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.
CIAPIN1 targets Na⁺/H⁺ exchanger 1 to mediate MDA-MB-231 cells' metastasis through regulation of MMPs via ERK1/2 signaling pathway.
Wang, J, Xu, H, Wang, Q, Zhang, H, Lin, Y, Zhang, H, Li, Q, Pang, T
Experimental cell research. 2015;(1):60-72
Abstract
Cytokine-induced antiapoptotic inhibitor 1 (CIAPIN1) was recently identified as an essential downstream effector of the Ras signaling pathway and has been confirmed to be closely associated with various malignant tumors. However, its potential role in regulating breast cancer metastasis remains unclear. Matrix metalloproteinases (MMPs) are a broad family of zinc-biding endopeptidases that participate in the extracellular matrix (ECM) degradation that accompanies cancer cell invasion, metastasis and angiogenesis. In this study, we found up-regulation of CIAPIN1 by lentiviral expression vector inhibited the migration, invasion and MMPs expression of MDA-MB-231 cells. Further, CIAPIN1 over-expression decreased NHE1 (Na(+)/H(+) exchanger 1) expression and ERK1/2 phosphorylation. Importantly, treating CIAPIN1 over-expressed MDA-MB-231 cells with the NHE1 specific inhibitor, Cariporide, further inhibited the metastatic capacity, MMPs expression and phosphorylated ERK1/2. Treatment with the MEK1 specific inhibitor, PD98059, induced nearly the same suppression of CIAPIN1 over-expression-dependent migration, invasion and MMPs expression as was observed with Cariporide. Further, Cariporide and PD98059 synergistically suppressed migration, invasion and MMPs expression of CIAPIN1 over-expressed MDA-MB-231 cells. Thus, our results revealed the mechanism by which CIAPIN1 targeted NHE1 to mediate migration and invasion of MDA-MB-231 cells through regulation of MMPs via ERK1/2 signaling pathway.
3.
Mechanistic insights into metal ion activation and operator recognition by the ferric uptake regulator.
Deng, Z, Wang, Q, Liu, Z, Zhang, M, Machado, AC, Chiu, TP, Feng, C, Zhang, Q, Yu, L, Qi, L, et al
Nature communications. 2015;:7642
Abstract
Ferric uptake regulator (Fur) plays a key role in the iron homeostasis of prokaryotes, such as bacterial pathogens, but the molecular mechanisms and structural basis of Fur-DNA binding remain incompletely understood. Here, we report high-resolution structures of Magnetospirillum gryphiswaldense MSR-1 Fur in four different states: apo-Fur, holo-Fur, the Fur-feoAB1 operator complex and the Fur-Pseudomonas aeruginosa Fur box complex. Apo-Fur is a transition metal ion-independent dimer whose binding induces profound conformational changes and confers DNA-binding ability. Structural characterization, mutagenesis, biochemistry and in vivo data reveal that Fur recognizes DNA by using a combination of base readout through direct contacts in the major groove and shape readout through recognition of the minor-groove electrostatic potential by lysine. The resulting conformational plasticity enables Fur binding to diverse substrates. Our results provide insights into metal ion activation and substrate recognition by Fur that suggest pathways to engineer magnetotactic bacteria and antipathogenic drugs.