Polymerase I and Transcript Release Factor Regulates Lipolysis via a Phosphorylation-Dependent Mechanism

OBJECTIVE: Polymerase I and transcript release factor (PTRF) is a protein highly expressed in adipose tissue and is an integral structural component of caveolae. Here, we report on a novel role of PTRF in lipid mobilization. RESEARCH DESIGN AND METHODS: PTRF expression was examined in different adipose depots of mice during fasting, refeeding, and after administration of catecholamines and insulin. Involvement of PTRF during lipolysis was studied upon PTRF knockdown and overexpression and mutation of PTRF phosphorylation sites in 3T3-L1 adipocytes. RESULTS: PTRF expression in mouse white adipose tissue (WAT) is regulated by nutritional status, increasing during fasting and decreasing to baseline after refeeding. Expression of PTRF also is hormonally regulated because treatment of mice with insulin leads to a decrease in expression, whereas isoproterenol increases expression in WAT. Manipulation of PTRF levels revealed a role of PTRF in lipolysis. Lentiviral-mediated knockdown of PTRF resulted in a marked attenuation of glycerol release in response to isoproterenol. Conversely, overexpressing PTRF enhanced isoproterenol-stimulated glycerol release. Mass-spectrometric analysis revealed that PTRF is phosphorylated at multiple sites in WAT. Mutation of serine 42, threonine 304, or serine 368 to alanine reduced isoproterenol-stimulated glycerol release in 3T3-L1 adipocytes. CONCLUSIONS: Our study is the first direct demonstration for a novel adipose tissue–specific function of PTRF as a mediator of lipolysis and also shows that phosphorylation of PTRF is required for efficient fat mobilization

SNIP/p140Cap mRNA expression is an unfavourable prognostic factor in breast cancer and is not expressed in normal breast tissue

The prevalence and clinical relevance of SNIP/p140Cap has not been extensively investigated. Here SNIP/p140Cap mRNA expression was studied in 103 breast tumour biopsies, where it was detected in ∼37% of tumour specimens, but not in any normal breast specimens. Expression correlated significantly with unfavourable overall survival. This suggests that SNIP/p140Cap may be a useful diagnostic and prognostic marker for breast cancer and its expression in breast cancer, but not in normal breast tissue, suggests that it may have potential as a therapeutic target

IgM Augments Complement Bactericidal Activity with Serum from a Patient with a Novel CD79a Mutation

Antibody replacement therapy for patients with antibody deficiencies contains only IgG. As a result, concurrent IgM and IgA deficiency present in a large proportion of antibody deficient patients persists. Especially patients with IgM deficiency remain at risk for recurrent infections of the gastrointestinal and respiratory tract. The lack of IgM in the current IgG replacement therapy is likely to contribute to the persistence of these mucosal infections because this antibody class is especially important for complement activation on the mucosal surface. We evaluated whether supplementation with IgM increased serum bactericidal capacity in vitro. Serum was collected from a patient with agammaglobulinemia and supplemented with purified serum IgM to normal levels. Antibody and complement deposition on the bacterial surface was determined by multi-color flow cytometry. Bacterial survival in serum was determined by colony-forming unit counts. We present a patient previously diagnosed with agammaglobulinemia due to CD79A (Igα) deficiency revealing a novel pathogenic insertion variant in the CD79a gene (NM_001783.3:c.353_354insT). Despite IgG replacement therapy and antibiotic prophylaxis, this patient developed a Campylobacter jejuni spondylodiscitis of lumbar vertebrae L4–L5. We found that serum IgM significantly contributes to complement activation on the bacterial surface of C. jejuni. Furthermore, supplementation of serum IgM augmented serum bactericidal activity significantly. In conclusion, supplementation of intravenous IgG replacement therapy with IgM may potentially offer greater protection against bacterial infections, also in the context of increasing antibiotic resistance

?-Tanycytes of the adult hypothalamic third ventricle include distinct populations of FGF-responsive neural progenitors

Emerging evidence suggests that new cells, including neurons, can be generated within the adult hypothalamus, suggesting the existence of a local neural stem/progenitor cell niche. Here, we identify a-tanycytes as key components of a hypothalamic niche in the adult mouse. Long-term lineage tracing in vivo using a GLAST::CreERT2 conditional driver indicates that α-tanycytes are self-renewing cells that constitutively give rise to new tanycytes, astrocytes and sparse numbers of neurons. In vitro studies demonstrate that α-tanycytes, but not β-tanycytes or parenchymal cells, are neurospherogenic. Distinct subpopulations of α-tanycytes exist, amongst which only GFAP-positive dorsal α2-tanycytes possess stem-like neurospherogenic activity. Fgf-10 and Fgf-18 are expressed specifically within ventral tanycyte subpopulations; α-tanycytes require fibroblast growth factor signalling to maintain their proliferation ex vivo and elevated fibroblast growth factor levels lead to enhanced proliferation of a-tanycytes in vivo. Our results suggest that α-tanycytes form the critical component of a hypothalamic stem cell niche, and that local fibroblast growth factor signalling governs their proliferation. © 2013 Macmillan Publishers Limited. All rights reserved

Transgenic amplification of glucocorticoid action in adipose tissue causes high blood pressure in mice

Obesity is closely associated with the metabolic syndrome, a combination of disorders including insulin resistance, diabetes, dyslipidemia, and hypertension. A role for local glucocorticoid reamplification in obesity and the metabolic syndrome has been suggested. The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) regenerates active cortisol from inactive 11-keto forms, and aP2-HSD1 mice with relative transgenic overexpression of this enzyme in fat cells develop visceral obesity with insulin resistance and dyslipidemia. Here we report that aP2-HSD1 mice also have high arterial blood pressure (BP). The mice have increased sensitivity to dietary salt and increased plasma levels of angiotensinogen, angiotensin II, and aldosterone. This hypertension is abolished by selective angiotensin II receptor AT-1 antagonist at a low dose that does not affect BP in non-Tg littermates. These findings suggest that activation of the circulating renin-angiotensin system (RAS) develops in aP2-HSD1 mice. The long-term hypertension is further reflected by an appreciable hypertrophy and hyperplasia of the distal tubule epithelium of the nephron, resembling salt-sensitive or angiotensin II–mediated hypertension. Taken together, our findings suggest that overexpression of 11β-HSD1 in fat is sufficient to cause salt-sensitive hypertension mediated by an activated RAS. The potential role of adipose 11β-HSD1 in mediating critical features of the metabolic syndrome extends beyond obesity and metabolic complications to include the most central cardiovascular feature of this disorder

Matrix metalloproteinase-9 activity and a downregulated Hedgehog pathway impair blood-brain barrier function in an <i>in vitro</i> model of CNS tuberculosis

Central nervous system tuberculosis (CNS TB) has a high mortality and morbidity associated with severe inflammation. The blood-brain barrier (BBB) protects the brain from inflammation but the mechanisms causing BBB damage in CNS TB are uncharacterized. We demonstrate that Mycobacterium tuberculosis (Mtb) causes breakdown of type IV collagen and decreases tight junction protein (TJP) expression in a co-culture model of the BBB. This increases permeability, surface expression of endothelial adhesion molecules and leukocyte transmigration. TJP breakdown was driven by Mtb-dependent secretion of matrix metalloproteinase (MMP)-9. TJP expression is regulated by Sonic hedgehog (Shh) through transcription factor Gli-1. In our model, the hedgehog pathway was downregulated by Mtb-stimulation, but Shh levels in astrocytes were unchanged. However, Scube2, a glycoprotein regulating astrocyte Shh release was decreased, inhibiting Shh delivery to brain endothelial cells. Activation of the hedgehog pathway by addition of a Smoothened agonist or by addition of exogenous Shh, or neutralizing MMP-9 activity, decreased permeability and increased TJP expression in the Mtb-stimulated BBB co-cultures. In summary, the BBB is disrupted by downregulation of the Shh pathway and breakdown of TJPs, secondary to increased MMP-9 activity which suggests that these pathways are potential novel targets for host directed therapy in CNS TB