1.
Roles of UndA and MtrC of Shewanella putrefaciens W3-18-1 in iron reduction.
Yang, Y, Chen, J, Qiu, D, Zhou, J
BMC microbiology. 2013;:267
Abstract
BACKGROUND The completion of genome sequencing in a number of Shewanella species, which are most renowned for their metal reduction capacity, offers a basis for comparative studies. Previous work in Shewanella oneidensis MR-1 has indicated that some genes within a cluster (mtrBAC-omcA-mtrFED) were involved in iron reduction. To explore new features of iron reduction pathways, we experimentally analyzed Shewanella putrefaciens W3-18-1 since its gene cluster is considerably different from that of MR-1 in that the gene cluster encodes only four ORFs. RESULTS Among the gene cluster, two genes (mtrC and undA) were shown to encode c-type cytochromes. The ΔmtrC deletion mutant revealed significant deficiencies in reducing metals of Fe2O3, α-FeO(OH), β-FeO(OH), ferric citrate, Mn(IV) and Co(III), but not organic compounds. In contrast, no deficiency of metal reduction was observed in the ΔundA deletion mutant. Nonetheless, undA deletion resulted in progressively slower iron reduction in the absence of mtrC and fitness loss under the iron-using condition, which was indicative of a functional role of UndA in iron reduction. CONCLUSIONS These results provide physiological and biochemical evidences that UndA and MtrC of Shewanella putrefaciens W3-18-1 are involved in iron reduction.
2.
Hereditary hemochromatosis and transferrin receptor 2.
Chen, J, Enns, CA
Biochimica et biophysica acta. 2012;(3):256-63
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Abstract
BACKGROUND Multicellular organisms regulate the uptake of calories, trace elements, and other nutrients by complex feedback mechanisms. In the case of iron, the body senses internal iron stores, iron requirements for hematopoiesis, and inflammatory status, and regulates iron uptake by modulating the uptake of dietary iron from the intestine. Both the liver and the intestine participate in the coordination of iron uptake and distribution in the body. The liver senses inflammatory signals and iron status of the organism and secretes a peptide hormone, hepcidin. Under high iron or inflammatory conditions hepcidin levels increase. Hepcidin binds to the iron transport protein, ferroportin (FPN), promoting FPN internalization and degradation. Decreased FPN levels reduce iron efflux out of intestinal epithelial cells and macrophages into the circulation. Derangements in iron metabolism result in either the abnormal accumulation of iron in the body, or in anemias. The identification of the mutations that cause the iron overload disease, hereditary hemochromatosis (HH), or iron-refractory iron-deficiency anemia has revealed many of the proteins used to regulate iron uptake. SCOPE OF THE REVIEW In this review we discuss recent data concerning the regulation of iron homeostasis in the body by the liver and how transferrin receptor 2 (TfR2) affects this process. MAJOR CONCLUSIONS TfR2 plays a key role in regulating iron homeostasis in the body. GENERAL SIGNIFICANCE The regulation of iron homeostasis is important. One third of the people in the world are anemic. HH is the most common inherited disease in people of Northern European origin and can lead to severe health complications if left untreated. This article is part of a Special Issue entitled Transferrins: Molecular mechanisms of iron transport and disorders.
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[Effects of vitamin A, vitamin A plus iron and multiple micronutrient-fortified seasoning powder on iron metabolic homeostasis].
Chen, K, Liu, YF, Chen, L, Zhang, X, Liu, YX, Chen, J, Li, TY
Zhonghua er ke za zhi = Chinese journal of pediatrics. 2011;(12):926-32
Abstract
OBJECTIVE To evaluate the effect of vitamin A, vitamin A plus iron and "7 + 1" multiple micronutrient-fortified seasoning powder on iron metabolic homeostasis in preschool children. METHODS This was a randomized, controlled and blinded interventional field trial. A total of 226 2 - 7 years old preschool children were recruited from three nurseries in the area, and they were randomly assigned into three different fortified diet groups for 6 months. The subjects in Group I were fortified with vitamin A; those in Group II and III were fortified with vitamin A plus iron and vitamin A plus iron, thiamine, riboflavin, folic acid, niacinamide, zinc and calcium (7 + 1), respectively. The concentration of serum vitamin A was measured by high-performance liquid chromatography (HPLC), serum ferritin (SF) was measured by enzyme-linked immunosorbent assay (ELISA), soluble transferrin receptor (sTfR) was measured by microparticle-enhanced, and hemoglobin (HB) by hemiglobincyanide, the sTfR-SF index (TFR-F index) and total body iron content were computed respectively before and after intervention. Simultaneously, children's demographic data, socio-economic status and eating habits, etc. were investigated by questionnaires. RESULTS A total of 226 preschool children were included in the study with age ranged from 2 to 7 years with average age (4.0 ± 0.85) (means ± standard deviation). The prevalence of anemia, deficient iron storage, vitamin A deficiency (VAD) and suspect sub-clinical vitamin A deficiency (SSVAD) were 23.5%, 15.0%, 6.3% and 25.9%, respectively. The levels of SF and sTfR significantly decreased after intervention in all groups (χ(2) = 8.3298, χ(2) = 16.1471, χ(2) = 15.1371, χ(2) = 15.1171, χ(2) = 5.2617, χ(2) = 4.8844, P < 0.05) especially in group II and group III for SF (χ(2) = 16.1471, χ(2) = 15.1371, P < 0.05) and group I for sTfR (χ(2) = 15.1171, P < 0.05). No marked change of TFR-F index and total body iron contents was observed in group I (t = 0.1817, t = 1.7736, P > 0.05), while TFR-F index decreased and total body iron contents increased in group II and group III (t = 5.3561, t = 6.5979, t = 11.1663, t = 8.7306, P < 0.05) after intervention. CONCLUSION Vitamin A intervention has significant effect on iron storage and mobilization but seldom effect on iron absorption in small intestine. The combination of vitamin A and other micronutrients might be a better intervention for the improvement of iron deficiency for preschool-children.
4.
Effects of wheat flour fortified with different iron fortificants on iron status and anemia prevalence in iron deficient anemic students in Northern China.
Sun, J, Huang, J, Li, W, Wang, L, Wang, A, Huo, J, Chen, J, Chen, C
Asia Pacific journal of clinical nutrition. 2007;(1):116-21
Abstract
OBJECTIVES To compare the effects of wheat flours fortified with NaFeEDTA, FeSO4 and elemental iron (electrolytic iron), in improving iron status in anemic students. METHODS Four hundreds anemic students (11 to 18 years old) were divided into four groups and given wheat flour fortified with different iron fortificants at different concentrations: control group (no added iron); NaFeEDTA group (20 mg Fe/kg); FeSO4 group (30 mg Fe/kg); and elemental iron group (60 mg Fe/kg). The trial lasted for 6 months and the following parameters were examined every 2 months: whole blood hemoglobin, free erythrocyte protoporphyrin, serum ferritin, serum iron, total iron binding capacity and transferrin receptor. RESULTS The flour consumption in the 4 groups was 300-400 g/person/day, accounted for 70% of total cereal consumption in the diets. There were no significant differences in flour consumption among the 4 groups. Blood hemoglobin level increased in all the 3 intervened groups, but the increment in the NaFeEDTA group was significantly higher and earlier than the other 2 groups; and only 1% of the subjected remained anemic at the end of the trial in the NaFeEDTA group, while 40% and 60% of the subjects in the FeSO4 and electrolytic iron group remained anemic, respectively. The order of improvements in free erythrocyte protoporphyrin, serum ferritin and transferring receptor levels were: NaFeEDTA > FeSO4 > electrolytic iron. No significant changes were found in the control group on all the tested parameters during the trial. CONCLUSIONS The results indicated that even NaFeEDTA was added at a lower level, it has better effects than FeSO4 and elemental iron on controlling iron deficiency anemia and improving iron status in anemic children; while elemental iron was the least effective.