| 1. |
- Brannmark, Cecilia, et al.
(författare)
-
Adiponectin is secreted via caveolin 1-dependent mechanisms in white adipocytes
- 2020
-
Ingår i: Journal of Endocrinology. - : BIOSCIENTIFICA LTD. - 0022-0795 .- 1479-6805. ; 247:1, s. 25-38
-
Tidskriftsartikel (refereegranskat)abstract
- Here we have investigated the role of the protein caveolin 1 (Cav1) and caveolae in the secretion of the white adipocyte hormone adiponectin. Using mouse primary subcutaneous adipocytes genetically depleted of Cav1, we show that the adiponectin secretion, stimulated either adrenergically or by insulin, is abrogated while basal (unstimulated) release of adiponectin is elevated. Adiponectin secretion is similarly affected in wildtype mouse and human adipocytes where the caveolae structure was chemically disrupted. The altered ex vivo secretion in adipocytes isolated from Cav1 null mice is accompanied by lowered serum levels of the high-molecular weight (HMW) form of adiponectin, whereas the total concentration of adiponectin is unaltered. Interestingly, levels of HMW adiponectin are maintained in adipose tissue from Cav1-depleted mice, signifying that a secretory defect is present. The gene expression of key regulatory proteins known to be involved in cAMP/adrenergically triggered adiponectin exocytosis (the beta-3-adrenergic receptor and exchange protein directly activated by cAMP) remains intact in Cav1 null adipocytes. Microscopy and fractionation studies indicate that adiponectin vesicles do not co-localise with Cav1 but that some vesicles are associated with a specific fraction of caveolae. Our studies propose that Cav1 has an important role in secretion of HMW adiponectin, even though adiponectin-containing vesicles are not obviously associated with this protein. We suggest that Cav1, and/or the caveolae domain, is essential for the organisation of signalling pathways involved in the regulation of HMW adiponectin exocytosis, a function that is disrupted in Cav1/caveolae-depleted adipocytes.
|
|
| 2. |
- Engström, Linda, et al.
(författare)
-
Lipopolysaccharide-Induced Fever Depends on Prostaglandin E2 Production Specifically in Brain Endothelial Cells
- 2012
-
Ingår i: Endocrinology. - : Endocrine Society. - 0013-7227 .- 1945-7170. ; 153:10, s. 4849-4861
-
Tidskriftsartikel (refereegranskat)abstract
- Immune-induced prostaglandin E2 (PGE2) synthesis is critical for fever and other centrally elicited disease symptoms. The production of PGE2 depends on cyclooxygenase-2 and microsomal prostaglandin E synthase-1 (mPGES-1), but the identity of the cells involved has been a matter of controversy. We generated mice expressing mPGES-1 either in cells of hematopoietic or nonhematopoietic origin. Mice lacking mPGES-1 in hematopoietic cells displayed an intact febrile response to lipopolysaccharide, associated with elevated levels of PGE2 in the cerebrospinal fluid. In contrast, mice that expressed mPGES-1 only in hematopoietic cells, although displaying elevated PGE2 levels in plasma but not in the cerebrospinal fluid, showed no febrile response to lipopolysaccharide, thus pointing to the critical role of brain-derived PGE2 for fever. Immunohistochemical stainings showed that induced cyclooxygenase-2 expression in the brain exclusively occurred in endothelial cells, and quantitative PCR analysis on brain cells isolated by flow cytometry demonstrated that mPGES-1 is induced in endothelial cells and not in vascular wall macrophages. Similar analysis on liver cells showed induced expression in macrophages and not in endothelial cells, pointing at the distinct role for brain endothelial cells in PGE2 synthesis. These results identify the brain endothelial cells as the PGE2-producing cells critical for immune-induced fever.
|
|
| 3. |
- Engström, Linda, et al.
(författare)
-
Preproenkephalin mRNA expression in rat parabrachial neurons: relation to cells activated by systemic immune challenge
- 2001
-
Ingår i: Neuroscience Letters. - : Elsevier Science B.V., Amsterdam.. - 0304-3940 .- 1872-7972. ; 316:3, s. 165-168
-
Tidskriftsartikel (refereegranskat)abstract
- By using a dual-labeling immunohistochemical/in situ hybridization technique we examined if enkephalin-expressing neurons in the pontine parabrachial nucleus, a major brain stem relay for ascending visceral and homeostatic information, were activated by systemic immune challenge. While rats subjected to intravenous injection of bacterial wall lipopolysaccharide expressed dense labeling for the immediate-early gene product FOS in parts of the parabrachial nucleus that also demonstrated dense preproenkephalin expression, only a small proportion of the enkephalin-positive neurons were FOS-positive. These data indicate that enkephalins, although implicated in a variety of autonomic responses, are not primarily involved in the transmission of immune-related information from the parabrachial nucleus to its different forebrain and brain stem targets.
|
|
| 4. |
- Fagerholm, Siri, et al.
(författare)
-
Rapid insulin-dependent endocytosis of the insulin receptor by caveolae in primary adipocytes
- 2009
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:6, s. e5985-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The insulin receptor is localized in caveolae and is dependent on caveolae or cholesterol for signaling in adipocytes. When stimulated with insulin, the receptor is internalized. Methodology/Principal Findings: We examined primary rat adipocytes by subcellular fractionation to examine if the insulin receptor was internalized in a caveolae-mediated process. Insulin induced a rapid, t1/2 less than3 min, endocytosis of the insulin receptor in parallel with receptor tyrosine autophosphorylation. Concomitantly, caveolin-1 was phosphorylated at tyrosine(14) and endocytosed. Vanadate increased the phosphorylation of caveolin-1 without affecting insulin receptor phosphorylation or endocytosis. Immunocapture of endosomal vesicles with antibodies against the insulin receptor co-captured caveolin-1 and immunocapture with antibodies against tyrosine(14)-phosphorylated caveolin-1 co-captured the insulin receptor, demonstrating that the insulin receptor was endocytosed together with tyrosine(14)-phosphorylated caveolin-1. By immunogold electron microscopy the insulin receptor and caveolin-1 were colocalized in endosome vesicles that resembled caveosomes. Clathrin was not endocytosed with the insulin receptor and the inhibitor of clathrin-coated pit-mediated endocytosis, chlorpromazine, did not inhibit internalization of the insulin receptor, while transferrin receptor internalization was inhibited. Conclusion: It is concluded that in response to insulin stimulation the autophosphorylated insulin receptor in primary adipocytes is rapidly endocytosed in a caveolae-mediated process, involving tyrosine phosphorylation of caveolin-1.
|
|
| 5. |
- Fritz, Michael, et al.
(författare)
-
Prostaglandin-dependent modulation of dopaminergic neurotransmission elicits inflammation-induced aversion in mice
- 2016
-
Ingår i: Journal of Clinical Investigation. - : AMER SOC CLINICAL INVESTIGATION INC. - 0021-9738 .- 1558-8238. ; 126:2, s. 695-705
-
Tidskriftsartikel (refereegranskat)abstract
- Systemic inflammation causes malaise and general feelings of discomfort. This fundamental aspect of the sickness response reduces the quality of life for people suffering from chronic inflammatory diseases and is a nuisance during mild infections like common colds or the flu. To investigate how inflammation is perceived as unpleasant and causes negative affect, we used a behavioral test in which mice avoid an environment that they have learned to associate with inflammation-induced discomfort. Using a combination of cell-type-specific gene deletions, pharmacology, and chemogenetics, we found that systemic inflammation triggered aversion through MyD88-dependent activation of the brain endothelium followed by COX1-mediated cerebral prostaglandin E-2 (PGE(2)) synthesis. Further, we showed that inflammation-induced PGE(2) targeted EP1 receptors on striatal dopamine D1 receptor-expressing neurons and that this signaling sequence induced aversion through GABA-mediated inhibition of dopaminergic cells. Finally, we demonstrated that inflammation-induced aversion was not an indirect consequence of fever or anorexia but that it constituted an independent inflammatory symptom triggered by a unique molecular mechanism. Collectively, these findings demonstrate that PGE(2)-mediated modulation of the dopaminergic motivational circuitry is a key mechanism underlying the negative affect induced by inflammation.
|
|
| 6. |
- Hamzic, Namik, et al.
(författare)
-
Interleukin-6 produced by non-hematopoietic cells mediates the lipopolysaccharide-induced febrile response
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Interleukin-6 (IL-6) is critical for the lipopolysaccharide (LPS)-induced febrile response. However, the exact source(s) of IL-6 involved in regulating the LPS-elicited fever is still to be identified. One known source of IL-6 is hematopoietic cells, such as monocytes. To clarify the contribution of hematopoietically derived IL-6 to fever, we created chimeric mice expressing IL-6 either in cells of hematopoietic or, conversely, in cells of non-hematopoietic origin. This was performed by extinguishing hematopoetic cells in wild-type (WT) or IL-6 knockout (IL-6 KO) mice by whole-body irradiation and transplanting them with new stem cells. Mice lacking IL-6 in hematopoietic cells displayed normal fever to LPS and were found to have similar levels of IL-6 in the cerebrospinal fluid (CSF) and in plasma as well as similar expression of the IL-6 gene in the brain as WT mice. In contrast, IL-6 KO mice, with intact IL-6 production in cells of hematopoietic origin, only showed a minor elevation of the body temperature after peripheral LPS injection. While they displayed significantly elevated levels of IL-6 both in plasma and CSF compared with control mice, the increase was modest compared with that seen in LPS injected mice on WT background, the latter being approximately 20 times larger in magnitude. These results suggest that IL-6 of nonhematopoietic origin is the main source of IL-6 in LPS-induced fever, and that IL-6 produced by hematopoietic cells only plays a minor role.
|
|
| 7. |
- Hamzik, Namik, et al.
(författare)
-
Interleukin-6 primarily produced by non-hematopoietic cells mediates the lipopolysaccharide-induced febrile response
- 2013
-
Ingår i: Brain, behavior, and immunity. - : Elsevier. - 0889-1591 .- 1090-2139. ; 33, s. 123-130
-
Tidskriftsartikel (refereegranskat)abstract
- Interleukin-6 (IL-6) is critical for the lipopolysaccharide (LPS)-induced febrile response. However, the exact source(s) of IL-6 involved in regulating the LPS-elicited fever is still to be identified. One known source of IL-6 is hematopoietic cells, such as monocytes. To clarify the contribution of hematopoietically derived IL-6 to fever, we created chimeric mice expressing IL-6 selectively either in cells of hematopoietic or, conversely, in cells of non-hematopoietic origin. This was performed by extinguishing hematopoietic cells in wild-type (WT) or IL-6 knockout (IL-6 KO) mice by whole-body irradiation and transplanting them with new stem cells. Mice on a WT background but lacking IL-6 in hematopoietic cells displayed normal fever to LPS and were found to have similar levels of IL-6 protein in the cerebrospinal fluid (CSF) and in plasma and of IL-6 mRNA in the brain as WT mice. In contrast, mice on an IL-6 KO background, but with intact IL-6 production in cells of hematopoietic origin, only showed a minor elevation of the body temperature after peripheral LPS injection. While they displayed significantly elevated levels of IL-6 both in plasma and CSF compared with control mice, the increase was modest compared with that seen in LPS injected mice on a WT background, the latter being approximately 20 times larger in magnitude. These results suggest that IL-6 of non-hematopoietic origin is the main source of IL-6 in LPS-induced fever, and that IL-6 produced by hematopoietic cells only plays a minor role.
|
|
| 8. |
- Matsuwaki, Takashi, et al.
(författare)
-
Interleukin-1 beta induced activation of the hypothalamus-pituitary-adrenal axis is dependent on interleukin-1 receptors on non-hematopoietic cells
- 2014
-
Ingår i: Brain, behavior, and immunity. - : Elsevier. - 0889-1591 .- 1090-2139. ; 40, s. 166-173
-
Tidskriftsartikel (refereegranskat)abstract
- The proinflammatory cytokine interleukin-1 beta (IL-beta) plays a major role in the signal transduction of immune stimuli from the periphery to the central nervous system, and has been shown to be an important mediator of the immune-induced stress hormone release. The signaling pathway by which IL-1 beta exerts this function involves the blood-brain-barrier and induced central prostaglandin synthesis, but the identity of the blood-brain-barrier cells responsible for this signal transduction has been unclear, with both endothelial cells and perivascular macrophages suggested as critical components. Here, using an irradiation and transplantation strategy, we generated mice expressing IL-1 type 1 receptors (IL-1 RI) either in hematopoietic or non-hematopoietic cells and subjected these mice to peripheral immune challenge with IL-beta. Following both intraperitoneal and intravenous administration of IL-beta, mice lacking IL-1R1 in hematopoietic cells showed induced expression of the activity marker c-Fos in the paraventricular hypothalamic nucleus, and increased plasma levels of ACTH and corticosterone. In contrast, these responses were not observed in mice with IL-1R1 expression only in hematopoietic cells. Immunoreactivity for IL-1R1 was detected in brain vascular cells that displayed induced expression of the prostaglandin synthesizing enzyme cyclooxygenase-2 and that were immunoreactive for the endothelial cell marker CD31, but was not seen in cells positive for the brain macrophage marker CD206. These results imply that activation of the HPA-axis by IL-1 beta is dependent on IL-1R1 s on non-hematopoietic cells, such as brain endothelial cells, and that IL-1R1 on perivascular macrophages are not involved.
|
|
| 9. |
- Nilsson, Anna, et al.
(författare)
-
The involvement of prostaglandin E2 in interleukin-1β evoked anorexia is strain dependent
- 2017
-
Ingår i: Brain, behavior, and immunity. - : Academic Press. - 0889-1591 .- 1090-2139. ; 60, s. 27-31
-
Tidskriftsartikel (refereegranskat)abstract
- From experiments in mice in which the prostaglandin E2 (PGE2) synthesizing enzyme mPGES-1 was genetically deleted, as well as from experiments in which PGE2 was injected directly into the brain, PGE2 has been implicated as a mediator of inflammatory induced anorexia. Here we aimed at examining which PGE2 receptor (EP1–4) that was critical for the anorexic response to peripherally injected interleukin-1β (IL-1β). However, deletion of neither EP receptor in mice, either globally (for EP1, EP2, and EP3) or selectively in the nervous system (EP4), had any effect on the IL-1β induced anorexia. Because these mice were all on a C57BL/6 background, whereas previous observations demonstrating a role for induced PGE2 in IL-1β evoked anorexia had been carried out on mice on a DBA/1 background, we examined the anorexic response to IL-1β in mice with deletion of mPGES-1 on a C57BL/6 background and a DBA/1 background, respectively. We confirmed previous findings that mPGES-1 knock-out mice on a DBA/1 background displayed attenuated anorexia to IL-1β; however, mice on a C57BL/6 background showed the same profound anorexia as wild type mice when carrying deletion of mPGES-1, while displaying almost normal food intake after pretreatment with a cyclooxygenase-2 inhibitor. We conclude that the involvement of induced PGE2 in IL-1β evoked anorexia is strain dependent and we suggest that different routes that probably involve distinct prostanoids exist by which inflammatory stimuli may evoke an anorexic response and that these routes may be of different importance in different strains of mice.
|
|
| 10. |
- Nätt, Daniel, et al.
(författare)
-
Human sperm displays rapid responses to diet
- 2019
-
Ingår i: PLoS biology. - San Francisco, CA United States : PUBLIC LIBRARY SCIENCE. - 1544-9173 .- 1545-7885. ; 17:12
-
Tidskriftsartikel (refereegranskat)abstract
- The global rise in obesity and steady decline in sperm quality are two alarming trends that have emerged during recent decades. In parallel, evidence from model organisms shows that paternal diet can affect offspring metabolic health in a process involving sperm tRNA-derived small RNA (tsRNA). Here, we report that human sperm are acutely sensitive to nutrient flux, both in terms of sperm motility and changes in sperm tsRNA. Over the course of a 2-week diet intervention, in which we first introduced a healthy diet followed by a diet rich in sugar, sperm motility increased and stabilized at high levels. Small RNA-seq on repeatedly sampled sperm from the same individuals revealed that tsRNAs were up-regulated by eating a high-sugar diet for just 1 week. Unsupervised clustering identified two independent pathways for the biogenesis of these tsRNAs: one involving a novel class of fragments with specific cleavage in the T-loop of mature nuclear tRNAs and the other exclusively involving mitochondrial tsRNAs. Mitochondrial involvement was further supported by a similar up-regulation of mitochondrial rRNA-derived small RNA (rsRNA). Notably, the changes in sugar-sensitive tsRNA were positively associated with simultaneous changes in sperm motility and negatively associated with obesity in an independent clinical cohort. This rapid response to a dietary intervention on tsRNA in human sperm is attuned with the paternal intergenerational metabolic responses found in model organisms. More importantly, our findings suggest shared diet-sensitive mechanisms between sperm motility and the biogenesis of tsRNA, which provide novel insights about the interplay between nutrition and male reproductive health.
|
|
