Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lipocytes have been classified as vitamin A-storing, desmin-positive cells. In hepatic fibrogenesis, lipocytes transform into myofibroblasts, which express alpha-smooth muscle actin (alpha-SMA) and produce increased amounts of collagen. We isolated a population of vitamin A-poor lipocytes (VAPL) from normal rat liver and examined the morphological and biochemical differences between VAPL and vitamin A-replete lipocytes (VARL). Desmin and alpha-SMA expression were determined by Western blot in quiescent cells and in cells activated by culture on uncoated plastic. Both cell types were alpha-SMA-negative; however, in contrast to VARL, freshly isolated VAPL did not contain desmin. Desmin expression was induced in VAPL on activation. With time in culture, both VAPL and VARL expressed alpha-SMA and produced collagen, indicative of transformation to myofibroblasts. Ferritin receptor expression was demonstrated in cultured VARL after 1 day and in VAPL after 5 days, indicating that this is an early marker of lipocyte activation. After 7 days, VARL and VAPL were indistinguishable in terms of desmin, ferritin receptor expression, and collagen production. This study demonstrates the first isolation and characterization of two distinct quiescent subpopulations of lipocytes from normal rat liver: desmin-negative VAPL and desmin-positive VARL. Both populations of cells can be activated to myofibroblasts, the phenotype associated with hepatic fibrogenesis.
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PMID:Vitamin A-poor lipocytes: a novel desmin-negative lipocyte subpopulation, which can be activated to myofibroblasts. 748 5

The role of ferritin in lipocyte activation is unknown. This study examined the effect of rat liver ferritin (RLF), human recombinant H-ferritin (HrHF), human recombinant L-ferritin (HrLF), apo-ferritin (apo-RLF), and hemin on lipocyte activation. Lipocytes were cultured on uncoated plastic and were incubated with these agents for 7 days, at concentrations ranging from 10(-14) to 10(-7) M (0.5 to 50 microM for hemin). Collagen/noncollagen protein production and lipocyte proliferation were determined by [3H]proline and [3H]thymidine incorporation, respectively, and the expression of alpha-smooth muscle actin (alpha-SMA) and desmin was determined by Western blot. RLF, at concentrations ranging from 10(-10) to 10(-7) M, decreased alpha-SMA expression by 65-88%. Apo-RLF, HrHF, and HrLF decreased alpha-SMA by 17-45% at 10(-7) and 10(-8) M. Hemin (10 or 50 microM) inhibited alpha-SMA by 37 and 54%, respectively. Desmin expression was not altered by ferritin or hemin. Collagen and noncollagen protein production were not altered by either RLF or apo-RLF. Lipocyte proliferation was decreased by 54, 32, and 40%, by 10(-7) M RLF, HrHF, and HrLF, respectively, whereas apo-RLF had no effect. Thus RLF inhibited lipocyte alpha-SMA expression, which may be due to an effect of sequestered iron, since neither apo-RLF, HrHF, nor HrLF had a potent effect on alpha-SMA expression and all are essentially iron-free. The inhibitory effect of iron-loaded RLF on alpha-SMA expression suggests that tissue ferritin does not initiate lipocyte activation in iron overload, but rather may have a suppressive action on this process.
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PMID:Rat liver ferritin selectively inhibits expression of alpha-smooth muscle actin in cultured rat lipocytes. 877 81

We describe liver fibrosis caused by iron overload after a long history of blood transfusion in a patient with chronic renal failure. Pertinent laboratory data were: serum (s)-Fe 148 microg/dl; unsaturated iron binding capacity (UIBC) 14 microg/dl; s-ferritin 9350 ng/ml; human leukocyte antigen (HLA) A2, A24, B39, B55, Cw1, Cw7. Computed tomography revealed a high density in the liver, and laparoscopy revealed a brown liver. Liver histology showed bridging fibrosis from portal tracts. A heavy iron deposit was seen in Kupffer cells as well as in hepatocytes surrounded by fibrosis around the portal tracts. Immunocytochemistry revealed alpha-smooth muscle actin in many stellate cells distributed along the fibrotic area, and electron microscopy revealed infiltrating myofibroblastic stellate cells coexisting with collagen fibers around degenerated hepatocytes containing iron deposits. The findings are consistent with the notion that stellate cells play an important role in liver fibrogenesis in both genetic and transfusional iron overload hemochromatosis.
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PMID:Activated hepatic stellate cells participate in liver fibrosis in a patient with transfusional iron overload. 977 45

Activated hepatic stellate cells have been implicated in the fibrogenic process associated with iron overload, both in animal models and in human hemochromatosis. Previous studies have evaluated the role of ferritin/ferritin receptor interactions in the activation of stellate cells and subsequent fibrogenesis; however, the role of transferrin in hepatic stellate cell biology is unknown. This study was designed to identify and characterize the stellate cell transferrin receptor and to evaluate the influence of transferrin on stellate cell activation. Identification and characterization of the stellate cell transferrin receptor was determined by competitive displacement assays. The effect of transferrin on stellate cell activation was assessed using western blot analysis for alpha-smooth muscle actin expression, [(3)H]Thymidine incorporation, and real-time RT-PCR for procollagen alpha1(I) mRNA expression. A specific receptor for rat transferrin was observed on activated but not quiescent stellate cells. Transferrin significantly increased the expression of alpha-smooth muscle actin, but caused a decrease in proliferation. Transferrin induced a significant increase in procollagen alpha1(I) mRNA expression. In conclusion, this study has demonstrated for the first time a specific, high affinity receptor for rat transferrin on activated hepatic stellate cells, which via interaction with transferrin regulates stellate cell activation. This suggests that transferrin may be an important factor in the activation of hepatic stellate cells in conditions of iron overload.
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PMID:Identification and characterization of the hepatic stellate cell transferrin receptor. 1270 50

The absence of complement receptor 1 (CR1) related gene/protein y (Crry) leads to embryonic lethality as a result of unrestricted complement activation and concomitant neutrophil infiltration. Here we used Crry(-/-)C3(+/-) mice to investigate the role of Crry in the pathogenesis of immune complex glomerulonephritis (GN). After 3 weeks of immunization with horse spleen apoferritin, six of nine Crry(-/-) C3(+/-) mice and none of the six control C3(+/-) mice developed proliferative GN (P = 0.010). After 5 weeks of immunization, GN scores in Crry(-/-) C3(+/-) mice were 0.67 +/- 0.22 mean +/- standard error of the mean (SEM), compared with 0.32 +/- 0.16 in C3(+/-) mice. Glomerular hypercellularity was attributable to neutrophil infiltration in mice with GN (1.7 +/- 0.3/glomerulus) compared with those without GN (0.4 +/- 0.1/glomerulus) (P = 0.001). Absent staining for alpha-smooth muscle actin and proliferating cell nuclear antigen suggested that mesangial cell proliferation did not play a significant role in this model. Serum C3 levels in Crry(-/-) C3(+/-) mice were approximately 20% and 30% those of wild-type mice and C3(+/-) mice, respectively. To determine whether this acquired hypocomplementaemia was relevant to this GN model system, Crry(-/-) C3(+/-) mouse kidneys were transplanted into wild-type mice followed by immunization with apoferritin for 1 or 2 weeks. Surprisingly, none of the Crry(-/-) C3(+/-) mouse kidneys developed GN at these early time-points, indicating that increasing circulating C3 levels several-fold did not increase susceptibility to GN. Renal expression of decay-accelerating factor was not different among any of the groups studied. Thus, our data indicate that mesangial cell Crry limits complement activation and subsequent neutrophil recruitment in the setting of local immune complex deposition.
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PMID:Mesangial cell complement receptor 1-related protein y limits complement-dependent neutrophil accumulation in immune complex glomerulonephritis. 1974 Mar 50