Behazun-gatzen garraioaren fisiologia

Heste mehera isurtzen diren behazun-gatzek lipidoen digestioan eta xurgapenean laguntzen dute. Behazun-gatzak hepatozitoek sintetizatzen dituzte kolesterola erabiliz; beren izaera anfipatikoa eta egitura molekularra direla-eta, detergente gisa jokatzen dute, eta beraz toxikoak izan daitezke kontzentrazio handietan. Hori horrela izanda, beren sintesia eta garraioa oso modu finean erregulatu behar dira, bai gibelean bai behazun-gatzen garraioan parte hartzen duten beste ehunetan. Lan honetan gainbegirada bat egin diegu behazun-gatzen metabolismoari eta garraio-prozesuei, azken hauen transkripzio mailako kontrolari buruz argitaratu diren azken lanak ere bilduz

Fat: Quality, or Quantity? What Matters Most for the Progression of Metabolic Associated Fatty Liver Disease (MAFLD)

Fibrosi; Obesitat; Àcid palmític (AP)Fibrosis; Obesidad; Ácido palmítico (AP)Fibrosis; Obesity; Palmitic acid (PA)Objectives: Lately, many countries have restricted or even banned transfat, and palm oil has become a preferred replacement for food manufacturers. Whether palm oil is potentially an unhealthy food mainly due to its high content of saturated Palmitic Acid (PA) is a matter of debate. The aim of this study was to test whether qualitative aspects of diet such as levels of PA and the fat source are risk factors for Metabolic Syndrome (MS) and Metabolic Associated Fatty Liver Disease (MAFLD). Methods: C57BL/6 male mice were fed for 14 weeks with three types of Western diet (WD): 1. LP-WD—low concentration of PA (main fat source—corn and soybean oils); 2. HP-WD—high concentration of PA (main fat source—palm oil); 3. HP-Trans-WD—high concentration of PA (mainly transfat). Results: All types of WD caused weight gain, adipocyte enlargement, hepatomegaly, lipid metabolism alterations, and steatohepatitis. Feeding with HP diets led to more prominent obesity, hypercholesterolemia, stronger hepatic injury, and fibrosis. Only the feeding with HP-Trans-WD resulted in glucose intolerance and elevation of serum transaminases. Brief withdrawal of WDs reversed MS and signs of MAFLD. However, mild hepatic inflammation was still detectable in HP groups. Conclusions: HP and HP-Trans-WD play a crucial role in the genesis of MS and MAFLD.This work was supported by the MINECO Retos SAF2016-78711, SAF2017-87919-R, PID2020-117827RB-IOO, PID2020-117941RB-IOO, EXOHEP-CM S2017/BMD-3727, NanoLiver-CM Y2018/NMT-4949, AMMF 2018/117, COST Action CA17112 and UCM-25/2019, German Research Foundation (SFB/TRR57/P04, SFB 1382-403224013/A02). F.J.C. and Y.A.N. are Ramón y Cajal Researchers RYC-2014-15242 and RYC-2015-17438. F.J.C. is a Gilead Liver Research Scholar. The research group belongs to the validated Research Groups Ref. 970935 ¨Liver Pathophysiology¨, 920631 ¨Lymphocyte immunobiology¨, 920361 “Inmunogenética e6937 inmunología de las mucosas” and IBL-6 (imas12-associated). O.E.-V. is supported by Beca FPI (associated with MINECO SAF2017-87919R), C.-S.G. by Atracción de Talento 2019-T1/BMD-1331 and R.B.-U. by Contratos predoctorales de personal investigador en formación UCM-Banco Santander (CT63/19). F.G. is a Chinese Scholarship Council (CSC) fellow. T.B. is supported by the German Research Foundation SFB 1382-403224013/B07, and P.A. by Ayudas para apoyar grupos de investigación del sistema Universitario Vasco (IT971-16) and MCIU/AEI/FEDER, UE (RTI2018-095134-B-100)

Targeting E2F Sensitizes Prostate Cancer Cells to Drug-Induced Replication Stress by Promoting Unscheduled CDK1 Activity

E2F1/E2F2 expression correlates with malignancy in prostate cancer (PCa), but its functional significance remains unresolved. To define the mechanisms governed by E2F in PCa, we analyzed the contribution of E2F target genes to the control of genome integrity, and the impact of modulating E2F activity on PCa progression. We show that silencing or inhibiting E2F1/E2F2 induces DNA damage during S phase and potentiates 5-FU-induced replication stress and cellular toxicity. Inhibition of E2F downregulates the expression of E2F targets involved in nucleotide biosynthesis (TK1, DCK, TYMS), whose expression is upregulated by 5-FU. However, their enzymatic products failed to rescue DNA damage of E2F1/E2F2 knockdown cells, suggesting additional mechanisms for E2F function. Interestingly, targeting E2F1/E2F2 in PCa cells reduced WEE1 expression and resulted in premature CDK1 activation during S phase. Inhibition of CDK1/CDK2 prevented DNA damage induced by E2F loss, suggesting that E2F1/E2F2 safeguard genome integrity by restraining CDK1/CDK2 activity. Importantly, combined inhibition of E2F and ATR boosted replication stress and dramatically reduced tumorigenic capacity of PCa cells in xenografts. Collectively, inhibition of E2F in combination with drugs targeting nucleotide biosynthesis or DNA repair is a promising strategy to provoke catastrophic levels of replication stress that could be applied to PCa treatment.This work was supported by grants from the MCIU/AEI/FEDER, UE (RTI2018-097497-B-100, PID2021-122922OB-100 and RED2018-102723-T) to A.M.Z., MCIU/AEI/FEDER, UE (PID2021-124425OB-I00) to P.A., Basque Government, Department of Education (IT1257-19 and IT1547-22) to A.M.Z and Basque Government, Department of Education (IT1476-2) to P.A. M.H. is recipient of the Asociación Española Contra el Cancer (AECC) predoctoral fellowship. J.M. is recipient of an Ikerbasque Research Foundation Fellowship

Role of Oxidative Stress and Lipid Peroxidation in the Pathophysiology of NAFLD

Non-alcoholic fatty liver disease (NAFLD) is characterised by an excess of hepatic fat that can progress to steatohepatitis, fibrosis, cirrhosis and hepatocarcinoma. The imbalance between lipid uptake/lipogenesis and lipid oxidation/secretion in the liver is a major feature of NAFLD. Given the lack of a non-invasive and reliable methods for the diagnosis of non-alcoholic steatohepatitis (NASH), it is important to find serum markers that are capable of discriminating or defining patients with this stage of NASH. Blood samples were obtained from 152 Caucasian subjects with biopsy-proven NAFLD due to persistently elevated liver enzyme levels. Metabolites representative of oxidative stress were assessed. The findings derived from this work revealed that NAFLD patients with a NASH score of ≥ 4 showed significantly higher levels of lipid peroxidation (LPO). Indeed, LPO levels above the optimal operating point (OOP) of 315.39 μM are an independent risk factor for presenting a NASH score of ≥ 4 (OR: 4.71; 95% CI: 1.68–13.19; p = 0.003). The area under the curve (AUC = 0.81, 95% CI = 0.73–0.89, p < 0.001) shows a good discrimination ability of the model. Therefore, understanding the molecular mechanisms underlying the basal inflammation present in these patients is postulated as a possible source of biomarkers and therapeutic targets in NASH.This research was funded by Consejería de Educación de Castilla y León (VA256P20), Instituto de Salud Carlos III (Grant CB21/13/0005, PI21/00917 and COV20/00491), Junta de Castilla y León (18IGOF), Gerencia Regional de Salud de Castilla y León (GRS2398/A/21), Fundación Ramón Areces (CIVP19A5953) and 7th Call for Gilead Biomedical Research Grants in HIV, Liver Diseases and Haemato-oncology

BIRC6 Is Associated with Vulnerability of Carotid Atherosclerotic Plaque

Carotid atherosclerotic plaque rupture can lead to cerebrovascular accident (CVA). By comparing RNA-Seq data from vascular smooth muscle cells (VSMC) extracted from carotid atheroma surgically excised from a group of asymptomatic and symptomatic subjects, we identified more than 700 genomic variants associated with symptomatology (p < 0.05). From these, twelve single nucleotide polymorphisms (SNPs) were selected for further validation. Comparing genotypes of a hospital-based cohort of asymptomatic with symptomatic patients, an exonic SNP in the BIRC6 (BRUCE/Apollon) gene, rs35286811, emerged as significantly associated with CVA symptomatology (p = 0.002; OR = 2.24). Moreover, BIRC6 mRNA levels were significantly higher in symptomatic than asymptomatic subjects upon measurement by qPCR in excised carotid atherosclerotic tissue (p < 0.0001), and significantly higher in carriers of the rs35286811 risk allele (p < 0.0001). rs35286811 is a proxy of a GWAS SNP reported to be associated with red cell distribution width (RDW); RDW was increased in symptomatic patients (p < 0.03), but was not influenced by the rs35286811 genotype in our cohort. BIRC6 is a negative regulator of both apoptosis and autophagy. This work introduces BIRC6 as a novel genetic risk factor for stroke, and identifies autophagy as a genetically regulated mechanism of carotid plaque vulnerability.This work was financially supported by grants from the Departments of Education (Ref. PIBA2018-67) and Health (Ref. RIS3-2019222038) of the Basque Government, Vitoria-Gasteiz, Spain; by the Spanish Neurovascular Network (INVICTUSplus) (Ref. RD16/0019/0007) funded by the Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación, Madrid, Spain; and by the research project grant (IKERIKTUS) funded by the RefbioII Trans-Pyrenean Cooperation Network for Biomedical Research financed by Horizon 2020. I.A. is supported by the Maratón EiTB 2017 for Funding of Research into Stroke, Bilbao, Spain (Ref. BIO18/IC/005); R.T.N. is the recipient of a fellowship from the Secretaría Nacional de Ciencia y Tecnología e Innovación (SENACYT; Convocatoria Doctorado de Investigación Ronda III, 2018; Ref. BIDP-III-2018-12) of the Gobierno Nacional, República de Panamá

A UHPLC-Mass Spectrometry View of Human Melanocytic Cells Uncovers Potential Lipid Biomarkers of Melanoma

Melanoma is the deadliest form of skin cancer due to its ability to colonize distant sites and initiate metastasis. Although these processes largely depend on the lipid-based cell membrane scaffold, our understanding of the melanoma lipid phenotype lags behind most other aspects of this tumor cell. Here, we examined a panel of normal human epidermal and nevus melanocytes and primary and metastatic melanoma cell lines to determine whether distinctive cell-intrinsic lipidomes can discern non-neoplastic from neoplastic melanocytes and define their metastatic potential. Lipidome profiles were obtained by UHPLC-ESI mass-spectrometry, and differences in the signatures were analyzed by multivariate statistical analyses. Significant and highly specific changes in more than 30 lipid species were annotated in the initiation of melanoma, whereas less numerous changes were associated with melanoma progression and the non-malignant transformation of nevus melanocytes. Notably, the “malignancy lipid signature” features marked drops in pivotal membrane lipids, like sphingomyelins, and aberrant elevation of ether-type lipids and phosphatidylglycerol and phosphatidylinositol variants, suggesting a previously undefined remodeling of sphingolipid and glycerophospholipid metabolism. Besides broadening the molecular definition of this neoplasm, the different lipid profiles identified may help improve the clinical diagnosis/prognosis and facilitate therapeutic interventions for cutaneous melanoma.This research was funded in part by grants from the Ministry of Economy; Industry and Competitiveness (RTC-2015-3693-1); Ministry of Science and Innovation (RTI-2018-095134-B-I00); Basque Government (IT971-16; IT1162-19; KK2016-036; KK2017-041 and KK2018-00090) and UPV/EHU (GIU17/066)

Membrane-Bound sn-1,2-Diacylglycerols Explain the Dissociation of Hepatic Insulin Resistance from Hepatic Steatosis in MTTP Knockout Mice

Microsomal triglyceride transfer protein (MTTP) deficiency results in a syndrome of hypolipidemia and accelerated NAFLD. Animal models of decreased hepatic MTTP activity have revealed an unexplained dissociation between hepatic steatosis and hepatic insulin resistance. Here, we performed comprehensive metabolic phenotyping of liver-specific MTTP knockout (L-Mttp(-/-)) mice and age-weight matched wild-type control mice. Young (10-12-week-old) L-Mttp(-/-) mice exhibited hepatic steatosis and increased DAG content; however, the increase in hepatic DAG content was partitioned to the lipid droplet and was not increased in the plasma membrane. Young L-Mttp(-/-) mice also manifested normal hepatic insulin sensitivity, as assessed by hyperinsulinemic-euglycemic clamps, no PKC epsilon activation, and normal hepatic insulin signaling from the insulin receptor through AKT Ser/Thr kinase. In contrast, aged (10-month-old) L-Mttp(-/-) mice exhibited glucose intolerance and hepatic insulin resistance along with an increase in hepatic plasma membrane sn-1,2-DAG content and PKC epsilon activation. Treatment with a functionally liver-targeted mitochondrial uncoupler protected the aged L-Mttp(-/-) mice against the development of hepatic steatosis, increased plasma membrane sn-1,2-DAG content, PKC epsilon activation, and hepatic insulin resistance. Furthermore, increased hepatic insulin sensitivity in the aged controlled-release mitochondrial protonophore-treated L-Mttp(-/-) mice was not associated with any reductions in hepatic ceramide content. Taken together, these data demonstrate that differences in the intracellular compartmentation of sn-1,2-DAGs in the lipid droplet versus plasma membrane explains the dissociation of NAFLD/lipid-induced hepatic insulin resistance in young L-Mttp(-/-) mice as well as the development of lipid-induced hepatic insulin resistance in aged L-Mttp(-/-) miceThis work was supported by National Institutes of Health Grants R01 DK116774, R01 DK119968, R01 DK114793, R01 DK113984, K23 DK10287, P30 DK045735, DK121490, and HL137202 and the Veterans Health Administration Merit Review Awards I01 BX000901 and BX004113. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the U.S. Department of Veterans Affair