-regulated genes suggests that the source of this variation resides within the HIF system itself.

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Related in: MedlinePlus

Relative expression of vascular endothelial growth factor (VEGF), aldolase C (ALDC), adrenomedullin (AM), and prolyl-4-hydroxylase α1 (P4HA1) over a range of oxygen tensions in peripheral blood lymphocytes. Data are for 3 repeat experiments on each of 10 human subjects.
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f1: Relative expression of vascular endothelial growth factor (VEGF), aldolase C (ALDC), adrenomedullin (AM), and prolyl-4-hydroxylase α1 (P4HA1) over a range of oxygen tensions in peripheral blood lymphocytes. Data are for 3 repeat experiments on each of 10 human subjects.

Mentions: To show the overall variation in transcript level with oxygen tension in human subjects, the data from all of the repeat experiments at each oxygen tension are plotted for each gene in Fig. 1 (where β2MG has been used as an internal control). All four genes show a similar response profile to oxygen; there is a relatively small increase in gene expression from 20% to 2% oxygen and a very large increase from 2% to 0.1% oxygen, with no indication of a plateau in the response being reached. In contrast, the threshold cycle values from the RTqPCR for the internal control gene, β2MG, showed no relationship with hypoxia. It is also clear from Fig. 1 that there is inherently more variation in the gene expression measurements at lower oxygen tensions. When the same values are plotted on a double logarithmic scale as shown in Fig. 2, the relationship between transcript expression and oxygen tension appears to be linear, with a similar degree of variation in gene expression measurements occurring at each oxygen tension. These appearances are further confirmed in Fig. 3, where the mean values for gene expression at each value for oxygen tension are plotted in a double logarithmic format together with the intersubject standard deviations. The linear nature of the response when plotted in double logarithmic format is apparent from the simple linear regressions shown for each of the genes.


Variations within oxygen-regulated gene expression in humans.

Brooks JT, Elvidge GP, Glenny L, Gleadle JM, Liu C, Ragoussis J, Smith TG, Talbot NP, Winchester L, Maxwell PH, Robbins PA - J. Appl. Physiol. (2008)

Relative expression of vascular endothelial growth factor (VEGF), aldolase C (ALDC), adrenomedullin (AM), and prolyl-4-hydroxylase α1 (P4HA1) over a range of oxygen tensions in peripheral blood lymphocytes. Data are for 3 repeat experiments on each of 10 human subjects.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2636937&req=5

f1: Relative expression of vascular endothelial growth factor (VEGF), aldolase C (ALDC), adrenomedullin (AM), and prolyl-4-hydroxylase α1 (P4HA1) over a range of oxygen tensions in peripheral blood lymphocytes. Data are for 3 repeat experiments on each of 10 human subjects.
Mentions: To show the overall variation in transcript level with oxygen tension in human subjects, the data from all of the repeat experiments at each oxygen tension are plotted for each gene in Fig. 1 (where β2MG has been used as an internal control). All four genes show a similar response profile to oxygen; there is a relatively small increase in gene expression from 20% to 2% oxygen and a very large increase from 2% to 0.1% oxygen, with no indication of a plateau in the response being reached. In contrast, the threshold cycle values from the RTqPCR for the internal control gene, β2MG, showed no relationship with hypoxia. It is also clear from Fig. 1 that there is inherently more variation in the gene expression measurements at lower oxygen tensions. When the same values are plotted on a double logarithmic scale as shown in Fig. 2, the relationship between transcript expression and oxygen tension appears to be linear, with a similar degree of variation in gene expression measurements occurring at each oxygen tension. These appearances are further confirmed in Fig. 3, where the mean values for gene expression at each value for oxygen tension are plotted in a double logarithmic format together with the intersubject standard deviations. The linear nature of the response when plotted in double logarithmic format is apparent from the simple linear regressions shown for each of the genes.

Bottom Line: Double logarithmic transformation of these data resulted in a linear relationship that allowed the response to be parameterized through a gradient and intercept.Analysis of variance (ANOVA) on these parameters showed that the level of between-subject variation in the gradients of the responses that was common across all four HIF-regulated transcripts was significant (P = 0.008).The common nature of the variability across all four HIF-regulated genes suggests that the source of this variation resides within the HIF system itself.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Physiology, University of Oxford, Oxford OX1 3PT, UK.

ABSTRACT
The effects of hypoxia on gene transcription are mainly mediated by a transcription factor complex termed hypoxia-inducible factor (HIF). Genetic manipulation of animals and studies of humans with rare hereditary disease have shown that modifying the HIF pathway affects systems-level physiological responses to hypoxia. It is, however, an open question whether variations in systems-level responses to hypoxia between individuals could arise from variations within the HIF system. This study sought to determine whether variations in the responsiveness of the HIF system at the cellular level could be detected between normal individuals. Peripheral blood lymphocytes (PBL) were isolated on three separate occasions from each of 10 healthy volunteers. After exposure of PBL to eight different oxygen tensions ranging from 20% to 0.1%, the expression levels of four HIF-regulated transcripts involved in different biological pathways were measured. The profile of expression of all four transcripts in PBL was related to oxygen tension in a curvilinear manner. Double logarithmic transformation of these data resulted in a linear relationship that allowed the response to be parameterized through a gradient and intercept. Analysis of variance (ANOVA) on these parameters showed that the level of between-subject variation in the gradients of the responses that was common across all four HIF-regulated transcripts was significant (P = 0.008). We conclude that statistically significant variation within the cellular response to hypoxia can be detected between normal humans. The common nature of the variability across all four HIF-regulated genes suggests that the source of this variation resides within the HIF system itself.

Show MeSH
Related in: MedlinePlus