Alteration of mitochondrial function in the livers of mice with glycogen branching enzyme deficiency.

Glycogen storage disease type IV (GSD IV) is caused by mutations in the glycogen branching enzyme gene (GBE1) that lead to the accumulation of aberrant glycogen in affected tissues, mostly in the liver. To determine whether dysfunctional glycogen metabolism in GSD IV affects other components of cellular bioenergetics, we studied mitochondrial function in heterozygous Gbe1 knockout (Gbe1+/-) mice. Mitochondria isolated from the livers of Gbe1+/- mice showed elevated respiratory complex I activity and increased reactive oxygen species production, particularly by respiratory chain complex III. These observations indicate that GBE1 deficiency leads to broader rearrangements in energy metabolism and that the mechanisms underlying GSD IV pathogenesis may include more than merely mechanical cell damage caused by the presence of glycogen aggregates.

An Asynchronous, Mobile Text-Based Platform (XatJove Anoia) for Providing Health Services to Teenagers: Protocol for a Quasiexperimental Study.

BACKGROUND: Due to the COVID-19 pandemic, it is more essential than ever to implement protective measures in primary care centers to ensure patients' safety. This protocol describes a quasiexperimental study on the use of a mobile chat platform as a clinical consultation tool for adolescents and primary health care physicians. OBJECTIVE: The purpose of the quasiexperimental study is to demonstrate that the use of mobile phones and messaging apps increases the number of health consultations. The study will be performed as part of the Health and School program in the Anoia region. METHODS: The quasiexperimental study will compare the number of face-to-face consultations to the number of consultations conducted on XatJove Anoia, as part of the Health in Schools program in the Anoia region. The study will involve the use of a new communication platform (ie, XatJove Anoia) for health care professionals and adolescents, and data on the number of face-to-face consultations will be collected as part of the same program in another region. Data will be collected from secondary schools during the academic year 2020-2021. Statistical analyses will be performed on the data that users will enter in the registration form. These data will be collected by means of a questionnaire, which will be submitted once the questionnaire is closed. The questionnaire will consist of multiple-choice questions, which will allow numerical values to be assigned to various responses in order to carry out statistical analyses. RESULTS: The study is projected to start at the beginning of November 2020 and finish in June 2021, which is when data analysis is expected to start. CONCLUSIONS: The results of the quasiexperimental study may assist in the development and planning of school health programs. TRIAL REGISTRATION: ClinicalTrials.gov NCT04562350; https://clinicaltrials.gov/ct2/show/NCT04562350. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/25062.

Pulmonary glycogen deficiency as a new potential cause of respiratory distress syndrome.

The glycogenin knockout mouse is a model of Glycogen Storage Disease type XV. These animals show high perinatal mortality (90%) due to respiratory failure. The lungs of glycogenin-deficient embryos and P0 mice have a lower glycogen content than that of wild-type counterparts. Embryonic lungs were found to have decreased levels of mature surfactant proteins SP-B and SP-C, together with incomplete processing of precursors. Furthermore, non-surviving pups showed collapsed sacculi, which may be linked to a significantly reduced amount of surfactant proteins. A similar pattern was observed in glycogen synthase1-deficient mice, which are devoid of glycogen in the lungs and are also affected by high perinatal mortality due to atelectasis. These results indicate that glycogen availability is a key factor for the burst of surfactant production required to ensure correct lung expansion at the establishment of air breathing. Our findings confirm that glycogen deficiency in lungs can cause respiratory distress syndrome and suggest that mutations in glycogenin and glycogen synthase 1 genes may underlie cases of idiopathic neonatal death.

Hallmarks of oxidative stress in the livers of aged mice with mild glycogen branching enzyme deficiency.

Glycogen branching enzyme (GBE1) introduces branching points in the glycogen molecule during its synthesis. Pathogenic GBE1 gene mutations lead to glycogen storage disease type IV (GSD IV), which is characterized by excessive intracellular accumulation of abnormal, poorly branched glycogen in affected tissues and organs, mostly in the liver. Using heterozygous Gbe1 knock-out mice (Gbe1+/-), we analyzed the effects of moderate GBE1 deficiency on oxidative stress in the liver. The livers of aged Gbe1+/- mice (22 months old) had decreased GBE1 protein levels, which caused a mild decrease in the degree of glycogen branching, but did not affect the tissue glycogen content. GBE1 deficiency was accompanied by increased protein carbonylation and elevated oxidation of the glutathione pool, indicating the existence of oxidative stress. Furthermore, we have observed increased levels of glutathione peroxidase and decreased activity of respiratory complex I in Gbe1+/- livers. Our data indicate that even mild changes in the degree of glycogen branching, which did not lead to excessive glycogen accumulation, may have broader effects on cellular bioenergetics and redox homeostasis. In young animals cellular homeostatic mechanisms are able to counteract those changes, while in aged tissues the changes may lead to increased oxidative stress.

A proteomic study of mesenchymal stem cells from equine umbilical cord.

To the best of our knowledge, this is the first study describing the proteome of equine umbilical cord intervascular matrix mesenchymal stem cells (UCIM-MSCs) in a global and functional manner. The aim of this work was to analyze the proteome of previously characterized UCIM-MSCs to determine protein abundance and classify the identified proteins according to Gene Ontology (GO) terms. Protein classification analysis according to biological process, molecular function and cellular component was performed using the PANTHER (Protein ANalysis THrough Evolutionary Relationships) Classification System, which revealed enrichment for 42 biological processes, 23 molecular functions and 18 cellular components. Protein abundance was estimated according to the emPAI method (Exponential Modified Protein Abundance Index). The two most abundant proteins in the proteome of UCIM-MSCs were the cytoskeletal proteins actin and vimentin, which have important roles in cell stability and motility. Additionally, we identified 14 cell surface antigens. Three of them, CD44, CD90 and CD105, had been previously validated by flow cytometry. In the present study, we also identified important information about the biological properties of UCIM-MSCs such as differentiation potential, low immunogenicity (low MHC-II expression) and chromosomal stability, which reinforces their use for cell therapy. Together with the proteomic findings, this information allowed us to infer the functional relevance of several activities related to primary metabolic processes, protein synthesis, production of vesicle coats, vesicle-mediated transport and antioxidant activity. In addition, the identification of different cell surface markers may help establish an immunophenotypic panel suitable for the characterization of MSCs from equine fetal membranes.

Lack of Glycogenin Causes Glycogen Accumulation and Muscle Function Impairment.

Glycogenin is considered essential for glycogen synthesis, as it acts as a primer for the initiation of the polysaccharide chain. Against expectations, glycogenin-deficient mice (Gyg KO) accumulate high amounts of glycogen in striated muscle. Furthermore, this glycogen contains no covalently bound protein, thereby demonstrating that a protein primer is not strictly necessary for the synthesis of the polysaccharide in vivo. Strikingly, in spite of the higher glycogen content, Gyg KO mice showed lower resting energy expenditure and less resistance than control animals when subjected to endurance exercise. These observations can be attributed to a switch of oxidative myofibers toward glycolytic metabolism. Mice overexpressing glycogen synthase in the muscle showed similar alterations, thus indicating that this switch is caused by the excess of glycogen. These results may explain the muscular defects of GSD XV patients, who lack glycogenin-1 and show high glycogen accumulation in muscle.

FoxA and LIPG endothelial lipase control the uptake of extracellular lipids for breast cancer growth.

The mechanisms that allow breast cancer (BCa) cells to metabolically sustain rapid growth are poorly understood. Here we report that BCa cells are dependent on a mechanism to supply precursors for intracellular lipid production derived from extracellular sources and that the endothelial lipase (LIPG) fulfils this function. LIPG expression allows the import of lipid precursors, thereby contributing to BCa proliferation. LIPG stands out as an essential component of the lipid metabolic adaptations that BCa cells, and not normal tissue, must undergo to support high proliferation rates. LIPG is ubiquitously and highly expressed under the control of FoxA1 or FoxA2 in all BCa subtypes. The downregulation of either LIPG or FoxA in transformed cells results in decreased proliferation and impaired synthesis of intracellular lipids.