Localized in the basolateral membrane of human small intestines, thyroid hormone transporters
MCT10 and LAT2 are the proposed molecules involved in visceral thyroid hormone metabolism.
To our best knowledge, the age-dependent expression patterns of these transporters
have not been evaluated. Yet, alterations in transcription may be anticipated, because
thyroid metabolism in general changes with age. We therefore analyzed the expression
profiles of primary and secondary thyroid hormone transporters Mct8, Mct10, Lat1 &
2, Ntcp and Oatps within the intestines of young and aged C57BL/6-mice by quantitative
PCR. Young mice (age = 4 months) and old mice (age = 18 months) were sacrificed and
RNA was isolated from the different intestinal segments. Highest expression levels
were shown for candidate molecules Mct10 and Lat2, confirming their assumed role in
small intestine. Other thyroid transporters could be neglected due to low transcription
in intestinal tissues. We now examined Mct10- and Lat2-expression of old compared
to young mice (Fig. 1). An age-dependent down-regulation may be estimated in ileum
for Mct10 and both in jejunum and ileum for Lat2. In the remaining intestinal parts
transcription of both molecules seems to be unaffected from age and in general no
up-regulation was observed. In summary, our results have to be classified as preliminary
and further analysis based on larger mouse groups and additional immunohistochemistry
will be necessary.
Tab. 1
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Mct 10
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Lat2
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Duodenum
n = 8 (old) n = 5 (young)
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↔
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↔
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Jejunum
n = 6 (old) n = 4 (young)
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↔
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↓
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Ileum
n = 8 (old) n = 5 (young)
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↓
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↓
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Colon
n = 8 (old) n = 4 (young)
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↔
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↔
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Expression pattern of Mct10 and Lat2 in the respective tissues.
Old C57BL/6-mice (mean age = 18 months) were compared to young (mean age = 4 months).
↓: down-regulation. ↑: up-regulation. ↔: stable expression
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This project is funded by DFG SPP 1629 FU356/8 – 1.
