TY  - JOUR
A1  - Regn, Michael
A1  - Laggerbauer, Bernhard
A1  - Jentzsch, Claudia
A1  - Ramanujam, Deepak
A1  - Ahles, Andrea
A1  - Sichler, Sonja
A1  - Calzada-Wack, Julia
A1  - Koenen, Rory R.
A1  - Braun, Attila
A1  - Nieswandt, Bernhard
A1  - Engelhardt, Stefan
T1  - Peptidase inhibitor 16 is a membrane-tethered regulator of chemerin processing in the myocardium
JF  - Journal of Molecular and Cellular Cardiology
N2  - A key response of the myocardium to stress is the secretion of factors with paracrine or endocrine function. Intriguing in this respect is peptidase inhibitor 16 (PI16), a member of the CAP family of proteins which we found to be highly upregulated in cardiac disease. Up to this point, the mechanism of action and physiological function of PI16 remained elusive. Here, we show that PI16 is predominantly expressed by cardiac fibroblasts, which expose PI16 to the interstitium via a glycophosphatidylinositol (-GPI) membrane anchor. Based on a reported genetic association of PI16 and plasma levels of the chemokine chemerin, we investigated whether PI16 regulates post-translational processing of its precursor pro-chemerin. PI16-deficient mice were engineered and found to generate higher levels of processed chemerin than wildtype mice. Purified recombinant PI16 efficiently inhibited cathepsin K, a chemerin-activating protease, in vitro. Moreover, we show that conditioned medium from PI16-overexpressing cells impaired the activation of pro-chemerin. Together, our data indicate that PI16 suppresses chemerin activation in the myocardium and suggest that this circuit may be part of the cardiac stress response.
KW  - Cells
KW  - Activation
KW  - Purification
KW  - Protein
KW  - Peptidase inhibitor 16 (PI16)
KW  - Identification
KW  - Inflammation
KW  - Adipokine
KW  - Metabolism
KW  - Heart
KW  - Mice
KW  - Chemerin
KW  - RARRES2
KW  - TIG2
KW  - Protease inhibition
KW  - Chemerin processing
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-187039
VL  - 99
ER  - 
TY  - JOUR
A1  - Schmitt, Dominique
A1  - Funk, Natalia
A1  - Blum, Robert
A1  - Asan, Esther
A1  - Andersen, Lill
A1  - Rülicke, Thomas
A1  - Sendtner, Michael
A1  - Buchner, Erich
T1  - Initial characterization of a Syap1 knock-out mouse and distribution of Syap1 in mouse brain and cultured motoneurons
JF  - Histochemistry and Cell Biology
N2  - Synapse-associated protein 1 (Syap1/BSTA) is the mammalian homologue of Sap47 (synapse-associated protein of 47 kDa) in Drosophila. Sap47 null mutant larvae show reduced short-term synaptic plasticity and a defect in associative behavioral plasticity. In cultured adipocytes, Syap1 functions as part of a complex that phosphorylates protein kinase B alpha/Akt1 (Akt1) at Ser\(^{473}\) and promotes differentiation. The role of Syap1 in the vertebrate nervous system is unknown. Here, we generated a Syap1 knock-out mouse and show that lack of Syap1 is compatible with viability and fertility. Adult knock-out mice show no overt defects in brain morphology. In wild-type brain, Syap1 is found widely distributed in synaptic neuropil, notably in regions rich in glutamatergic synapses, but also in perinuclear structures associated with the Golgi apparatus of specific groups of neuronal cell bodies. In cultured motoneurons, Syap1 is located in axons and growth cones and is enriched in a perinuclear region partially overlapping with Golgi markers. We studied in detail the influence of Syap1 knockdown and knockout on structure and development of these cells. Importantly, Syap1 knockout does not affect motoneuron survival or axon growth. Unexpectedly, neither knockdown nor knockout of Syap1 in cultured motoneurons is associated with reduced Ser\(^{473}\) or Thr\(^{308}\) phosphorylation of Akt. Our findings demonstrate a widespread expression of Syap1 in the mouse central nervous system with regionally specific distribution patterns as illustrated in particular for olfactory bulb, hippocampus, and cerebellum.
KW  - Protein kinase B
KW  - Spinal Muscular-arthropy
KW  - Rictor-mTOR complex
KW  - Neurotrophic factors
KW  - Plasma-membrane
KW  - Axon growth
KW  - SAP47 gene
KW  - Phosphorylation
KW  - Drosophilia
KW  - Cells
KW  - BSTA
KW  - Viability
KW  - Brain
KW  - Syap1 localization
KW  - Glutamatergic synapses
KW  - PKB/Akt phosphorylation
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-187258
VL  - 146
IS  - 4
ER  -