BioMetals (v.31, #5)

Variation on a theme: investigating the structural repertoires used by ferric uptake regulators to control gene expression by Sabina Sarvan; James Butcher; Alain Stintzi; Jean-François Couture (681-704).
In every living organism, the control of metal homoeostasis is a tightly regulated process coordinated by several intertwined biological pathways. In many bacteria, the ferric uptake regulator (Fur) family of transcriptional factors (TFs) are key factors in controlling the expression of genes involved in metal homeostasis and can also regulate the expression of genes involved in responses to oxidative stresses. Since the crystallization of Escherichia coli Fur DNA binding domain, the crystal structure of several metalloregulators have been reported. While the Fur family of proteins adopt similar structures, each contains unique structural features relating to their specific biological functions. Moreover, recent groundbreaking studies have provided additional insights into the mechanisms underlying the binding of DNA by these metalloregulators. In this review, we present a comprehensive overview of the crystal structure of Fur family metalloregulators with a specific focus on the new structures of these TFs bound to DNA.
Keywords: Metalloregulators; Ferric uptake regulators; Iron; Manganese; Iron uptake; Gene regulation

Due to a technical error, the copyright line of the above mentioned article was incorrect. The original publication has been corrected.Alzheimer’s disease (AD) is characterized by an excessive accumulation of toxic amyloid beta (Aβ) plaques and memory dysfunction. The onset of AD is influenced by age, genetic background, and impaired glucose metabolism in the brain. Several studies have demonstrated that diabetes involving insulin resistance and glucose tolerance could lead to AD, ultimately resulting in cognitive dysfunction. Even though the relationship between diabetes and AD was indicated by significant evidences, the critical mechanisms and metabolic alterations in diabetes induced AD are not clear until now. Recently, iron metabolism has been shown to play multiple roles in the central nervous system (CNS). Iron deficiency and overload are associated with neurodegenerative diseases. Iron binds to Aβ and subsequently regulates Aβ toxicity in the CNS. In addition, previous studies have shown that iron is involved in the aggravation of insulin resistance. Considering these effects of iron metabolism in CNS, we expect that iron metabolism may play crucial roles in diabetic AD brain. Thus, we review the recent evidence regarding the relationship between diabetes-induced AD and iron metabolism.
Keywords: Iron; Diabetes; Alzheimer’s disease (AD); Amyloid beta (Aβ); Insulin resistance

Oxidative stress and neurodegeneration: the involvement of iron by Alessia Carocci; Alessia Catalano; Maria Stefania Sinicropi; Giuseppe Genchi (715-735).
Many evidences indicate that oxidative stress plays a significant role in a variety of human disease states, including neurodegenerative diseases. Iron is an essential metal for almost all living organisms due to its involvement in a large number of iron-containing proteins and enzymes, though it could be also toxic. Actually, free iron excess generates oxidative stress, particularly in brain, where anti-oxidative defences are relatively low. Its accumulation in specific regions is associated with pathogenesis in a variety of neurodegenerative diseases (i.e., Parkinson’s disease, Alzheimer’s disease, Huntington’s chorea, Amyotrophic Lateral Sclerosis and Neurodegeneration with Brain Iron Accumulation). Anyway, the extent of toxicity is dictated, in part, by the localization of the iron complex within the cell (cytosolic, lysosomal and mitochondrial), its biochemical form, i.e., ferritin or hemosiderin, as well as the ability of the cell to prevent the generation and propagation of free radical by the wide range of antioxidants and cytoprotective enzymes in the cell. Particularly, ferrous iron can act as a catalyst in the Fenton reaction that potentiates oxygen toxicity by generating a wide range of free radical species, including hydroxyl radicals (·OH). The observation that patients with neurodegenerative diseases show a dramatic increase in their brain iron content, correlated with the production of reactive oxigen species in these areas of the brain, conceivably suggests that disturbances in brain iron homeostasis may contribute to the pathogenesis of these disorders. The aim of this review is to describe the chemical features of iron in human beings and iron induced toxicity in neurodegenerative diseases. Furthermore, the attention is focused on metal chelating drugs therapeutic strategies.
Keywords: Alzheimer’s disease; Parkinson’s disease; Huntintgton’s disease; Amyotrophic lateral sclerosis; NBIA; Iron; Metal chelators; Antioxidants

Prevention of progression in Parkinson’s disease by Jan Aaseth; Petr Dusek; Per M. Roos (737-747).
Environmental influences affecting genetically susceptible individuals seem to contribute significantly to the development of Parkinson’s disease (PD). Xenobiotic exposure including transitional metal deposition into vulnerable CNS regions appears to interact with PD genes. Such exposure together with mitochondrial dysfunction evokes a destructive cascade of biochemical events, including oxidative stress and degeneration of the sensitive dopamine (DA) production system in the basal ganglia. Recent research indicates that the substantia nigra degeneration can be decelerated by treatment with iron binding compounds such as deferiprone. Interestingly compounds known to decrease PD risk including caffeine, niacin, nicotine and salbutamol also possess iron binding properties. Adequate function of antioxidative mechanisms in the vulnerable brain cells can be restored by acetylcysteine supplementation to normalize intracellular glutathione activity. Other preventive measures to reduce deterioration of dopaminergic neurons may involve life-style changes such as intake of natural antioxidants and physical exercise. Further research is recommended to identify therapeutic targets of the proposed interventions, in particular protection of the DA biosynthesis by oxygen radical scavengers and iron binding agents.
Keywords: Substantia nigra; Dopamine; Iron; Copper; Oxidative stress; Metal binding

Recently, more and more studies indicate that iron overload would cause osteopenia or osteoporosis. However, the molecular mechanism of it remains unclear. Moreover, very little is known about the iron metabolism in bone tissue at present. Therefore, the mRNA expression of iron-regulators, transferrin receptor1 (Tfr1), divalent metal transporter1 (Dmt1 + IRE and Dmt1 − IRE), ferritin (FtH and FtL), and ferroportin1 (Ireg1), and the localization of ferroportin1 protein were examined in the bone tissue of rats. In addition, the mRNA expression of each gene was compared between groups of rats with and without iron overload. The results showed that ferroportin1 protein was localized in the cytoplasm of osteoblast, osteocyte, chondrocyte and osteoclast of rats’ femur. The six iron-regulatory genes, Tfr1, ferritin (FtH and FtL), (Dmt1 + IRE and Dmt1 − IRE) and ferroportin1 (Ireg1), were found in femurs of rats. In addition, significantly up-regulated expression of FtH and FtL mRNA, and markedly down-regulated expression of Tfr1, Dmt1 + IRE and Ireg1 mRNA, were observed in the iron overload group compared with the control group. The result indicates that ferroportin1 protein is localized in the cytoplasm of bone cells of rats. Tfr1, Dmt1, ferritin and ferroportin1 exist in bone tissue of rats, and they may be involved in the pathological process of iron overload-induced bone lesion.
Keywords: Iron overload; TfR1; Ferritin; DMT1; Ferroportin1; Bone

Antimicrobial properties of ternary eutectic aluminum alloys by Claudia Hahn; Michael Hans; Christina Hein; Anne Dennstedt; Frank Mücklich; Petra Rettberg; Christine Elisabeth Hellweg; Lars Ingo Leichert; Christopher Rensing; Ralf Moeller (759-770).
Several Escherichia coli deletion mutants of the Keio collection were selected for analysis to better understand which genes may play a key role in copper or silver homeostasis. Each of the selected E. coli mutants had a deletion of a single gene predicted to encode proteins for homologous recombination or contained functions directly linked to copper or silver transport or transformation. The survival of these strains on pure copper surfaces, stainless steel, and alloys of aluminum, copper and/or silver was investigated. When exposed to pure copper surfaces, E. coli ΔcueO was the most sensitive, whereas E. coli ΔcopA was the most resistant amongst the different strains tested. However, we observed a different trend in sensitivities in E. coli strains upon exposure to alloys of the system Al–Ag–Cu. While minor antimicrobial effects were detected after exposure of E. coli ΔcopA and E. coli ΔrecA to Al–Ag alloys, no effect was detected after exposure to Al–Cu alloys. The release of copper ions and cell-associated copper ion concentrations were determined for E. coli ΔcopA and the wild-type E. coli after exposure to pure copper surfaces. Altogether, compared to binary alloys, ternary eutectic alloys (Al–Ag–Cu) had the highest antimicrobial effect and thus, warrant further investigation.
Keywords: Antimicrobial surfaces; Copper/silver alloys; Aluminum; Contact killing; Escherichia coli ; Copper release; CopA

Lanthanum (La)-based binder appears effective in reducing serum inorganic phosphate (Pi) levels among chronic dialysis patients, yet concern remains about La accumulation in bone during long-term oral administration. In this study, the effect of lanthanum chloride (LaCl3) on bone marrow stromal cells (BMSCs) viability was investigated under high Pi situation. We found low concentration (10−9 M) of LaCl3 increased BMSCs viability, while high concentration (10−5 M) of LaCl3 not only inhibited BMSCs viability but also stimulated high Pi induced cell apoptosis. In addition, La-containing calcium phosphate (CaP) particles can be detected on cell surfaces and inside cells. We also found that inhibition of CaP formation by adding sodium pyrophosphate, a recognized inhibitor of hydroxyapatite formation, abrogated LaCl3 induced the BMSCs viability. For isolated La-containing CaP particles, the particle size increased and crystal phase switched with elevated concentration of LaCl3. These results demonstrated that La-containing CaP particles were associated with the process of LaCl3 mediated BMSCs viability and the physicochemical properties of these particles played an important role in modulating BMSCs function.
Keywords: Lanthanum-containing calcium phosphate particles; High phosphate; Bone marrow stromal cells; Cells viability; Cell apoptosis

The structures of three previously unknown siderophores produced by the fluorescent, biotechnologically relevant Pseudomonas taiwanensis (P. taiwanensis) VLB120 bacteria were elucidated by means of hydrophilic interaction liquid chromatography (HILIC) hyphenated to high-resolution tandem mass spectrometry (HRMS/MS). They could be verified as iron(III)- and aluminum(III) complexes as well as the protonated molecules of the siderophores formed by in-source fragmentation. The siderophores were separated according to their different acyl side chains and additionally according their central ions. One of the siderophores was identified as pyoverdine with a malic acid (hydroxy succinic acid) amide side chain and a peptide moiety consisting of Orn-Asp-OHAsn-Thr-AcOHOrn-Ser-cOHOrn. The other analytes were assigned to an azotobactin with the identical peptide chain linked to the characteristic chromophoric unit and a pyoverdine with a variation in the amino acid sequence. Proline is directly linked to the pyoverdine chromophore instead of ornithine. Acidic and enzymatic hydrolyses were carried out to analyze the individual amino acids. Beside OHAsn, each amino acid of the peptide part was identified by HILIC–HRMS and comparison to authentic standards. Additionally, 15N-labeled cellular supernatants were analyzed by means of HRMS/MS. The results of the MS/MS experiments complemented by accurate mass data facilitated elucidation of the structures studied in this work and provided further confirmation of the three recently described pyoverdines of P. taiwanensis VLB120 (Baune et al. in Biometals 30:589–597, 2017.
Keywords: Pseudomonas taiwanensis ; Structure characterization; Siderophores; Pyoverdines; Azotobactin; Hydrophilic interaction liquid chromatography (HILIC)

Iron chelation inhibits cancer cell growth and modulates global histone methylation status in colorectal cancer by Lin-Lin Cao; Hangqi Liu; Zhihong Yue; Lianhua Liu; Lin Pei; Junxu Gu; Hui Wang; Mei Jia (797-805).
Colorectal cancer (CRC) is one of the most common malignancies worldwide, and new treatment strategies for CRC are required because of the existing chemotherapy resistance. Iron chelators, which have been used widely for the treatment of iron-overload disease, were reported to exert anti-proliferative effects in cancer. However, the role of iron chelation in CRC was largely unknown. In this study, we found that the iron chelator DFO inhibited CRC cell growth significantly. In addition, the gene expression profile was greatly changed by DFO treatment, and many cell growth-related genes were dysregulated. Further study showed that DFO induced a significant increase in global histone methylation in CRC cells. However, the levels of histone methyltransferases and histone demethylases did not change in response to DFO treatment, implying that the enzymatic activity of these enzymes might be regulated by iron chelation. In conclusion, this study reveals a novel role for DFO in CRC cell growth, and is the first to demonstrate that global histone methylation is modulated by iron chelation in CRC cells.
Keywords: Iron chelation; Deferoxamine; Colorectal cancer; Histone methylation

Neurotoxic metals have been implicated in the pathogenesis of multiple sclerosis, neurodegenerative disorders and brain tumours but studies of the location of heavy metals in human brains are rare. In a man who injected himself with metallic mercury the cellular location of mercury in his brain was studied after 5 months of continuous exposure to inorganic mercury arising from metallic mercury deposits in his organs. Paraffin sections from the primary motor and sensory cortices and the locus ceruleus in the pons were stained with autometallography to detect inorganic mercury and combined with glial fibrillary acidic protein immunohistochemistry to identify astrocytes. Inorganic mercury was found in grey matter subpial, interlaminar, protoplasmic and varicose astrocytes, white matter fibrous astrocytes, grey but not white matter oligodendrocytes, corticomotoneurons and some locus ceruleus neurons. In summary, inorganic mercury is taken up by five types of human brain astrocytes, as well as by cortical oligodendrocytes, corticomotoneurons and locus ceruleus neurons. Mercury can induce oxidative stress, stimulate autoimmunity and damage DNA, mitochondria and lipid membranes, so its location in these CNS cells suggests it could play a role in the pathogenesis of multiple sclerosis, neurodegenerative conditions such as Alzheimer’s disease and amyotrophic lateral sclerosis, and glial tumours.
Keywords: Human brain; Inorganic mercury; Astrocyte; Oligodendrocyte; Corticomotoneuron; Locus ceruleus; Multiple sclerosis; Alzheimer’s disease; Amyotrophic lateral sclerosis (ALS); Brain tumour

Zinc preconditioning protects against renal ischaemia reperfusion injury in a preclinical sheep large animal model by Dermot O’Kane; Luke Gibson; Clive N. May; Justin du Plessis; Arthur Shulkes; Graham S. Baldwin; Damien Bolton; Joseph Ischia; Oneel Patel (821-834).
Ischaemia–reperfusion injury (IRI) during various surgical procedures, including partial nephrectomy for kidney cancer or renal transplantation, is a major cause of acute kidney injury and chronic kidney disease. Currently there are no drugs or methods for protecting human organs, including the kidneys, against the peril of IRI. The aim of this study was therefore to investigate the reno-protective effect of Zn2+ preconditioning in a clinically relevant large animal sheep model of IRI. Further the reno-protective effectiveness of Zn2+ preconditioning was tested on normal human kidney cell lines HK-2 and HEK293. Anaesthetised sheep were subjected to uninephrectomy and 60 min of renal ischaemia followed by reperfusion. Sheep were preconditioned with intravenous injection of zinc chloride prior to occlusion. Serum creatinine and urea were measured before ischaemia and for 7 days after reperfusion. HK-2 and HEK293 cells were subjected to in vitro IRI using the oxygen- and glucose-deprivation model. Zn2+ preconditioning reduced ischaemic burden determined by creatinine and urea rise over time by ~ 70% in sheep. Zn2+ preconditioning also increased the survival of normal human kidney cells subjected to cellular stress such as hypoxia, hydrogen peroxide injury, and serum starvation. Overall, our protocol incorporating specific Zn2+ dosage, number of dosages (two), time of injection (24 and 4 h prior), mode of Zn2+ delivery (IV) and testing of efficacy in a rat model, a large preclinical sheep model of IRI and cells of human origin has laid the foundation for assessment of the benefit of Zn2+ preconditioning for human applications.
Keywords: Ischaemia reperfusion injury; Preconditioning; Zinc; Sheep; Oxygen–glucose deprivation

High Selenium Yeast mitigates aluminum-induced cerebral inflammation by increasing oxidative stress and blocking NO production by Changyu Cao; Xiaowen Li; Lei Qin; Junchong Luo; Mengdan Zhang; Zijian Ou; Kai Wang (835-843).
High Selenium Yeast (SeY) serves many important roles with respect to the maintenance of normal nervous system functioning. Studies have reported the nerve inflammation induced by Aluminum (Al) was associated with the increase of mortality. However, in-depth studies are required to verify the hypothesized neuro-protective efficacy of SeY against Al-induced cerebral damage through modulation of the inflammatory response. Here, mice were treated with SeY (0.1 mg/kg) and/or Al (10 mg/kg) by oral gavage for 28 days. Inflammation was assessed by histopathological examination and expression of biomarkers for inflammation. Furthermore, the oxidation–reduction levels and the NO production were assessed using diagnostic kits and RT-PCR. The data indicated that SeY significantly protected cerebrum against Al-induced pathological changes, in addition to the disordered expression of biomarkers of inflammation, the imbalance of oxidation–reduction, and the increase of NO production. Therefore, the chemoprotective potential of SeY against Al-induced cerebral inflammation via restore the levels of oxidation–reduction and the generation of NO was demonstrated.
Keywords: Aluminum; Selenium-rich-yeast; Inflammation; Oxidation–reduction balance; NO production; Mouse cerebrum

In recent years there has been increasing interest in the use of selenised yeast (Se-Y) as an antioxidant feed supplement. Here, three selenised yeast products are differentiated in terms of bioefficiency and the ameliorative effect on Cadmium (Cd) toxicity in porcine epithelial cells. A porcine digestion in vitro model was chosen to more accurately simulate the bioavailability of different Se-Y preparations, allowing a comprehensive understanding of the bio efficiency of each Se-Y compound in the porcine model. To elucidate a possible mechanism of action of selenium a number of bioassays were applied. Levels of Se dependent antioxidant enzymes (glutathione peroxidase and thioredoxin reductase) were evaluated to analyze the ROS neutralizing capacity of each Se-Y compound. The effects of Se-Y sources on Cd-induced DNA damage and apoptosis-associated DNA fragmentation was assessed using comet and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays, respectively. Lesion-specific DNA damage analysis and in vitro DNA repair assay determined the DNA repair capacity of each Se-Y source. The results presented in this study confirm that the ability of different commercially available Se-Y preparations to enhance a range of cellular mechanisms that protect porcine gut epithelial cells from Cd-induced damage is concentration-dependent and illustrates the difference in bioefficiency of different Se-Y compounds.
Keywords: Selenium yeast; Cadmium; Comet assay; TUNEL

Effects of lead and lead–melatonin exposure on protein and gene expression of metal transporters, proteins and the copper/zinc ratio in rats by Karla J. Soto-Arredondo; Juvencio Robles; Erik Díaz-Cervantes; Carolina Ruiz-Ramírez; Marco A. García-Revilla; Katarzyna Wrobel; Kazimierz Wrobel; Mauricio Díaz-Muñoz; Isabel Méndez; Alberto Flores; Francisco Javier Acevedo-Aguilar; Minerva Martínez-Alfaro (859-871).
Human lead (Pb) exposure induces many adverse health effects, including some related to lead accumulation in organs. Although lead bio-distribution in the body has been described, the molecular mechanism underlying distribution and excretion is not well understood. The transport of essential and toxic metals is principally mediated by proteins. How lead affects the expression of metal transporter proteins in the principal metal excretory organs, i.e., the liver and kidney, is unknown. Considering that co-administration of melatonin and lead reduces the toxic effects of lead and lead levels in the blood in vivo, we examined how lead and co-administration of lead and melatonin affect the gene and protein expression of metal transporter proteins (ZIP8, ZIP14, CTR1 and DMT1) in these organs. Rats were exposed intraperitoneally to lead or lead-melatonin. Our results show that Pb exposure induces changes in the protein and gene expression of ZIP8, ZIP14 and CTR1. Alterations in the copper/zinc ratio found in the blood, liver and kidney were likely related to these changes. With DMT1 expression (gene and protein), a positive correlation was found with lead levels in the kidney. Co-administration of melatonin and lead reduced lead-induced DMT1 expression through an unknown mechanism. This effect of melatonin relates to reduced lead levels in the blood and kidney. The metal transport protein function and our results suggest that DMT1 likely contributes to lead accumulation in organs. These data further elucidate the effects of lead on Cu and Zn and the molecular mechanism underlying lead bio-distribution in animals.
Keywords: Pb exposure; DMT1; ZIP8; ZIP14; CTR1; Cu/Zn ratio; Melatonin

Ferrous and ferric differentially deteriorate proliferation and differentiation of osteoblast-like UMR-106 cells by Kornkamon Lertsuwan; Ketsaraporn Nammultriputtar; Supanan Nanthawuttiphan; Supathra Phoaubon; Jomnarong Lertsuwan; Jirawan Thongbunchoo; Kannikar Wongdee; Narattaphol Charoenphandhu (873-889).
The association between iron overload and osteoporosis has been found in many diseases, such as hemochromatosis, β-thalassemia and sickle cell anemia with multiple blood transfusion. One of the contributing factors is iron toxicity to osteoblasts. Some studies showed the negative effects of iron on osteoblasts; however, the effects of two biological available iron species, i.e., ferric and ferrous, on osteoblasts are elusive. Since most intracellular ionized iron is ferric, osteoblasts was hypothesized to be more responsive to ferric iron. Herein, ferric ammonium citrate (FAC) and ferrous ammonium sulfate (FAS) were used as ferric and ferrous donors. Our results showed that both iron species suppressed cell survival and proliferation. Both also induced osteoblast cell death consistent with the higher levels of cleaved caspase 3 and caspase 7 in osteoblasts, indicating that iron induced osteoblast apoptosis. Iron treatments led to the elevated intracellular iron in osteoblasts as determined by atomic absorption spectrophotometry, thereby leading to a decreased expression of genes for cellular iron import and increased expression of genes for cellular iron export. Effects of FAC and FAS on osteoblast differentiation were determined by the activity of alkaline phosphatase (ALP). The lower ALP activity from osteoblast with iron exposure was found. In addition, ferric and ferrous differentially induced osteoblastic and osteoblast-derived osteoclastogenic gene expression alterations in osteoblast. Even though both iron species had similar effects on osteoblast cell survival and differentiation, the overall effects were markedly stronger in FAC-treated groups, suggesting that osteoblasts were more sensitive to ferric than ferrous.
Keywords: Alkaline phosphatase; Ferric; Ferrous; Iron overload; Osteoblast

Chromium malate alleviates high-glucose and insulin resistance in L6 skeletal muscle cells by regulating glucose uptake and insulin sensitivity signaling pathways by Weiwei Feng; Yangyang Ding; Weijie Zhang; Yao Chen; Qian Li; Wei Wang; Hui Chen; Yun Feng; Ting Zhao; Guanghua Mao; Liuqing Yang; Xiangyang Wu (891-908).
Previous study revealed that chromium malate improved the regulation of fasting blood glucose and insulin resistance in type 2 diabetic rats. In this study, the effect of chromium malate on anti-high-glucose and improve insulin resistance activities in L6 skeletal muscle cells with insulin resistance and its acting mechanism were investigated. Chromium malate showed direct anti-high-glucose activity in vitro. The glucose levels had a significant downward trend compared to chromium trichloride. Compared with model group, chromium malate could significantly promote the secretion levels of GLUT-4, Akt, Irs-1, PPARγ, PI3K and p38-MAPK, promote AMPKβ1 phosphorylation, and reduced the level of p-Irs-1 in L6 cells with insulin resistance. And the relate mRNA expression of chromium malate was significantly increased. Chromium malate is more effective at improving the related proteins and mRNA expression than those of chromium trichloride and chromium picolinate. Pretreatment with the specific p38MAPK inhibitor completely inhibited the GLUT-4 and Irs-1 proteins and mRNA expression induced by the chromium malate when compared with model group, but GLUT-4 and Irs-1 proteins and mRNA expression was partially inhibited after inhibiting p38MAPK/PI3K expression. The results suggested that chromium malate had a beneficial influence on the improvement of controlling glucose levels and insulin resistance in L6 cells with insulin resistance by regulating proteins production and genes expression in glucose uptake and insulin sensitivity signaling pathways.The signaling pathways of glucose uptake and insulin sensitivity. This study shown that chromium malate could significant increase in the production levels of GLUT-4, p-AMPKβ1, Akt, Irs-1, PPARγ, PI3K and p38-MAPK proteins and mRNA in L6 cells with insulin resistant. Pretreatment with the specific p38MAPK inhibitor completely inhibited the GLUT-4 and Irs-1 proteins and mRNA expression induced by the chromium malate compared to model group, but the proteins and mRNA were partially inhibited after inhibiting p38MAPK/PI3K. Therefore, chromium malate had beneficial influence on improvement of controlling glucose levels and insulin resistant in L6 cells by regulating proteins production and genes expression in glucose uptake and insulin sensitivity signaling pathways. The key proteins of glucose uptake and insulin sensitivity signaling pathways were p38MAPK, PI3K and PPARγ.
Keywords: Chromium malate; Insulin resistance; Glucose uptake; Signaling pathway