Ovariectomy and estrogen treatment modulate iron metabolism in rat adipose tissue

Abstract

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Page 1 of 30A c c e p t e d M a n u s c r i p Graphical AbstractPage 2 of 30 A c c e p t e d M a n u s c r i p t E-mail address: rsantama@unina.it (R. Santamaria). * ManuscriptPage 3 of 30 A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 ABSTRACTIron is essential for many biological processes and its deficiency or excess is involved in pathological conditions. At cellular level, the maintenance of iron homeostasis is largely accomplished by the transferrin receptor (TfR)-1 and by ferritin, whose expression is mainly regulated post-transcriptionally by Iron Regulatory Proteins (IRPs).This study examines the hypothesis that modification of serum estrogen levels by ovariectomy and 17β-estradiol (E 2 ) treatment in rats modulate serum iron-status parameters and iron metabolism in adipose tissue. In particular, we evaluated the RNA binding of IRP1 by electrophoretic mobility shift assay and IRP1, ferritin, and TfR-1 expression in adipose tissue by Western blot analysis.Ovariectomy, besides a lowered serum iron and transferrin iron binding capacity, remarkably decreased the binding activity of IRP1 in peritoneal and subcutaneous adipose tissues, and these effects were reversed by E 2 treatment. Moreover, ovariectomy determined a decrease of IRP1 expression, which was significant in subcutaneous adipose tissue. Consistent with IRP1 regulation, an increase of ferritin and a decrease of TfR-1 expression were observed in peritoneal adipose tissue from ovariectomized animals, while the treatment with E 2 reconstituted TfR-1 level. A similar expression profile of TfR-1 was observed in subcutaneous adipose tissue, where ferritin level did not change in ovariectomized animals, and was increased after E 2 treatment.Our results indicate that estrogen level changes can regulate the binding activity of the IRP1, and consequently ferritin and TfR-1 expression in adipose tissue, suggesting a relationship among serum and tissue iron parameters, estrogen status and adiposity.

Estrogen-Dependent Downregulation of Hepcidin Synthesis Induces Intracellular Iron Efflux in Cancer Cells In Vitro

“…These findings are consistent with previous reports, which have shown that E2 downregulates hepcidin synthesis and increases systemic iron availability [9][10][11][12][13][14][15][16]. The ability of E2 to perturb iron homeostasis was more evident at high doses (Figures 1,3,4,5 and 6), which is consistent with the observation that elevated, rather than physiologic, levels of E2 associate with increased systemic iron availability [9][10][11][12][13][14][15][16]42]. As reported previously [12], E2-driven changes in iron status relates to the need to compensate for E2-triggered iron loss though menstruation and E2-dependent pregnancy in premenopausal women.…”

“…In that, while ovariectomy in mammals results in decreased serum iron [9], use of oral contraceptives [10] and treatment of ovariectomized mice with E2 [11,12] results in increased serum iron levels [13]. The expression of several genes involved in iron metabolism including lactotransferrin, ceruloplasmin ferroxidase, lipocalin 2 and ferroportin [12] upregulate during uterine growth and differentiation.…”

Estrogen regulates iron homeostasis through governing hepatic hepcidin expression via an estrogen response element

“…1A). Consistent with previous studies (Mattace Raso et al, 2009;Thompson et al, 1995), the OVX mice developed greater body weight than the Sham control mice (p b 0.05, Fig. 1B).…”

“…2A, the level of serum iron was reduced by 14.0% in the OVX group compared to the Sham group. This observation was similar to the study performed on rats, as the OVX rats had reduced serum iron and estradiol treatment could reverse this situation (Mattace Raso et al, 2009). The hepatic and splenic iron levels were increased by 26.0% and 9.5%, respectively, in the OVX mice compared to the control ( Fig.…”

“…For example, most studies in evaluating the ovariectomized models for postmenopausal osteoporosis are performed over 1 month after ovariectomy (G. Liu et al, 2006Liu et al, , 2008Sottile et al, 2004;Thompson et al, 1995). Considering iron metabolism upon certain chronic physiological alternation, the end-point of iron-related studies are normally set over 1 month after ovariectomy when using ovariectomized models (Ikeda et al, 2012;Liu et al, 2006;Mattace Raso et al, 2009). Moreover, a previous study by Ramos et al has demonstrated that hepcidin expression were distinct in response to long-term (3 weeks) or acute (1 day) iron loading (Ramos et al, 2011).…”