http://www.jci.org/current en-us 2012 The American Society for Clinical Investigation http://www.jci.org/icons/banner/rss_title.gif http://content.jci.org http://www.jci.org/articles/view/62225 info:doi/10.1172/JCI62225 American Society for Clinical Investigation http://www.jci.org/articles/view/62577 info:doi/10.1172/JCI62577 American Society for Clinical Investigation http://www.jci.org/articles/view/62577 info:doi/10.1172/JCI62577 American Society for Clinical Investigation http://www.jci.org/articles/view/62760 info:doi/10.1172/JCI62760 American Society for Clinical Investigation http://www.jci.org/articles/view/57114 RB1). RB1 was the first identified tumor suppressor gene and has defined roles in the regulation of cell cycle progression, DNA replication, and terminal differentiation. However, despite the abundance of work demonstrating the molecular function and identifying binding partners of pRb, the challenge facing molecular biologists and clinical oncologists is how to integrate this vast body of molecular knowledge into the development of targeted therapies for treatment of retinoblastoma. We propose that a more thorough genetic understanding of retinoblastoma would inform targeted treatment decisions and could improve outcomes and quality of life in children affected by this disease. ]]> info:doi/10.1172/JCI57114 American Society for Clinical Investigation http://www.jci.org/articles/view/62237 JCI is dedicated to publishing. ]]> info:doi/10.1172/JCI62237 American Society for Clinical Investigation http://www.jci.org/articles/view/57416 info:doi/10.1172/JCI57416 American Society for Clinical Investigation http://www.jci.org/articles/view/57414 info:doi/10.1172/JCI57414 American Society for Clinical Investigation http://www.jci.org/articles/view/58779 info:doi/10.1172/JCI58779 American Society for Clinical Investigation http://www.jci.org/articles/view/57415 info:doi/10.1172/JCI57415 American Society for Clinical Investigation http://www.jci.org/articles/view/61978 info:doi/10.1172/JCI61978 American Society for Clinical Investigation http://www.jci.org/articles/view/61857 JCI, Owens et al. report possible mechanisms underlying the prothrombotic, proinflammatory state accompanying hypercholesterolemia. Using rodent, monkey, and human subjects, they show that circulating oxidized LDL and circulating monocyte-derived tissue factor are important instigating factors driving the thrombotic, inflammatory phenotype and, surprisingly, that statin therapy ameliorated the phenotype even in the absence of lowering cholesterol levels. The studies raise the intriguing possibility that therapies directed at pathways generating oxidant stress or pathways involved in transmitting oxidized LDL–mediated signals in circulating platelets and monocytes could have antiatherothrombotic potential, probably with minimal anticoagulant and hemorrhagic potential. ]]> info:doi/10.1172/JCI61857 American Society for Clinical Investigation http://www.jci.org/articles/view/61345 JCI, Drobits and colleagues demonstrate that topical application of imiquimod suppresses cutaneous melanoma by TLR7-dependent recruitment and transformation of plasmacytoid dendritic cells into killer cells; this occurs independently of conventional adaptive immune mechanisms. ]]> info:doi/10.1172/JCI61345 American Society for Clinical Investigation http://www.jci.org/articles/view/62002 JCI, Varela and colleagues extend this list of systems to include neural derivatives of human embryonic stem cells, which they show exhibit a repeated gain of material from chromosome 1q. Although this raises safety issues for therapeutic use of such cells, the frequent observation of a particular change may direct screening strategies for detection and removal of these unwanted cellular variants. ]]> info:doi/10.1172/JCI62002 American Society for Clinical Investigation http://www.jci.org/articles/view/60941 JCI, Ouellet et al. demonstrate that metabolism in brown fat really is increased when adult humans are exposed to cold. This boosts the possibility that calorie combustion in brown fat may be of significance for our metabolism and, correspondingly, that the absence of brown fat may increase our proneness to obesity — provided that brown fat becomes activated not only by cold but also through food-related stimuli. ]]> info:doi/10.1172/JCI60941 American Society for Clinical Investigation http://www.jci.org/articles/view/62204 JCI, Maegdefessel and colleagues demonstrate that decreasing the levels of miR-29b in the aortic wall can attenuate aortic aneurysm progression in two different mouse models of abdominal aortic aneurysms. This study highlights the relevance of miR-29b in aortic disease but also raises questions about its specific role. ]]> info:doi/10.1172/JCI62204 American Society for Clinical Investigation http://www.jci.org/articles/view/60957 JCI, Grenz and coworkers provide novel insight into how preservation of postischemic renal perfusion by endothelial cell adenosine A2B receptors is antagonized by adenosine reuptake into proximal tubule cells by equilibrative nucleotide transporter 1, which can be inhibited by dipyridamole. The work suggests that adenosine A2B receptor agonists and inhibition of equilibrative nucleoside transporters by dipyridamole may have therapeutic potential in ischemic acute kidney injury, a condition for which there are currently no specific therapeutic interventions. ]]> info:doi/10.1172/JCI60957 American Society for Clinical Investigation http://www.jci.org/articles/view/61598 Apoe^–/– mice. AAA development was accompanied by decreased aortic expression of miR-29b, along with increased expression of known miR-29b targets, Col1a1, Col3a1, Col5a1, and Eln, in both models. In vivo administration of locked nucleic acid anti–miR-29b greatly increased collagen expression, leading to an early fibrotic response in the abdominal aortic wall and resulting in a significant reduction in AAA progression over time in both models. In contrast, overexpression of miR-29b using a lentiviral vector led to augmented AAA expansion and significant increase of aortic rupture rate. Cell culture studies identified aortic fibroblasts as the likely vascular cell type mediating the profibrotic effects of miR-29b modulation. A similar pattern of reduced miR-29b expression and increased target gene expression was observed in human AAA tissue samples compared with that in organ donor controls. These data suggest that therapeutic manipulation of miR-29b and its target genes holds promise for limiting AAA disease progression and protecting from rupture. ]]> info:doi/10.1172/JCI61598 American Society for Clinical Investigation http://www.jci.org/articles/view/58470 PNKD) are responsible for PNKD. Here, we report the generation of antibodies specific for the PNKD protein and show that it is widely expressed in the mouse brain, exclusively in neurons. One PNKD isoform is a membrane-associated protein. Transgenic mice carrying mutations in the mouse Pnkd locus equivalent to those found in patients with PNKD recapitulated the human PNKD phenotype. Staining for c-fos demonstrated that administration of alcohol or caffeine induced neuronal activity in the basal ganglia in these mice. They also showed nigrostriatal neurotransmission deficits that were manifested by reduced extracellular dopamine levels in the striatum and a proportional increase of dopamine release in response to caffeine and ethanol treatment. These findings support the hypothesis that the PNKD protein functions to modulate striatal neuro­transmitter release in response to stress and other precipitating factors. ]]> info:doi/10.1172/JCI58470 American Society for Clinical Investigation http://www.jci.org/articles/view/59526 info:doi/10.1172/JCI59526 American Society for Clinical Investigation http://www.jci.org/articles/view/58847 info:doi/10.1172/JCI58847 American Society for Clinical Investigation http://www.jci.org/articles/view/60560 REEP1), atlastin-1 (ATL1), and spastin (SPAST) — have been found to underlie many cases of HSP in Northern Europe and North America. Applying Sanger and exome sequencing, we have now identified 3 mutations in reticulon 2 (RTN2), which encodes a member of the reticulon family of prototypic ER-shaping proteins, in families with spastic paraplegia 12 (SPG12). These autosomal dominant mutations included a complete deletion of RTN2 and a frameshift mutation predicted to produce a highly truncated protein. Wild-type reticulon 2, but not the truncated protein potentially encoded by the frameshift allele, localized to the ER. RTN2 interacted with spastin, and this interaction required a hydrophobic region in spastin that is involved in ER localization and that is predicted to form a curvature-inducing/sensing hairpin loop domain. Our results directly implicate a reticulon protein in axonopathy, show that this protein participates in a network of interactions among HSP proteins involved in ER shaping, and further support the hypothesis that abnormal ER morphogenesis is a pathogenic mechanism in HSP. ]]> info:doi/10.1172/JCI60560 American Society for Clinical Investigation http://www.jci.org/articles/view/60433 18F-fluorodeoxyglucose (¹⁸FDG) have shown the presence of BAT in adult humans. However, whether BAT contributes to cold-induced nonshivering thermogenesis in humans has not been proven. Using PET with ¹¹C-acetate, ¹⁸FDG, and ¹⁸F-fluoro-thiaheptadecanoic acid (¹⁸FTHA), a fatty acid tracer, we have quantified BAT oxidative metabolism and glucose and nonesterified fatty acid (NEFA) turnover in 6 healthy men under controlled cold exposure conditions. All subjects displayed substantial NEFA and glucose uptake upon cold exposure. Furthermore, we demonstrated cold-induced activation of oxidative metabolism in BAT, but not in adjoining skeletal muscles and subcutaneous adipose tissue. This activation was associated with an increase in total energy expenditure. We found an inverse relationship between BAT activity and shivering. We also observed an increase in BAT radio density upon cold exposure, indicating reduced BAT triglyceride content. In sum, our study provides evidence that BAT acts as a nonshivering thermogenesis effector in humans. ]]> info:doi/10.1172/JCI60433 American Society for Clinical Investigation http://www.jci.org/articles/view/59309 PIK3CA) that result in enhanced PI3K activity are frequently observed in human cancers. To better understand the role of mutant PIK3CA in the initiation or progression of tumorigenesis, we generated mice in which a PIK3CA mutation commonly detected in human cancers (the H1047R mutation) could be conditionally knocked into the endogenous Pik3ca locus. Activation of this mutation in the mouse ovary revealed that alone, Pik3ca^H1047R induced premalignant hyperplasia of the ovarian surface epithelium but no tumors. Concomitantly, we analyzed several human ovarian cancers and found PIK3CA mutations coexistent with KRAS and/or PTEN mutations, raising the possibility that a secondary defect in a co-regulator of PI3K activity may be required for mutant PIK3CA to promote transformation. Consistent with this notion, we found that Pik3ca^H1047R mutation plus Pten deletion in the mouse ovary led to the development of ovarian serous adenocarcinomas and granulosa cell tumors. Both mutational events were required for early, robust Akt activation. Pharmacological inhibition of PI3K/mTOR in these mice delayed tumor growth and prolonged survival. These results demonstrate that the Pik3ca^H1047R mutation with loss of Pten is enough to promote ovarian cell transformation and that we have developed a model system for studying possible therapies. ]]> info:doi/10.1172/JCI59309 American Society for Clinical Investigation http://www.jci.org/articles/view/58969 info:doi/10.1172/JCI58969 American Society for Clinical Investigation http://www.jci.org/articles/view/46268 info:doi/10.1172/JCI46268 American Society for Clinical Investigation http://www.jci.org/articles/view/61034 + and induced tumor regression in a TLR7/MyD88- and IFNAR1-dependent manner. Lack of TLR7 and IFNAR1 or depletion of pDCs or CD8α⁺ cells from tumor-bearing mice completely abolished the effect of imiquimod. TLR7 was essential for imiquimod-stimulated pDCs to produce IFN-α/β, which led to TRAIL and granzyme B secretion by pDCs via IFNAR1 signaling. Blocking these cytolytic molecules impaired pDC-mediated tumor killing. Our results demonstrate that imiquimod treatment leads to CCL2-dependent recruitment of pDCs and their transformation into a subset of killer DCs able to directly eliminate tumor cells. ]]> info:doi/10.1172/JCI61034 American Society for Clinical Investigation http://www.jci.org/articles/view/43937 info:doi/10.1172/JCI43937 American Society for Clinical Investigation http://www.jci.org/articles/view/58780 CHCHD4 in this context. We found that CHCHD4 encodes 2 alternatively spliced, differentially expressed isoforms (CHCHD4.1 and CHCHD4.2). CHCHD4.1 is identical to MIA40, the homolog of yeast Mia40, a key component of the mitochondrial disulfide relay system that regulates electron transfer to cytochrome c. Further analysis revealed that CHCHD4 proteins contain an evolutionarily conserved coiled-coil-helix-coiled-coil-helix (CHCH) domain important for mitochondrial localization. Modulation of CHCHD4 protein expression in tumor cells regulated cellular oxygen consumption rate and metabolism. Targeting CHCHD4 expression blocked HIF-1α induction and function in hypoxia and resulted in inhibition of tumor growth and angiogenesis in vivo. Overexpression of CHCHD4 proteins in tumor cells enhanced HIF-1α protein stabilization in hypoxic conditions, an effect insensitive to antioxidant treatment. In human cancers, increased CHCHD4 expression was found to correlate with the hypoxia gene expression signature, increasing tumor grade, and reduced patient survival. Thus, our study identifies a mitochondrial mechanism that is critical for regulating the hypoxic response in tumors. ]]> info:doi/10.1172/JCI58780 American Society for Clinical Investigation http://www.jci.org/articles/view/58620 CBX7 gene encodes a polycomb group protein that is known to be downregulated in many types of human cancers, although the role of this protein in carcinogenesis remains unclear. To shed light on this issue, we generated mice null for Cbx7. Mouse embryonic fibroblasts derived from these mice had a higher growth rate and reduced susceptibility to senescence compared with their WT counterparts. This was associated with upregulated expression of multiple cell cycle components, including cyclin E, which is known to play a key role in lung carcinogenesis in humans. Adult Cbx7-KO mice developed liver and lung adenomas and carcinomas. In in vivo and in vitro experiments, we demonstrated that CBX7 bound to the CCNE1 promoter in a complex that included HDAC2 and negatively regulated CCNE1 expression. Finally, we found that the lack of CBX7 protein expression in human lung carcinomas correlated with CCNE1 overexpression. These data suggest that CBX7 is a tumor suppressor and that its loss plays a key role in the pathogenesis of cancer. ]]> info:doi/10.1172/JCI58620 American Society for Clinical Investigation http://www.jci.org/articles/view/45977 + LSCs and leukemia progenitor cells were found to express CD27. Binding of CD27 by its ligand, CD70, increased expression of Wnt target genes in LSCs by enhancing nuclear localization of active β-catenin and TRAF2- and NCK-interacting kinase (TNIK). This resulted in increased proliferation and differentiation of LSCs. Blocking CD27 signaling in LSCs delayed disease progression and prolonged survival. Furthermore, CD27 was expressed on CML stem/progenitor cells in the bone marrow of CML patients, and CD27 signaling promoted growth of BCR/ABL⁺ human leukemia cells by activating the Wnt pathway. Since expression of CD70 is limited to activated lymphocytes and dendritic cells, our results reveal a mechanism by which adaptive immunity contributes to leukemia progression. In addition, targeting CD27 on LSCs may represent an attractive therapeutic approach to blocking the Wnt/β-catenin pathway in CML. ]]> info:doi/10.1172/JCI45977 American Society for Clinical Investigation http://www.jci.org/articles/view/59227 KRAS gene, most commonly KRAS^G12D, that result in a dominant-active form of the KRAS GTPase. However, how KRAS mutations promote pancreatic carcinogenesis is not fully understood, and whether oncogenic KRAS is required for the maintenance of pancreatic cancer has not been established. To address these questions, we generated two mouse models of pancreatic tumorigenesis: mice transgenic for inducible Kras^G12D, which allows for inducible, pancreas-specific, and reversible expression of the oncogenic Kras^G12D, with or without inactivation of one allele of the tumor suppressor gene p53. Here, we report that, early in tumorigenesis, induction of oncogenic Kras^G12D reversibly altered normal epithelial differentiation following tissue damage, leading to precancerous lesions. Inactivation of Kras^G12D in established precursor lesions and during progression to cancer led to regression of the lesions, indicating that Kras^G12D was required for tumor cell survival. Strikingly, during all stages of carcinogenesis, Kras^G12D upregulated Hedgehog signaling, inflammatory pathways, and several pathways known to mediate paracrine interactions between epithelial cells and their surrounding microenvironment, thus promoting formation and maintenance of the fibroinflammatory stroma that plays a pivotal role in pancreatic cancer. Our data establish that epithelial Kras^G12D influences multiple cell types to drive pancreatic tumorigenesis and is essential for tumor maintenance. They also strongly support the notion that inhibiting Kras^G12D, or its downstream effectors, could provide a new approach for the treatment of pancreatic cancer. ]]> info:doi/10.1172/JCI59227 American Society for Clinical Investigation http://www.jci.org/articles/view/60556 + T effector T cells. The HSV-1 proteome was prepared in a flexible format for analyzing both CD8⁺ and CD4⁺ T cells from study participants. Scans with participant-specific panels of artificial APCs identified an oligospecific response in each individual. Parallel CD137-based CD4⁺ T cell research showed discrete oligospecific recognition of HSV-1 antigens. Unexpectedly, the two HSV-1 proteins not previously considered as vaccine candidates elicited both CD8⁺ and CD4⁺ T cell responses in most HSV-1–infected individuals. In this era of microbial genomics, our methods — also demonstrated in principle for vaccinia virus for both CD8⁺ and CD4⁺ T cells — should be broadly applicable to the selection of T cell antigens for inclusion in candidate vaccines for many pathogens. ]]> info:doi/10.1172/JCI60556 American Society for Clinical Investigation http://www.jci.org/articles/view/60070 info:doi/10.1172/JCI60070 American Society for Clinical Investigation http://www.jci.org/articles/view/60214 Ent1^–/– mice. Comprehensive examination of adenosine receptor–knockout mice exposed to AKI demonstrated that renal protection by ENT inhibitors involves the A2B adenosine receptor. Indeed, crosstalk between renal Ent1 and Adora2b expressed on vascular endothelia effectively prevented a postischemic no-reflow phenomenon. These studies identify ENT1 and adenosine receptors as key to the process of reestablishing renal perfusion following ischemic AKI. If translatable from mice to humans, these data have important therapeutic implications. ]]> info:doi/10.1172/JCI60214 American Society for Clinical Investigation http://www.jci.org/articles/view/43027 Ccr5^–/– mice, Ccr5^+/+ BM cells, but not Ccr5^–/– cells, accumulated in the wound site, were incorporated into the vasculature, and restored normal neovascularization. Consistent with these observations, CCL5 induced in vitro EPC migration in a CCR5-dependent manner. Moreover, expression of VEGF and TGF-β was substantially diminished at wound sites in Ccr5^–/– mice, which suggests that EPCs are important not only as the progenitors of endothelial cells, but also as the source of growth factors during tissue repair. Taken together, these data identify the CCL5/CCR5 interaction as what we believe to be a novel molecular target for modulation of neovascularization and eventual tissue repair. ]]> info:doi/10.1172/JCI43027 American Society for Clinical Investigation http://www.jci.org/articles/view/58618 info:doi/10.1172/JCI58618 American Society for Clinical Investigation http://www.jci.org/articles/view/46116 RASA1 mutations cause capillary malformation–arteriovenous malformation (CM-AVM); whether it also functions as a regulator of the lymphatic vasculature is unknown. We investigated this issue using mice in which Rasa1 could be inducibly deleted by administration of tamoxifen. Systemic loss of RASA1 resulted in a lymphatic vessel disorder characterized by extensive lymphatic vessel hyperplasia and leakage and early lethality caused by chylothorax (lymphatic fluid accumulation in the pleural cavity). Lymphatic vessel hyperplasia was a consequence of increased proliferation of lymphatic endothelial cells (LECs) and was also observed in mice in which induced deletion of Rasa1 was restricted to LECs. RASA1-deficient LECs showed evidence of constitutive activation of Ras in situ. Furthermore, in isolated RASA1-deficient LECs, activation of the Ras signaling pathway was prolonged and cellular proliferation was enhanced after ligand binding to different growth factor receptors, including VEGFR-3. Blockade of VEGFR-3 was sufficient to inhibit the development of lymphatic vessel hyperplasia after loss of RASA1 in vivo. These findings reveal a role for RASA1 as a physiological negative regulator of LEC growth that maintains the lymphatic vasculature in a quiescent functional state through its ability to inhibit Ras signal transduction initiated through LEC-expressed growth factor receptors such as VEGFR-3. ]]> info:doi/10.1172/JCI46116 American Society for Clinical Investigation http://www.jci.org/articles/view/58815 info:doi/10.1172/JCI58815 American Society for Clinical Investigation http://www.jci.org/articles/view/57313 E. coli O157:H7, which produces Shiga toxins (Stx) that cause hemolytic anemia, thrombocytopenia, and renal injury. Stx-mediated changes in endothelial phenotype have been linked to the pathogenesis of HUS. Here we report our studies investigating Stx-induced changes in gene expression and their contribution to the pathogenesis of HUS. Stx function by inactivating host ribosomes but can also alter gene expression at concentrations that minimally affect global protein synthesis. Gene expression profiling of human microvascular endothelium treated with Stx implicated a role for activation of CXCR4 and CXCR7 by their shared cognate chemokine ligand (stromal cell–derived factor-1 [SDF-1]) in Stx-mediated pathophysiology. The changes in gene expression required a catalytically active Stx A subunit and were mediated by enhanced transcription and mRNA stability. Stx also enhanced the association of CXCR4, CXCR7, and SDF1 mRNAs with ribosomes. In a mouse model of Stx-mediated pathology, we noted changes in plasma and tissue content of CXCR4, CXCR7, and SDF-1 after Stx exposure. Furthermore, inhibition of the CXCR4/SDF-1 interaction decreased endothelial activation and organ injury and improved animal survival. Finally, in children infected with E. coli O157:H7, plasma SDF-1 levels were elevated in individuals who progressed to HUS. Collectively, these data implicate the CXCR4/CXCR7/SDF-1 pathway in Stx-mediated pathogenesis and suggest novel therapeutic strategies for prevention and/or treatment of complications associated with E. coli O157:H7 infection. ]]> info:doi/10.1172/JCI57313 American Society for Clinical Investigation http://www.jci.org/articles/view/61899 info:doi/10.1172/JCI61899 American Society for Clinical Investigation http://www.jci.org/articles/view/62813 info:doi/10.1172/JCI62813 American Society for Clinical Investigation http://www.jci.org/articles/view/62188 info:doi/10.1172/JCI62188 American Society for Clinical Investigation http://www.jci.org/articles/view/62538 info:doi/10.1172/JCI62538 American Society for Clinical Investigation http://www.jci.org/articles/view/62812 info:doi/10.1172/JCI62812 American Society for Clinical Investigation http://www.jci.org/articles/view/62817 info:doi/10.1172/JCI62817 American Society for Clinical Investigation http://www.jci.org/articles/view/62879 info:doi/10.1172/JCI62879 American Society for Clinical Investigation http://www.jci.org/articles/view/62856 info:doi/10.1172/JCI62856 American Society for Clinical Investigation http://www.jci.org/articles/view/62827 info:doi/10.1172/JCI62827 American Society for Clinical Investigation