1.
A novel SLC40A1 p.Y333H mutation with gain of function of ferroportin: A recurrent cause of haemochromatosis in China.
Zhang, W, Xu, A, Li, Y, Zhao, S, Zhou, D, Wu, L, Zhang, B, Zhao, X, Wang, Y, Wang, X, et al
Liver international : official journal of the International Association for the Study of the Liver. 2019;(6):1120-1127
Abstract
BACKGROUND & AIMS Haemochromatosis type 4, also known as ferroportin disease, is an autosomal dominant genetic disorder caused by pathogenic mutations in the SLC40A1 gene, which encodes ferroportin 1 (FPN1). We have identified a novel SLC40A1 p.Y333H mutation in our previous study. In the present study, we tried to investigate the frequency and pathogenicity of the SLC40A1 p.Y333H mutation in haemochromatosis in China. METHODS Patients were analysed for SLC40A1 p.Y333H as well as mutations in the other classic haemochromatosis-related genes by Sanger sequencing. To analyse iron export capacity of the SLC40A1 p.Y333H mutant, the 293T cells were transfected with the SLC40A1 p.Y333H construct and then treated with hepcidin after exposure to ferric ammonium citrate. Cellular localization of mutant FPN1, expression of FPN1 and intracellular ferritin were analysed by immunofluorescence and Western blotting. RESULTS Of 22 unrelated cases with primary iron overload, three cases (3/22, 13.6%) harboured the SLC40A1 p.Y333H, with no missense mutations identified in any other classical haemochromatosis-related genes including HFE, HJV, HAMP and TFR2. Pedigree analysis showed that three probands and the son of one proband had haemochromatosis of stage 3, while the son of another proband with age of 16 showed elevated transferrin saturation but normal serum ferritin level. In vitro studies showed the mutant p.Y333H ferroportin was resistant to hepcidin, affecting the subsequent internalization and degradation of FPN1, and was associated with ferroportin gain of function. CONCLUSIONS The SLC40A1 p.Y333H mutation is associated with gain of function of ferroportin, representing one of the major aetiological factors of haemochromatosis in China.
2.
Ferroportin mRNA is down-regulated in granulosa and cervical cells from infertile women.
Moreno-Navarrete, JM, López-Navarro, E, Candenas, L, Pinto, F, Ortega, FJ, Sabater-Masdeu, M, Fernández-Sánchez, M, Blasco, V, Romero-Ruiz, A, Fontán, M, et al
Fertility and sterility. 2017;(1):236-242
Abstract
OBJECTIVE To explore the relationship between iron and infertility by investigating iron-related gene expression in granulosa and uterine cervical cells. DESIGN Case-control study. SETTING Two tertiary hospitals. PATIENT(S): Two independent cohorts of fertile (n = 18 and n = 17) and infertile (n = 31 and n = 35) women. INTERVENTION(S): In vitro fertilization. MAIN OUTCOME MEASURE(S): Gene expression levels of ferritin light chain (FTL), ferritin heavy chain (FTH), transferrin receptor (TFRC), and ferroportin (SLC40A1) mRNA were analyzed in granulosa and cervical cells. RESULT(S): In the first cohort, fertile and infertile women were similar in body mass index. Ferroportin mRNA levels were decreased in granulosa cells from infertile women in parallel with increased serum hepcidin levels. A positive association between ferroportin and TFRC mRNA, a gene associated with intracellular iron deficiency, was observed only in granulosa cells from fertile women. The major findings were replicated in a second independent cohort. CONCLUSION(S): Ferroportin mRNAs and circulating hepcidin identify a subset of infertile women and may constitute a target for therapy.
3.
Endometrial expression and in vitro modulation of the iron transporter divalent metal transporter-1: implications for endometriosis.
Alvarado-Díaz, CP, Núñez, MT, Devoto, L, González-Ramos, R
Fertility and sterility. 2016;(2):393-401
Abstract
OBJECTIVE To evaluate divalent metal transporter-1 (DMT1) expression in healthy women's and endometriosis patients' endometrium and to analyze DMT1 and ferritin light chain (Fn-L) expression modulation by iron overload and IL-1β in endometrial stromal cells (ESCs). DESIGN Observational and experimental study. SETTING University hospital research laboratory. PATIENT(S): Thirty-one healthy women and 24 endometriosis patients. INTERVENTION(S): Menstrual, proliferative, and secretory endometrial biopsies. Isolated ESCs from seven endometrial biopsies incubated with IL-1β or FeSO4 overload for 24 hours. MAIN OUTCOME MEASURE(S): Divalent metal transporter-1 endometrial protein expression assessed by immunohistochemistry and Western blot. Divalent metal transporter-1 and Fn-L proteins expression in stimulated ESCs evaluated by Western blot. RESULT(S): Divalent metal transporter-1 is expressed throughout the menstrual cycle in human endometrium. Four endometrial DMT1 variants were identified accordingly to their molecular weight: DMT-80, -65, -55, and -50. Endometrial expression of DMT-80 and -55 is higher in endometriosis patients than in healthy women. In ESCs, iron overload induces an overexpression of DMT-80, DMT-50, and Fn-L, whereas IL-1β increases DMT-80 and -50 expressions and decreases Fn-L expression. CONCLUSION(S): Divalent metal transporter-1 overexpression in endometriosis patients' endometrium can increase iron influx to endometrial cells, inducing oxidative stress-mediated proinflammatory signaling. In turn, endometriosis-related conditions, as iron overload and inflammation (IL-1β), enhance endometriosis patients endometrial DMT1 expression, creating a vicious circle on DMT-1-modulated pathways.