Hepatic nutrient and hormone signaling to mTORC1 instructs the postnatal metabolic zonation of the liver.

The metabolic functions of the liver are spatially organized in a phenomenon called zonation, linked to the differential exposure of portal and central hepatocytes to nutrient-rich blood. The mTORC1 signaling pathway controls cellular metabolism in response to nutrients and insulin fluctuations. Here we show that simultaneous genetic activation of nutrient and hormone signaling to mTORC1 in hepatocytes results in impaired establishment of postnatal metabolic and zonal identity of hepatocytes. Mutant hepatocytes fail to upregulate postnatally the expression of Frizzled receptors 1 and 8, and show reduced Wnt/ß-catenin activation. This defect, alongside diminished paracrine Wnt2 ligand expression by endothelial cells, underlies impaired postnatal maturation. Impaired zonation is recapitulated in a model of constant supply of nutrients by parenteral nutrition to piglets. Our work shows the role of hepatocyte sensing of fluctuations in nutrients and hormones for triggering a latent metabolic zonation program.

NGFR regulates stromal cell activation in germinal centers.

Nerve growth factor receptor (NGFR) is expressed by follicular dendritic cells (FDCs). However, the role of NGFR in the humoral response is not well defined. Here, we study the effect of Ngfr loss on lymph node organization and function, demonstrating that Ngfr depletion leads to spontaneous germinal center (GC) formation and an expansion of the GC B cell compartment. In accordance with this effect, stromal cells are altered in Ngfr-/- mice with a higher frequency of FDCs, characterized by CD21/35, MAdCAM-1, and VCAM-1 overexpression. GCs are located ectopically in Ngfr-/- mice, with lost polarization together with impaired high-affinity antibody production and an increase in circulating autoantibodies. We observe higher levels of autoantibodies in Bcl2 Tg/Ngfr-/- mice, concomitant with a higher incidence of autoimmunity and lower overall survival. Our work shows that NGFR is involved in maintaining GC structure and function, participating in GC activation, antibody production, and immune tolerance.

Atypical disseminated histiocytic sarcoma in a 7-month-old dog.

A 7-month-old intact female bearded collie dog was admitted after a 2-week history of progressive cough, inappetence, and lethargy, with no response to previous treatment with doxycycline and steroids. Mild attenuation of lung sounds in the right middle hemithorax was the only abnormality detected on physical examination. Abdominal ultrasound and thoracic radiographs were performed and revealed multifocally distributed nodules and masses, well-circumscribed and of variable size in the kidneys and pulmonary parenchyma. Ultrasound-guided fine needle aspirates of the renal and pulmonary masses were taken. A cytologic evaluation of these lesions pointed towards a malignant mesenchymal neoplasia. Euthanasia was elected due to the poor prognosis and rapid progression. The post-mortem histopathology, a positive result to IBA1 immunoperoxidase staining, and a lack of detection of infectious agents, and negative E-cadherin immunostaining enabled the final diagnosis of a disseminated histiocytic sarcoma. We report an atypical form, both in breed and age, of canine disseminated histiocytic sarcoma. While all breeds can be affected, there is a clear predisposition in some, and no cases have been previously described in bearded collies. Moreover, to the authors' knowledge, this is the youngest dog with this histiocytic disorder described to date. Disseminated histiocytic sarcoma should be considered as a differential diagnosis of multinodular tumors in dogs, regardless of the anatomic location and age of the dogs, even in puppies.

Folliculin-interacting protein FNIP2 impacts on overweight and obesity through a polymorphism in a conserved 3' untranslated region.

BACKGROUND: Overweight and obesity are defined by an anomalous or excessive fat accumulation that may compromise health. To find single-nucleotide polymorphisms (SNPs) influencing metabolic phenotypes associated with the obesity state, we analyze multiple anthropometric and clinical parameters in a cohort of 790 healthy volunteers and study potential associations with 48 manually curated SNPs, in metabolic genes functionally associated with the mechanistic target of rapamycin (mTOR) pathway. RESULTS: We identify and validate rs2291007 within a conserved region in the 3'UTR of folliculin-interacting protein FNIP2 that correlates with multiple leanness parameters. The T-to-C variant represents the major allele in Europeans and disrupts an ancestral target sequence of the miRNA miR-181b-5p, thus resulting in increased FNIP2 mRNA levels in cancer cell lines and in peripheral blood from carriers of the C allele. Because the miRNA binding site is conserved across vertebrates, we engineered the T-to-C substitution in the endogenous Fnip2 allele in mice. Primary cells derived from Fnip2 C/C mice show increased mRNA stability, and more importantly, Fnip2 C/C mice replicate the decreased adiposity and increased leanness observed in human volunteers. Finally, expression levels of FNIP2 in both human samples and mice negatively associate with leanness parameters, and moreover, are the most important contributor in a multifactorial model of body mass index prediction. CONCLUSIONS: We propose that rs2291007 influences human leanness through an evolutionarily conserved modulation of FNIP2 mRNA levels.

Performance of the Sysmex XN-V body fluid module for canine cerebrospinal fluid cell count.

BACKGROUND: Microscopic cell counts and nucleated cell identification are the "gold standard" for cerebrospinal fluid (CSF) assessments and are labor intensive and subject to operator variability. The use of automated methods could be an alternative to the current manual technique. OBJECTIVES: We aimed to assess the utility of the Sysmex XN-V body fluid (BF) module analyzer to count and differentiate nucleated cells in canine CSF and evaluate the accuracy and correlation between this and the manual method. METHODS: We prospectively analyzed 150 CSF samples from dogs using the Sysmex XN-V BF module and compared the results with those obtained using the manual counting method. We also evaluated the linearity, detection limits, and imprecision of the Sysmex XN-V BF module. RESULTS: The Sysmex XN-V BF module analyzer performance had a sensitivity of 92.59% and specificity of 94.30%. The lower limit of quantification for the total nucleated cell count (TNCC) was 0 cells/µL. A Pearson´s correlation coefficient of 0.945 was found between both methods for TNCC, with 0.997 and 0.940 for samples with TNCC >10 cells/µL and TNCC >5 cells/µL, respectively. The correlation coefficient for the mononuclear and polymorphonuclear differential cell count was -0.031 and -0.019, respectively, and it was 0.576 for the RBC count. CONCLUSIONS: The Sysmex XN-V BF module provides reliable TNCCs for canine CSF, even for samples with low cell numbers, but manual cytologic evaluation is still needed for differential cell counts.

Comparison of the use of a standard cytology brush versus a mini cytology brush to obtain conjunctival samples for cytologic examination in healthy dogs.

OBJECTIVE: To compare the quality of conjunctival samples for cytologic examination obtained with 2 conjunctival exfoliative brushes, a mini cytology brush (MCB) and a standard cytology brush (SCB), in healthy dogs. ANIMALS: 20 client-owned dogs that were free of ocular disease. PROCEDURES: A prospective single-center randomized trial was performed. For each dog, conjunctival samples of the right eye were obtained with the 2 brushes (ie, SCB or MCB) at 2 time points that were 5 to 11 days apart. The left eye was used as a control. Cytologic quality of conjunctival samples was scored on the basis of cellularity, clearness of background, uniformity of distribution of cells on the cytology slide, artifacts, cellular overlapping, cell preservation, presence of mucus on the cytology slide, and number of RBCs. RESULTS: On cytologic evaluation, conjunctival samples collected with an SCB scored significantly better in terms of higher cellularity, less background debris, and more uniformity in the distribution of cells, compared with conjunctival samples collected with an MCB. Conjunctival samples collected with an MCB scored significantly better in terms of less cellular overlapping and less mucus in the background, compared with conjunctival samples collected with an SCB. CONCLUSIONS AND CLINICAL RELEVANCE: Overall conjunctival samples obtained with an SCB for cytologic evaluation had better diagnostic quality, compared with conjunctival samples obtained with an MCB. Use of an MCB, however, was advantageous to access localized conjunctival areas as well as collect conjunctival samples from patients with small palpebral fissures.

Inhibition of Rag GTPase signaling in mice suppresses B cell responses and lymphomagenesis with minimal detrimental trade-offs.

B lymphocytes are exquisitely sensitive to fluctuations in nutrient signaling by the Rag GTPases, and 15% of follicular lymphomas (FLs) harbor activating mutations in RRAGC. Hence, a potential therapeutic approach against malignant B cells is to inhibit Rag GTPase signaling, but because such inhibitors are still to be developed, efficacy and safety remain unknown. We generated knockin mice expressing a hypomorphic variant of RagC (Q119L); RagCQ119L/+ mice are viable and show attenuated nutrient signaling. B lymphocyte activation is cell-intrinsically impaired in RagCQ119L/+ mice, which also show significant suppression of genetically induced lymphomagenesis and autoimmunity. Surprisingly, no overt systemic trade-offs or phenotypic alterations caused by partial suppression of nutrient signaling are seen in other organs, and RagCQ119L/+ mice show normal longevity and normal age-dependent health decline. These results support the efficacy and safety of moderate inhibition of nutrient signaling against pathological B cells.

Diagnostic imaging and pathological findings of an abdominal mesenteric granular cell tumour in a dog.

A 12-year-old mixed-breed dog was presented for a follow-up examination after ablation of an auricular mast cell tumour. An abdominal ultrasound and computed tomography were performed and an irregular, ill-defined and partially mineralised lesion was observed around the caudal duodenal flexure without evidence of metastasis. The cytologic examination was highly suggestive of a granular cell tumour. Partial surgical ablation with histological and immunohistochemical examination of the lesion confirmed the diagnosis. According to our review of the literature, this is the first report documenting an abdominal granular cell tumour in a dog.

Oncogenic Rag GTPase signaling enhances B cell activation and drives follicular lymphoma sensitive to pharmacological inhibition of mTOR.

The humoral immune response demands that B cells undergo a sudden anabolic shift and high cellular nutrient levels which are required to sustain the subsequent proliferative burst. Follicular lymphoma (FL) originates from B cells that have participated in the humoral response, and 15% of FL samples harbor point, activating mutations in RRAGC, an essential activator of mTORC1 downstream of the sensing of cellular nutrients. The impact of recurrent RRAGC mutations in B cell function and lymphoma is unexplored. RRAGC mutations, targeted to the endogenous locus in mice, confer a partial insensitivity to nutrient deprivation, but strongly exacerbate B cell responses and accelerate lymphomagenesis, while creating a selective vulnerability to pharmacological inhibition of mTORC1. This moderate increase in nutrient signaling synergizes with paracrine cues from the supportive T cell microenvironment that activates B cells via the PI3K-Akt-mTORC1 axis. Hence, Rragc mutations sustain induced germinal centers and murine and human FL in the presence of decreased T cell help. Our results support a model in which activating mutations in the nutrient signaling pathway foster lymphomagenesis by corrupting a nutrient-dependent control over paracrine signals from the T cell microenvironment.

IntOGen-mutations identifies cancer drivers across tumor types.

The IntOGen-mutations platform (http://www.intogen.org/mutations/) summarizes somatic mutations, genes and pathways involved in tumorigenesis. It identifies and visualizes cancer drivers, analyzing 4,623 exomes from 13 cancer sites. It provides support to cancer researchers, aids the identification of drivers across tumor cohorts and helps rank mutations for better clinical decision-making.

The mutational landscape of chromatin regulatory factors across 4,623 tumor samples.

BACKGROUND: Chromatin regulatory factors are emerging as important genes in cancer development and are regarded as interesting candidates for novel targets for cancer treatment. However, we lack a comprehensive understanding of the role of this group of genes in different cancer types. RESULTS: We have analyzed 4,623 tumor samples from thirteen anatomical sites to determine which chromatin regulatory factors are candidate drivers in these different sites. We identify 34 chromatin regulatory factors that are likely drivers in tumors from at least one site, all with relatively low mutational frequency. We also analyze the relative importance of mutations in this group of genes for the development of tumorigenesis in each site, and indifferent tumor types from the same site. CONCLUSIONS: We find that, although tumors from all thirteen sites show mutations in likely driver chromatin regulatory factors, these are more prevalent in tumors arising from certain tissues. With the exception of hematopoietic, liver and kidney tumors, as a median, the mutated factors are less than one fifth of all mutated drivers across all sites analyzed. We also show that mutations in two of these genes, MLL and EP300, correlate with broad expression changes across cancer cell lines, thus presenting at least one mechanism through which these mutations could contribute to tumorigenesis in cells of the corresponding tissues.

Expression of polycomb targets predicts breast cancer prognosis.

Global changes in the epigenome are increasingly being appreciated as key events in cancer progression. The pathogenic role of enhancer of zeste homolog 2 (EZH2) has been connected to its histone 3 lysine 27 (H3K27) methyltransferase activity and gene repression; however, little is known about relationship of changes in expression of EZH2 target genes to cancer characteristics and patient prognosis. Here we show that through expression analysis of genomic regions with H3K27 trimethylation (H3K27me3) and EZH2 binding, breast cancer patients can be stratified into good and poor prognostic groups independent of known cancer gene signatures. The EZH2-bound regions were downregulated in tumors characterized by aggressive behavior, high expression of cell cycle genes, and low expression of developmental and cell adhesion genes. Depletion of EZH2 in breast cancer cells significantly increased expression of the top altered genes, decreased proliferation, and improved cell adhesion, indicating a critical role played by EZH2 in determining the cancer phenotype.

Inhibition of specific NF-κB activity contributes to the tumor suppressor function of 14-3-3σ in breast cancer.

14-3-3σ is frequently lost in human breast cancers by genetic deletion or promoter methylation. We have now investigated the involvement of 14-3-3σ in the termination of NF-κB signal in mammary cells and its putative role in cancer relapse and metastasis. Our results show that 14-3-3σ regulates nuclear export of p65-NF-κB following chronic TNFα stimulation. Restoration of 14-3-3σ in breast cancer cells reduces migration capacity and metastatic abilities in vivo. By microarray analysis, we have identified a genetic signature that responds to TNFα in a 14-3-3σ-dependent manner and significantly associates with different breast and other types of cancer. By interrogating public databases, we have found that over-expression of this signature correlates with poor relapse-free survival in breast cancer patients. Finally, screening of 96 human breast tumors showed that NF-κB activation strictly correlates with the absence of 14-3-3σ and it is significantly associated with worse prognosis in the multivariate analysis. Our findings identify a genetic signature that is important for breast cancer prognosis and for future personalized treatments based on NF-κB targeting.