Multiorgan Systems Study Reveals Igfbp7 as a Suppressor of Gluconeogenesis after Gastric Bypass Surgery.

Roux-en-Y gastric bypass (RYGB) surgery reduces weight in obese patients. A marked decrease in blood glucose levels occurs before weight loss; however, key molecules that improve the glycemic profile remain largely unknown. Using a murine RYGB surgery model, we performed multiorgan proteomics and bioinformatics to monitor the proteins and molecular pathways that change in this early glycemic response. Multiplexed proteomic kinetics data analysis revealed that the Roux limb, biliopancreatic limb, liver, and pancreas each exhibited unique temporal and molecular responses to the RYGB surgery. In addition, protein-protein network analysis indicated that the changes to the microbial environment in the intestine may play a crucial role in the beneficial effects of RYGB surgery. Furthermore, insulin-like growth factor binding protein 7 (Igfbp7) was identified as an early induced protein in the Roux limb. Known secretory properties of Igfbp7 prompted us to further investigate its role as a remote organ regulator of glucose metabolism. Igfbp7 overexpression decreased blood glucose levels in diet-induced obese mice and attenuated gluconeogenic gene expression in the liver. Secreted Igfbp7 appeared to mediate these beneficial effects. These results demonstrate that organs responded differentially to RYGB surgery and indicate that Igfbp7 may play an important role in improving blood glucose levels.

PARP9 and PARP14 cross-regulate macrophage activation via STAT1 ADP-ribosylation.

Despite the global impact of macrophage activation in vascular disease, the underlying mechanisms remain obscure. Here we show, with global proteomic analysis of macrophage cell lines treated with either IFNγ or IL-4, that PARP9 and PARP14 regulate macrophage activation. In primary macrophages, PARP9 and PARP14 have opposing roles in macrophage activation. PARP14 silencing induces pro-inflammatory genes and STAT1 phosphorylation in M(IFNγ) cells, whereas it suppresses anti-inflammatory gene expression and STAT6 phosphorylation in M(IL-4) cells. PARP9 silencing suppresses pro-inflammatory genes and STAT1 phosphorylation in M(IFNγ) cells. PARP14 induces ADP-ribosylation of STAT1, which is suppressed by PARP9. Mutations at these ADP-ribosylation sites lead to increased phosphorylation. Network analysis links PARP9-PARP14 with human coronary artery disease. PARP14 deficiency in haematopoietic cells accelerates the development and inflammatory burden of acute and chronic arterial lesions in mice. These findings suggest that PARP9 and PARP14 cross-regulate macrophage activation.

Cystathionine γ-lyase accelerates osteoclast differentiation: identification of a novel regulator of osteoclastogenesis by proteomic analysis.

OBJECTIVE: Clinical evidence has linked vascular calcification in advanced atherosclerotic plaques with overt cardiovascular disease and mortality. Bone resorbing monocyte-derived osteoclast-like cells are sparse in these plaques, indicating that their differentiation capability could be suppressed. Here, we seek to characterize the process of osteoclastogenesis by identifying novel regulators and pathways, with the aim of exploring possible strategies to reduce calcification. APPROACH AND RESULTS: We used a quantitative mass spectrometry strategy, tandem mass tagging, to quantify changes in the proteome of osteoclast-like cells differentiated from RAW264.7 cells in response to, receptor activator of nuclear factor κ-B ligand induction, a common in vitro model for osteogenesis. More than 4000 proteins were quantified, of which 138 were identified as novel osteoclast-related proteins. We selected 5 proteins for subsequent analysis (cystathionine γ-lyase [Cth/CSE], EGF-like repeat and discoidin I-like domain-containing protein 3, integrin α FG-GAP repeat containing 3, adseverin, and serpinb6b) and show that gene expression levels are also increased. Further analysis of the CSE transcript profile reveals an early onset of an mRNA increase. Silencing of CSE by siRNA and dl-propargylglycine, a CSE inhibitor, attenuated receptor activator of nuclear factor κ-B ligand-induced tartrate-resistant acid phosphatase type 5 activity and pit formation, suggesting that CSE is a potent inducer of calcium resorption. Moreover, knockdown of CSE suppressed expression of osteoclast differentiation markers. CONCLUSIONS: Our large-scale proteomics study identified novel candidate regulators or markers for osteoclastogenesis and demonstrated that CSE may act in early stages of osteoclastogenesis.