The differential diagnosis of well-differentiated tumors of follicular cell origin remains the most problematic task in thyroid pathology. Specific morphologic criteria (capsular and/or vascular invasion, nuclear characteristics) are crucial in the diagnosis of these neoplasms. However, the assessment of malignant features is inconclusive in some cases. Moreover, oncocytic thyroid tumors remain controversial in a respect to their pathobiology, behavior and management. Therefore, the useful diagnostic/prognostic thyroid markers are awaited. The aim of our study was to evaluate the expression of galectin-3 and thyroid peroxidase (TPO) in benign and malignant thyroid tumors of follicular cell origin. A total of 186 archival thyroid samples including 38 non-oncocytic follicular adenomas, 53 oncocytic (Hürthle cell) adenomas, 6 non-oncocytic follicular carcinomas, 23 oncocytic (Hürthle cell) carcinomas, 43 non-oncocytic papillary carcinomas, and 23 oncocytic papillary carcinomas were analyzed for galectin-3 and TPO expression by immunohistochemistry. Both types of papillary carcinomas showed significant upregulation of galectin-3 in comparison with the other tumor types, likewise, significant differences in galectin-3 expression were discovered between non-oncocytic and oncocytic variants of studied tumors excluding follicular carcinoma. Significant lowering of TPO was revealed in oncocytic adenomas and papillary carcinomas. In conclusion, the combined use of galectin-3 and TPO markers could help to improve the differential diagnosis of thyroid tumors. Differences in the galectin-3 and TPO expression between some oncocytic and non-oncocytic tumors support their separation in the latest WHO classification of thyroid tumors.
- MeSH
- autoantigeny genetika MeSH
- diferenciální diagnóza MeSH
- galektin 3 genetika MeSH
- jodidperoxidasa genetika MeSH
- lidé MeSH
- nádorové biomarkery genetika MeSH
- nádory štítné žlázy klasifikace diagnóza MeSH
- proteiny vázající železo genetika MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Frataxin is a small conserved mitochondrial protein; in humans, mutations affecting frataxin expression or function result in Friedreich's ataxia. Much of the current understanding of frataxin function comes from informative studies with yeast models, but considerable debates remain with regard to the primary functions of this ubiquitous protein. We exploit the tractable reverse genetics of Trypanosoma brucei in order to specifically consider the importance of frataxin in an early branching lineage. Using inducible RNAi, we show that frataxin is essential in T. brucei and that its loss results in reduced activity of the marker Fe-S cluster-containing enzyme aconitase in both the mitochondrion and cytosol. Activities of mitochondrial succinate dehydrogenase and fumarase also decreased, but the concentration of reactive oxygen species increased. Trypanosomes lacking frataxin also exhibited a low mitochondrial membrane potential and reduced oxygen consumption. Crucially, however, iron did not accumulate in frataxin-depleted mitochondria, and as T. brucei frataxin does not form large complexes, it suggests that it plays no role in iron storage. Interestingly, RNAi phenotypes were ameliorated by expression of frataxin homologues from hydrogenosomes of another divergent protist Trichomonas vaginalis. Collectively, the data suggest trypanosome frataxin functions primarily only in Fe-S cluster biogenesis and protection from reactive oxygen species.
- MeSH
- buněčné linie MeSH
- eukaryotické buňky fyziologie klasifikace MeSH
- exprese genu MeSH
- fenotyp MeSH
- financování organizované MeSH
- fylogeneze MeSH
- lidé MeSH
- mitochondriální proteiny genetika chemie metabolismus MeSH
- molekulární evoluce MeSH
- molekulární sekvence - údaje MeSH
- prokaryotické buňky fyziologie klasifikace MeSH
- proteiny obsahující železo a síru genetika chemie metabolismus MeSH
- proteiny vázající železo genetika chemie metabolismus MeSH
- protozoální proteiny genetika chemie metabolismus MeSH
- RNA interference MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- Trichomonas genetika chemie klasifikace metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
Trypanosoma brucei, the agent of human sleeping sickness and ruminant nagana, is the most genetically tractable representative of the domain Excavata. It is evolutionarily very distant from humans, with a last common ancestor over 1 billion years ago. Frataxin, a highly conserved small protein involved in iron-sulfur cluster synthesis, is present in both organisms, and its deficiency is responsible for Friedreich's ataxia in humans. We have found that T. brucei growth-inhibition phenotype caused by down-regulated frataxin is rescued by means of human frataxin. The rescue is fully dependent on the human frataxin being imported into the trypanosome mitochondrion. Processing of the imported protein by mitochondrial processing peptidase can be blocked by mutations in the signal peptide, as in human cells. Although in human cells frataxin must be processed to execute its function, the same protein in the T. brucei mitochondrion is functional even in the absence of processing. Our results illuminate remarkable conservation of the mechanisms of mitochondrial protein import and processing.
- MeSH
- buněčné linie MeSH
- cytosol metabolismus MeSH
- financování organizované MeSH
- geneticky modifikovaná zvířata MeSH
- lidé MeSH
- mitochondrie metabolismus MeSH
- molekulární sekvence - údaje MeSH
- proteiny obsahující železo a síru genetika metabolismus MeSH
- proteiny vázající železo genetika chemie metabolismus MeSH
- sekvence aminokyselin MeSH
- Trypanosoma brucei brucei genetika metabolismus růst a vývoj MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
Recent data suggest that frataxin plays a key role in eukaryote cellular iron metabolism, particularly in mitochondrial heme and iron-sulfur (FeS) cluster biosynthesis. We have now identified a frataxin homologue (T. vaginalis frataxin) from the human parasite Trichomonas vaginalis. Instead of mitochondria, this unicellular eukaryote possesses hydrogenosomes, peculiar organelles that produce hydrogen but nevertheless share common ancestry with mitochondria. T. vaginalis frataxin contains conserved residues implicated in iron binding, and in silico, it is predicted to form a typical alpha-beta sandwich motif. The short N-terminal extension of T. vaginalis frataxin resembles presequences that target proteins to hydrogenosomes, a prediction confirmed by the results of overexpression of T. vaginalis frataxin in T. vaginalis. When expressed in the mitochondria of a frataxin-deficient Saccharomyces cerevisiae strain, T. vaginalis frataxin partially restored defects in heme and FeS cluster biosynthesis. Although components of heme synthesis or heme-containing proteins have not been found in T. vaginalis to date, T. vaginalis frataxin was also shown to interact with S. cerevisiae ferrochelatase by using a Biacore assay. The discovery of conserved iron-metabolizing pathways in mitochondria and hydrogenosomes provides additional evidence not only of their common evolutionary history, but also of the fundamental importance of this pathway for eukaryotes.
- MeSH
- financování organizované MeSH
- genetická transkripce MeSH
- konzervovaná sekvence MeSH
- mitochondriální proteiny genetika metabolismus MeSH
- molekulární modely MeSH
- molekulární sekvence - údaje MeSH
- organely metabolismus MeSH
- proteiny vázající železo genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- Trichomonas vaginalis genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- MeSH
- proteiny vázající železo genetika MeSH
- železo metabolismus nedostatek MeSH
- Publikační typ
- kongresy MeSH
We have previously described a case of severe hypochromic microcytic anemia caused by a homozygous mutation in the divalent metal transporter 1 (DMT1 1285G > C). This mutation encodes for an amino acid substitution (E399D) and causes preferential skipping of exon 12 during processing of the DMT1 mRNA. To examine the functional consequences of this mutation, full-length DMT1 transcript with the patient's point mutation or a DMT1 transcript with exon 12 deleted was expressed in Chinese hamster ovary (CHO) cells. Our results demonstrate that the E399D substitution has no effect on protein expression and function. In contrast, deletion of exon 12 led to a decreased expression of the protein and disruption of its subcellular localization and iron uptake activity. We hypothesize that the residual protein in hematopoietic cells represents the functional E399D DMT1 variant, but because of its quantitative reduction, the iron uptake activity of DMT1 in the patient's erythroid cells is severely suppressed.
- MeSH
- bodová mutace MeSH
- CHO buňky MeSH
- financování organizované MeSH
- fluorescenční protilátková technika MeSH
- hypochromní anemie genetika MeSH
- křečci praví MeSH
- lidé MeSH
- proteiny přenášející kationty genetika metabolismus MeSH
- proteiny vázající železo genetika metabolismus MeSH
- transfekce MeSH
- western blotting MeSH
- železo metabolismus MeSH
- zvířata MeSH
- Check Tag
- křečci praví MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
