LIST OF ABBREVIATIONS (in order cited) chromatin bound NPM1. In fact, as NPM1 expression has been previously shown to be induced by HIF-1 and hypoxia [28], a finding in agreement with our data (see Suppl. Fig. S6A,F), our results also suggest the operation of an ERK-controlled positive feed-forward mechanism, based on amplification of HIF-1 activity following upregulation of NPM1 expression by HIF-1 itself. NPM1 is required for the cellular transcriptional response to hypoxiaTo address the above hypothesis, we performed sequencing of RNA extracted from HeLa cells subjected or not to NPM1 silencing, both under normoxia or hypoxia, or HIF-1α silencing under hypoxia. In cells treated with control siRNAs (Nt), hypoxia heavily affected gene expression, with 1068 genes exhibiting altered mRNA levels (487 downregulated, 581 upregulated) when compared to normoxia (Suppl. Fig. S8A). These genes are mostly involved in transcriptional regulation, response to hypoxia or drugs and control of apoptosis, angiogenesis, cell cycle and metabolism (Suppl. Fig. S8B). Knocking-down NPM1 in normoxic cells resulted in the differential expression of a limited number of genes, 114 in total (68 down-, 46 up-regulated), which are mainly implicated in functions related to the immune response (Fig. 4A left panel; Suppl. Fig. S8C,D) a subset of which (33 genes) were also regulated by HIF-1 (Suppl. Fig. S8C,E). In contrast, when NPM1 silencing was performed in hypoxic cells (Fig. 4A, right panel), it had a profound effect on gene expression with 761 deregulated genes (320 down-, 441 up-regulated), 123 of which were common with the ones affected by the hypoxic shift (Fig. 4B). A similar, strong, effect on differential gene expression was also observed when HIF-1α was silenced under hypoxia with 844 deregulated genes (561 down-, 283 up-regulated) (Fig. 4A, middle panel), 257 of which were common with the ones affected by hypoxia (as compared to normoxia) (Fig. 4B). Analysis of those results revealed a significant number of genes commonly regulated by HIF-1α and NPM1 (130 genes in total, out of which 36 also deregulated during the hypoxic shift) (Fig. 4B). These common genes were involved in processes known to rely on HIF-1 and hypoxia-mediated reprogramming, such as cell adhesion, migration and ECM organization, redox and apoptosis control, metabolism and angiogenesis (Suppl. Fig. S8F). From the 67 genes that were upregulated by hypoxia and repressed by both NPM1 and HIF-1α knockdown (Suppl. Fig. S9), marker genes were selected as typical examples of NPM1/HIF-1α-dependent cellular functions (ALDOC: metabolism, BIRC3: apoptosis, TGFBI: angiogenesis and ECM organization, FA2H: oxidation-reduction), for validation of the RNAsequencing results with RT-PCR. Indeed, expression of ALDOC, BIRC3, TGFBI and FA2H was decreased when either HIF-1α or NPM1 were silenced under hypoxia (Fig. 4C). These data support the notion that NPM1, by stabilizing the interaction between HIF-1 and HRE-containing chromatin, supports the general transcriptional response to hy...

Hepcidin regulates iron metabolism by inhibiting intestinal iron absorption and iron release from iron stores. In addition to iron overload, inflammatory conditions also up-regulate hepcidin synthesis, which may serve as an antimicrobial defense by reducing iron availability to the invading microbes. The purpose of this study is to test this hypothesis in human patients by determining serum hepcidin concentration by enzyme linked immunosorbent assay (ELISA) in healthy blood donors (n = 60) and patients hospitalized because of bacteremia (n = 50), before (day 0) and after seven days (day 7) of appropriate antibiotic treatment. Serum hepcidin was significantly increased in patients with bacteremia, both at day 0 and at day 7, compared to healthy controls. However, there was significant reduction of serum hepcidin after 7-day treatment, in concert with changes in serum C-reactive protein (CRP). The hepcidin changes were similar for both Gram-negative and Gram-positive single infection cases, while CRP was significantly reduced only in the former. In contrast to hepcidin, the levels of serum ferritin in the patients remained high after treatment, irrespective of infection type. These data confirm the stimulation of hepcidin secretion in human subjects upon different types of systemic microbial infection and suggest that hepcidin is a more sensitive and treatment-responsive acute-phase marker than ferritin in bacteremia, which needs to be explored with bigger-sized and better-matched patient cohorts.

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