bims-meglyc 2024-06-09 papers

Int J Biochem Cell Biol. 2024 Jun 04. pii: S1357-2725(24)00094-3. [Epub ahead of print] 106602

Mutations in the SLC35C1 gene, contributing to significant differences in fucosylation patterns, may underlie the diverse phenotypic manifestations observed in leukocyte adhesion deficiency type II patients.

E Skurska, B Szulc, K Kreczko, M Olczak.

Congenital disorders of glycosylation (CDG) are a large family of genetic diseases resulting from defects in the synthesis of glycans and the attachment of glycans to macromolecules. The CDG known as leukocyte adhesion deficiency II (LAD II) is an autosomal, recessive disorder caused by mutations in the SLC35C1 gene, encoding a transmembrane protein of the Golgi apparatus, involved in GDP-fucose transport from the cytosol to the Golgi lumen. In this study, a cell-based model was used as a tool to characterize the molecular background of a therapy based on a fucose-supplemented diet. Such therapies have been successfully introduced in some (but not all) known cases of LAD II. In this study, the effect of external fucose was analyzed in SLC35C1 KO cell lines, expressing 11 mutated SLC35C1 proteins, previously discovered in patients with an LAD II diagnosis. For many of them, the cis-Golgi subcellular localization was affected; however, some proteins were localized properly. Additionally, although mutated SLC35C1 caused different α-1-6 core fucosylation of N-glycans, which explains previously described, more or less severe disorder symptoms, the differences practically disappeared after external fucose supplementation, with fucosylation restored to the level observed in healthy cells. This indicates that additional fucose in the diet should improve the condition of all patients. Thus, for patients diagnosed with LAD II we advocate careful analysis of particular mutations using the SLC35C1-KO cell line-based model, to predict changes in localization and fucosylation rate. We also recommend searching for additional mutations in the human genome of LAD II patients, when fucose supplementation does not influence patients' state.

Keywords: GDP-fucose transporter; LADII; SLC35C1; cell model of glycosylation defect; congenital disorder of glycosylation

DOI: https://doi.org/10.1016/j.biocel.2024.106602

Am J Med Genet A. 2024 Jun 01. e63721

NANS-CDG: Expanding clinical insights with a novel patient with novel variants.

Sukdong Yoo, Chong Kun Cheon.

N-acetyl-d-neuraminic acid synthase-congenital disorder of glycosylation (NANS-CDG) is a rare autosomal recessive defect in the N-acetyl-neuraminic acid biosynthesis pathway. Herein, we report the first Korean NANS-CDG patient. A 10-year-old boy was referred to our clinic because of incidental radiographic findings indicating spondyloepimetaphyseal dysplasia. The patient had microcephaly, cavum septum pellucidum, and ventriculomegaly at birth, and at 10 years, a very short stature. He had a history of idiopathic chronic immune thrombocytopenia, central adrenal insufficiency, and hypothyroidism since infancy. The first unprovoked seizure occurred at the age of 2 years, and he was subsequently admitted to the hospital frequently because of respiratory infections and intractable seizures. Exome sequencing identified unreported biallelic variants of the NANS gene. Clinical and genetic confirmation of NANS-CDG highlights its expanding phenotypic and genotypic diversity.

Keywords: N‐acetyl‐neuraminic acid; congenital disorders of glycosylation; skeletal dysplasia; thrombocytopenia

DOI: https://doi.org/10.1002/ajmg.a.63721

J Dermatol. 2024 Jun 03.

Novel compound heterozygous MPDU1 variants causing congenital disorders of glycosylation presenting with erythrokeratodermia variabilis.

Ziyu Wei, Ran Mo, Yong Yang, Zhiming Chen.

DOI: https://doi.org/10.1111/1346-8138.17321

Dev Cell. 2024 Jun 04. pii: S1534-5807(24)00325-3. [Epub ahead of print]

Neuronal activity-driven O-GlcNAcylation promotes mitochondrial plasticity.

Seungyoon B Yu, Haoming Wang, Richard G Sanchez, Natasha M Carlson, Khanh Nguyen, Andrew Zhang, Zachary D Papich, Ahmed A Abushawish, Zachary Whiddon, Weronika Matysik, Jie Zhang, Thomas C Whisenant, Majid Ghassemian, John N Koberstein, Melissa L Stewart, Samuel A Myers, Gulcin Pekkurnaz.

Neuronal activity is an energy-intensive process that is largely sustained by instantaneous fuel utilization and ATP synthesis. However, how neurons couple ATP synthesis rate to fuel availability is largely unknown. Here, we demonstrate that the metabolic sensor enzyme O-linked N-acetyl glucosamine (O-GlcNAc) transferase regulates neuronal activity-driven mitochondrial bioenergetics in hippocampal and cortical neurons. We show that neuronal activity upregulates O-GlcNAcylation in mitochondria. Mitochondrial O-GlcNAcylation is promoted by activity-driven glucose consumption, which allows neurons to compensate for high energy expenditure based on fuel availability. To determine the proteins that are responsible for these adjustments, we mapped the mitochondrial O-GlcNAcome of neurons. Finally, we determine that neurons fail to meet activity-driven metabolic demand when O-GlcNAcylation dynamics are prevented. Our findings suggest that O-GlcNAcylation provides a fuel-dependent feedforward control mechanism in neurons to optimize mitochondrial performance based on neuronal activity. This mechanism thereby couples neuronal metabolism to mitochondrial bioenergetics and plays a key role in sustaining energy homeostasis.

Keywords: ATP synthesis; O-GlcNAc transferase; O-GlcNAcylation; glycosylation; mitochondria; neuronal metabolism; synaptic activity

DOI: https://doi.org/10.1016/j.devcel.2024.05.008

Cell Metab. 2024 Jun 04. pii: S1550-4131(24)00178-5. [Epub ahead of print]36(6): 1394-1410.e12

Imaging brain glucose metabolism in vivo reveals propionate as a major anaplerotic substrate in pyruvate dehydrogenase deficiency.

Isaac Marin-Valencia, Arif Kocabas, Carlos Rodriguez-Navas, Vesselin Z Miloushev, Manuel González-Rodríguez, Hannah Lees, Kelly E Henry, Jake Vaynshteyn, Valerie Longo, Kofi Deh, Roozbeh Eskandari, Arsen Mamakhanyan, Marjan Berishaj, Kayvan R Keshari.

A vexing problem in mitochondrial medicine is our limited capacity to evaluate the extent of brain disease in vivo. This limitation has hindered our understanding of the mechanisms that underlie the imaging phenotype in the brain of patients with mitochondrial diseases and our capacity to identify new biomarkers and therapeutic targets. Using comprehensive imaging, we analyzed the metabolic network that drives the brain structural and metabolic features of a mouse model of pyruvate dehydrogenase deficiency (PDHD). As the disease progressed in this animal, in vivo brain glucose uptake and glycolysis increased. Propionate served as a major anaplerotic substrate, predominantly metabolized by glial cells. A combination of propionate and a ketogenic diet extended lifespan, improved neuropathology, and ameliorated motor deficits in these animals. Together, intermediary metabolism is quite distinct in the PDHD brain-it plays a key role in the imaging phenotype, and it may uncover new treatments for this condition.

Keywords: brain; glucose; imaging; ketogenic diet; metabolism; propionate; pyruvate; pyruvate dehydrogenase deficiency

DOI: https://doi.org/10.1016/j.cmet.2024.05.002

Nat Cancer. 2024 Jun 06.

Nucleotide metabolism in cancer cells fuels a UDP-driven macrophage cross-talk, promoting immunosuppression and immunotherapy resistance.

Many individuals with cancer are resistant to immunotherapies. Here, we identify the gene encoding the pyrimidine salvage pathway enzyme cytidine deaminase (CDA) among the top upregulated metabolic genes in several immunotherapy-resistant tumors. We show that CDA in cancer cells contributes to the uridine diphosphate (UDP) pool. Extracellular UDP hijacks immunosuppressive tumor-associated macrophages (TAMs) through its receptor P2Y6. Pharmacologic or genetic inhibition of CDA in cancer cells (or P2Y6 in TAMs) disrupts TAM-mediated immunosuppression, promoting cytotoxic T cell entry and susceptibility to anti-programmed cell death protein 1 (anti-PD-1) treatment in resistant pancreatic ductal adenocarcinoma (PDAC) and melanoma models. Conversely, CDA overexpression in CDA-depleted PDACs or anti-PD-1-responsive colorectal tumors or systemic UDP administration (re)establishes resistance. In individuals with PDAC, high CDA levels in cancer cells correlate with increased TAMs, lower cytotoxic T cells and possibly anti-PD-1 resistance. In a pan-cancer single-cell atlas, CDAhigh cancer cells match with T cell cytotoxicity dysfunction and P2RY6high TAMs. Overall, we suggest CDA and P2Y6 as potential targets for cancer immunotherapy.

DOI: https://doi.org/10.1038/s43018-024-00771-8