Prep1 Controls Insulin Glucoregulatory Function in Liver by Transcriptional Targeting of SHP1 Tyrosine Phosphatase

AbstractObjective. We have investigated the function of the Prep1 gene in insulin-dependent glucose homeostasis in liver. Research design and methods. Prep1 action on insulin glucoregulatory function has been analyzed in liver of Prep1-hypomorphic mice (Prep1(i/i)), which express 2 to 3% of Prep1 mRNA. Results. Based on euglycemic hyperinsulinemic clamp studies, pyruvate tolerance tests and measurement of glycogen content, livers from Prep1(i/i) mice feature increased sensitivity to insulin. Tyrosine phosphorylation of both insulin receptor (IR) and IRS1/2 was significantly enhanced in Prep1(i/i) livers accompanied by a specific down-regulation of the SYP and SHP1 tyrosine phosphatases. Prep1 overexpression in HepG2 liver cells upregulated SYP and SHP1 and inhibited insulin-induced IR and IRS1/2 phosphorylation and was accompanied by reduced glycogen content. Consistently, overexpression of the Prep1 partner Pbx1 but not of p160MBP, mimicked Prep1 effects on tyrosine phosphorylations, glycogen content and on SYP and SHP1 expression. In Prep1 overexpressing cells, antisense silencing of SHP1, but not that of SYP, rescued insulin-dependent IR phosphorylation and glycogen accumulation. Both Prep1 and Pbx1 bind SHP1 promoter at a site located between nt -2113 and -1778. This fragment features enhancer activity and induces luciferase function by 7, 6 and 30-fold, respectively, in response to Prep1, Pbx1 or both. Conclusions. SHP1, a known silencer of insulin signal, is a transcriptional target of Prep1. In liver, transcriptional activation of SHP1 gene by Prep1 attenuates insulin signal transduction and reduces glucose storage

Regulation of hepatic lipogenesis by the transcription complex Prep1-Pbx1

Prep1 is an homeodomain transcription factor belonging to the TALE proteins, including also Pbx1, which plays an essential role in hematopoiesis, organogenesis and development. Prep1 forms transcriptionally active complexes with Pbx1 and regulates the activity of several genes. The Prep1 null mutation leads to embryonic death at a very early stage. Therefore, Prep1 hypomorphic (Prep1i/i) mice have been generated. Prep1 heterozygous (Prep1i/+) mice, which express only 55-57% of protein, have a complex metabolic phenotype with at least two relevant features. One is the presence of smaller but otherwise normally structured islets with reduced fasting and post-loading plasma insulin levels. The second is increased insulin sensitivity in skeletal muscle and in liver which is accompanied by protection from streptozotocin-induced diabetes. In muscle, decreased Prep1 levels are followed by an increase of the PGC1alpha/Glut4-mediated glucose uptake. In liver, better insulin sensitivity is due to a reduced SHP1 tyrosine phosphatase expression followed by an increase of insulin signaling. Also, triglyceride levels are significantly reduced in the liver of Prep1i/+ mice. However, the molecular mechanism by which Prep1 controls lipogenesis is unclear. In this study, we have focused our attention on the role of Prep1 on the regulation of the triglyceride synthesis. To study the lipogenesis in the liver of the Prep1 heterozygous mice, we have examined the expression of the lipogenetic enzyme FAS (Fatty Acid Synthase) by real-time RT-PCR analysis. Hepatic expression of FAS is significantly decreased. Western Blot analysis have shown increased phosphorylation of PKCzeta, LKB1, AMPK and ACC, which may control FAS expression and triglycerides production in Prep1i/+ mice liver. Protein and mRNA levels of the lipid phosphatase SHIP2, an inhibitor of PI3Kinase/PKCzeta signaling, are reduced by 40% in the liver of Prep1i/+ mice. Consistent with these data, HepG2 (Human Hepatocarcinoma cell line) cells overexpressing Prep1 display increased triglyceride levels and FAS expression, while PKCzeta, LKB1, AMPK and ACC phosphorylation is strongly reduced. Moreover, SHIP2 levels are increased by 50%. Interestingly, overexpression of Pbx1 cDNA in HepG2 cells mimicked Prep1-induced triglyceride synthesis. At the opposite, Prep1HR1 mutant, which is unable to bind Pbx1, fails to elicit these effects. ChIP and Re-ChIP experiments indicate that Prep1/Pbx1 complex can bind SHIP2 promoter region and regulate its expression. These data suggest that Prep1/Pbx1 dimer regulates hepatic triglycerides production by increasing SHIP2 levels and thereby inhibiting the PKCzeta/AMPK signaling

Prep1 Deficiency Affects Olfactory Perception and Feeding Behavior by Impairing BDNF-TrkB Mediated Neurotrophic Signaling

Prep1 is a homeodomain transcription factor which has an important role in hindbrain development. Prep1 expression is also kept in adult mouse brain and in particular within the olfactory bulbs. Moreover, many Prep1 neurons co-localize with Calbindin-positive periglomerular interneurons in olfactory glomerular layer. However, Prep1 function in this brain region is still unknown. In this study, we show that Prep1 hypomorphic heterozygous (Prep1i/+) mice express low levels of protein and feature a 30% reduction of olfactory bulb area, compared to WT mice. In addition, Prep1i/+ mice olfactory bulb histological analysis indicated a 20% lower cytochrome C oxidase activity within the glomerular layer, accompanied by a reduced number of periglomerular interneurons, compared to the WT littermates. Consistently, olfactory perception test highlighted that Prep1 hypomorphic heterozygous mice display a scant ability to distinguish odors, which significantly impacts on feeding behavior, as Prep1i/+ mice revealed a reduced preference for high-fat food. Analysis of BDNF signaling, which represents the main molecular mediator of olfactory plasticity, showed that Prep1i/+ mouse olfactory bulbs feature a 30% reduction of TrkB receptor levels and a decreased activation of ERK1/2. Similarly, overexpression of Prep1 in mouse neuronal cells (N2A) caused an increase of TrkB expression levels, BDNF-induced ERK phosphorylation, and cell viability, compared to control cells. We conclude that Prep1 deficiency alters olfactory morpho-functional integrity and olfaction-mediated eating behavior by affecting BDNF-TrkB signaling. Prep1 could, therefore, play a crucial role in behavioral dysfunctions associated to impaired responsiveness to BDNF

Prep1, A Homeodomain Transcription Factor Involved in Glucose and Lipid Metabolism

The three-amino acid loop extension (TALE) homeodomain proteins are a family of transcription factor including the mammalian Pbx, MEIS and Prep proteins. TALE proteins can bind other transcription factors such as Pdx-1 and play an important role in the regulation of glucose metabolism. Experiments performed in mutant mice have shown that while the single Pbx1 or Pdx-1 knockout mice feature pancreatic islet malformations, impaired glucose tolerance and hypoinsulinemia, the trans-heterozygous Pbx1+/-Pdx1+/- mice develop age-dependent overt diabetes mellitus. In contrast, Prep1 plays a different role with respect to these proteins. Indeed, Prep1 hypomorphic mice, expressing low levels of protein, feature pancreatic islet hypoplasia accompanied by hypoinsulinemia similar to Pbx1 or Pdx1. Nevertheless, these animals show increased insulin sensitivity in skeletal muscle, liver and adipose tissue accompanied by protection from streptozotocin-induced diabetes. In addition, Prep1 hypomorphic mice feature reduced triglyceride synthesis and do not develop steatohepatitis after a methionine and coline deficient diet. In this review we have underlined how important metabolic functions are controlled by TALE proteins, in particular by Prep1, leading to hypothesis that its suppression might represent beneficial effect in the care of metabolic diseases

SARS-CoV-2 Affects Both Humans and Animals: What Is the Potential Transmission Risk? A Literature Review

In March 2020, the World Health Organization Department declared the coronavirus (COVID-19) outbreak a global pandemic, as a consequence of its rapid spread on all continents. The COVID-19 pandemic has been not only a health emergency but also a serious general problem as fear of contagion and severe restrictions put economic and social activity on hold in many countries. Considering the close link between human and animal health, COVID-19 might infect wild and companion animals, and spawn dangerous viral mutants that could jump back and pose an ulterior threat to us. The purpose of this review is to provide an overview of the pandemic, with a particular focus on the clinical manifestations in humans and animals, the different diagnosis methods, the potential transmission risks, and their potential direct impact on the human–animal relationship

Vitamin D Deficiency in a Cohort of Neapolitan Pregnant Women: Do We Really Live in the City of the Sun?

Background: Insufficient serum 25-hydroxyvitamin D [25(OH)D] levels are a global public health issue, and pregnant women are a significant at-risk group. We aimed to assess maternal serum 25(OH)D concentrations in a cohort of Neapolitan pregnant women and the association with dietary habits, to define which patients are at increased risk of hypovitaminosis and how we can identify them. Methods: This was a prospective observational study. We included 103 pregnant women attending a routine third trimester obstetric examination. Information on obstetrical history and socio-demographic characteristics were obtained through interviews and medical records. Vitamin D intake was assessed using a food frequency questionnaire. Serum 25(OH)D concentration was measured by DiaSorin Liaison and the cut-off value for deficiency was set at 20 ng/mL. Results: Among the 103 pregnant women recruited, 71 (68.9%) were Vitamin D deficient (mean value 12.6 +/- 0.5 ng/mL). No statistically significant differences were found between the women involved in the study for: maternal age, pre-pregnancy body mass index (BMI), gestational weight gain, and gestational age at investigation. Women with hypovitaminosis reported a significantly lower intake of milk/yoghurt, cheeses/dairy products and fish. Maternal hypovitaminosis D significantly correlated with low birth weight. Conclusions: Our study confirms that Vitamin D deficiency is a common finding also in sunny areas. Patients with low level of Vitamin D reported a lower intake of food rich of this micronutrient. An accurate anamnesis can be an easy way to identify pregnant women at risk of hypovitaminosis D for whom screening and supplementation can be suitable

miR-214-Dependent Increase of PHLPP2 Levels Mediates the Impairment of Insulin-Stimulated Akt Activation in Mouse Aortic Endothelial Cells Exposed to Methylglyoxal

Evidence has been provided linking microRNAs (miRNAs) and diabetic complications, by the regulation of molecular pathways, including insulin-signaling, involved in the pathophysiology of vascular dysfunction. Methylglyoxal (MGO) accumulates in diabetes and is associated with cardiovascular complications. This study aims to analyze the contribution of miRNAs in the MGO-induced damaging effect on insulin responsiveness in mouse aortic endothelial cells (MAECs). miRNA modulation was performed by transfection of specific miRNA mimics and inhibitors in MAECs, treated or not with MGO. miRNA-target protein levels were evaluated by Western blot. PH domain leucine-rich repeat protein phosphatase 2 (PHLPP2) regulation by miR-214 was tested by luciferase assays and by the use of a target protector specific for miR-214 on PHLPP2-3′UTR. This study reveals a 4-fold increase of PHLPP2 in MGO-treated MAECs. PHLPP2 levels inversely correlate with miR-214 modulation. Moreover, miR-214 overexpression is able to reduce PHLPP2 levels in MGO-treated MAECs. Interestingly, a direct regulation of PHLPP2 is proved to be dependent by miR-214. Finally, the inhibition of miR-214 impairs the insulin-dependent Akt activation, while its overexpression rescues the insulin effect on Akt activation in MGO-treated MAECs. In conclusion, this study shows that PHLPP2 is a target of miR-214 in MAECs, and identifies miR-214 downregulation as a contributing factor to MGO-induced endothelial insulin-resistance

Differences in Metabolic Factors Between Antipsychotic-Induced Weight Gain and Non-pharmacological Obesity in Youths

Background: Youth exposed to antipsychotics may experience several metabolic consequences that often limit the effectiveness of this class of drugs. Objectives: The aim of this study was to compare several metabolic markers between subjects who experienced antipsychotic-induced weight gain and untreated obese patients. Methods: Nineteen non-diabetic youth (mean age 159 months, mean body mass index z-score 1.81) experiencing antipsychotic-induced weight gain and an age-, sex-, and body mass index-matched group of non-diabetic obese patients with no record of treatment (n = 19, mean age 147 months, mean body mass index z-score 2) were compared for a wide range of metabolic factors using a Bioplex Multiplex system. Results: C-peptide, glucose-dependent insulinotropic polypeptide, and adipsin were significantly higher in the antipsychotic-induced weight gain group, whereas visfatin was significantly higher in the untreated obese patients. When age, sex, pubertal status, and body mass index were controlled, C-peptide, glucose-dependent insulinotropic polypeptide, and visfatin remained significant, whereas adipsin fell slightly below the threshold of statistical significance. No other statistically significant difference emerged. Conclusions: Antipsychotic-induced weight gain and untreated obesity showed some similarities, confirming that levels of some hormones, such as leptin and ghrelin, are related to body mass index rather than to antipsychotic exposure. Some differences were also noted; for example, the antipsychotic-induced weight gain group displayed higher C-peptide, glucose-dependent insulinotropic polypeptide, and adipsin, which may reflect β-cell stress and may suggest susceptibility to insulin resistance and lower visfatin, possibly indicating a lower inflammatory status

Caulerpin Mitigates Helicobacter pylori-Induced Inflammation via Formyl Peptide Receptors

The identification of novel strategies to control Helicobacter pylori (Hp)-associated chronic inflammation is, at present, a considerable challenge. Here, we attempt to combat this issue by modulating the innate immune response, targeting formyl peptide receptors (FPRs), G-protein coupled receptors that play key roles in both the regulation and the resolution of the innate inflammatory response. Specifically, we investigated, in vitro, whether Caulerpin—a bis-indole alkaloid isolated from algae of the genus Caulerpa—could act as a molecular antagonist scaffold of FPRs. We showed that Caulerpin significantly reduces the immune response against Hp culture filtrate, by reverting the FPR2-related signaling cascade and thus counteracting the inflammatory reaction triggered by Hp peptide Hp(2–20). Our study suggests Caulerpin to be a promising therapeutic or adjuvant agent for the attenuation of inflammation triggered by Hp infection, as well as its related adverse clinical outcomes