Gene deletion of Interleukin-1α reduces ER stress-induced CHOP expression in macrophages and attenuates the progression of atherosclerosis in apoE-deficient mice.

The pathophysiology of atherosclerosis initiation and progression involves many inflammatory cytokines, one of them is interleukin (IL)-1α that has been shown to be secreted by activated macrophages. We have previously shown that IL-1α from bone marrow-derived cells is critical for early atherosclerosis development in mice. It is known that endoplasmic reticulum (ER) stress in macrophages is involved in progression to more advanced atherosclerosis, but it is still unknown whether this effect is mediated through cytokine activation or secretion. We previously demonstrated that IL-1α is required in ER stress-induced activation of inflammatory cytokines in hepatocytes and in the associated induction of steatohepatitis. In the current study, we aimed to examine the potential role of IL-1α in ER stress-induced activation of macrophages, which is relevant to progression of atherosclerosis. First, we demonstrated that IL-1α is required for atherosclerosis development and progression in the apoE knockout (KO) mouse model of atherosclerosis. Next, we showed that ER stress in mouse macrophages results in the protein production and secretion of IL-1α in a dose-dependent manner, and that IL-1α is required in ER stress-induced production of the C/EBP homologous protein (CHOP), a critical step in ER stress-mediated apoptosis. We further demonstrated that IL-1α-dependent CHOP production in macrophages is specifically mediated through the PERK-ATF4 signaling pathway. Altogether, these findings highlight IL-1α as a potential target for prevention and treatment of atherosclerotic cardiovascular disease.

ß-Carotene from the Alga Dunaliella bardawil Decreases Gene Expression of Adipose Tissue Macrophage Recruitment Markers and Plasma Lipid Concentrations in Mice Fed a High-Fat Diet.

Vitamin A and provitamin A carotenoids are involved in the regulation of adipose tissue metabolism and inflammation. We examined the effect of dietary supplementation using all-trans and 9-cis ß-carotene-rich Dunaliella bardawil alga as the sole source of vitamin A on obesity-associated comorbidities and adipose tissue dysfunction in a diet-induced obesity mouse model. Three-week-old male mice (C57BL/6) were randomly allocated into two groups and fed a high-fat, vitamin A-deficient diet supplemented with either vitamin A (HFD) or ß-carotene (BC) (HFD-BC). Vitamin A levels in the liver, WATs, and BAT of the HFD-BC group were 1.5-2.4-fold higher than of the HFD group. BC concentrations were 5-6-fold greater in BAT compared to WAT in the HFD-BC group. The eWAT mRNA levels of the Mcp-1 and Cd68 were 1.6- and 2.1-fold lower, respectively, and the plasma cholesterol and triglyceride concentrations were 30% and 28% lower in the HFD-BC group compared with the HFD group. Dietary BC can be the exclusive vitamin A source in mice fed a high-fat diet, as shown by the vitamin A concentration in the plasma and tissues. Feeding BC rather than vitamin A reduces adipose tissue macrophage recruitment markers and plasma lipid concentrations.

Interleukin-1α dependent survival of cardiac fibroblasts is associated with StAR/STARD1 expression and improved cardiac remodeling and function after myocardial infarction.

AIMS: One unaddressed aspect of healing after myocardial infarction (MI) is how non-myocyte cells that survived the ischemic injury, keep withstanding additional cellular damage by stress forms typically arising during the post-infarction inflammation. Here we aimed to determine if cell survival is conferred by expression of a mitochondrial protein novel to the cardiac proteome, known as steroidogenic acute regulatory protein, (StAR/STARD1). Further studies aimed to unravel the regulation and role of the non-steroidogenic cardiac StAR after MI. METHODS AND RESULTS: Following permanent ligation of the left anterior descending coronary artery in mouse heart, timeline western blot analyses showed that StAR expression corresponds to the inflammatory response to MI. Following the identification of StAR in mitochondria of cardiac fibroblasts in culture, confocal microscopy immunohistochemistry (IHC) identified StAR expression in left ventricular (LV) activated interstitial fibroblasts, adventitial fibroblasts and endothelial cells. Further work with the primary fibroblasts model revealed that interleukin-1α (IL-1α) signaling via NF-κB and p38 MAPK pathways efficiently upregulates the expression of the Star gene products. At the functional level, IL-1α primed fibroblasts were protected against apoptosis when exposed to cisplatin mimicry of in vivo apoptotic stress; yet, the protective impact of IL-1α was lost upon siRNA mediated StAR downregulation. At the physiological level, StAR expression was nullified during post-MI inflammation in a mouse model with global IL-1α deficiency, concomitantly resulting in a 4-fold elevation of apoptotic fibroblasts. Serial echocardiography and IHC studies of mice examined 24 days after MI revealed aggravation of LV dysfunction, LV dilatation, anterior wall thinning and adverse tissue remodeling when compared with loxP control hearts. CONCLUSIONS: This study calls attention to overlooked aspects of cellular responses evolved under the stress conditions associated with the default inflammatory response to MI. Our observations suggest that LV IL-1α is cardioprotective, and at least one mechanism of this action is mediated by induction of StAR expression in border zone fibroblasts, which renders them apoptosis resistant. This acquired survival feature also has long-term ramifications on the heart recovery by diminishing adverse remodeling and improving the heart function after MI.

Addition of fish oil to atherogenic high fat diet inhibited atherogenesis while olive oil did not, in LDL receptor KO mice.

BACKGROUND AND AIMS: Mediterranean diet has been associated with decreased cardiovascular morbidity and mortality. Both fish and olive oil are key components of this diet. Therefore, we compared their effects on nonalcoholic fatty liver disease (NAFLD) and atherogenesis in a mouse model, fed a high fat diet. METHODS AND RESULTS: Forty nine, female LDL receptor knockout (LDLR KO) mice were allocated into 3 groups and fed an atherogenic high fat (HF) diet for 9 weeks. The HF group was fed a high fat diet alone. A HF + OO group was fed a HF diet with added olive oil (60 ml/kg feed), and the third group (HF + FO) was fed a HF diet with added fish oil (60 ml/kg feed). Both additions of fish and olive oil, significantly decreased plasma cholesterol elevation compared to HF diet. Nevertheless, only fish oil addition reduced significantly atherosclerotic lesion area by 51% compared to HF group. Liver levels of eicosapentenoic (EPA) and docosahexaenoic (DHA) acids were several folds higher in HF + FO group than in HF and HF + OO groups. Liver levels of oleic acid were higher in HF + OO compared to the other groups. Moreover, Fish oil addition significantly decreased NAFLD scores related to steatosis and inflammation and lowered the expression of the inflammatory genes interleukin 6 (IL6) and monocyte chemoattractant protein 1 (MCP1). CONCLUSION: These results suggest that fish oil addition on top of an atherogenic, HF diet, is beneficial, while olive oil is not, in its effect on plaque formation and NAFLD in LDLR KO mice.

Interleukin-1 deficiency prolongs ovarian lifespan in mice.

Oocyte endowment dwindles away during prepubertal and adult life until menopause occurs, and apoptosis has been identified as a central mechanism responsible for oocyte elimination. A few recent reports suggest that uncontrolled inflammation may adversely affect ovarian reserve. We tested the possible role of the proinflammatory cytokine IL-1 in the age-related exhaustion of ovarian reserve using IL-1α and IL-1ß-KO mice. IL-1α-KO mice showed a substantially higher pregnancy rate and litter size compared with WT mice at advanced age. The number of secondary and antral follicles was significantly higher in 2.5-mo-old IL-1α-KO ovaries compared with WT ovaries. Serum anti-Müllerian hormone, a putative marker of ovarian reserve, was markedly higher in IL-1α-KO mice from 2.5 mo onward, along with a greater ovarian response to gonadotropins. IL-1ß-KO mice displayed a comparable but more subtle prolongation of ovarian lifespan compared with IL-1α-KO mice. The protein and mRNA of both IL-1α and IL-1ß mice were localized within the developing follicles (oocytes and granulosa cells), and their ovarian mRNA levels increased with age. Molecular analysis revealed decreased apoptotic signaling [higher B-cell lymphoma 2 (BCL-2) and lower BCL-2-associated X protein levels], along with a marked attenuation in the expression of genes coding for the proinflammatory cytokines IL-1ß, IL-6, and TNF-α in ovaries of IL-1α-KO mice compared with WT mice. Taken together, IL-1 emerges as an important participant in the age-related exhaustion of ovarian reserve in mice, possibly by enhancing the expression of inflammatory genes and promoting apoptotic pathways.

Interleukin-1α deficiency attenuates endoplasmic reticulum stress-induced liver damage and CHOP expression in mice.

BACKGROUND & AIMS: ER stress promotes liver fat accumulation and induction of inflammatory cytokines, which contribute to the development of steatohepatitis. Unresolved ER stress upregulates the pro-apoptotic CHOP. IL-1α is localized to the nucleus in apoptotic cells, but is released when these cells become necrotic and induce sterile inflammation. We investigated whether IL-1α is involved in ER stress-induced apoptosis and steatohepatitis. METHODS: We employed WT and IL-1α-deficient mice to study the role of IL-1α in ER stress-induced steatohepatitis. RESULTS: Liver CHOP mRNA was induced in a time dependent fashion in the atherogenic diet-induced steatohepatitis model, and was twofold lower in IL-1α deficient compared to WT mice. In the ER stress-driven steatohepatitis model, IL-1α deficiency decreased the elevation in serum ALT levels, the number of apoptotic cells (measured as caspase-3-positive hepatocytes), and the expression of IL-1ß, IL-6, TNFα, and CHOP, with no effect on the degree of fatty liver formation. IL-1α was upregulated in ER-stressed-macrophages and the protein was localized to the nucleus. IL-1ß mRNA and CHOP mRNA and protein levels were lower in ER-stressed-macrophages from IL-1α deficient compared to WT mice. ER stress induced the expression of IL-1α and IL-1ß also in mouse primary hepatocytes. Recombinant IL-1α treatment in hepatocytes did not affect CHOP expression but upregulated both IL-1α and IL-1ß mRNA levels. CONCLUSION: We show that IL-1α is upregulated in response to ER stress and IL-1α deficiency reduces ER stress-induced CHOP expression, apoptosis and steatohepatitis. As a dual function cytokine, IL-1α may contribute to the induction of CHOP intracellularly, while IL-1α released from necrotic cells accelerates steatohepatitis via induction of inflammatory cytokines by neighboring cells.

Knockdown of interleukin-1α does not attenuate LPS-induced production of interleukin-1ß in mouse macrophages.

IL-1α and IL-1ß are synthesized as 31kDa cell-associated precursors following TLR-4 stimulation, but their processing to the mature form and secretion require a second intracellular stimulus. The unique localization of the precursor of IL-1α (pro-IL-1α) to the nucleus suggested a role in transcriptional regulation of inflammatory cytokines. We explored the hypothesis that pro-IL-1α is involved in regulation of IL-1ß expression following TLR-4 stimulation. IL-1ß mRNA and protein levels were specifically decreased in macrophages from IL-1α-deficient mice following TLR-1/2, TLR-4 or TLR-9 stimulation, supporting the hypothesis. However, activation of the main upstream regulators of IL-1ß expression, IRF3, NFkB and p38/JNK, were not reduced in macrophages from IL-1α-deficient mice. In order to assess the specific role of IL-1α in macrophages, we generated mice with myeloid cell deficiency of IL-1α (LyzMCre-loxp). Despite over 90% knockdown of IL-1α, TLR-4 stimulated macrophages from LyzMCre-loxp mice did not produce lower levels of IL-1ß compared to IL-1α-loxp-flanked mice. In order to overcome the possibility that effects are caused by the incomplete deficiency of IL-1α, we generated new whole-body IL-1α knockout mice (GeneralCre-IL-1α) and the findings were similar to myeloid cell-deficient IL-1α. Collectively, our findings do not support the previously suggested role of nuclear IL-1α in gene regulation of IL-1ß. Rather, they suggest that IL-1α acts mainly as an alarmin that is sequestered in the nucleus following stimulation with TLR-4.

Lack of interleukin-1α or interleukin-1ß inhibits transformation of steatosis to steatohepatitis and liver fibrosis in hypercholesterolemic mice.

BACKGROUND & AIMS: The identification of the cellular and molecular pathways that mediate the development of non-alcoholic steatohepatitis is of crucial importance. Cytokines produced by liver-resident and infiltrating inflammatory cells, play a pivotal role in liver inflammation. The role of the proinflammatory cytokines IL-1α and IL-1ß in steatohepatitis remains elusive. METHODS: We employed IL-1α and IL-1ß-deficient mice and transplanted marrow cells to study the role of liver-resident and bone marrow-derived IL-1 in steatosis and its progression to steatohepatitis. RESULTS: Atherogenic diet-induced steatohepatitis in wild-type mice was associated with 16 and 4.6 fold-elevations in mRNA levels of hepatic IL-1α and IL-1ß, respectively. In mice deficient in either IL-1α or IL-1ß the transformation of steatosis to steatohepatitis and liver fibrosis was markedly reduced. This protective effect in IL-1α-deficient mice was noted despite increased liver cholesterol levels. Deficiency of IL-1α markedly reduced plasma serum amyloid A and steady-state levels of mRNA coding for inflammatory genes (P-selectin, CXCL1, IL-6, and TNFα) as well as pro-fibrotic genes (MMP-9 and Collagen) and particularly a 50% decrease in TGFß levels (p = 0.004). IL-1α mRNA levels were two-folds lower in IL-1ß-deficient mice, and IL-1ß transcripts were three-folds lower in IL-1α-deficient compared to wild-type mice. Hepatic cell derived IL-1α rather than from recruited bone marrow-derived cells was required for steatohepatitis development. CONCLUSIONS: These data demonstrate the critical role of IL-1α and IL-1ß in the transformation of steatosis to steatohepatitis and liver fibrosis in hypercholesterolemic mice. Therefore, the potential of neutralizing IL-1α and/or IL-1ß to inhibit the development of steatohepatitis should be explored.

Dietary alpha linolenic acid in pregnant mice and during weaning increases brain docosahexaenoic acid and improves recognition memory in the offspring.

Docosahexaenoic acid (DHA) is critical for normal brain development and function. DHA is in danger of being significantly reduced in the human food supply, and the question of whether its metabolic precursor, the essential n-3 alpha linolenic acid (ALA) during pregnancy, can support fetal brain DHA levels for optimal neurodevelopment, is fundamental. Female mice were fed either ALA-enriched or Control diet during pregnancy and lactation. The direct effect of maternal dietary ALA on lipids was analyzed in liver, red blood cells, brain and brain vasculature, together with genes of fatty acid metabolism and transport in three-week-old offspring. The long-term effect of maternal dietary ALA on brain fatty acids and memory was studied in 19-week-old offspring. Three-week-old ALA offspring showed higher levels of n-3 fatty acids in liver, red blood cell, blood-brain barrier (BBB) vasculature and brain parenchyma, DHA enrichment in brain phospholipids and higher gene and protein expression of the DHA transporter, major facilitator superfamily domain containing 2a, compared to Controls. 19-week-old ALA offspring showed higher brain DHA levels and better memory performance than Controls. The increased brain DHA levels induced by maternal dietary ALA during pregnancy-lactation, together with the up-regulated levels of major facilitator superfamily domain containing 2a, may indicate a mode for greater DHA uptake with long-term impact on better memory in ALA offspring.

Blood fatty acid analysis reveals similar n-3 fatty acid composition in non-pregnant and pregnant women and their neonates in an Israeli pilot study.

Maternal docosahexaenoic acid (DHA) is required during pregnancy to supply for normal fetal growth and development. This pilot study aimed to assess the unknown fatty acid (FA) composition in a cohort of non-pregnant and pregnant Israeli women at term and their offspring on a normal diet without n-3 FA supplementation. The fatty acid profile, analyzed using gas chromatography, showed significantly higher plasma monounsaturated (MUFA) and lower n-6 FA percent distribution with similar n-3 index, in pregnant compared to non-pregnant women. RBC exhibited significantly higher MUFA with similar n-3 index, in pregnant compared to non-pregnant women. N-3 FA significantly correlated between neonates' plasma, with higher n-3 index, and pregnant women's DHA. Conclusion: DHA levels in non-pregnant and pregnant Israeli women at term were comparable and the DHA in pregnant women's plasma positively correlated with their neonate's level, suggesting an efficient mother-fetus FA transfer and/or fetal fatty acid metabolism to longer FA products.

IFNγ potentiates TNFα/TNFR1 signaling to induce FAT10 expression in macrophages.

INTRODUCTION: The tight regulation of the cytokine network during macrophage activation is of prime importance to enable a fast and potent innate immune response against exogenous pathogens. The inflammation mediating ubiquitin-like protein HLA-F adjacent transcript number 10 (FAT10) was shown to be transcriptionally regulated by and also regulate the nuclear factor-κB (NFκB) signaling pathway. However, very little is known about the regulation of FAT10 gene expression during macrophage activation. RESULTS: RNA sequencing of interferon (IFN)γ-stimulated mouse peritoneal macrophages analyzed by ingenuity pathway analysis revealed significant involvement of tumor necrosis factor receptor 1 (TNFR1) signaling in addition to IFNγ signaling. Subsequently, IFNγ robustly upregulated FAT10 expression compared to a milder induction seen with TNFα or lipopolysaccharide (LPS) stimulation. While low dose IFNγ with TNFα synergistically elevated FAT10 expression, preincubation of macrophages with IFNγ strongly augmented TNFα-induced FAT10 expression. Moreover, a short preincubation with IFNγ, which did not elevate FAT10, was sufficient to potentiate the induction of FAT10 by TNFα. A double augmentation mechanism of TNFα signaling was demonstrated, where IFNγ rapidly induced the expression of TNFα and TNFR1, which further augmented the induction of TNFα and TNFR1 expression by TNFα. Importantly, the induction of FAT10 by IFNγ in macrophages from TNFα-deficient or TNFR1-deficient mice was completely inhibited compared to macrophages from wild type (WT) mice. Finally, we show that TNFα-induced FAT10 expression is dependent on NFκB signaling. CONCLUSION: IFNγ potentiates the TNFα/TNFR1 signaling pathway to induce FAT10 expression in mouse macrophages, mediated through NFκB network.

Dietary ß-Carotene Rescues Vitamin A Deficiency and Inhibits Atherogenesis in Apolipoprotein E-Deficient Mice.

Vitamin A deficiency (VAD) is a major health problem, especially in developing countries. In this study, we investigated the effect of VAD from weaning to adulthood in apoE-/- mice. Three-week-old male mice were allocated into four diet groups: I. VAD II. VAD+vitamin A (VA), 1500 IU retinyl-palmitate; III. VAD+ß-carotene (BC), 6 g/kg feed, containing 50% all-trans and 50% 9-cis BC. IV. VAD with BC and VA (BC+VA). After 13 weeks, we assessed the size of atherosclerotic plaques and measured VA in tissues and BC in plasma and tissues. VAD resulted in diminished hepatic VA levels and undetectable brain VA levels compared to the other groups. BC completely replenished VA levels in the liver, and BC+VA led to a two-fold elevation of hepatic VA accumulation. In adipose tissue, mice fed BC+VA accumulated only 13% BC compared to mice fed BC alone. Atherosclerotic lesion area of BC group was 73% lower compared to VAD group (p < 0.05). These results suggest that BC can be a sole source for VA and inhibits atherogenesis.

Interleukin-1α deficiency reduces adiposity, glucose intolerance and hepatic de-novo lipogenesis in diet-induced obese mice.

Objective: While extensive research revealed that interleukin (IL)-1ß contributes to insulin resistance (IR) development, the role of IL-1α in obesity and IR was scarcely studied. Using control, whole body IL-1α knockout (KO) or myeloid-cell-specific IL-1α-deficient mice, we tested the hypothesis that IL-1α deficiency would protect against high-fat diet (HFD)-induced obesity and its metabolic consequences. Research design and methods: To induce obesity and IR, control and IL-1α KO mice were given either chow or HFD for 16 weeks. Glucose tolerance test was performed at 10 and 15 weeks, representing early and progressive stages of glucose intolerance, respectively. Liver and epididymal white adipose tissue (eWAT) samples were analyzed for general morphology and adipocyte size. Plasma levels of adiponectin, insulin, total cholesterol and triglyceride (TG), lipoprotein profile as well as hepatic lipids were analyzed. Expression of lipid and inflammation-related genes in liver and eWAT was analyzed. Primary mouse hepatocytes isolated from control mice were treated either with dimethyl sulfoxide (DMSO) (control) or 20 ng/mL recombinant IL-1α for 24 hours and subjected to gene expression analysis. Results: Although total body weight gain was similar, IL-1α KO mice showed reduced adiposity and were completely protected from HFD-induced glucose intolerance. In addition, plasma total cholesterol and TG levels were lower and HFD-induced accumulation of liver TGs was completely inhibited in IL-1α KO compared with control mice. Expression of stearoyl-CoA desaturase1 (SCD1), fatty acid synthase (FASN), elongation of long-chain fatty acids family member 6 (ELOVL6), acetyl-CoA carboxylase (ACC), key enzymes that promote de-novo lipogenesis, was lower in livers of IL-1α KO mice. Treatment with recombinant IL-1α elevated the expression of ELOVL6 and FASN in mouse primary hepatocytes. Finally, mice with myeloid-cell-specific deletion of IL-1α did not show reduced adiposity and improved glucose tolerance. Conclusions: We demonstrate a novel role of IL-1α in promoting adiposity, obesity-induced glucose intolerance and liver TG accumulation and suggest that IL-1α blockade could be used for treatment of obesity and its metabolic consequences.

Lack of interleukin-1α in Kupffer cells attenuates liver inflammation and expression of inflammatory cytokines in hypercholesterolaemic mice.

BACKGROUND: The role of Kupffer cell interleukin (IL)-1 in non-alcoholic steatohepatitis development remains unclear. AIMS: To evaluate the role of Kupffer cell IL-1α, IL-1ß or IL-1 receptor type-1 (IL-1R1) in steatohepatitis. METHODS: C57BL/6 mice were irradiated and transplanted with bone marrow-derived cells from WT, IL-1α-/-, IL-1ß-/- or IL-1R1-/- mice combined with Kupffer cell ablation with Gadolinium Chloride, and fed atherogenic diet. Plasma and liver triglycerides and cholesterol, serum alanine aminotransferase (ALT), liver histology and expression levels of inflammatory genes were assessed. RESULTS: The ablation and replacement of Kupffer cells with bone marrow-derived cells was confirmed. The atherogenic diet elevated plasma and liver cholesterol, reduced plasma and liver triglycerides and increased serum ALT levels in all groups. Steatosis and steatohepatitis were induced, but without liver fibrosis. A reduction in the severity of portal inflammation was observed only in mice with Kupffer cell deficiency of IL-1α. Accordingly, liver mRNA levels of inflammatory genes encoding for IL-1α, IL-1ß, TNFα, SAA1 and IL-6 were significantly lower in mice with Kupffer cell deficiency of IL-1α compared to WT mice. CONCLUSION: Selective deficiency of IL-1α in Kupffer cells reduces liver inflammation and expression of inflammatory cytokines, which may implicate Kupffer cell-derived IL-1α in steatohepatitis development.

Interleukin-1 receptor type-1 in non-hematopoietic cells is the target for the pro-atherogenic effects of interleukin-1 in apoE-deficient mice.

OBJECTIVES: Interleukin (IL)-1 produced by vascular and bone marrow-derived cells exerts proinflammatory effects in these cell types by binding to IL-1 receptor type-1 (IL-1R1). We have previously shown that bone marrow-derived IL-1α and IL-1ß are critical for atherogenesis in apoE knockout (KO) mice. The aim of the present study was to investigate whether IL-1R1 on vascular wall resident or bone marrow-derived cells mediates IL-1's effects in atherogenesis. METHODS AND RESULTS: We generated apoE-/-/IL-1R1-/- double knockout (DKO) mice and created radiation chimeras. Aortic sinus lesion area was 20-47% lower in DKO compared to apoE KO mice with similar plasma lipids. The production of IL-1α and IL-1ß upon stimulation with LPS was not altered in IL-1R1-/- compared to IL-1R1+/+ peritoneal macrophages. DKO mice transplanted with IL-1R1+/+ bone marrow-derived cells had reduced (48%) aortic sinus lesion compared to apoE KO mice while specific deficiency of IL-1R1 in bone marrow-derived cells did not attenuate atherosclerosis. The mRNA levels of genes that promote macrophage recruitment to the vascular wall, namely CD68, VCAM-1, ICAM-1 and MCP-1 were lower in aortas from DKO compared to apoE KO mice. Finally, blockade of IL-1R1 with IL-1R antagonist (IL-1Ra) resulted in complete abrogation of IL-1ß-induced expression of adhesion and chemotactic molecules and IL-1α, in isolated human umbilical vein endothelial cells (HUVEC). CONCLUSIONS: Vascular wall resident cells are the main targets for the pro-atherogenic effects of bone marrow-derived IL-1 through IL-1R1, partly by induction of adhesion and chemotactic molecules in endothelial cells.

Evidence for intracellular spatial separation of hexokinases and fructokinases in tomato plants.

Four hexokinase (LeHXK1-4) and four fructokinase (LeFRK1-4) genes were identified in tomato plants. Previous GFP fusion studies indicate that the gene product of LeHXK3 is associated with the mitochondria while that of LeHXK4 is located within plastids. In this study we found that the enzyme encoded by the fructokinase gene LeFRK3 is also located within plastids. The presence of LeFrk3 enzyme in plastids raises the question of the origin of fructose in these organelles. The other three FRKs enzymes, LeFrk1&2&4, are located in the cytosol. Unlike LeFrk1&2&4, the two additional HXKs, LeHxk1&2, share a common membrane anchor domain and are associated with the mitochondria similar to LeHxk3. The difference in the locations of the cytoplasmic FRK and HXK isozymes suggests that glucose phosphorylation is confined to defined special intracellular localizations while fructose phosphorylation is less confined.