Network-based approach elucidates critical genes in BRCA subtypes and chemotherapy response in triple negative breast cancer.

Breast cancers (BRCA) exhibit substantial transcriptional heterogeneity, posing a significant clinical challenge. The global transcriptional changes in a disease context, however, are likely mediated by few key genes which reflect disease etiology better than the differentially expressed genes (DEGs). We apply our network-based tool PathExt to 1,059 BRCA tumors across 4 subtypes to identify key mediator genes in each subtype. Compared to conventional differential expression analysis, PathExt-identified genes exhibit greater concordance across tumors, revealing shared and subtype-specific biological processes; better recapitulate BRCA-associated genes in multiple benchmarks, and are more essential in BRCA subtype-specific cell lines. Single-cell transcriptomic analysis reveals a subtype-specific distribution of PathExt-identified genes in multiple cell types from the tumor microenvironment. Application of PathExt to a TNBC chemotherapy response dataset identified subtype-specific key genes and biological processes associated with resistance. We described putative drugs that target key genes potentially mediating drug resistance.

Separate gut-brain circuits for fat and sugar reinforcement combine to promote overeating.

Food is a powerful natural reinforcer that guides feeding decisions. The vagus nerve conveys internal sensory information from the gut to the brain about nutritional value; however, the cellular and molecular basis of macronutrient-specific reward circuits is poorly understood. Here, we monitor in vivo calcium dynamics to provide direct evidence of independent vagal sensing pathways for the detection of dietary fats and sugars. Using activity-dependent genetic capture of vagal neurons activated in response to gut infusions of nutrients, we demonstrate the existence of separate gut-brain circuits for fat and sugar sensing that are necessary and sufficient for nutrient-specific reinforcement. Even when controlling for calories, combined activation of fat and sugar circuits increases nigrostriatal dopamine release and overeating compared with fat or sugar alone. This work provides new insights into the complex sensory circuitry that mediates motivated behavior and suggests that a subconscious internal drive to consume obesogenic diets (e.g., those high in both fat and sugar) may impede conscious dieting efforts.

Phase 1/2 Study of the Timing and Efficacy of 3 mg Peg-GCSF in Neo/Adjuvant Dose Dense Breast Cancer Treatment Protocols.

Amol PatelBackground Peg-GCSF has similar efficacy at a dose of 60 µg/kg and 100 µg/kg. The conventional 6 mg SC dose was based on the maximum tolerable dose. In Japan, 3.6 mg dose was approved on the basis of dose finding studies. Peg-GCSF is an integral part of dose-dense chemotherapy protocols. Dose finding and scheduling study of peg-GCSF have not been conducted in Indian patients. Materials and Methods We conducted two-center phase 1/2 clinical study addressing the timing and efficacy of peg-GCSF in Indian breast cancer patients (CTRI no: 2021/07/034751). Three groups of timing administration were studied, namely 1, 6, and 24 hours post chemotherapy. The phase 2 part was the expansion of the best timing group. The primary objective was dose density, which was defined as receiving chemotherapy on < 3 days of scheduled date. Adriamycin/epirubicin cyclophosphamide (AC/EC) was administered q2 weeks. The total leucocyte (TLC) and absolute neutrophil (ANC) kinetics were studied. Other outcomes were incidence of grade 4 neutropenia, febrile neutropenia (FN), and requirement of additional doses of G-CSF. Bone pain, fever, and myalgia were studied for adverse effects. Results From November 20 to December 21, 36 patients were enrolled. Patient characteristics are depicted in Table 1. Initially, three patients received the peg-GCSF in each timing group. One patient in each 1-hour and 6 hours needed G-CSF support for maintaining the dose density. The 24-hour group was carried to phase 2 part. Dose density was maintained in 97% of patients. None of the patient in 24-hour group had FN. Also, 4/30 patients had grade 4 neutropenia and required an additional dose of GCSF. Grade 3 or 4 bone pain was not noticed by any of the patients. During the first cycle, the mean ANC (cells/µL) was 5284, 20704, 3010, 6954 on D0, D + 3, D + 7, and D + 13, respectively (Fig. 1A-TLC and 1B-ANC). The mean ANC (cells/µL) rise on D + 3 in cycles 1, 2, 3, 4 was 23810, 29209, 32428,22455, respectively. Conclusion Dose density of AC/EC breast cancer protocol is maintained with peg-GCSF 3 mg. Post chemotherapy 24-hour timing of peg-GCSF administration remains as the standard. A phase 3 trial of 6 mg versus 3 mg is warranted.

Network-based approach elucidates critical genes in BRCA subtypes and chemotherapy response in Triple Negative Breast Cancer.

Breast cancers exhibit substantial transcriptional heterogeneity, posing a significant challenge to the prediction of treatment response and prognostication of outcomes. Especially, translation of TNBC subtypes to the clinic remains a work in progress, in part because of a lack of clear transcriptional signatures distinguishing the subtypes. Our recent network-based approach, PathExt, demonstrates that global transcriptional changes in a disease context are likely mediated by a small number of key genes, and these mediators may better reflect functional or translationally relevant heterogeneity. We apply PathExt to 1059 BRCA tumors and 112 healthy control samples across 4 subtypes to identify frequent, key-mediator genes in each BRCA subtype. Compared to conventional differential expression analysis, PathExt-identified genes (1) exhibit greater concordance across tumors, revealing shared as well as BRCA subtype-specific biological processes, (2) better recapitulate BRCA-associated genes in multiple benchmarks, and (3) exhibit greater dependency scores in BRCA subtype-specific cancer cell lines. Single cell transcriptomes of BRCA subtype tumors reveal a subtype-specific distribution of PathExt-identified genes in multiple cell types from the tumor microenvironment. Application of PathExt to a TNBC chemotherapy response dataset identified TNBC subtype-specific key genes and biological processes associated with resistance. We described putative drugs that target top novel genes potentially mediating drug resistance. Overall, PathExt applied to breast cancer refines previous views of gene expression heterogeneity and identifies potential mediators of TNBC subtypes, including potential therapeutic targets.

Effect of extrusion processing on techno-functional properties, textural properties, antioxidant activities, in vitro nutrient digestibility and glycemic index of sorghum-chickpea-based extruded snacks.

Physico-chemical, textural, functional, and nutritional properties of the twin screw extruded whole sorghum-chickpea (8:2) snacks was investigated using in vitro procedures. The extruded snacks were analyzed for the effect of variations in extruded conditions on their properties: barrel BT (BT) (130-170°C) and feed moisture (FM) (14%-18%), keeping screw speed constant (400 rpm). The results revealed that specific mechanical energy (SME) decreased (74.4-60.0) in response to rise in both BT and FM, whereas expansion ratio (ER) had shown an alternative relation as it decreased with elevated FM (2.17 at 14%, 130°C to 2.14 at 16%, 130°C) and increased with BT (1.75 at 18%, 130°C to 2.48 at 18%, 170°C). The values of WAI and WSI improved with the surge in BT, which was associated with enhanced disruption of starch granules at higher BT. Raise in FM incremented the total phenolic content (TPC) and hence the antioxidant activity (AA) (FRAP and DPPH) along with the hardness of snacks. As per in vitro starch digestibility is concerned, slowly digestible starch (SDS) content as well as glycemic index (51-53) of the extrudates depressed with increasing BT and FM. Also, lower BT and FM improved the functional properties such as expansion ratio, in-vitro protein digestibility, and overall acceptability of the snacks. A positive correlation was seen among SME and hardness of the snacks, WSI and ER, TPC and AA, SDS and Exp-GI, color and OA, texture and OA.

Physical, morphological and storage stability of clove oil nanoemulsion based delivery system.

Clove oil based Nanoemulsions (NE) were prepared ultrasonically using Tween 80 and soy lecithin as synthetic and natural surfactants, respectively. The developed NEs were characterized for various parameters (particle size, polydispersity index, zeta potential, morphology, viscosity, colour, turbidity and pH) and the comparative effect of both the surfactants at variable levels (oil:tween 80-1:1, 1:2, 1:3 and 1:4 and oil: soy lecithin- 1:1, 1:1.5 and 1:2) was assessed. It was found that the type of surfactant and oil to surfactant ratio significantly affected particle size and stability of NEs. The NE prepared using tween 80 @1:3 had smallest average droplet diameter (40.9 nm). The formulated NEs were stored at 25 °C and 4 °C and analyzed for turbidity, pH and phase separation up to 90 days. Results revealed that the type and concentration of the surfactant significantly influenced the particle size and stability of NEs. NEs prepared using tween 80 were found to be more viscous than those prepared with soy lecithin. The prepared clove oil NEs have important implication to be used as a natural delivery system to increase the shelf life of food products.

Beetroot as a novel ingredient for its versatile food applications.

Beta vulgaris, also known as Beetroot, is a member of a family of Chenopodiaceae and is widely used as a natural food colorant. It gets its distinctive color due to nitrogen-containing water-soluble pigments betalains. Beetroot is an exquisite cradle of nutrients, including proteins, sucrose, carbohydrates, vitamins (B complex and vitamin C), minerals, fiber. They also contain an appreciable amount of phenolic compounds and antioxidants such as coumarins, carotenoids, sesquiterpenoids, triterpenes, flavonoids (astragalin, tiliroside, rhamnocitrin, kaempferol, rhamnetin). Recent studies evidenced that beetroot consumption had favorable physiological benefits, leading to improved cardiovascular diseases, hypertension, diabetes, cancer, hepatic steatosis, liver damage, etc. This review gives insights into developing beetroot as a potential and novel ingredient for versatile food applications and the latest research conducted worldwide. The phytochemical diversity of beetroot makes them potential sources of nutraceutical compounds from which functional foods can be obtained. The article aimed to comprehensively collate some of the vital information published on beetroot incurred in the agri-food sector and a comprehensive review detailing the potentiality of tapping bioactive compounds in the entire agriculture-based food sector.

Broad misappropriation of developmental splicing profile by cancer in multiple organs.

Oncogenesis mimics key aspects of embryonic development. However, the underlying mechanisms are incompletely understood. Here, we demonstrate that the splicing events specifically active during human organogenesis, are broadly reactivated in the organ-specific tumor. Such events are associated with key oncogenic processes and predict proliferation rates in cancer cell lines as well as patient survival. Such events preferentially target nitrosylation and transmembrane-region domains, whose coordinated splicing in multiple genes respectively affect intracellular transport and N-linked glycosylation. We infer critical splicing factors potentially regulating embryonic splicing events and show that such factors are potential oncogenic drivers and are upregulated specifically in malignant cells. Multiple complementary analyses point to MYC and FOXM1 as potential transcriptional regulators of critical splicing factors in brain and liver. Our study provides a comprehensive demonstration of a splicing-mediated link between development and cancer, and suggest anti-cancer targets including splicing events, and their upstream splicing and transcriptional regulators.

MPYS Modulates Fatty Acid Metabolism and Immune Tolerance at Homeostasis Independent of Type I IFNs.

MPYS/STING (stimulator of IFN genes) senses cyclic dinucleotides (CDNs), generates type I IFNs, and plays a critical role in infection, inflammation, and cancer. In this study, analyzing genotype and haplotype data from the 1000 Genomes Project, we found that the R71H-G230A-R293Q (HAQ) MPYS allele frequency increased 57-fold in East Asians compared with sub-Saharan Africans. Meanwhile, the G230A-R293Q (AQ) allele frequency decreased by 98% in East Asians compared with sub-Saharan Africans. We propose that the HAQ and AQ alleles underwent a natural selection during the out-of-Africa migration. We used mouse models of HAQ and AQ to investigate the underlying mechanism. We found that the mice carrying the AQ allele, which disappeared in East Asians, had normal CDN-type I IFN responses. Adult AQ mice, however, had less fat mass than did HAQ or wild-type mice on a chow diet. AQ epididymal adipose tissue had increased regulatory T cells and M2 macrophages with protein expression associated with enhanced fatty acid oxidation. Conditional knockout mice and adoptive cell transfer indicate a macrophage and regulatory T cell-intrinsic role of MPYS in fatty acid metabolism. Mechanistically, AQ/IFNAR1-/- mice had a similar lean phenotype as for the AQ mice. MPYS intrinsic tryptophan fluorescence revealed that the R71H change increased MPYS hydrophilicity. Lastly, we found that the second transmembrane (TM) and the TM2-TM3 linker region of MPYS interact with activated fatty acid, fatty acyl-CoA. In summary, studying the evolution of the human MPYS gene revealed an MPYS function in modulating fatty acid metabolism that may be critical during the out-of-Africa migration.

Shelf life extension of muffins coated with cinnamon and clove oil nanoemulsions.

Clove and cinnamon based nanoemulsions (NE) were prepared with different levels of soy lecithin as a surfactant employing ultrasonication treatment. Increase in surfactant levels decreased the particle size (PS), polydispersity index (PDI) and zeta potential in both the NE. Cinnamon and clove based nanoemulsions were optimized at 1.5 and 2.0% SL, respectively based on their PS and PDI value. Nanoemulsions having the highest thermo stability were further selected to coat the muffin samples. NE Coated and uncoated muffins were evaluated for changes in density, moisture content, water activity, weight loss, texture, antioxidant activity, microbial activity and sensory scores during storage. NE coating significantly increased antioxidant activity of muffins by 26.89% (Cinnamon oil NE) and 37.31% (Clove oil NE). Furthermore during storage, coating of NE maintains the texture of the muffins, reduce the weight loss, density and moisture content to a greater extent in comparison to uncoated muffins. Antioxidant activity and total plate count of clove oil NE coated muffins were significantly higher than cinnamon oil NE coated muffins and while both the NE coating also effectively facilitated in extending the shelf life up to 6 days without any quality deterioration, which facilitated their use as a functional ingredient.

Immune cell gene expression signatures in diffuse glioma are associated with IDH mutation status, patient outcome and malignant cell state, and highlight the importance of specific cell subsets in glioma biology.

The tumor micro-environment (TME) plays an important role in various cancers, including gliomas. We estimated immune cell type-specific gene expression profiles in 3 large clinically annotated glioma datasets using CIBERSORTx and LM22/LM10 blood-based immune signatures and found that the proportions and estimated gene expression patterns of specific immune cells significantly varied according to IDH mutation status. When IDH-WT and IDH-MUT tumors were considered separately, cluster-of-cluster analyses of immune cell gene expression identified groups with distinct survival outcomes. We confirmed and extended these findings by applying a signature matrix derived from single-cell RNA-sequencing data derived from 19 glioma tumor samples to the bulk profiling data, validating findings from the LM22/LM10 results. To link immune cell signatures with outcomes in checkpoint therapy, we then showed a significant association of monocytic lineage cell gene expression clusters with patient survival and with mesenchymal gene expression scores. Integrating immune cell-based gene expression with previously described malignant cell states in glioma demonstrated that macrophage M0 abundance significantly correlated with mesenchymal state in IDH-WT gliomas, with evidence of a previously implicated role of the Oncostatin-M receptor and macrophages in the mesenchymal state. Among IDH-WT tumors that were enriched for the mesenchymal cell state, the estimated M0 macrophage expression signature coordinately also trended to a mesenchymal signature. We also examined IDH-MUT tumors stratified by 1p/19q status, showing that a mesenchymal gene expression signature the M0 macrophage fraction was enriched in IDH-MUT, non-codeleted tumors. Overall, these results highlight the biological and clinical significance of the immune cell environment related to IDH mutation status, patient prognosis and the mesenchymal state in diffuse gliomas.

Prioritizing and characterizing functionally relevant genes across human tissues.

Knowledge of genes that are critical to a tissue's function remains difficult to ascertain and presents a major bottleneck toward a mechanistic understanding of genotype-phenotype links. Here, we present the first machine learning model-FUGUE-combining transcriptional and network features, to predict tissue-relevant genes across 30 human tissues. FUGUE achieves an average cross-validation auROC of 0.86 and auPRC of 0.50 (expected 0.09). In independent datasets, FUGUE accurately distinguishes tissue or cell type-specific genes, significantly outperforming the conventional metric based on tissue-specific expression alone. Comparison of tissue-relevant transcription factors across tissue recapitulate their developmental relationships. Interestingly, the tissue-relevant genes cluster on the genome within topologically associated domains and furthermore, are highly enriched for differentially expressed genes in the corresponding cancer type. We provide the prioritized gene lists in 30 human tissues and an open-source software to prioritize genes in a novel context given multi-sample transcriptomic data.

A Transcriptionally Distinct Subpopulation of Healthy Acinar Cells Exhibit Features of Pancreatic Progenitors and PDAC.

Pancreatic ductal adenocarcinoma (PDAC) tumors can originate either from acinar or ductal cells in the adult pancreas. We re-analyze multiple pancreas and PDAC single-cell RNA-seq datasets and find a subset of nonmalignant acinar cells, which we refer to as acinar edge (AE) cells, whose transcriptomes highly diverge from a typical acinar cell in each dataset. Genes upregulated among AE cells are enriched for transcriptomic signatures of pancreatic progenitors, acinar dedifferentiation, and several oncogenic programs. AE-upregulated genes are upregulated in human PDAC tumors, and consistently, their promoters are hypomethylated. High expression of these genes is associated with poor patient survival. The fraction of AE-like cells increases with age in healthy pancreatic tissue, which is not explained by clonal mutations, thus pointing to a nongenetic source of variation. The fraction of AE-like cells is also significantly higher in human pancreatitis samples. Finally, we find edge-like states in lung, liver, prostate, and colon tissues, suggesting that subpopulations of healthy cells across tissues can exist in pre-neoplastic states. SIGNIFICANCE: These findings show "edge" epithelial cell states with oncogenic transcriptional activity in human organs without oncogenic mutations. In the pancreas, the fraction of acinar cells increases with age.

Demystifying functional role of cocaine- and amphetamine-related transcript (CART) peptide in control of energy homeostasis: A twenty-five year expedition.

Cocaine- and amphetamine-related transcript (CART) is a neuropeptide first discovered in the striatum of the rat brain. Later, the genetic sequence and function of CART peptide (CARTp) was found to be conserved among multiple mammalian species. Over the 25 years, since its discovery, CART mRNA (Cartpt) expression has been reported widely throughout the central and peripheral nervous systems underscoring its role in diverse physiological functions. Here, we review the localization and function of CARTp as it relates to energy homeostasis. We summarize the expression changes of central and peripheral Cartpt in response to metabolic states and make use of available large data sets to gain additional insights into the anatomy of the Cartpt expressing vagal neurons and their expression patterns in the gut. Furthermore, we provide an overview of the role of CARTp as an anorexigenic signal and its effect on energy expenditure and body weight control with insights from both pharmacological and transgenic animal studies. Subsequently, we discuss the role of CARTp in the pathophysiology of obesity and review important new developments towards identifying a candidate receptor for CARTp signalling. Altogether, the field of CARTp research has made rapid and substantial progress recently, and we review the case for considering CARTp as a potential therapeutic target for stemming the obesity epidemic.

Enhancement of Digestibility of Nutrients (In vitro), Antioxidant Potential and Functional Attributes of Wheat Flour Through Grain Germination.

Wheat grains were germinated at different time (12, 24, 36, and 48 h) and temperature (25, 30, and 35°C) to enhance the functionality of resultant flour. Results revealed that an increase in germination time and temperature enhanced the in vitro digestibility of starch (10.35-42.30 %) and proteins (6.31-44.02 %) owing to their depolymerization by hydrolytic enzymes. Total phenolic and flavonoid content of wheat during germination at variable conditions were enhanced significantly (p < 0.05) from 3.62 to 5.54 mg GAE/g and 32.06 to 54.33 mg QE/100 g, respectively. Germination at elevated temperature (35°C) for a prolonged time (48 h) increased the DPPH RSA by 58.85 %, reducing power by 80.40 % and metal chelating activity by 112.26 % as a result of the structural breakdown of bound phenolics. Increased activity of hydrolytic enzymes also results in a continuous reduction in the viscosity and lightness values of wheat flour. Tailored germination, therefore, can be offered as a tool to increase the nutrient digestibility and bioactive potential of wheat thus resulting in producing the naturally modified flour with enhanced functionality.

Cross-species identification of PIP5K1-, splicing- and ubiquitin-related pathways as potential targets for RB1-deficient cells.

The RB1 tumor suppressor is recurrently mutated in a variety of cancers including retinoblastomas, small cell lung cancers, triple-negative breast cancers, prostate cancers, and osteosarcomas. Finding new synthetic lethal (SL) interactions with RB1 could lead to new approaches to treating cancers with inactivated RB1. We identified 95 SL partners of RB1 based on a Drosophila screen for genetic modifiers of the eye phenotype caused by defects in the RB1 ortholog, Rbf1. We validated 38 mammalian orthologs of Rbf1 modifiers as RB1 SL partners in human cancer cell lines with defective RB1 alleles. We further show that for many of the RB1 SL genes validated in human cancer cell lines, low activity of the SL gene in human tumors, when concurrent with low levels of RB1 was associated with improved patient survival. We investigated higher order combinatorial gene interactions by creating a novel Drosophila cancer model with co-occurring Rbf1, Pten and Ras mutations, and found that targeting RB1 SL genes in this background suppressed the dramatic tumor growth and rescued fly survival whilst having minimal effects on wild-type cells. Finally, we found that drugs targeting the identified RB1 interacting genes/pathways, such as UNC3230, PYR-41, TAK-243, isoginkgetin, madrasin, and celastrol also elicit SL in human cancer cell lines. In summary, we identified several high confidence, evolutionarily conserved, novel targets for RB1-deficient cells that may be further adapted for the treatment of human cancer.

Central and peripheral GLP-1 systems independently suppress eating.

The anorexigenic peptide glucagon-like peptide-1 (GLP-1) is secreted from gut enteroendocrine cells and brain preproglucagon (PPG) neurons, which, respectively, define the peripheral and central GLP-1 systems. PPG neurons in the nucleus tractus solitarii (NTS) are widely assumed to link the peripheral and central GLP-1 systems in a unified gut-brain satiation circuit. However, direct evidence for this hypothesis is lacking, and the necessary circuitry remains to be demonstrated. Here we show that PPGNTS neurons encode satiation in mice, consistent with vagal signalling of gastrointestinal distension. However, PPGNTS neurons predominantly receive vagal input from oxytocin-receptor-expressing vagal neurons, rather than those expressing GLP-1 receptors. PPGNTS neurons are not necessary for eating suppression by GLP-1 receptor agonists, and concurrent PPGNTS neuron activation suppresses eating more potently than semaglutide alone. We conclude that central and peripheral GLP-1 systems suppress eating via independent gut-brain circuits, providing a rationale for pharmacological activation of PPGNTS neurons in combination with GLP-1 receptor agonists as an obesity treatment strategy.

Intact vagal gut-brain signalling prevents hyperphagia and excessive weight gain in response to high-fat high-sugar diet.

AIM: The tools that have been used to assess the function of the vagus nerve lack specificity. This could explain discrepancies about the role of vagal gut-brain signalling in long-term control of energy balance. Here we use a validated approach to selectively ablate sensory vagal neurones that innervate the gut to determine the role of vagal gut-brain signalling in the control of food intake, energy expenditure and glucose homoeostasis in response to different diets. METHODS: Rat nodose ganglia were injected bilaterally with either the neurotoxin saporin conjugated to the gastrointestinal hormone cholecystokinin (CCK), or unconjugated saporin as a control. Food intake, body weight, glucose tolerance and energy expenditure were measured in both groups in response to chow or high-fat high-sugar (HFHS) diet. Willingness to work for fat or sugar was assessed by progressive ratio for orally administered solutions, while post-ingestive feedback was tested by measuring food intake after an isocaloric lipid or sucrose pre-load. RESULTS: Vagal deafferentation of the gut increases meal number in lean chow-fed rats. Switching to a HFHS diet exacerbates overeating and body weight gain. The breakpoint for sugar or fat solution did not differ between groups, suggesting that increased palatability may not drive HFHS-induced hyperphagia. Instead, decreased satiation in response to intra-gastric infusion of fat, but not sugar, promotes hyperphagia in CCK-Saporin-treated rats fed with HFHS diet. CONCLUSIONS: We conclude that intact sensory vagal neurones prevent hyperphagia and exacerbation of weight gain in response to a HFHS diet by promoting lipid-mediated satiation.

Blunted Vagal Cocaine- and Amphetamine-Regulated Transcript Promotes Hyperphagia and Weight Gain.

The vagus nerve conveys gastrointestinal cues to the brain to control eating behavior. In obesity, vagally mediated gut-brain signaling is disrupted. Here, we show that the cocaine- and amphetamine-regulated transcript (CART) is a neuropeptide synthesized proportional to the food consumed in vagal afferent neurons (VANs) of chow-fed rats. CART injection into the nucleus tractus solitarii (NTS), the site of vagal afferent central termination, reduces food intake. Conversely, blocking endogenous CART action in the NTS increases food intake in chow-fed rats, and this requires intact VANs. Viral-mediated Cartpt knockdown in VANs increases weight gain and daily food intake via larger meals and faster ingestion rate. In obese rats fed a high-fat, high-sugar diet, meal-induced CART synthesis in VANs is blunted and CART antibody fails to increase food intake. However, CART injection into the NTS retains its anorexigenic effect in obese rats. Restoring disrupted VAN CART signaling in obesity could be a promising therapeutic approach.

Low-Protein Diets with Fixed Carbohydrate Content Promote Hyperphagia and Sympathetically Mediated Increase in Energy Expenditure.

SCOPE: Dietary protein restriction elicits hyperphagia and increases energy expenditure; however, less is known of whether these responses are a consequence of increasing carbohydrate content. The effects of protein-diluted diets with fixed carbohydrate content on energy balance, hormones, and key markers of protein sensing and thermogenesis in tissues are determined. METHODS AND RESULTS: Obesity-prone rats (n = 13-16 per group) are randomized to diets containing fixed carbohydrate (52% calories) and varying protein concentrations: 15% (control), 10% (mild protein restriction), 5% (moderate protein restriction) or 1% (severe protein restriction) protein calories, or protein-matched to 5% protein, for 21 days. Propranolol and ondansetron are administered to interrogate the roles of sympathetic and serotonergic systems, respectively, in diet-induced changes in energy expenditure. It is found that mild-to-moderate protein restriction promotes transient hyperphagia, whereas severe protein restriction induces hypophagia, with alterations in meal patterns. Protein restriction enhances energy expenditure that is partly attenuated by propranolol, but not ondansetron. Moderate to severe protein restriction decreases gains in body weight, lean and fat mass, decreased postprandial glucose and leptin, but increased fibroblast growth factor-21 concentrations. Protein-matching retains lean mass suggesting that intake of dietary protein, but not calories, is important for preserving lean mass. Notably, protein restriction increases the protein and/or transcript abundance of key amino acid sensing molecules in liver and intestine (PERK, eIF2α, ATF2, CHOP, 4EBP1, FGF21), and upregulated thermogenic markers (ß2AR, Klotho, HADH, UCP-1) in brown adipose tissue. CONCLUSION: Low-protein diets promote hyperphagia and sympathetically mediated increase in energy expenditure, prevent gains in tissue reserves, and concurrently upregulate hepatic and intestinal amino acid sensing intermediaries and thermogenic markers in brown adipose tissue.