bims-meglyc 2024-01-28 papers

Issue of 2024–01–28
seven papers selected by
Silvia Radenkovic

Int J Mol Sci. 2024 Jan 18. pii: 1191. [Epub ahead of print]25(2):

Targeted Proteomics Reveals Quantitative Differences in Low-Abundance Glycosyltransferases of Patients with Congenital Disorders of Glycosylation.

Roman Sakson, Lars Beedgen, Patrick Bernhard, K Merve Alp, Nicole Lübbehusen, Ralph Röth, Beate Niesler, Marcin Luzarowski, Olga Shevchuk, Matthias P Mayer, Christian Thiel, Thomas Ruppert.

Protein glycosylation is an essential post-translational modification in all domains of life. Its impairment in humans can result in severe diseases named congenital disorders of glycosylation (CDGs). Most of the glycosyltransferases (GTs) responsible for proper glycosylation are polytopic membrane proteins that represent challenging targets in proteomics. We established a multiple reaction monitoring (MRM) assay to comprehensively quantify GTs involved in the processes of N-glycosylation and O- and C-mannosylation in the endoplasmic reticulum. High robustness was achieved by using an enriched membrane protein fraction of isotopically labeled HEK 293T cells as an internal protein standard. The analysis of primary skin fibroblasts from eight CDG type I patients with impaired ALG1, ALG2, and ALG11 genes, respectively, revealed a substantial reduction in the corresponding protein levels. The abundance of the other GTs, however, remained unchanged at the transcript and protein levels, indicating that there is no fail-safe mechanism for the early steps of glycosylation in the endoplasmic reticulum. The established MRM assay was shared with the scientific community via the commonly used open source Skyline software environment, including Skyline Batch for automated data analysis. We demonstrate that another research group could easily reproduce all analysis steps, even while using different LC-MS hardware.

Keywords: MRM; Skyline; congenital disorders of glycosylation; endoplasmic reticulum; glycosylation; nCounter; proteomics

DOI: https://doi.org/10.3390/ijms25021191

Arch Pediatr. 2024 Jan 22. pii: S0929-693X(23)00192-6. [Epub ahead of print]

Single-center experience of congenital disorders of glycosylation syndrome screening in Tunisia: A retrospective study over a 15-year period (2007-2021).

Wiem Zidi, Sameh Hadj-Taieb, Ichraf Kraoua, Mongia Hachicha, Hassen Seboui, Kamel Monastiri, Saayda Ben Becher, Ilhem Turki, Haifa Sanhaji, Neji Tebib, Naziha Kaabachi, Moncef Feki, Monia Allal-Elasmi.

BACKGROUND: We report the results gathered over 15 years of screening for congenital disorders of glycosylation syndrome (CDGS) in Tunisia according to clinical and biochemical characteristics.
METHODS: Our laboratory received 1055 analysis requests from various departments and hospitals, for children with a clinical suspicion of CDGS. The screening was carried out through separation of transferrin isoforms by capillary zone electrophoresis.
RESULTS: During the 15-year period, 23 patients were diagnosed with CDGS (19 patients with CDG-Ia, three patients with CDG-IIx, and one patient with CDG-X). These patients included 13 boys and 10 girls aged between 3 months and 13 years, comprising 2.18 % of the total 1055 patients screened. The incidence for CDGS was estimated to be 1:23,720 live births (4.21 per 100,000) in Tunisia. The main clinical symptoms related to clinical disease state in newborn and younger patients were psychomotor retardation (91 %), cerebellar atrophy (91 %), ataxia (61 %), strabismus (48 %), dysmorphic symptoms (52 %), retinitis pigmentosa, cataract (35 %), hypotonia (30 %), and other symptoms.
CONCLUSION: In Tunisia, CDGS still remains underdiagnosed or misdiagnosed. The resemblance to other diseases, especially neurological disorders, and physicians' unawareness of the existence of these diseases are the main reasons for the underdiagnosis. In routine diagnostics, the screening for CDGS by biochemical tests is mandatory to complete the clinical diagnosis.

Keywords: Carbohydrate-deficient transferrin; Congenital disorders of glycosylation; Incidence; Inherited autosomal recessive; Screening

DOI: https://doi.org/10.1016/j.arcped.2023.10.003

J Alzheimers Dis. 2024 Jan 13.

O-GlcNAcylation and Its Roles in Neurodegenerative Diseases.

Pengyang Du, Xiaomin Zhang, Xia Lian, Christian Hölscher, Guofang Xue.

As a non-classical post-translational modification, O-linked β-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) is widely found in human organ systems, particularly in our brains, and is indispensable for healthy cell biology. With the increasing age of the global population, the incidence of neurodegenerative diseases is increasing, too. The common characteristic of these disorders is the aggregation of abnormal proteins in the brain. Current research has found that O-GlcNAcylation dysregulation is involved in misfolding or aggregation of these abnormal proteins to mediate disease progression, but the specific mechanism has not been defined. This paper reviews recent studies on O-GlcNAcylation's roles in several neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, Machado-Joseph's disease, and giant axonal neuropathy, and shows that O-GlcNAcylation, as glucose metabolism sensor, mediating synaptic function, participating in oxidative stress response and signaling pathway conduction, directly or indirectly regulates characteristic pathological protein toxicity and affects disease progression. The existing results suggest that targeting O-GlcNAcylation will provide new ideas for clinical diagnosis, prevention, and treatment of neurodegenerative diseases.

Keywords: Alzheimer’s disease; O-GlcNAc transferase; O-GlcNAcase inhibitors; O-GlcNAcylation; Parkinson’s disease; neurodegenerative diseases

DOI: https://doi.org/10.3233/JAD-230955

Neurotherapeutics. 2024 Jan 19. pii: S1878-7479(23)02027-5. [Epub ahead of print]21(1): e00311

Challenges and opportunities to bridge translational to clinical research for personalized mitochondrial medicine.

Andrea L Gropman, Martine N Uittenbogaard, Anne E Chiaramello.

Mitochondrial disorders are a group of rare and heterogeneous genetic diseases characterized by dysfunctional mitochondria leading to deficient adenosine triphosphate synthesis and chronic energy deficit in patients. The majority of these patients exhibit a wide range of phenotypic manifestations targeting several organ systems, making their clinical diagnosis and management challenging. Bridging translational to clinical research is crucial for improving the early diagnosis and prognosis of these intractable mitochondrial disorders and for discovering novel therapeutic drug candidates and modalities. This review provides the current state of clinical testing in mitochondrial disorders, discusses the challenges and opportunities for converting basic discoveries into clinical settings, explores the most suited patient-centric approaches to harness the extraordinary heterogeneity among patients affected by the same primary mitochondrial disorder, and describes the current outlook of clinical trials.

Keywords: Clinical trial; Energy metabolism; Mitochondrial medicine; Next generation therapeutics; Patient-centric approach

DOI: https://doi.org/10.1016/j.neurot.2023.e00311

Biomedicines. 2024 Jan 12. pii: 174. [Epub ahead of print]12(1):

Inherited Metabolic Disorders: From Bench to Bedside.

Tiago Fonseca, M Fátima Macedo.

Inherited metabolic disorders (IMDs), commonly referred to as inborn errors of metabolism, represent a spectrum of disorders with a defined (or presumed) primary genetic cause which disrupts the normal metabolism of essential molecules in the body [...].

DOI: https://doi.org/10.3390/biomedicines12010174

Cells. 2024 Jan 21. pii: 199. [Epub ahead of print]13(2):

Nonsynonymous Mutations in Intellectual Disability and Autism Spectrum Disorder Gene PTCHD1 Disrupt N-Glycosylation and Reduce Protein Stability.

Connie T Y Xie, Stephen F Pastore, John B Vincent, Paul W Frankland, Paul A Hamel.

PTCHD1 has been implicated in Autism Spectrum Disorders (ASDs) and/or intellectual disability, where copy-number-variant losses or loss-of-function coding mutations segregate with disease in an X-linked recessive fashion. Missense variants of PTCHD1 have also been reported in patients. However, the significance of these mutations remains undetermined since the activities, subcellular localization, and regulation of the PTCHD1 protein are currently unknown. This paucity of data concerning PTCHD1 prevents the effective evaluation of sequence variants identified during diagnostic screening. Here, we characterize PTCHD1 protein binding partners, extending previously reported interactions with postsynaptic scaffolding protein, SAP102. Six rare missense variants of PTCHD1 were also identified from patients with neurodevelopmental disorders. After modelling these variants on a hypothetical three-dimensional structure of PTCHD1, based on the solved structure of NPC1, PTCHD1 variants harboring these mutations were assessed for protein stability, post-translational processing, and protein trafficking. We show here that the wild-type PTCHD1 post-translational modification includes complex N-glycosylation and that specific mutant proteins disrupt normal N-link glycosylation processing. However, regardless of their processing, these mutants still localized to PSD95-containing dendritic processes and remained competent for complexing SAP102.

Keywords: PTCHD1; autism spectrum disorder; mutations; neurons; post-translational processing; protein stability

DOI: https://doi.org/10.3390/cells13020199

Free Radic Biol Med. 2024 Jan 22. pii: S0891-5849(24)00042-X. [Epub ahead of print]

Cardiomyocyte maturation alters molecular stress response capacities and determines cell survival upon mitochondrial dysfunction.

Nina Schraps, Michaela Tirre, Simon Pyschny, Anna Reis, Hannah Schlierbach, Matthias Seidl, Hans-Gerd Kehl, Anne Schänzer, Jacqueline Heger, Christian Jux, Jörg-Detlef Drenckhahn.

Cardiomyocyte maturation during pre- and postnatal development requires multiple intertwined processes, including a switch in energy generation from glucose utilization in the embryonic heart towards fatty acid oxidation after birth. This is accompanied by a boost in mitochondrial mass to increase capacities for oxidative phosphorylation and ATP generation required for efficient contraction. Whether cardiomyocyte differentiation is paralleled by augmented capacities to deal with reactive oxygen species (ROS), physiological byproducts of the mitochondrial electron transport chain (ETC), is less clear. Here we show that expression of genes and proteins involved in redox homeostasis and protein quality control within mitochondria increases after birth in the mouse and human heart. Using primary embryonic, neonatal and adult mouse cardiomyocytes in vitro we investigated how excessive ROS production induced by mitochondrial dysfunction affects cell survival and stress response at different stages of maturation. Embryonic and neonatal cardiomyocytes largely tolerate inhibition of ETC complex III by antimycin A (AMA) as well as ATP synthase (complex V) by oligomycin but are susceptible to complex I inhibition by rotenone. All three inhibitors alter the intracellular distribution and ultrastructure of mitochondria in neonatal cardiomyocytes. In contrast, adult cardiomyocytes treated with AMA undergo rapid morphological changes and cellular disintegration. At the molecular level embryonic cardiomyocytes activate antioxidative defense mechanisms, the integrated stress response (ISR) and ER stress but not the mitochondrial unfolded protein response upon complex III inhibition. In contrast, adult cardiomyocytes fail to activate the ISR and antioxidative proteins following AMA treatment. In conclusion, our results identified fundamental differences in cell survival and stress response in differentiated compared to immature cardiomyocytes subjected to mitochondrial dysfunction. The high stress tolerance of immature cardiomyocytes might allow outlasting unfavorable intrauterine conditions thereby preventing fetal or perinatal heart disease and may contribute to the regenerative capacity of the embryonic and neonatal mammalian heart.

Keywords: Cardiomyocyte differentiation; Cardiomyocyte survival; Cellular stress response; Mitochondrial dysfunction; Oxidative stress

DOI: https://doi.org/10.1016/j.freeradbiomed.2024.01.034