HIPK2 directs cell type-specific regulation of STAT3 transcriptional activity in Th17 cell differentiation.

SignificanceSTAT3 (signal transducer and activator of transcription 3) is a master transcription factor that organizes cellular responses to cytokines and growth factors and is implicated in inflammatory disorders. STAT3 is a well-recognized therapeutic target for human cancer and inflammatory disorders, but how its function is regulated in a cell type-specific manner has been a major outstanding question. We discovered that Stat3 imposes self-directed regulation through controlling transcription of its own regulator homeodomain-interacting protein kinase 2 (Hipk2) in a T helper 17 (Th17) cell-specific manner. Our validation of the functional importance of the Stat3-Hipk2 axis in Th17 cell development in the pathogenesis of T cell-induced colitis in mice suggests an approach to therapeutically treat inflammatory bowel diseases that currently lack a safe and effective therapy.

Inhibition of HIPK2 Alleviates Thoracic Aortic Disease in Mice With Progressively Severe Marfan Syndrome.

Objective: Despite considerable research, the goal of finding nonsurgical remedies against thoracic aortic aneurysm and acute aortic dissection remains elusive. We sought to identify a novel aortic PK (protein kinase) that can be pharmacologically targeted to mitigate aneurysmal disease in a well-established mouse model of early-onset progressively severe Marfan syndrome (MFS). Approach and Results: Computational analyses of transcriptomic data derived from the ascending aorta of MFS mice predicted a probable association between thoracic aortic aneurysm and acute aortic dissection development and the multifunctional, stress-activated HIPK2 (homeodomain-interacting protein kinase 2). Consistent with this prediction, Hipk2 gene inactivation significantly extended the survival of MFS mice by slowing aneurysm growth and delaying transmural rupture. HIPK2 also ranked among the top predicted PKs in computational analyses of DEGs (differentially expressed genes) in the dilated aorta of 3 MFS patients, which strengthened the clinical relevance of the experimental finding. Additional in silico analyses of the human and mouse data sets identified the TGF (transforming growth factor)-ß/Smad3 signaling pathway as a potential target of HIPK2 in the MFS aorta. Chronic treatment of MFS mice with an allosteric inhibitor of HIPK2-mediated stimulation of Smad3 signaling validated this prediction by mitigating thoracic aortic aneurysm and acute aortic dissection pathology and partially improving aortic material stiffness. Conclusions: HIPK2 is a previously unrecognized determinant of aneurysmal disease and an attractive new target for antithoracic aortic aneurysm and acute aortic dissection multidrug therapy.

Cell Type-Specific Contributions of the Angiotensin II Type 1a Receptor to Aorta Homeostasis and Aneurysmal Disease-Brief Report.

OBJECTIVE: Two were the aims of this study: first, to translate whole-genome expression profiles into computational predictions of functional associations between signaling pathways that regulate aorta homeostasis and the activity of angiotensin II type 1a receptor (At1ar) in either vascular endothelial or smooth muscle cells; and second, to characterize the impact of endothelial cell- or smooth muscle cell-specific At1ar disruption on the development of thoracic aortic aneurysm in fibrillin-1 hypomorphic (Fbn1mgR/mgR ) mice, a validated animal model of early onset progressively severe Marfan syndrome. APPROACH AND RESULTS: Cdh5-Cre and Sm22-Cre transgenic mice were used to inactivate the At1ar-coding gene (Agt1ar) in either intimal or medial cells of both wild type and Marfan syndrome mice, respectively. Computational analyses of differentially expressed genes predicted dysregulated signaling pathways of cell survival and matrix remodeling in Agt1arCdh5-/- aortas and of cell adhesion and contractility in Agt1arSm22-/- aortas. Characterization of Fbn1mgR/mgR;Agt1arCdh5-/- mice revealed increased median survival associated with mitigated aneurysm growth and media degeneration, as well as reduced levels of phosphorylated (p-) Erk1/2 but not p-Smad2. By contrast, levels of both p-Erk1/2 and p-Smad2 proteins were normalized in Fbn1mgR/mgR;Agt1arSm22-/- aortas in spite of them showing no appreciable changes in thoracic aortic aneurysm pathology. CONCLUSIONS: Physiological At1ar signaling in the intimal and medial layers is associated with distinct regulatory processes of aorta homeostasis and function; improper At1ar activity in the vascular endothelium is a significant determinant of thoracic aortic aneurysm development in Marfan syndrome mice.

Colony stimulating factor-1 receptor signaling networks inhibit mouse macrophage inflammatory responses by induction of microRNA-21.

Macrophage polarization between the M2 (repair, protumorigenic) and M1 (inflammatory) phenotypes is seen as a continuum of states. The detailed transcriptional events and signals downstream of colony-stimulating factor 1 receptor (CSF-1R) that contributes to amplification of the M2 phenotype and suppression of the M1 phenotype are largely unknown. Macrophage CSF-1R pTyr-721 signaling promotes cell motility and enhancement of tumor cell invasion in vitro. Combining analysis of cellular systems for CSF-1R gain of function and loss of function with bioinformatic analysis of the macrophage CSF-1R pTyr-721-regulated transcriptome, we uncovered microRNA-21 (miR-21) as a downstream molecular switch controlling macrophage activation and identified extracellular signal-regulated kinase1/2 and nuclear factor-κB as CSF-1R pTyr-721-regulated signaling nodes. We show that CSF-1R pTyr-721 signaling suppresses the inflammatory phenotype, predominantly by induction of miR-21. Profiling of the miR-21-regulated messenger RNAs revealed that 80% of the CSF-1-regulated canonical miR-21 targets are proinflammatory molecules. Additionally, miR-21 positively regulates M2 marker expression. Moreover, miR-21 feeds back to positively regulate its own expression and to limit CSF-1R-mediated activation of extracellular signal-regulated kinase1/2 and nuclear factor-κB. Consistent with an anti-inflammatory role of miRNA-21, intraperitoneal injection of mice with a miRNA-21 inhibitor increases the recruitment of inflammatory monocytes and enhances the peritoneal monocyte/macrophage response to lipopolysaccharide. These results identify the CSF-1R-regulated miR-21 network that modulates macrophage polarization.

A Transcriptome-Based Precision Oncology Platform for Patient-Therapy Alignment in a Diverse Set of Treatment-Resistant Malignancies.

Predicting in vivo response to antineoplastics remains an elusive challenge. We performed a first-of-kind evaluation of two transcriptome-based precision cancer medicine methodologies to predict tumor sensitivity to a comprehensive repertoire of clinically relevant oncology drugs, whose mechanism of action we experimentally assessed in cognate cell lines. We enrolled patients with histologically distinct, poor-prognosis malignancies who had progressed on multiple therapies, and developed low-passage, patient-derived xenograft models that were used to validate 35 patient-specific drug predictions. Both OncoTarget, which identifies high-affinity inhibitors of individual master regulator (MR) proteins, and OncoTreat, which identifies drugs that invert the transcriptional activity of hyperconnected MR modules, produced highly significant 30-day disease control rates (68% and 91%, respectively). Moreover, of 18 OncoTreat-predicted drugs, 15 induced the predicted MR-module activity inversion in vivo. Predicted drugs significantly outperformed antineoplastic drugs selected as unpredicted controls, suggesting these methods may substantively complement existing precision cancer medicine approaches, as also illustrated by a case study. SIGNIFICANCE: Complementary precision cancer medicine paradigms are needed to broaden the clinical benefit realized through genetic profiling and immunotherapy. In this first-in-class application, we introduce two transcriptome-based tumor-agnostic systems biology tools to predict drug response in vivo. OncoTarget and OncoTreat are scalable for the design of basket and umbrella clinical trials. This article is highlighted in the In This Issue feature, p. 1275.

Active-site determinants of substrate recognition by the metalloproteinases TACE and ADAM10.

The metalloproteinases TACE [tumour necrosis factor alpha-converting enzyme; also known as ADAM17 (a disintegrin and metalloproteinase 17)] and ADAM10 are the primary enzymes responsible for catalysing release of membrane-anchored proteins from the cell surface in metazoan organisms. Although the repertoire of protein substrates for these two proteases is partially overlapping, each one appears to target a subset of unique proteins in vivo. The mechanisms by which the two proteases achieve specificity for particular substrates are not completely understood. We have used peptide libraries to define the cleavage site selectivity of TACE and ADAM10. The two proteases have distinct primary sequence requirements at multiple positions surrounding the cleavage site in their substrates, which allowed us to generate peptide substrates that are highly specific for each of these proteases. The major difference between the two protease specificities maps to the P1' position (immediately downstream of the cleavage site) of the substrate. At this position, TACE is selective for smaller aliphatic residues, whereas ADAM10 can accommodate aromatic amino acids. Using mutagenesis we identified three residues in the S1' pockets of these enzymes that dramatically influence specificity for both peptide and protein substrates. Our results suggest that substrate selectivity of TACE and ADAM10 can be at least partly rationalized by specific features of their active sites.

Systems pharmacology-based integration of human and mouse data for drug repurposing to treat thoracic aneurysms.

Marfan syndrome (MFS) is associated with mutations in fibrillin-1 that predispose afflicted individuals to progressive thoracic aortic aneurysm (TAA) leading to dissection and rupture of the vessel wall. Here we combined computational and experimental approaches to identify and test FDA-approved drugs that may slow or even halt aneurysm progression. Computational analyses of transcriptomic data derived from the aortas of MFS patients and MFS mice (Fbn1mgR/mgR mice) predicted that subcellular pathways associated with reduced muscle contractility are key TAA determinants that could be targeted with the GABAB receptor agonist baclofen. Systemic administration of baclofen to Fbn1mgR/mgR mice validated our computational prediction by mitigating arterial disease progression at the cellular and physiological levels. Interestingly, baclofen improved muscle contraction-related subcellular pathways by upregulating a different set of genes than those downregulated in the aorta of vehicle-treated Fbn1mgR/mgR mice. Distinct transcriptomic profiles were also associated with drug-treated MFS and wild-type mice. Thus, systems pharmacology approaches that compare patient- and mouse-derived transcriptomic data for subcellular pathway-based drug repurposing represent an effective strategy to identify potential new treatments of human diseases.

Bifidobacterium longum requires a fructokinase (Frk; ATP:D-fructose 6-phosphotransferase, EC 2.7.1.4) for fructose catabolism.

Although the ability of Bifidobacterium spp. to grow on fructose as a unique carbon source has been demonstrated, the enzyme(s) needed to incorporate fructose into a catabolic pathway has hitherto not been defined. This work demonstrates that intracellular fructose is metabolized via the fructose-6-P phosphoketolase pathway and suggests that a fructokinase (Frk; EC 2.7.1.4) is the enzyme that is necessary and sufficient for the assimilation of fructose into this catabolic route in Bifidobacterium longum. The B. longum A10C fructokinase-encoding gene (frk) was expressed in Escherichia coli from a pET28 vector with an attached N-terminal histidine tag. The expressed enzyme was purified by affinity chromatography on a Co(2+)-based column, and the pH and temperature optima were determined. A biochemical analysis revealed that Frk displays the same affinity for fructose and ATP (Km(fructose) = 0.739 +/- 0.18 mM and Km(ATP) = 0.756 +/- 0.08 mM), is highly specific for D-fructose, and is inhibited by an excess of ATP (>12 mM). It was also found that frk is inducible by fructose and is subject to glucose-mediated repression. Consequently, this work presents the first characterization at the molecular and biochemical level of a fructokinase from a gram-positive bacterium that is highly specific for D-fructose.