Urocortin 3 in obesity and type 2 diabetes : -

Diabesity is a major health burden worldwide, particularly in Kuwait, where several epidemiologic studies reveal the parallel escalation of the prevalence of obesity and diabetes. There is still a lack of complete understanding of the pathways and their interactions triggering the development of obesity-related co-morbidities. Urocortin 3 (UCN3) is a novel neuropeptide implicated in the regulation of food intake, energy homeostasis, cardioprotection, and identified as a regulator of insulin secretion and as a marker for functional pancreatic β-cells. Hence, UCN3 could be a potential therapeutic target for managing metabolic diseases. In this thesis we have assessed UCN3 expression in two cross-sectional populations living in Kuwait: adults with obesity and type 2 diabetes (T2D) and children with overweight and obesity. In addition, we have examined associations of UCN3 with metabolic markers and stressors and assessed the effect of UCN3 overexpression on signaling pathways of insulin, glucose uptake, endoplasmic reticulum (ER) stress, and heat shock response in an adipocyte cell model. In study (I), we investigated the circulating UCN3 levels in the plasma of adults with obesity and T2D. The effect of inflammatory microenvironment in adipose tissue on the expression of UCN3 and the effect of physical exercise training on UCN3 expression was also investigated. We demonstrated that UCN3 expression levels were impaired in response to an inflammatory microenvironment, obesity, and T2D. In study (II), the effect of UCN3 overexpression on apoptotic, ER, and heat-shock stress response pathways was studied in 3T3L1 adipocytes. We showed that the overexpression of UCN3 attenuated markers of apoptosis, inflammation, ER stress, and heat shock response. These events were associated with improved glucose uptake and insulin signaling. We showed that the levels of UCN3 and the other corticotropin-releasing factor (CRF) family are impaired with obesity both in plasma and peripheral blood mononuclear cells obtained from children. In studies (III) and (IV), the circulating levels of UCN3 were assessed in children with different levels of adiposity. Metabolic stressors such as palmitic acid and high glucose concentrations differentially modulated the neuropeptide levels in human monocytic cell line (THP1) cells depending on the duration of the exposure. The homeostasis of energy balance and metabolism is regulated by the central nervous system and peripheral mechanisms. The progression of obesity and T2D is associated with disturbances in this homeostasis, dysregulation of insulin secretion, and alterations in inflammatory and stress response pathways. Most of the thesis findings were shown for the first time and highlighted the role of UCN3 in metabolic dysregulations in obesity and T2D. UCN3 might be a promising marker in future approaches to monitor the progression of obesity, T2D, and related metabolic co-morbidities.Diabetes on merkittävä terveystaakka maailmanlaajuisesti ja erityisesti Kuwaitissa, jossa useat epidemiologiset tutkimukset ovat todenneet lihavuuden ja diabeteksen esiintyvyyden lisääntyvän samanaikaisesti. Tieto lihavuuteen liittyvien sairauksien syntyyn vaikuttavista eri reiteistä sekä niiden vuorovaikutuksista on edelleen puutteellista. Urokortiini 3 (UCN3) on neuropeptidi, joka säätelee ruokailua ja energiatasapainoa sekä suojaa sydäntä. UCN3 säätelee insuliinieritystä ja se on tunnistettu haiman kypsien β-solujen merkkiaineeksi. UCN3 voi olla mahdollinen terapeuttinen kohde hoidettaessa aineenvaihduntasairauksia. Tässä väitöskirjatyössä tutkittin UCN3:n ilmentymistä kahdessa Kuwaitissa asuvassa väestössä: lihavilla ja tyypin 2 diabetesta (T2D) sairastavilla aikuisilla sekä ylipainoisilla ja lihavilla lapsilla. Lisäksi selvitettiin yhteyksiä UCN3:n ja aineenvaihdunnan merkkiaineiden sekä stressitekijöiden välillä. UCN3:n yli-ilmentymisen vaikutusta insuliinin signaalinsiirtoon, glukoosin soluunottoon, endoplasmisen kalvoston stressiin sekä lämpösokkivasteeseen tutkittiin rasvasolumallissa. Tutkimuksessa I tutkimme plasman UCN3 pitoisuuksia lihavilla ja T2D:ta sairastavilla aikuisilla. Tutkimme myös tulehduksellisen mikroympäristön vaikutusta UCN3:n ilmentymiseen sekä liikuntaharjoittelun vaikutusta UCN3:n ilmentymiseen. Osoitimme, että UCN3:n ilmentyminen vähenee vasteena tulehdukselliselle mikroympäristölle, lihavuudelle ja T2D:lle. Liikuntaharjoittelu vaikutti rasvakudoksen UCN3:n ilmentymiseen. Tutkimuksessa II tutkittiin UCN3:n yli-ilmentymisen vaikutusta apoptoosin, endoplasmisen kalvoston stressin sekä lämpösokkivasteen signaalinsiirtoreitteihin 3T3L1-rasvasoluissa. UCN3:n yli-ilmentyminen vähensi apoptoosia, tulehdusta, endoplasmisen kalvoston stressiä sekä lämpösokkivasteen merkkiaineita. Nämä tapahtumat liittyivät parantuneeseen glukoosin soluunottoon ja insuliinin signaalinsiirtoon. Tutkimuksissa III ja IV plasman UCN3 pitoisuuksia arvioitiin ylipainoisilla ja lihavilla lapsilla. Lasten ylipaino ja lihavuus vaikuttivat UCN3:n ja kortikotropiinia vapauttavan tekijän (CRF) ilmentymiseen plasmassa ja perifeerisen veren mononukleaarisoluissa. Metaboliset stressitekijät, kuten palmitaatti ja korkea glukoosipitoisuus, vaikuttivat myös näiden neuropeptidien ilmentymiseen THP1-soluissa altistuksen kestosta riippuvalla tavalla. Sekä keskushermosto että perifeeriset mekanismit säätelevät energiatasapainon ja aineenvaihdunnan homeostaasia. Lihavuuden ja T2D:n eteneminen näyttää liittyvän häiriöihin tässä homeostaasissa, muutoksiin insuliinin erityksessä, sekä poikkeamiin tulehdus- ja stressivasteissa. Väitöskirjatutkimuksessani on useita alkuperäishavaintoja ja se tuo uutta tietoa UCN3:sta lihavuudessa ja T2D:ssa. UCN3 saattaa olla uusi lupaava merkkiaine lihavuuden, T2D:n ja näihin liittyvien sairauksien etenemisen seuraamiseksi

Urocortin 3 overexpression reduces ER stress and heat shock response in 3T3-L1 adipocytes

The neuropeptide urocortin 3 (UCN3) has a beneficial effect on metabolic disorders, such as obesity, diabetes, and cardiovascular disease. It has been reported that UCN3 regulates insulin secretion and is dysregulated with increasing severity of obesity and diabetes. However, its function in the adipose tissue is unclear. We investigated the overexpression of UCN3 in 3T3-L1 preadipocytes and differentiated adipocytes and its effects on heat shock response, ER stress, inflammatory markers, and glucose uptake in the presence of stress-inducing concentrations of palmitic acid (PA). UCN3 overexpression significantly downregulated heat shock proteins (HSP60, HSP72 and HSP90) and ER stress response markers (GRP78, PERK, ATF6, and IRE1 alpha) and attenuated inflammation (TNF alpha) and apoptosis (CHOP). Moreover, enhanced glucose uptake was observed in both preadipocytes and mature adipocytes, which is associated with upregulated phosphorylation of AKT and ERK but reduced p-JNK. Moderate effects of UCN3 overexpression were also observed in the presence of 400 mu M of PA, and macrophage conditioned medium dramatically decreased the UCN3 mRNA levels in differentiated 3T3-L1 cells. In conclusion, the beneficial effects of UCN3 in adipocytes are reflected, at least partially, by the improvement in cellular stress response and glucose uptake and attenuation of inflammation and apoptosis.Peer reviewe

Circulating levels of urocortin neuropeptides are impaired in children with overweight

Objective The corticotropin-releasing factor neuropeptides (corticotropin-releasing hormone [CRH] and urocortin [UCN]-1,2,3) and spexin contribute to the regulation of energy balance and inhibit food intake in mammals. However, the status of these neuropeptides in children with overweight has yet to be elucidated. This study investigated the effect of increased body weight on the circulating levels of these neuropeptides. Methods A total of 120 children with a mean age of 12 years were enrolled in the study. Blood samples were collected to assess the circulating levels of neuropeptides and were correlated with various anthropometric, clinical, and metabolic markers. Results Plasma levels of UCNs were altered in children with overweight but less so in those with obesity. Furthermore, the expression pattern of UCN1 was opposite to that of UCN2 and UCN3, which suggests a compensatory effect. However, no significant effect of overweight and obesity was observed on CRH and spexin levels. Finally, UCN3 independently associated with circulating zinc-alpha-2-glycoprotein and UCN2 levels, whereas UCN1 was strongly predicted by TNF alpha levels. Conclusions Significant changes in neuropeptide levels were primarily observed in children with overweight and were attenuated with increased obesity. This suggests the presence of a compensatory mechanism for neuropeptides to curb the progression of obesity.Peer reviewe

Urocortin 3 Levels Are Impaired in Overweight Humans With and Without Type 2 Diabetes and Modulated by Exercise

Urocortin3 (UCN3) regulates metabolic functions and is involved in cellular stress response. Although UCN3 is expressed in human adipose tissue, the association of UCN3 with obesity and diabetes remains unclear. This study investigated the effects of Type 2 diabetes (T2D) and increased body weight on the circulatory and subcutaneous adipose tissue (SAT) levels of UCN3 and assessed UCN3 modulation by a regular physical exercise. Normal-weight (n = 37) and overweight adults with and without T2D (n = 98 and n = 107, respectively) were enrolled in the study. A subset of the overweight subjects (n = 39 for each group) underwent a supervised 3-month exercise program combining both moderate intensity aerobic exercise and resistance training with treadmill. UCN3 levels in SAT were measured by immunofluorescence and RT-PCR. Circulatory UCN3 in plasma was assessed by ELISA and was correlated with various clinical and metabolic markers. Our data revealed that plasma UCN3 levels decreased in overweight subjects without T2D compared with normal-weight controls [median; 11.99 (0.78–86.07) and 6.27 (0.64–77.04), respectively; p <0.001], whereas plasma UCN3 levels increased with concomitant T2D [median; 9.03 (0.77–104.92) p <0.001]. UCN3 plasma levels were independently associated with glycemic index; fasting plasma glucose and hemoglobin A1c (r = 0.16 and r = 0.20, p <0.05, respectively) and were significantly different between both overweight, with and without T2D, and normal-weight individuals (OR = 2.11 [1.84–4.11, 95% CI] and OR = 2.12 [1.59–3.10, 95% CI], p <0.01, respectively). Conversely, the UCN3 patterns observed in SAT were opposite to those in circulation; UCN3 levels were significantly increased with body weight and decreased with T2D. After a 3-month supervised exercise protocol, UCN3 expression showed a significant reduction in SAT of both overweight groups (2.3 and 1.6-fold change; p <0.01, respectively). In conclusion, UCN levels are differentially dysregulated in obesity in a tissue-dependent manner and can be mitigated by regular moderate physical exercise.Peer reviewe

Urocortin Neuropeptide Levels Are Impaired in the PBMCs of Overweight Children

The corticotropin-releasing hormone (CRH) and urocortins (UCNs) have been implicated in energy homeostasis and the cellular stress response. However, the expression of these neuropeptides in children remains unclear. Therefore, we determined the impact of obesity on their expression in 40 children who were normal weight, overweight, and had obesity. Peripheral blood mononuclear cells (PBMCs) and plasma were used to assess the expression of neuropeptides. THP1 cells were treated with 25 mM glucose and 200 µM palmitate, and gene expression was measured by real-time polymerase chain reaction (RT-PCR). Transcript levels of neuropeptides were decreased in PBMCs from children with increased body mass index as indicated by a significant decrease in UCN1, UCN3, and CRH mRNA in overweight and obese children. UCN3 mRNA expression was strongly correlated with UCN1, UCN2, and CRH. Exposure of THP1 cells to palmitate or a combination of high glucose and palmitate for 24 h increased CRH, UCN2, and UCN3 mRNA expression with concomitant increased levels of inflammatory and endoplasmic reticulum stress markers, suggesting a crosstalk between these neuropeptides and the cellular stress response. The differential impairment of the transcript levels of CRH and UCNs in PBMCs from overweight and obese children highlights their involvement in obesity-related metabolic and cellular stress

Gender-Specific Association of Oxidative Stress and Inflammation with Cardiovascular Risk Factors in Arab Population

Background. The impact of gender difference on the association between metabolic stress and cardiovascular disease (CVD) remains unclear. We have investigated, for the first time, the gender effect on the oxidative and inflammatory stress responses and assessed their correlation with classical cardiometabolites in Arab population. Methods. A total of 378 adult Arab participants (193 females) were enrolled in this cross-sectional study. Plasma levels of CRP, IL-6, IL-8, TNF-α, ROS, TBARs, and PON1 were measured and correlated with anthropometric and cardiometabolite parameters of the study population. Results. Compared to females, males had significantly higher FBG, HbA1c, TG, and blood pressure but lower BMI, TC, and HDL (P < 0.05). After adjustment for BMI and WC, females had higher levels of ROS, TBARS, and CRP (P < 0.001) whereas males had increased levels of IL-8, IL-6, and TNF-α (P < 0.05). Moreover, after adjustment for age, BMI, and gender, the levels of TNF-α, IL-6, and ROS were associated with central obesity but not general obesity. Conclusion. Inflammation and oxidative stress contribution to CVD risk in Arab population linked to gender and this risk is better reflected by central obesity. Arab females might be at risk of CVD complications due to increased oxidative stress