Apolipoprotein D Transgenic Mice Develop Hepatic Steatosis through Activation of PPARγ and Fatty Acid Uptake

Does glial lipid dysregulation alter sleep in Alzheimer's and Parkinson's disease?

In this opinion article, we discuss potential connections between sleep disturbances observed in Alzheimer's disease (AD) and Parkinson's disease (PD) and the dysregulation of lipids in the brain. Research using Drosophila has highlighted the role of glial-mediated lipid metabolism in sleep and diurnal rhythms. Relevant to AD, the formation of lipid droplets in glia, which occurs in response to elevated neuronal reactive oxygen species (ROS), is required for sleep. In disease models, this process is disrupted, arguing a connection to sleep dysregulation. Relevant to PD, the degradation of neuronally synthesized glucosylceramides by glia requires glucocerebrosidase (GBA, a PD-associated risk factor) and this regulates sleep. Loss of GBA in glia causes an accumulation of glucosylceramides and neurodegeneration. Overall, research primarily using Drosophila has highlighted how dysregulation of glial lipid metabolism may underlie sleep disturbances in neurodegenerative diseases.

Apolipoprotein D in Oxidative Stress and Inflammation

Apolipoprotein D (ApoD) is lipocalin able to bind hydrophobic ligands. The APOD gene is upregulated in a number of pathologies, including Alzheimer's disease, Parkinson's disease, cancer, and hypothyroidism. Upregulation of ApoD is linked to decreased oxidative stress and inflammation in several models, including humans, mice, Drosophila melanogaster and plants. Studies suggest that the mechanism through which ApoD modulates oxidative stress and regulate inflammation is via its capacity to bind arachidonic acid (ARA). This polyunsaturated omega-6 fatty acid can be metabolised to generate large variety of pro-inflammatory mediators. ApoD serves as a sequester, blocking and/or altering arachidonic metabolism. In recent studies of diet-induced obesity, ApoD has been shown to modulate lipid mediators derived from ARA, but also from eicosapentaenoic acid and docosahexaenoic acid in an anti-inflammatory way. High levels of ApoD have also been linked to better metabolic health and inflammatory state in the round ligament of morbidly obese women. Since ApoD expression is upregulated in numerous diseases, it might serve as a therapeutic agent against pathologies aggravated by OS and inflammation such as many obesity comorbidities. This review will present the most recent findings underlying the central role of ApoD in the modulation of both OS and inflammation.

Apolipoprotein D modulates lipid mediators and osteopontin in an anti-inflammatory direction

BACKGROUND

HDL has been proposed to possess anti-inflammatory properties; however, the detail mechanisms have not been fully elucidated.

METHODS

We investigated the roles of Apolipoprotein D (ApoD) in the pathogenesis of inflammation in the mouse model of diet-induced obesity and that of lipopolysaccharide-induced sepsis and the in vitro experiments. Furthermore, we analyzed serum ApoD levels in human subjects.

RESULTS

The overexpression of human ApoD decreased the plasma IL-6 and TNF-a levels in both mice models. Lipidomics analyses demonstrated association of ApoD with increase of arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, as well as of their metabolites, and of the anti-inflammatory molecule sphingosine 1-phosphate, and decrease of proinflammatory lysophosphatidic acids and lysophosphatidylinositol. ApoD-containing lipoproteins might directly bind eicosapentaenoic acid and docosahexaenoic acid. The modulations of the lysophosphatidic acid and sphingosine 1-phosphate levels resulted from the suppression of autotaxin expression and elevation of apolipoprotein M (ApoM), respectively. Moreover, ApoD negatively regulated osteopontin, a proinflammatory adipokine. The activation of PPARg by ApoD might suppress autotaxin and osteopontin. Serum ApoD levels were negatively correlated with the serum osteopontin and autotaxin levels and, positively with serum ApoM levels.

CONCLUSION

ApoD is an anti-inflammatory apolipoprotein, which modulates lipid mediators and osteopontin in an anti-inflammatory direction.

A Short-Term High-Fat Diet Improved the Survival of Fat Grafts in Mice by Promoting Macrophage Infiltration and Angiogenesis

Background: Adipose tissue is an ideal filler material that is widely used for soft tissue defects. But the low survival rate and complications associated with such grafts pose a serious challenge, which limits their clinical application. Adipose tissue is a metabolic diet-responsive tissue; however, the influence of diets on fat grafting remains ambiguous.

Methods: We extracted inguinal fat pads from C57/BL6 male mice, and transplanted them into the dorsal region of recipient mice (0.3 ml). Post-fat-grafting, mice (n = 54) were randomized into three groups, namely normal diet (ND), high carbohydrate diet (HC), and high-fat diet (HF). Structural changes were assessed by histological staining. Lipolysis activity and vascular regeneration of grafts on day 30 were analyzed using real-time polymerase chain reaction, immunofluorescence, and western blotting.

Results: The grafts of mice on HC and HF diets exhibited significantly fewer oil cysts and larger volume retention (0.18 ± 0.01, 0.21 ± 0.01, and 0.25 ± 0.01 ml, for ND, HC, and HF group, respectively, p < 0.05) on day 90. In comparison, grafts for the mice belonging to the HF groups exhibited higher expression of lipolysis-related genes, including adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and carnitine palmitoyltransferase 1 (CPT1), on day 30. Furthermore, increased infiltration of macrophages (F4/80+) and the higher expression of angiogenesis genes were reported in the HF groups.

Conclusion: Altogether, the administration of short-term HF diet remarkably enhanced angiogenesis and improved the quality of fat grafts, which was characterized by fewer oil cysts and higher long-term volume retention. The possible mechanisms may be due to the increased macrophage infiltration, and the promoted angiogenesis in HF grafts.

Induction of lipid metabolism dysfunction, oxidative stress and inflammation response by tris(1-chloro-2-propyl)phosphate in larval/adult zebrafish

As an important organophosphate flame retardant, tris(1-chloro-2-propyl)phosphate (TCPP) is ubiquitous in the environment leading to inevitable human exposure. However, there is a paucity of information regarding its acute/chronic effects on obesity, lipid homeostasis, and hepatocellular carcinoma, especially regarding the underlying molecular mechanisms in humans. Herein, we investigated the effects of TCPP exposure (5-25 mg/L) on lipid homeostasis in larval and adult zebrafish (Danio rerio). TCPP exposure caused remarkable lipid-metabolism dysfunction, which was reflected in obesity and excessive lipid accumulation in zebrafish liver. Mechanistically, TCPP induced the over-expression of adipogenesis genes and suppressed the expression of fatty-acid β-oxidation genes. Consequently, excess lipid synthesis and deficient expenditure triggered oxidative damage and an inflammation response by disrupting the antioxidant system and over-expressing proinflammatory cytokine. Based on high-throughput transcriptome sequencing, we found that TCPP exposure led to enrichment of several pathways involved in lipid metabolism and inflammation, as well as several genes related to pathways of cancer. Notably, increasing expressions of Ki-67 and 53BP1 proteins, which are reliable biomarkers for recognition and risk prediction of cellular proliferation in cancer cells, were observed in liver tissues of adult zebrafish. These results imply that chronic TCPP exposure triggers a potential risk of hepatocellular carcinogenesis (HCC) progression. Collectively, these findings offer new insights into our mechanistic understanding for the health effects of organophosphorus flame retardants on humans.

The Lipocalin Apolipoprotein D Functional Portrait: A Systematic Review

Apolipoprotein D is a chordate gene early originated in the Lipocalin protein family. Among other features, regulation of its expression in a wide variety of disease conditions in humans, as apparently unrelated as neurodegeneration or breast cancer, have called for attention on this gene. Also, its presence in different tissues, from blood to brain, and different subcellular locations, from HDL lipoparticles to the interior of lysosomes or the surface of extracellular vesicles, poses an interesting challenge in deciphering its physiological function: Is ApoD a moonlighting protein, serving different roles in different cellular compartments, tissues, or organisms? Or does it have a unique biochemical mechanism of action that accounts for such apparently diverse roles in different physiological situations? To answer these questions, we have performed a systematic review of all primary publications where ApoD properties have been investigated in chordates. We conclude that ApoD ligand binding in the Lipocalin pocket, combined with an antioxidant activity performed at the rim of the pocket are properties sufficient to explain ApoD association with different lipid-based structures, where its physiological function is better described as lipid-management than by long-range lipid-transport. Controlling the redox state of these lipid structures in particular subcellular locations or extracellular structures, ApoD is able to modulate an enormous array of apparently diverse processes in the organism, both in health and disease. The new picture emerging from these data should help to put the physiological role of ApoD in new contexts and to inspire well-focused future research.

The Role of cAMP-PKA Pathway in Lactate-Induced Intramuscular Triglyceride Accumulation and Mitochondria Content Increase in Mice

The glycolytic product of exercise, lactate, has long been recognized to promote lipid accumulation by activation of G-protein-coupled receptor 81 (GPR81) and inhibition of the cyclic adenosine monophosphate-protein kinase A (cAMP -PKA) pathway in adipose tissue. Whether lactate causes a similar process in skeletal muscle is unclear. Lactate might also improve mitochondria content in skeletal muscle; however, the mechanism is not clarified either. In this study, using intramuscular injection of lactate to the gastrocnemius and intraperitoneal injection of forskolin (activator of cAMP-PKA pathway), we identified the role of the cAMP-PKA pathway in lactate-induced intramuscular triglyceride accumulation and mitochondrial content increase. The intramuscular triglyceride level in the gastrocnemius increased after 5weeks of lactate injection (p<0.05), and this effect was blocked by forskolin injection (p<0.05). Corresponding expression level changes of GPR81, P-PKA/PKA, P-CREB/cAMP-response element binding protein (CREB), and proteins related to lipid metabolism suggest that lactate could induce intramuscular triglyceride accumulation partly through the inhibition of the cAMP-PKA pathway. Meanwhile, the intramuscular expression of citrate synthase (CS) and the activity of CS increased after 5weeks of lactate injection (p<0.05), but the change of CS expression was not blocked by forskolin injection, suggesting other mechanisms might exist. Consequently, exploration for other potential mechanisms that might contribute to the lactate-induced mitochondria content increase was conducted. We found an increase in the contents of lactate-related metabolites in skeletal muscle mitochondria after acute lactate injection (the p-value of each analysis is less than 0.05). LHDA was also validated to exist in mitochondria in this study. These results provide a possibility for metabolism-related mechanisms of lactate-induced mitochondria content increase. Future study is needed to validate this hypothesis. In conclusion, lactate-induced intramuscular triglyceride accumulation is achieved by inhibition of lipolysis, and this process is regulated by the cAMP-PKA pathway. Promoted lipogenesis also contributes to lactate-induced triglyceride accumulation, and this process might also be regulated by the cAMP-PKA pathway. Lactate injection might increase mitochondria content and cAMP-PKA pathway might have a limited contribution, while other metabolism-related mechanisms might play a prominent role.

Adipose-Derived Lipid-Binding Proteins: The Good, the Bad and the Metabolic Diseases

Adipose tissue releases a large range of bioactive factors called adipokines, many of which are involved in inflammation, glucose homeostasis and lipid metabolism. Under pathological conditions such as obesity, most of the adipokines are upregulated and considered as deleterious, due to their pro-inflammatory, pro-atherosclerotic or pro-diabetic properties, while only a few are downregulated and would be designated as beneficial adipokines, thanks to their counteracting properties against the onset of comorbidities. This review focuses on six adipose-derived lipid-binding proteins that have emerged as key factors in the development of obesity and diabetes: Retinol binding protein 4 (RBP4), Fatty acid binding protein 4 (FABP4), Apolipoprotein D (APOD), Lipocalin-2 (LCN2), Lipocalin-14 (LCN14) and Apolipoprotein M (APOM). These proteins share structural homology and capacity to bind small hydrophobic molecules but display opposite effects on glucose and lipid metabolism. RBP4 and FABP4 are positively associated with metabolic syndrome, while APOD and LCN2 are ubiquitously expressed proteins with deleterious or beneficial effects, depending on their anatomical site of expression. LCN14 and APOM have been recently identified as adipokines associated with healthy metabolism. Recent findings on these lipid-binding proteins exhibiting detrimental or protective roles in human and murine metabolism and their involvement in metabolic diseases are also discussed.

The COP9 Signalosome Variant CSNCSN7A Stabilizes the Deubiquitylating Enzyme CYLD Impeding Hepatic Steatosis

Hepatic steatosis is a consequence of distorted lipid storage and plays a vital role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). This study aimed to explore the role of the COP9 signalosome (CSN) in the development of hepatic steatosis and its interplay with the deubiquitylating enzyme (DUB) cylindromatosis (CYLD). CSN occurs as CSNCSN7A and CSNCSN7B variants regulating the ubiquitin proteasome system. It is a deneddylating complex and associates with other DUBs. CYLD cleaves Lys63-ubiquitin chains, regulating a signal cascade that mitigates hepatic steatosis. CSN subunits CSN1 and CSN7B, as well as CYLD, were downregulated with specific siRNA in HepG2 cells and human primary hepatocytes. The same cells were transfected with Flag-CSN7A or Flag-CSN7B for pulldowns. Hepatic steatosis in cell culture was induced by palmitic acid (PA). Downregulation of CSN subunits led to reduced PPAR-γ expression. Flag-pulldowns in both LiSa-2 and HepG2 cells and human primary hepatocytes revealed binding of CYLD preferentially to CSNCSN7A. This was influenced by PA treatment. Silencing of CSNCSN7B blocked lipid droplet formation caused a compensatory increase of CSNCSN7A stabilizing CYLD. Our results demonstrate that CSNCSN7A-mediated CYLD stabilization impedes hepatic steatosis. Therefore, stabilizing CSNCSN7A-CYLD interaction might be a strategy to retard hepatic steatosis.

Cerebral Apolipoprotein D Exits the Brain and Accumulates in Peripheral Tissues

Apolipoprotein D (ApoD) is a secreted lipocalin associated with neuroprotection and lipid metabolism. In rodent, the bulk of its expression occurs in the central nervous system. Despite this, ApoD has profound effects in peripheral tissues, indicating that neural ApoD may reach peripheral organs. We endeavor to determine if cerebral ApoD can reach the circulation and accumulate in peripheral tissues. Three hours was necessary for over 40% of all the radiolabeled human ApoD (hApoD), injected bilaterally, to exit the central nervous system (CNS). Once in circulation, hApoD accumulates mostly in the kidneys/urine, liver, and muscles. Accumulation specificity of hApoD in these tissues was strongly correlated with the expression of lowly glycosylated basigin (BSG, CD147). hApoD was observed to pass through bEnd.3 blood brain barrier endothelial cells monolayers. However, cyclophilin A did not impact hApoD internalization rates in bEnd.3, indicating that ApoD exit from the brain is either independent of BSG or relies on additional cell types. Overall, our data showed that ApoD can quickly and efficiently exit the CNS and reach the liver and kidneys/urine, organs linked to the recycling and excretion of lipids and toxins. This indicated that cerebral overexpression during neurodegenerative episodes may serve to evacuate neurotoxic ApoD ligands from the CNS.

Genome-wide transcriptome study using deep RNA sequencing for myocardial infarction and coronary artery calcification

BACKGROUND

Coronary artery calcification (CAC) is a noninvasive measure of coronary atherosclerosis, the proximal pathophysiology underlying most cases of myocardial infarction (MI). We sought to identify expression signatures of early MI and subclinical atherosclerosis in the Framingham Heart Study (FHS). In this study, we conducted paired-end RNA sequencing on whole blood collected from 198 FHS participants (55 with a history of early MI, 72 with high CAC without prior MI, and 71 controls free of elevated CAC levels or history of MI). We applied DESeq2 to identify coding-genes and long intergenic noncoding RNAs (lincRNAs) differentially expressed in MI and high CAC, respectively, compared with the control.

RESULTS

On average, 150 million paired-end reads were obtained for each sample. At the false discovery rate (FDR) < 0.1, we found 68 coding genes and 2 lincRNAs that were differentially expressed in early MI versus controls. Among them, 60 coding genes were detectable and thus tested in an independent RNA-Seq data of 807 individuals from the Rotterdam Study, and 8 genes were supported by p value and direction of the effect. Immune response, lipid metabolic process, and interferon regulatory factor were enriched in these 68 genes. By contrast, only 3 coding genes and 1 lincRNA were differentially expressed in high CAC versus controls. APOD, encoding a component of high-density lipoprotein, was significantly downregulated in both early MI (FDR = 0.007) and high CAC (FDR = 0.01) compared with controls.

CONCLUSIONS

We identified transcriptomic signatures of early MI that include differentially expressed protein-coding genes and lincRNAs, suggesting important roles for protein-coding genes and lincRNAs in the pathogenesis of MI.

Metabolic syndrome is a predictor of all site and liver-specific recurrence following primary resection of colorectal cancer: Prospective cohort study of 1006 patients

INTRODUCTION

Large epidemiological studies have demonstrated the link between metabolic syndrome and cancer development, including colorectal cancer. However, the influence of metabolic syndrome on disease progression is less well studied, particularly in the post-surgical setting. This study investigates the effect of metabolic syndrome on colorectal cancer recurrence (all-site and liver-specific) after curative surgery for Stage I-III disease.

MATERIALS AND METHODS

Consecutive patients who underwent curative resection for Stage I-III colorectal cancer in a single UK centre were prospectively recruited. Disease-free and overall survival with metabolic syndrome as a factor, were determined using the Kaplan-Meier technique. Hazard ratios for all-site and liver-specific recurrence were determined using univariable and multivariable Cox-regression models.

RESULTS

1006 patients were recruited and followed up for a median of 50 months (IQR 30-67). 177 patients (17.6%) met the criteria for metabolic syndrome. 245 patients (25.4%) developed recurrence, 161 (16.0%) of these had liver recurrence. The presence of metabolic syndrome was associated with a reduction in disease-free survival from 69 to 58 months (p < 0.001) and overall survival from 74 to 61 months (p < 0.001). Metabolic syndrome was an independent predictor of all-site (HR 1.76; p < 0.001) and liver-specific (HR 1.74; p = 0.01) recurrence.

CONCLUSION

Metabolic syndrome is a predictor of all-site and liver-specific recurrence after primary resection of stage I-III colorectal cancer.

Apolipoprotein D

ApoD is a 25 to 30 kDa glycosylated protein, member of the lipocalin superfamily. As a transporter of several small hydrophobic molecules, its known biological functions are mostly associated to lipid metabolism and neuroprotection. ApoD is a multi-ligand, multi-function protein that is involved lipid trafficking, food intake, inflammation, antioxidative response and development and in different types of cancers. An important aspect of ApoD's role in lipid metabolism appears to involve the transport of arachidonic acid, and the modulation of eicosanoid production and delivery in metabolic tissues. ApoD expression in metabolic tissues has been associated positively and negatively with insulin sensitivity and glucose homeostasis in a tissue dependent manner. ApoD levels rise considerably in association with aging and neuropathologies such as Alzheimer's disease, stroke, meningoencephalitis, moto-neuron disease, multiple sclerosis, schizophrenia and Parkinson's disease. ApoD is also modulated in several animal models of nervous system injury/pathology.

Apolipoprotein D overexpression alters hepatic prostaglandin and omega fatty acid metabolism during the development of a non-inflammatory hepatic steatosis

Apolipoprotein D (ApoD) is a secreted lipocalin associated with neuroprotection and lipid metabolism. Overexpression of ApoD in mouse neural tissue induces the development of a non-inflammatory hepatic steatosis in 12-month-old transgenic animals. Previous data indicates that accumulation of arachidonic acid, ApoD's preferential ligand, and overactivation of PPARγ are likely the driving forces in the development of the pathology. However, the lack of inflammation under those conditions is surprising. Hence, we further investigated the apparent repression of inflammation during hepatic steatosis development in aging transgenic animals. The earliest modulation of lipid metabolism and inflammation occurred at 6 months with a transient overexpression of L-PGDS and concomitant overproduction of 15d-PGJ₂, a PPARγ agonist. Hepatic lipid accumulation was detectable as soon as 9 months. Inflammatory polarization balance varied in time, with a robust anti-inflammatory profile at 6 months coinciding with 15d-PGJ₂ overproduction. Omega-3 and omega-6 fatty acids were preferentially stored in the liver of 12-month-old transgenic mice and resulted in a higher omega-3/omega-6 ratio compared to wild type mice of the same age. Thus, inflammation seems to be controlled by several mechanisms in the liver of transgenic mice: first by an increase in 15d-PGJ₂ production and later by a beneficial omega-3/omega-6 ratio. PPARγ seems to play important roles in these processes. The accumulation of several omega fatty acids species in the transgenic mouse liver suggests that ApoD might bind to a broader range of fatty acids than previously thought.

Plant-derived oleanolic acid ameliorates markers associated with non-alcoholic fatty liver disease in a diet-induced pre-diabetes rat model

BACKGROUND

The increased prevalence of non-alcoholic fatty liver disease (NAFLD) in type 2 diabetes mellitus (T2DM) patients is becoming a worldwide health burden. Studies have indicated, however, that the onset of NAFLD occurs during pre-diabetes, a condition that often precedes the onset of T2DM. Oleanolic acid has been reported to improve glucose homeostasis in diet-induced pre-diabetes; however, the effects of this triterpene on liver function have not been evaluated.

PURPOSE

This study was aimed at evaluating the therapeutic effects of oleanolic acid (OA) on selected markers of NAFLD in a pre-diabetes rat model.

METHODS AND MATERIALS

Pre-diabetes was induced by exposing Sprague Dawley rats to a high-fat high-carbohydrate diet for 20 weeks. The pre-diabetic rats were then treated with OA (80 mg/kg) or metformin (500 mg/kg) in the presence and absence of dietary interventions for a period of 12 weeks. The effects of OA were evaluated on parameters including plasma triglycerides (TGs), very low-density lipoprotein (VLDL) particles, bilirubin, AST, ALT, SREBP and antioxidant profile while the livers were collected for histological analysis.

RESULTS

The findings of this study showed that the administration of OA to pre-diabetic rats ameliorated body/liver weights ratio and significantly decreased plasma triglycerides (TGs) and VLDL. Furthermore, OA also ameliorated hepatic oxidative stress, lowered the SREBP expression and intrahepatic TGs. In addition, OA administration decreased plasma concentrations of bilirubin and liver damage enzyme biomarkers.

CONCLUSION

The findings of the study suggest that OA ameliorates the risk of developing pre-diabetes-related NAFLD through the prevention of intrahepatic fat accumulation while also lowering hepatic inflammation.

High ApoD protein level in the round ligament fat depot of severely obese women is associated with an improved inflammatory profile

PURPOSE

Apolipoprotein D (ApoD) is a lipocalin participating in lipid transport. It binds to a variety of ligands, with a higher affinity for arachidonic acid, and is thought to have a diverse array of functions. We investigated a potential role for ApoD in insulin sensitivity, inflammation, and thrombosis-processes related to lipid metabolism-in severely obese women.

METHODS

We measured ApoD expression in a cohort of 44 severely obese women including dysmetabolic and non-dysmetabolic patients. Physical and metabolic characteristics of these women were determined from anthropometric measurements and blood samples. ApoD was quantified at the mRNA and protein levels in samples from three intra-abdominal adipose tissues (AT): omental, mesenteric and round ligament (RL).

RESULTS

ApoD protein levels were highly variable between AT of the same individual. High ApoD protein levels, particularly in the RL depot, were linked to lower plasma insulin levels (-40%, p = 0.015) and insulin resistance (-47%, p = 0.022), and increased insulin sensitivity (+10%, p = 0.008). Lower circulating pro-inflammatory PAI-1 (-39%, p = 0.001), and TNF-α (-19%, p = 0.030) levels were also correlated to high ApoD protein in the RL AT.

CONCLUSIONS

ApoD variability between AT was consistent with different accumulation efficiencies and/or metabolic functions according to the anatomic location of fat depots. Most statistically significant correlations implicated ApoD protein levels, in agreement with protein accumulation in target tissues. These correlations associated higher ApoD levels in fat depots with improved metabolic health in severely obese women.

Elevated HuR in Pancreas Promotes a Pancreatitis-Like Inflammatory Microenvironment That Facilitates Tumor Development

Human antigen R (ELAVL1; HuR) is perhaps the best-characterized RNA-binding protein. Through its overexpression in various tumor types, HuR promotes posttranscriptional regulation of target genes in multiple core signaling pathways associated with tumor progression. The role of HuR overexpression in pancreatic tumorigenesis is unknown and led us to explore the consequences of HuR overexpression using a novel transgenic mouse model that has a >2-fold elevation of pancreatic HuR expression. Histologically, HuR-overexpressing pancreas displays a fibroinflammatory response and other pathological features characteristic of chronic pancreatitis. This pathology is reflected in changes in the pancreatic gene expression profile due, in part, to genes whose expression changes as a consequence of direct binding of their respective mRNAs to HuR. Older mice develop pancreatic steatosis and severe glucose intolerance. Elevated HuR cooperated with mutant K-rasG12D to result in a 3.4-fold increase in pancreatic ductal adenocarcinoma (PDAC) incidence compared to PDAC presence in K-rasG12D alone. These findings implicate HuR as a facilitator of pancreatic tumorigenesis, especially in the setting of inflammation, and a novel therapeutic target for pancreatitis treatment.

A molecular conundrum involving hypothalamic responses to and roles of long non-coding RNAs following food deprivation

Long non-coding RNAs (lncRNAs) are one of most poorly understood RNA classes in the mammalian transcriptome. However, they are emerging as important players in transcriptional regulation, especially within the complexity of the nervous system. This review summarizes the known information about lncRNAs, and their roles in endocrine processes, as well as the lesser-known information about lncRNAs in the brain, and in the neuroendocrine hypothalamus. A "call-to-action" is presented for researchers to use archival transcriptome data to characterize differentially expressed lncRNA species within the hypothalamus. In accordance, we analyze for differential-expression of lncRNA between normal mice and mice with a targeted deletion of the nescient helix-loop-helix 2 gene, and between C57Bl/6 and 129Sv/J mice. Finally, strategies and approaches for researchers to analyze their own datasets or those on the NCBI GEO datasets repository are provided, in hopes that future studies will reveal many new roles for lncRNAs in hypothalamic physiological responses, solving this so-called "molecular conundrum" once and for all.