TMPRSS6 Research Articles

Genetic Variants Affecting Iron Metabolism in Healthy Adults: A Systematic Review to Support Personalized Nutrition Strategies

Background/Objectives: Increased interest in personalized nutrition has led to a growing focus on exploring genetic variants and their impact on nutritional uptake (nutrigenomics). Nevertheless, no systematic review to date has compiled scientific evidence on genetic variants (such as single-nucleotide polymorphisms (SNPs)) affecting mineral metabolism in humans. This review aims to fill this gap and enable optimized personalized nutrition recommendations in health care. Methods: Cochrane, Embase and MEDLINE databases were systematically searched for English and German studies published between 2007 and 2023, focusing on genetic variants linked to nutrition. Studies on overweight, diseased, or underage individuals were excluded. Papers with verified findings were assessed for methodological quality using the Joanna Briggs Institute critical appraisal tool. Results: Twenty-one scientific papers on SNPs associated with mineral metabolism were included. The majority were observational studies (n = 19) conducted on Caucasian populations. Women outnumbered men (37.4%) women, 18.9% men, 43.7% sex not reported. All identified SNPs linked to minerals influenced iron parameters, with the TMPRSS6 gene showing the strongest correlation. Two HFE SNPs (rs1800562 and rs1799945) and one TF SNP (rs1799852) exhibited protective effects, while the other 11 SNPs were linked to increased risk of iron deficiency, suggesting potential benefits from iron supplementation for individuals with those genetic variants. Conclusions: This review provides comprehensive insights into the association between genetic variants and mineral metabolism, and the findings highlight the relevance of genetic makeup in optimizing health through nutritional interventions. The generalizability of the findings may be limited to Caucasians, warranting future research with diverse populations. This review was registered with the International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY) on 12 July 2022, under INPLASY202270068 and funded by the University Centre for Prevention and Sports Medicine at Balgrist University Hospital Zurich and the Swiss Innovation Agency Innosuisse, Switzerland.

IRIDA- An Indian perspective

Iron deficiency anemia (IDA) is the most common type of anemia globally (IDA), the treatment being iron supplementation. However, in a few individuals, there is absent to suboptimal response to iron supplementation due to iron not being taken up by the body of the individual. This condition is known as iron-refractory IDA (IRIDA). Iron refractory iron deficiency anemia is a rare genetic condition that follows an autosomal recessive inheritance due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation, and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. This condition is likely being missed or under-diagnosed in our iron deficient endemic setting due to a lack of general awareness amongst physicians in establishing the diagnosis or due to the lack of availability of proper genetic testing.

Novel TMPRSS6 variants and their impact on iron-refractory iron deficiency anaemia in pregnancy: A North Indian genotype phenotype study.

Iron-refractory iron deficiency anaemia (IRIDA) is a rare autosomal recessive disorder, distinguished by hypochromic microcytic anaemia, low transferrin levels and inappropriately elevated hepcidin (HEPC) levels. It is caused by mutations in TMPRSS6 gene. Systematic screening of 500 pregnant women with iron deficiency anaemia having moderate to severe microcytosis with no other causes of anaemia were enrolled to rule out oral iron refractoriness. It identified a final cohort of 10 (2.15% prevalence) individuals with IRIDA phenotype. Haematological and biochemical analysis revealed significant differences between iron responders and iron non-responders, with iron non-responders showing lower haemoglobin, red blood cell count, serum iron and serum ferritin levels, along with elevated HEPC (9.47 ± 2.75 ng/mL, p = 0.0009) and erythropoietin (4.58 ± 4.07 µ/mL, p = 0.0196) levels. Genetic sequencing of the TMPRSS6 gene in this final cohort identified 10 novel variants, including seven missense and three frame-shift mutations, with four missense variants showing high functional impact defining the IRIDA phenotype. Structural analysis revealed significant damage caused by two variants (p.L83R and p.S235R). This study provides valuable insights into IRIDA among pregnant women in the Indian subcontinent, unveiling its underlying causes of unresponsiveness, genetic mechanisms and prevalence. Furthermore, research collaboration is essential to validate these findings and develop effective treatments.

V736A (rs855791) polymorphism in the TMPRSS6 gene is associated with iron deficiency anemia in females of reproductive age: A meta-analysis

BackgroundSeveral studies suggested that mutations in the TMPRSS6 gene affect hepcidin production, which may lead to iron deficiency anemia (IDA). Hence, this meta-analysis explored the association of the V736A or the rs855791 polymorphism in the TMPRSS6 gene with IDA development. MethodsRelated studies were searched as of December 24, 2023. Two authors screened the resulting studies, and data were extracted and collated in a customized spreadsheet. Review Manager 5.4 and Meta-Essentials were used to compute the odds ratios (ORs) and 95% confidence intervals (CIs). ResultsA total of 187 studies were screened. From this, only six studies satisfied the inclusion criteria and were included in the meta-analysis. Analysis of the allelic model showed a high degree of inter-study heterogeneity, which prompted us to determine the cause through sub-group analysis. Sub-groups were conceptualized based on the participant characteristics. Based on this, homogenous findings were observed for the allelic, co-dominant, and dominant models of the association between the polymorphism and the development of IDA among females of reproductive age still experiencing menstruation. Non-significant and highly heterogeneous outcomes were noted for the other sub-groups. ConclusionOverall, based on the pooled findings, the V736A polymorphism is associated with IDA development in females of reproductive age still experiencing menstruation. However, further studies are needed to verify these claims.

Iron Chelation Efficiency in Human Hepatocytes Is Enhanced By Exogenous Hepcidin

Iron chelation is clinically inefficient, with only a small percentage of the applied chelator being excreted in the iron-bound form. Chelation is also slow because only a small proportion of storage iron is in the chelatable labile iron pool (LIP) at any given moment. In principle, by increasing the magnitude of the LIP within hepatocyte, the major site of body storage iron in conditions of iron overload, the magnitude and hence the efficiency of chelation may be increased. Recent work has shown that SLN124, a RNAi-therapeutic inhibitor of Tmprss6 gene expression, increases iron chelation by deferiprone in a murine model of thalassemia (b-thalassemic Hbb th3/+ animals) (Vadolas et al Brit J Haematol 2021) and murine hereditary haemochromatosis (Altamura et al. HemaSphere 2019). We wished to determine whether the mechanism of increased chelation was consistent with the blocking of iron exit from hepatocyte through ferroportin channels by increased levels of hepcidin. Here we have examined whether application of exogenous hepcidin to a human hepatocyte cell line HepG2 can increase the chelation efficiency of deferiprone and whether this effect is also seen with other iron chelators such as deferasirox and deferoxamine. A model was developed from previous work (Vlachodimitropoulou et al. Blood 2017) where the net effect of iron uptake (from fetal bovine serum medium) versus intracellular iron removal by chelation, could be interrogated. The dose and time-dependent effect of exogenous hepcidin and its interaction with iron chelators on intracellular iron content was examined. Briefly, to load cells with iron, confluent HepG2 cells were incubated for 2h with 10% FBS followed by media change containing 10-30 uM iron binding equivalents (IBE) of therapeutic chelators, hepcidin, or control media. This loading method doubled the cellular iron; and subsequently increased cellular ferritin by at least 4-fold. Both effects could be completely inhibited with iron chelation. Following a pulse with hepcidin (100nM-10µM), intracellular iron content of HepG2 cells increased in a dose dependent manner, by 30-100% over the next 4h, followed by a decrease in cellular iron at 8 hours (Fig. 1A). This transient effect on iron retention could be prolonged with serial addition of hepcidin to the media (at 2 and 4h, data not shown). Co-treatment with the exclusively extracellular chelator CP40 demonstrated that while a substantial fraction of the hepcidin effect on iron retention was dependent on iron uptake from media (Fig 1B), the remaining increase in iron retention was independent of this effect and consistent with inhibition of iron egress from . Compared with control cells (without chelator but with or without hepcidin), a 50-200% enhancement of hepatocyte iron removal by 10uM IBE deferiprone was observed at 2 and 4 hours (Fig. 1C) with the addition of 300nM exogenous hepcidin. Correspondingly, cellular iron removal with deferoxamine (10-30 µM IBE) was enhanced by 250% at 4 h by exogenous hepcidin (Fig. 1D) whereas iron removal by deferasirox (30µM IBE) was enhanced by at least 50% at 2 and 4 h when hepcidin (300nM) was present (Fig. 1E), as compared to controls. Enhanced chelation with DFO was not observed until after 2h incubation, consistent with the known slower access of DFO to intracellular pools compared with deferiprone or deferasirox. Beyond 4h, the effect of hepcidin on enhanced chelation was not seen, suggesting that hepcidin is consumed or degraded in this culture system. We conclude that enhanced removal of intracellular iron by chelation is demonstrable with all three clinically available chelators following the application of exogenous hepcidin. This iron would be destined for increased excretion of chelate complexes in vivo and hence enhanced decrements in body iron. Two mechanisms for enhanced chelation are possible in this model; the first is by increased iron loading of hepatocytes incubated with hepcidin and secondly through the blocking by hepcidin of labile intracellular iron egress through ferroportin channels, thereby increasing the magnitude of chelatable intracellular iron pools. Future work in primary human hepatocytes will examine whether manipulation of intracellular hepcidin levels by SLN124 has similar chelation-enhancing effects.

Matriptase-2 regulates iron homeostasis primarily by setting the basal levels of hepatic hepcidin expression through a nonproteolytic mechanism

Matriptase-2 (MT2), encoded by TMPRSS6, is a membrane-anchored serine protease. It plays a key role in iron homeostasis by suppressing the iron-regulatory hormone, hepcidin. Lack of functional MT2 results in an inappropriately high hepcidin and iron-refractory iron-deficiency anemia. Mt2 cleaves multiple components of the hepcidin-induction pathway in vitro. It is inhibited by the membrane-anchored serine protease inhibitor, Hai-2. Earlier in vivo studies show that Mt2 can suppress hepcidin expression independently of its proteolytic activity. In this study, our data indicate that hepatic Mt2 was a limiting factor in suppressing hepcidin. Studies in Tmprss6-/- mice revealed that increases in the dietary iron to ∼0.5% were sufficient to overcome the high hepcidin barrier and to correct the iron-deficiency anemia. Interestingly, the increased iron in Tmprss6-/- mice was able to further upregulate hepcidin expression to a similar magnitude as in wild-type mice. These results suggest that lack of Mt2 does not impact the iron induction of hepcidin. Additional studies of wild-type Mt2 and the proteolytic-dead form, fMt2S762A, indicated that the function of Mt2 is to lower the basal levels of hepcidin expression in a manner that primarily relies on its nonproteolytic role. This idea is supported by the studies in mice with the hepatocyte-specific ablation of Hai-2, which showed a marginal impact on iron homeostasis and no significant effects on iron regulation of hepcidin. Together, these observations suggest that the function of Mt2 is to set the basal levels of hepcidin expression and that this process is primarily accomplished through a nonproteolytic mechanism.

Anaemia and iron deficiency associate with polymorphism TMPRSS6 rs855791 in Brazilian children attending day care centres.

Fe-deficiency anaemia is a major public health concern in children under 5 years of age. TMPRSS6 gene, encoding matriptase-2 protein, is implicated in Fe homoeostasis and has been associated with anaemia and Fe status in various populations. The aim of this cross-sectional study was to investigate the associations between the single nucleotide polymorphism (SNP) TMPRSS6 rs855791 and biomarkers of anaemia and Fe deficiency in Brazilian children attending day care centres. A total of 163 children aged 6-42 months were evaluated. Socio-economic, demographic, biochemical, haematological, immunological and genotype data were collected. Multiple logistic and linear regressions with hierarchical selection were used to assess the effects of independent variables on categorised outcomes and blood marker concentrations. Minor allele (T) frequency of rs855791 was 0·399. Each copy of the T allele was associated with a 4·49-fold increased risk of developing anaemia (P = 0·005) and a 4·23-fold increased risk of Fe deficiency assessed by serum soluble transferrin receptor (sTfR) (P < 0·001). The dose of the T allele was associated with an increase of 0·18 mg/l in sTfR concentrations and reductions of 1·41 fl and 0·52 pg in mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH), respectively. In conclusion, the T allele of SNP TMPRSS6 rs855791 was significantly associated with anaemia and Fe deficiency assessed by sTfR in Brazilian children attending day care centres. The effect was dose dependent, with each copy of the T allele being associated with lower MCV and MCH and higher concentrations of sTfR.

Genetic analysis of TMPRSS6 catalytic domain variants in Mexican patients with iron treatment refractoriness.

To identify the TMPRSS6 gene variants in Mexican patients with iron treatment refractoriness, to describe hematological and iron profile parameters, and to use bioinformatic prediction and protein modeling tools to assess a possible biological impact for the detected missense variants. Nineteen patients referred with iron treatment refractoriness were studied. Peripheral blood was collected to determine hematic cytometry, iron profile, hemoglobin electrophoresis, and quantification. Molecular screening was carried out for exons 15 through 18 of the TMPRSS6 gene by Sanger sequencing and for frequent thalassemia variants by amplification-refractory mutation system-polymerase chain reaction (PCR) and gap-PCR. The biological impact of the detected missense variants was assessed using bioinformatic prediction and protein modeling tools. We found 5 genetic variants in the matriptase-2 catalytic domain: 1 at intron-15/exon-16 junction (rs60484081) and 4 exonic, 3 missense (rs377054987, p.Gly626Asp; rs1384127820, p.Ser672Thr; rs855791, p.Val727Ala) and 1 synonymous (rs2235321, p.Tyr730=), with frequencies ranging from 0.18 to 0.53. No significant differences were observed in the hematological parameters or iron profile, considering type and number of variants. Bioinformatic predictions suggested a possible biological impact only for rs377054987. The TMPRSS6 variants observed in Mexican patients with oral iron treatment refractoriness have high frequencies; nevertheless, their relationship with hematological and iron profile parameters needs further research. The possible biological impact for rs377054987 is due to size and amino acid hydrophobicity changes and hydrogen bond modifications.

SLN124, a GalNAc conjugated 19-mer siRNA targeting tmprss6, reduces plasma iron and increases hepcidin levels of healthy volunteers.

SLN124, an N-acetylgalactosamine conjugated 19-mer short interfering RNA, is being developed to treat iron-loading anemias (including beta-thalassemia and myelodysplastic syndromes) and myeloproliferative neoplasms (polycythemia vera). Through hepatic targeting and silencing of the TMPRSS6 gene, SLN124 increases endogenous hepcidin synthesis. This is the first clinical report of an siRNA targeting a component of iron homeostasis. This first-in-human, phase 1 study assessed the safety, tolerability, pharmacokinetics, and pharmacodynamics of single ascending doses of SLN124 (1.0, 3.0, and 4.5 mg/kg) in healthy volunteers. Twenty-four participants were randomized in three sequential cohorts of eight subjects, each to receive a single dose of either SLN124 or placebo (6:2 randomization), administered subcutaneously. There were no serious or severe adverse events, or discontinuations due to adverse events, and most treatment-emergent adverse events were mild, including transient mild injection site reactions, resolving without intervention. SLN124 was rapidly absorbed, with a median tmax of 4-5 h across all treatment groups, and largely eliminated from plasma by 48 h. Plasma concentrations increased in a greater than dose proportional fashion between treatment groups. In all SLN124 groups, a dose-related effect was observed across iron metabolism markers, and across erythroid markers, SLN124 resulted in increased plasma hepcidin levels, peaking around Day 29, and consequent dose-related sustained reductions in plasma iron and transferrin saturation with decreased reticulocyte production, MCHC, and MCV. Results suggest duration of action lasting up to 56 days after a single SLN124 dose, on hepcidin and hematological parameters of iron metabolism (serum iron and TSAT).

The global prevalence and ethnic heterogeneity of iron-refractory iron deficiency anaemia

BackgroundIron-refractory iron deficiency anaemia (IRIDA) is an autosomal recessive iron deficiency anaemia caused by mutations in the TMPRSS6 gene. Iron deficiency anaemia is common, whereas IRIDA is rare. The prevalence of IRIDA is unclear. This study aimed to estimate the carrier frequency and genetic prevalence of IRIDA using Genome Aggregation Database (gnomAD) data.MethodsThe pathogenicity of TMPRSS6 variants was interpreted according to the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) standards and guidelines. The minor allele frequency (MAF) of TMPRSS6 gene disease-causing variants in 141,456 unique individuals was examined to estimate the global prevalence of IRIDA in seven ethnicities: African/African American (afr), American Admixed/Latino (amr), Ashkenazi Jewish (asj), East Asian (eas), Finnish (fin), Non-Finnish European (nfe) and South Asian (sas). The global and population-specific carrier frequencies and genetic prevalence of IRIDA were calculated using the Hardy–Weinberg equation.ResultsIn total, 86 pathogenic/likely pathogenic variants (PV/LPV) were identified according to ACMG/AMP guideline. The global carrier frequency and genetic prevalence of IRIDA were 2.02 per thousand and 1.02 per million, respectively.ConclusionsThe prevalence of IRIDA is greater than previous estimates.

Maternal &amp;lt;i&amp;gt;TMPRSS6&amp;lt;/i&amp;gt; Gene Polymorphism rs855791SNP in Women with Preeclampsia

Introduction: Preeclampsia can lead to several maternal and perinatal adverse effects. There are few published data on the association between transmembrane serine protease 6 (TMPRSS6) gene polymorphism and preeclampsia. Objective: To assess the association between TMPRSS6 gene polymorphism rs855791SNP in women with preeclampsia compared with healthy pregnant women. Method: A case-control study (60 women in each arm) was conducted at Saad Abuaela Maternity Hospital in Khartoum, Sudan. Sociodemographic and clinical data were gathered through a questionnaire. The participant was genotype for TMPRSS6 gene rs855791SNP using Polymerase Chain Reaction and Restriction Fragment Length Polymorphism (PCR-RFLP). The results were confirmed by DNA sequencing. Result: There was no significant difference in the median of age, parity, and body mass index. The distribution of the genotypes and alleles of TMPRSS6 rs855791 was consistent with the HWE. The overall TMPRSS6 rs855791 polymorphism was not significantly associated with preeclampsia. However, the proportion of heterozygotes (TC) was considerably higher in the women with preeclampsia (46.7%) than in the control group (23.3%) (p = 0.001; OR = 2.71; 95% CI = 1.21 - 6.07). The proportion of homozygotes (TT) and T alleles was not significantly different between women with preeclampsia and the control group. Conclusion: The overall TMPRSS6 rs855791 polymorphism was not significantly associated with preeclampsia and healthy control.

TMPRSS6 rs855791 polymorphism is associated with iron deficiency in a cohort of Sri Lankan pregnant women

BackgroundHepcidin is the key regulator of systemic iron homeostasis and is downregulated by matriptase 2 (MT2), a protease encoded by TMPRSS6 gene. In the presence of low iron levels, MT2 cleaves membrane-bound hemojuvelin (HJV), causing a negative regulation of hepcidin at the gene level, and restores iron balance. rs855791T > C, a missense variant in the catalytic domain of MT2, causes valine to alanine change at 736 position. The current study aimed to investigate the association of TMPRSS6 rs855791 on iron status among a cohort of pregnant women in Sri Lanka and to predict the possible molecular mechanisms.MethodsThe study was conducted among 73 pregnant women at ≤ 12 weeks of gestation. Iron deficiency was defined as serum ferritin < 30 μg/L after adjusting for inflammation. rs855791 was genotyped with a PCR–RFLP, and its association with iron deficiency was analyzed using binary logistic regression. Docking of HJV with MT2 protein encoded by the two rs855791 alleles was undertaken in silico to predict the molecular mechanism of the observed associations.ResultsThe majority of the study population (70%) were iron deficient. Among the subjects, T allele was prevalent in the iron deficient group with a frequency of 61.8%, with a nearly twofold enhanced risk for iron deficiency (OR = 2.566, 95%CI; P = 0.011). For TT genotype, the risk of iron deficiency was nearly sixfold (OR = 5.867; 95%CI; P = 0.023). According to the in silico analysis, MT2 736A and HJV complex is more stable with an interface energy of − 7.934 kJ/mol compared to the MT2 736 V and HJV complex which generates an interface energy of − 4.689 kJ/mol.ConclusionThe current study suggests that the iron regulatory effect of rs855791 of TMPRSS6 is brought about by the differences in thermodynamic stability of the two protein complexes made by MT2 and HJV proteins. The prevalence of iron deficiency observed among Sri Lankan pregnant women may be an interplay between the prevalence of rs855791 T allele and the low dietary iron intake.

Alkaloid fraction of Mirabilis jalapa Linn. flowers has low cytotoxicity and increases iron absorption through Erythropoietin-Matriptase-2-Hepcidin pathway in iron deficiency Hepatocarcinoma cell model

In this study, we investigated the effects of an alkaloid fraction of Mirabilis jalapa L. flowers in terms of cytotoxicity, Erythropoietin (EPO), hepcidin, and Matriptase-2 (MT-2) expression levels in iron deficiency Hepatocarcinoma (HepG2) cell model. The iron deficiency HepG2 cell model was generated by induction with Deferoxamine (DFO) and was then treated with standard therapy Ferric Ammonium Citrate (FAC) and different alkaloid fraction doses. Subsequently, the type II transmembrane serine proteases (TTSPs) activity and MT-2 expression were measured using a fluorometer and immunocytochemistry methods, while the EPO and hepcidin levels and total iron were examined using an ELISA kit and a colorimetric assay, respectively. The data were then analyzed using ANOVA with a significance level of 95 %. According to the UV–vis Spectrophotometry and HPLC results, the alkaloid fraction of M. jalapa flowers had 6.17- and 4-times higher Betaxanthin levels, respectively, compared to the ethanol extract of M. jalapa flower. Furthermore, LC-MS/MS analysis showed that the most dominant compound is Indicaxanthin. The ethanol extract and alkaloid fraction of M. jalapa flowers were not cytotoxic (IC50 > 30 ppm). Furthermore, the alkaloid fraction containing Indicaxanthin, Miraxanthin-V, and Boeravinone F is capable of increasing EPO levels, membrane and soluble TTSPs activity and MT-2 expression, decreasing hepcidin levels, and increasing intracellular iron levels in iron deficiency HepG2 cell model. In conclusion, the obtained alkaloid fraction of M. jalapa flowers has low cytotoxicity and the later increases iron absorption via EPO-MT2-hepcidin pathway in iron deficiency HepG2 cell model.

TMPRSS6 Inhibition with a Monoclonal Antibody Improves Red Blood Cell Health and Reduces Hepatic Iron Loading in Mouse Models of Iron Overload Diseases

Beta-thalassemia is a genetic disorder arising from loss of function mutations in the beta-globin gene, leading to ineffective erythropoiesis and organ iron overload. The latter contributes to liver fibrosis, type-2 diabetes, cancer, and cardiac toxicities. The major cause of increased iron loading is the reduced hepcidin levels because of the ineffective erythropoiesis. Iron is regulated by the hormone hepcidin. The BMP6-HJV signaling axis induces hepcidin expression via SMAD1/5 activation and the serine-protease TMPRSS6 is a negative regulator of HJV. Individuals with loss-of-function mutations in the TMPRSS6 gene have high levels of circulating hepcidin resulting in iron-restricted/iron-deficiency anemia. Thus, blocking TMPRSS6 may be a viable strategy to elevate hepcidin and reduce iron levels in beta-thalassemia or hereditary hemochromatosis. We generated a monoclonal antibody (REGN7999) that inhibits TMPRSS6 activity hence preventing HJV cleavage. This in turn accentuates BMP6-HJV signaling, consequently increasing serum hepcidin. In the Hbbth3/+ mouse model of beta-thalassemia, treatment with REGN7999 (10 mg/kg, s.c., weekly for 8 weeks) led to a significant reduction in liver iron (~50% reduction compared to the isotype treated group) and improved red blood cell health as determined by Annexin V staining, intracellular oxidative stress, and measurement of red blood cell turnover. This effect on red blood cells was reflected by a longer running distance of Hbbth3/+ mice during forced exercise and a reduction in serum lactate production. Our data shows, that targeting TMPRSS6 has significant advantages over current treatments, such as Luspatercept, an ACVR2b receptor trap or iron chelation. These therapeutics target either red blood cell formation (Luspatercept) or iron loading (iron chelators), but not both. Hence, blockade of TMPRSS6 seems a good addition to current therapeutics. In addition, we tested REGN7999 in HFE-/-mice, a mouse model of hereditary hemochromatosis. After 8 weeks treatment, liver iron from HFE-/- mice was significantly reduced in these animals. Taken together, inhibition of TMPRSS6 is an advantageous strategy in different iron overload diseases.

Response to Prolonged Duration of Therapeutic Dose Oral Iron Therapy in a Girl With Novel TMPRSS6 Gene Variants: A Case Report and Review Literature.

Iron-refractory iron deficiency anemia (IRIDA) is an autosomal recessive disorder caused by mutations in the TMPRSS6 gene, which impair iron homeostasis. We reported a 4-year-old girl who presented with a 1-year history of iron deficiency anemia. Her hemoglobin level increased from 6.5 g/dL to 12.6 g/dL with a prolonged duration of therapeutic dose oral iron therapy (5 mg/kg/d), and the level remained quite stable during the therapy. Genetic analysis of the TMPRSS6 gene revealed compound heterozygotes of 2 novel pathogenic variants: c.811C> T (NM_153609.3) in exon 7 (NP_705837: p.R271Ter) and c.1254C> G in exon 11 (p.Y418Ter). The results highlight the significance of genetic investigation and long-term iron therapy in iron-refractory iron deficiency anemia patients.

Associated Effect of SLC40A1 and TMPRSS6 Polymorphisms on Iron Overload.

Mutations in the ferroportin (FPN) gene SLC40A1 alter iron recycling and cause disturbances in iron homeostasis. The variants of TMPRSS6 contribute to the development of iron deficiencies. In this study, we determined the role of FPN and TMPRSS6 gene polymorphisms in the modulation of iron homeostasis based on biochemical parameters. PCR analysis and sequencing were performed to determine the single nucleotide polymorphisms (SNPs) SLC40A1 c.44–24G>C (rs1439816), SLC40A1 c.663T>C (rs2304704), and TMPRSS6 c.2207T>C (rs855791). Hemoglobin concentration and iron status were determined by standard procedures. We studied 79 iron-loaded individuals for SLC40A1 polymorphisms. Interestingly, 35/79 individuals with SLC40A1 SNPs also carried a TMPRSS6 c.2207T>C polymorphism. The biochemical values of the iron overloaded individuals were compared to those of the individuals carrying TMPRSS6 SNPs and the healthy individuals (wild-type group). The ferritin concentration, transferrin saturation % (TS%), and hemoglobin concentration were significantly higher in the participants with FPN SNPs than in the other three groups. The ferritin concentration and TS% were higher in participants with both SLC40A1 and TMPRSS6 SNPs than in the TMPRSS6 and wild-type groups, while hemoglobin concentration was significantly higher than that in the TMPRSS6 SNP group only. The participants with TMPRSS6 SNPs had significantly lower ferritin concentration, TS%, and hemoglobin concentration than all the other groups. SLC40A1 and TMPRSS6 SNPs might act in the opposite direction, preventing the development of severe iron overload, and the modulation of the iron status by TMPRSS6 SNPs might provide protection.

Matriptase-2/NR4A3 axis switches TGF-β action toward suppression of prostate cancer cell invasion, tumor growth, and metastasis.

Dysregulation of pericellular proteolysis is strongly implicated in cancer metastasis through alteration of cell invasion and the microenvironment. Matriptase-2 (MT-2) is a membrane-anchored serine protease which can suppress prostate cancer (PCa) cell invasion. In this study, we showed that MT-2 was down-regulated in PCa and could suppress PCa cell motility, tumor growth, and metastasis. Using microarray and biochemical analysis, we found that MT-2 shifted TGF-β action towards its tumor suppressor function by repressing epithelial-to-mesenchymal transition (EMT) and promoting Smad2 phosphorylation and nuclear accumulation to upregulate two TGF-β1 downstream effectors (p21 and PAI-1), culminating in hindrance of PCa cell motility and malignant growth. Mechanistically, MT-2 could dramatically up-regulate the expression of nuclear receptor NR4A3 via iron metabolism in PCa cells. MT-2-induced NR4A3 further coactivated Smad2 to activate p21 and PAI-1 expression. In addition, NR4A3 functioned as a suppressor of PCa and mediated MT-2 signaling to inhibit PCa tumorigenesis and metastasis. These results together indicate that NR4A3 sustains MT-2 signaling to suppress PCa cell invasion, tumor growth, and metastasis, and serves as a contextual factor for the TGF-β/Smad2 signaling pathway in favor of tumor suppression via promoting p21 and PAI-1 expression.

TMPRSS6- Mutation in Iron Deficiency Anemia: A Review

Introduction: Iron is one of the metals involved in a variety of physiological reactions, including the construction of haemoglobin, which transports oxygen to the tissues. Chronic blood loss or insufficient food intake are the most common causes of iron insufficiency.. A germline mutation in TMPRSS6, which encodes type two transmembrane serine protease generated by the liver and helps regulate the expression of systemic iron, can induce anaemia that is resistant to oral iron treatment.&#x0D; Structure: The plasma membrane is cleaved by TMPRSS6 in vitro. The signalling mechanism required for iron-dependent hepcidin transcription regulation is thought to be downregulated by TMPRSS6. They also investigated whether the robust physiologic inducer of hepcidin, iron, can affect TMPRSS6 mRNA levels in vivo, as one of the most important activators of hepcidin expression in vitro and in vivo.&#x0D; Role of TMPRSS6: Overexpression of normal TMPRSS6 protein reduces Hamp promoter activity, and the TMPRSS6 cytoplasmic domain mediates Hamp suppression via the proximal promoter element. TMPRSS6 polymorphisms are more common than mutations and have been linked to variations in iron and hematologic markers.&#x0D; Conclusion: Because TMPRSS6 is linked to haematological factors, it is essential for maintaining iron homeostasis and proper erythropoiesis. Overproduction of hepcidin is caused by the TMPRSS6 mutation, which contributes to poor iron absorption and utilisation. Patients with poor transferrin saturation, normal ferritin levels, high amounts of hepcidin molecules, and a family history of iron deficiency anemia should be aware of TMPRSS6 gene mutations.

Role of Tmprss6 gene in radiation-induced intestinal injury of mice

Role of Tmprss6 gene in radiation-induced intestinal injury of mice

Iron distribution in different tissues of homozygous Mask (msk/msk) mice and the effects of oral iron treatments

Iron‐refractory iron deficiency anemia (IRIDA) is an autosomal recessive disorder caused by genetic mutations on TMPRSS6 gene which encodes Matriptase2 (MT2). An altered MT2 cannot appropriately suppress hepatic BMP6/SMAD signaling in case of low iron, hence hepcidin excess blocks dietary iron absorption, leading to a form of anemia resistant to oral iron supplementation. In this study, using the IRIDA mouse model Mask, we characterized homozygous (msk/msk) compared to asymptomatic heterozygous (msk/wt) mice, assessing the major parameters of iron status in different organs, at different ages in both sexes. The effect of carbonyl iron diet was analyzed as control iron supplementation being used for many studies in mice. It resulted effective in both anemic control and msk/msk mice, as expected, even if there is no information about its mechanism of absorption. Then, we mainly compared two forms of oral iron supplement, largely used for humans: ferrous sulfate and Sucrosomial iron. In anemic control mice, the two oral formulations corrected hemoglobin levels from 11.40 ± 0.60 to 15.38 ± 1.71 g/dl in 2–4 weeks. Interestingly, in msk/msk mice, ferrous sulfate did not increase hemoglobin likely due to ferroportin/hepcidin‐dependent absorption, whereas Sucrosomial iron increased it from 11.50 ± 0.60 to 13.53 ± 0.64 g/dl mainly in the first week followed by a minor increase at 4 weeks with a stable level of 13.30 ± 0.80 g/dl, probably because of alternative absorption. Thus, Sucrosomial iron, already used in other conditions of iron deficiency, may represent a promising option for oral iron supplementation in IRIDA patients.