Developmental gene expression of lactoferrin and effect of dietary iron on gene regulation of lactoferrin in mouse mammary gland

Distribution of Lactoferrin Is Related with Dynamics of Neutrophils in Bacterial Infected Mice Intestine

Lactoferrin (Lf) is a conserved iron-binding glycoprotein with antimicrobial activity, which is present in secretions that recover mucosal sites regarded as portals of invaded pathogens. Although numerous studies have focused on exogenous Lf, little is known about its expression of endogenous Lf upon bacterial infection. In this study, we investigated the distribution of Lf in mice intestine during Escherichia coli (E. coli) K88 infection. PCR and immunohistology staining showed that mRNA levels of Lf significantly increased in duodenum, ileum and colon, but extremely decreased in jejunum at 8 h and 24 h after infection. Meanwhile, endogenous Lf was mostly located in the lamina propria of intestine villi, while Lf receptor (LfR) was in the crypts. It suggested that endogenous Lf-LfR interaction might not be implicated in the antibacterial process. In addition, it was interesting to find that the infiltration of neutrophils into intestine tissues was changed similarly to Lf expression. It indicated that the variations of Lf expression were rather due to an equilibrium between the recruitment of neutrophils and degranulation of activated neutrophils. Thus, this new knowledge will pave the way to a more effective understanding of the role of Lf in intestinal mucosal immunity.

Two faces of the estrogen metabolite 2-methoxyestradiol in vitro and in vivo

2-Methoxyestradiol (2-ME), an endogenous metabolite of 17β-estradiol (E2), interacts with estrogen receptors (ERs) and microtubules, however, 2-ME has a low affinity for ERs. Furthermore, 2‑ME has been identified as a potential novel antitumor agent, combining its anti‑proliferative effects on a variety of tumor cell types with its anti‑angiogenic action. Therefore, 2‑ME is of interest due to its potential anticancer therapeutic effects. In the current study, the estrogenic effect of 2‑ME on CaBP‑9k, ERα, and progesterone receptor (PR) mRNA levels in the absence and presence of E2 and progesterone (P4) in in vivo and in vitro models was examined. In GH3 cells, the mRNA level of CaBP‑9k was induced in the E2 treatment group (concentration, 10‑9 M), and the expression of CaBP‑9k was also upregulated in the 2‑ME‑treated group (concentration, 10‑7 M). Uterine lactoferrin (Ltf) mRNA expression was also increased in the 2‑ME group [dose, 40 mg/kg body weight (BW)], which was comparable to the response with E2 (dose, 40 µg/kg BW) observed in mice. As inhibitors of ER and PR activity, ICI 182,780 and mifepristone (RU486) were observed to reverse the E2 or 2‑ME mediated increase of CaBP‑9k and Ltf mRNA expression. In addition, it was found that 2‑ME significantly decreased the levels of ERα and increased PR transcripts. Consistent with the in vitro results, the mRNA levels revealed decreased ERα and increased PR in in vivo treatment of E2 and 2‑ME. These findings demonstrate that the expression of estrogenic markers, CaBP‑9k and Ltf, is regulated by 2‑ME in in vitro and in vivo models, therefore, estrogenic activi-ties of 2-ME may be increased in females during the estrous cycle via the ER and/or PR-mediated signaling pathway.

Iron administration reduces airway hyperreactivity and eosinophilia in a mouse model of allergic asthma

The prevalence of allergic diseases has increased dramatically during the last four decades and is paralleled by a striking increase in iron intake by infants in affluent societies. Several studies have suggested a link between increased iron intake and the marked increase in prevalence of allergic diseases. We hypothesized that the increased iron intake by infants offers an explanation for the increased prevalence of allergic disease in industrialized societies during the past four decades. A well-established mouse model of ovalbumin (OVA)-driven allergic asthma was used to test the effects of differences in iron intake and systemic iron levels on the manifestations of allergic asthma. Surprisingly, iron supplementation resulted in a significant decrease in airway eosinophilia, while systemic iron injections lead to a significant suppression of both allergen-induced airway eosinophilia and hyperreactivity compared to placebo. In contrast, mice fed on an iron-deprived diet did not show any difference in developing experimentally induced allergic asthma when compared to those fed on an iron-sufficient control diet. In contrast to our hypothesis, airway manifestations of allergic asthma are suppressed by both increased levels of iron intake and systemic iron administrations in the mouse model.

miR-214 regulates lactoferrin expression and pro-apoptotic function in mammary epithelial cells

Lactoferrin (Lf) is an abundantly expressed protein in human milk. Lactoferrin exhibits several important biological functions, and its expression is regulated by multiple environmental factors. Cellular endogenous factors, however, have not been extensively studied with regard to lactoferrin gene expression. In this study, we showed that lactoferrin gene expression and function are directly targeted by miR-214 in HC11 and MCF7 cells. In the lactoferrin mRNA 3 prime untranslated region (UTR) of human, mouse, rat, pig, bovine, camel, and goat species, there is a conserved region that perfectly matches the seed region of miR-214. Transfection of miR-214 mimic in HEK293 cells dose-dependently inhibited the activity of pGL3-control vector containing lactoferrin mRNA 3 prime UTR downstream of the luciferase gene. In HC11 cells, miR-214 overexpression inhibited the induction of lactoferrin expression by beta -estradiol (E2) and dexamethasone-prolactin-insulin (DPI). Furthermore, in MCF7 cells, overexpression of miR-214 markedly decreased lactoferrin expression (P lt 0.05), and inhibition of endogenous miR-214 expression increased lactoferrin expression and cellular apoptotic activities (P lt 0.05). In summary, our data showed that miR-214 is directly involved in lactoferrin expression and lactoferrin mediated cancer susceptibility (proapoptotic activities) in mammary epithelial cells.

Factors regulating lactoferrin gene expressionThis paper is one of a selection of papers published in this Special Issue, entitled 7th International Conference on Lactoferrin: Structure, Function, and Applications, and has undergone the Journal's usual peer review process

Regulation of gene expression by nuclear receptors and transcription factors involves the concerted action of multiple proteins. The process of transcriptional activation involves chromatin modification, nuclear receptor or transcription factor binding to the response element of the promoter, and coregulator recruitment. Despite advances in knowledge pertaining to the molecular mechanisms of gene regulation overall, there is very limited information available on the molecular mechanism of lactoferrin gene regulation. This review will outline novel information relating to general gene regulation and will discuss the current understanding of the regulation of lactoferrin gene expression by nuclear receptors and transcription factors.