Treatment of Primary Aldosteronism with mTORC1 Inhibitors

mTORC1 activity is often increased in the adrenal cortex of patients with primary aldosteronism and mTORC1 inhibition decreases aldosterone production in adrenocortical cells, suggesting the mTORC1 pathway as a possible target for treatment of primary aldosteronism.; To investigate the effect of mTORC1 inhibition on adrenal steroid hormones and hemodynamic parameters in mice and in patients with primary aldosteronism.; (i) Plasma aldosterone, corticosterone and angiotensin II were measured in mice treated for 24 hours with vehicle or rapamycin. (ii) Plasma aldosterone levels after a saline infusion test, plasma renin, 24-hour urine steroid hormone metabolome and hemodynamic parameters were measured during an open-label study in 12 patients with primary aldosteronism before and after two-weeks of treatment with everolimus and after a two-week washout period.; (i) Change in plasma aldosterone levels. (ii) Change in other steroid hormones, renin, angiotensin II and hemodynamic parameters.; Treatment of mice with rapamycin significantly decreased plasma aldosterone levels (P = 0.007). Overall, treatment of primary aldosteronism patients with everolimus significantly decreased blood pressure (P < 0.05) and increased renin levels (P = 0.001) but did not lead to a significant reduction in aldosterone levels. However, prominent reduction of aldosterone levels upon everolimus treatment was observed in 4 out of 12 patients.; In mice, mTORC1 inhibition was associated with reduced plasma aldosterone levels. In patients with primary aldosteronism, mTORC1 inhibition was associated with improved blood pressure and renin suppression. In addition, mTORC1 inhibition appeared to reduce plasma aldosterone in a subset of patients

Insulin resistance causes inflammation in adipose tissue

Obesity is a major risk factor for insulin resistance and type 2 diabetes. In adipose tissue, obesity-mediated insulin resistance correlates with the accumulation of proinflammatory macrophages and inflammation. However, the causal relationship of these events is unclear. Here, we report that obesity-induced insulin resistance in mice precedes macrophage accumulation and inflammation in adipose tissue. Using a mouse model that combines genetically induced, adipose-specific insulin resistance (mTORC2-knockout) and diet-induced obesity, we found that insulin resistance causes local accumulation of proinflammatory macrophages. Mechanistically, insulin resistance in adipocytes results in production of the chemokine monocyte chemoattractant protein 1 (MCP1), which recruits monocytes and activates proinflammatory macrophages. Finally, insulin resistance (high homeostatic model assessment of insulin resistance [HOMA-IR]) correlated with reduced insulin/mTORC2 signaling and elevated MCP1 production in visceral adipose tissue from obese human subjects. Our findings suggest that insulin resistance in adipose tissue leads to inflammation rather than vice versa

Current patch test results with the European baseline series and extensions to it from the 'European Surveillance System on Contact Allergy' network, 2007-2008

BACKGROUND: The pattern of contact sensitization to the supposedly most important allergens assembled in the baseline series differs between countries, presumably at least partly because of exposure differences. Objectives. To describe the prevalence of contact sensitization to allergens tested in consecutive patients in the years 2007 and 2008, and to discuss possible differences. METHODS: Data from the 39 departments in 11 European countries comprising the European Surveillance System on Contact Allergy network (www.essca-dc.org) in this period have been pooled and analysed according to common standards. RESULTS: Patch test results with the European baseline series, and country-specific or department-specific additions to it, obtained in 25 181 patients, showed marked international variation. Metals and fragrances are still the most frequent allergens across Europe. Some allergens tested nationally may be useful future additions to the European baseline series, for example methylisothiazolinone, whereas a few long-term components of the European baseline series, namely primin and clioquinol, no longer warrant routine testing. CONCLUSIONS: The present analysis points to 'excess' prevalences of specific contact sensitization in some countries, although interpretation must be cautious if only few, and possibly specialized, centres are representing one country. A comparison as presented may help to target in-depth research into possible causes of 'excess' exposure, and/or consideration of methodological issues, including modifications to the baseline series

eIF4A moonlights as an off switch for TORC1

TORC1 is actively inhibited upon amino acid withdrawal. Tsokanos et al (2016) shed light on the underlying molecular mechanism. They demonstrate that upon removal of exogenous amino acids, eIF4A inhibits TORC1 via TSC2. Thus, whereas it is well known that TORC1 regulates the translation machinery, we now know the inverse is also true

Secretion and Signaling Activities of Lipoprotein-Associated Hedgehog and Non-Sterol-Modified Hedgehog in Flies and Mammals

Hedgehog (Hh) proteins control animal development and tissue homeostasis. They activate gene expression by regulating processing, stability, and activation of Gli/Cubitus interruptus (Ci) transcription factors. Hh proteins are secreted and spread through tissue, despite becoming covalently linked to sterol during processing. Multiple mechanisms have been proposed to release Hh proteins in distinct forms; in Drosophila, lipoproteins facilitate long-range Hh mobilization but also contain lipids that repress the pathway. Here, we show that mammalian lipoproteins have conserved roles in Sonic Hedgehog (Shh) release and pathway repression. We demonstrate that lipoprotein-associated forms of Hh and Shh specifically block lipoprotein-mediated pathway inhibition. We also identify a second conserved release form that is not sterol-modified and can be released independently of lipoproteins (Hh-N*/Shh-N*). Lipoprotein-associated Hh/Shh and Hh-N*/Shh-N* have complementary and synergistic functions. In Drosophila wing imaginal discs, lipoprotein-associated Hh increases the amount of full-length Ci, but is insufficient for target gene activation. However, small amounts of non-sterol-modified Hh synergize with lipoprotein-associated Hh to fully activate the pathway and allow target gene expression. The existence of Hh secretion forms with distinct signaling activities suggests a novel mechanism for generating a diversity of Hh responses

Secretion and Signaling Activities of Lipoprotein-Associated Hedgehog and Non-Sterol-Modified Hedgehog in Flies and Mammals

<div><p>Hedgehog (Hh) proteins control animal development and tissue homeostasis. They activate gene expression by regulating processing, stability, and activation of Gli/Cubitus interruptus (Ci) transcription factors. Hh proteins are secreted and spread through tissue, despite becoming covalently linked to sterol during processing. Multiple mechanisms have been proposed to release Hh proteins in distinct forms; in <i>Drosophila</i>, lipoproteins facilitate long-range Hh mobilization but also contain lipids that repress the pathway. Here, we show that mammalian lipoproteins have conserved roles in Sonic Hedgehog (Shh) release and pathway repression. We demonstrate that lipoprotein-associated forms of Hh and Shh specifically block lipoprotein-mediated pathway inhibition. We also identify a second conserved release form that is not sterol-modified and can be released independently of lipoproteins (Hh-N*/Shh-N*). Lipoprotein-associated Hh/Shh and Hh-N*/Shh-N* have complementary and synergistic functions. In <i>Drosophila</i> wing imaginal discs, lipoprotein-associated Hh increases the amount of full-length Ci, but is insufficient for target gene activation. However, small amounts of non-sterol-modified Hh synergize with lipoprotein-associated Hh to fully activate the pathway and allow target gene expression. The existence of Hh secretion forms with distinct signaling activities suggests a novel mechanism for generating a diversity of Hh responses.</p> </div

Shh is secreted in lipoprotein-associated and lipoprotein-free forms.

<p>(A) Density of human Shh secreted by HeLa cells in the absence or presence of fetal bovine serum (FBS), analyzed by Optiprep density gradient centrifugation, and Western blotting (WB). HeLa cells transfected with Shh were grown in serum-free medium or in the presence of 10% FBS, and equal volumes of supernatants analyzed. Colors indicate fractions corresponding to bovine Very Low-, Low-, and High-Density Lipoproteins (VLDL, LDL, and HDL) <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001505#pbio.1001505-Chapman1" target="_blank">[68]</a>. (B) Density of non-lipid-modified Shh-N^C24S, analyzed by Optiprep density gradient centrifugation and WB. Supernatants were derived from HeLa cells transfected with Shh-N^C24S and grown in the presence of FBS. (C) Shh levels in cell lysates and supernatants derived from HeLa cells transfected with Shh, grown in serum-free medium supplemented with individual human lipoprotein classes. Equal protein amounts (cell lysates) or volumes (supernatants) were analyzed. (D) Density of Shh in HeLa cell supernatants shown in (C), analyzed by Optiprep density gradient centrifugation and WB. Colors indicate fractions corresponding to human VLDL, LDL, and HDL <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001505#pbio.1001505-Vance1" target="_blank">[43]</a>. (E) Co-Immunoprecipitation (Co-IP) of secreted Shh with different lipoprotein classes, analyzed by WB. Supernatants were derived from HeLa cells transfected with Shh or Shh-N^C24S, grown in serum-free medium supplemented with individual human lipoproteins classes. (F) Shh levels in supernatants derived from MIA PaCa-2 cells grown in serum-free medium supplemented with individual human lipoprotein classes. Equal volumes were used for WB. (G) Density of Shh in MIA PaCa-2 cell supernatants shown in (F), analyzed by Optiprep density gradient centrifugation and WB. (H) Density of Shh in supernatants from Shh-expressing HeLa cells grown in serum-free medium supplemented with hemolymph from <i>Drosophila</i> larvae, analyzed by Optiprep density gradient centrifugation and WB. Purple indicates fractions corresponding to <i>Drosophila</i> Lpp.</p

Signaling properties of lipoprotein-associated Shh and Shh-N* in Shh-LIGHT2 cells.

<p>(A, B) Concentration-dependent signaling activity of (A) lipoprotein-associated Shh and (B) Shh-N*. Lipoprotein concentration in (A) was kept constant, and only the fraction carrying Shh increased. Shh and Shh-N* levels used for signaling assays were assessed by WB. (C,D) Shh pathway activity in cells stimulated by Shh-N* in the absence or presence of lipoproteins, or cells stimulated with lipoprotein-associated Shh. Lipoproteins, where added, were kept at a constant level. (C) Mammalian lipoproteins, (D) <i>Drosophila</i> Lpp. (E) Synergistic signaling activity of Shh-N* and lipoprotein-associated Shh. Shh-N* and lipoprotein-associated Shh were applied to cells alone or in combination. Predicted additive values represent the combined activity of lipoprotein-associated Shh and Shh-N* in the presence of lipoproteins, minus the basal assay activity measured in unstimulated cells. Note that the same batch of samples was used for assays shown in (A) and (B). For (A–E), error bars indicate ± SD (<i>n</i> = 3; **<i>p</i><0.005; ***<i>p</i><0.0005) of one representative experiment. Experiments were repeated at least twice.</p