A patient-based medaka alg2 mutant as a model for hypo-N-glycosylation

ABSTRACT Defects in the evolutionarily conserved protein-glycosylation machinery during embryonic development are often fatal. Consequently, congenital disorders of glycosylation (CDG) in human are rare. We modelled a putative hypomorphic mutation described in an alpha-1,3/1,6-mannosyltransferase (ALG2) index patient (ALG2-CDG) to address the developmental consequences in the teleost medaka (Oryzias latipes). We observed specific, multisystemic, late-onset phenotypes, closely resembling the patient's syndrome, prominently in the facial skeleton and in neuronal tissue. Molecularly, we detected reduced levels of N-glycans in medaka and in the patient's fibroblasts. This hypo-N-glycosylation prominently affected protein abundance. Proteins of the basic glycosylation and glycoprotein-processing machinery were over-represented in a compensatory response, highlighting the regulatory topology of the network. Proteins of the retinal phototransduction machinery, conversely, were massively under-represented in the alg2 model. These deficiencies relate to a specific failure to maintain rod photoreceptors, resulting in retinitis pigmentosa characterized by the progressive loss of these photoreceptors. Our work has explored only the tip of the iceberg of N-glycosylation-sensitive proteins, the function of which specifically impacts on cells, tissues and organs. Taking advantage of the well-described human mutation has allowed the complex interplay of N-glycosylated proteins and their contribution to development and disease to be addressed.

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The medaka alg2 mutant is a model for hypo-N-glycosylation-associated retinitis pigmentosa

10.1101/2020.08.20.260430 ◽

2020 ◽

Author(s):

Sevinç Gücüm ◽

Roman Sakson ◽

Marcus Hoffmann ◽

Valerian Grote ◽

Lars Beedgen ◽

...

Keyword(s):

Retinitis Pigmentosa ◽

Index Patient ◽

Protein Glycosylation ◽

Protein Abundance ◽

Congenital Disorders Of Glycosylation ◽

Potential Treatment ◽

Medaka Fish ◽

Rod Photoreceptors ◽

Phenotypic Spectrum ◽

Glycoprotein Processing

AbstractPatients suffering from Congenital Disorders of Glycosylation (CDG) carry mutations in components of the evolutionarily highly conserved protein-glycosylation-machinery. Employing targeted genome editing, we modeled alleles in medaka fish based on a mutation described in an ALG2-index patient. The multisystemic phenotypes in our alg2 model closely resembled the patient’s syndromes. Molecularly, the mutation results in a reduction of the abundance of N-glycans without altering the profile of glycan structures in fish as well as in patient fibroblasts. This hypo-N-glycosylation impacted on protein abundance in two directions. We discovered a putative compensatory upregulation of the basic glycosylation and glycoprotein processing machinery highlighting the regulatory topology of the network. Conversely, proteins of the retinal phototransduction machinery were massively downregulated in the alg2 model. Those relate to the specific loss of rod photoreceptors that fail to be maintained in the alg2 mutants, a condition known as retinitis pigmentosa. Transient supply of human or medaka alg2 mRNA efficiently rescued the phenotypic spectrum and restored viability demonstrating that our alg2 model delivers key traits for the potential treatment of the disorder.

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Late onset renal hypertension in old rats alters left ventricular structure and function

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1992.262.2.h531 ◽

1992 ◽

Vol 262 (2) ◽

pp. H531-H538 ◽

Cited By ~ 1

Author(s):

R. J. Tomanek ◽

M. R. Aydelotte

Keyword(s):

Cellular Response ◽

Late Onset ◽

Renal Hypertension ◽

Left Ventricular ◽

Lv Function ◽

Stroke Index ◽

Sprague Dawley ◽

Compensatory Response ◽

Absolute Increase ◽

Old Rats

This study was designed to test the hypothesis that the left ventricle of the senescent rat has a limited compensatory response to late onset hypertension. Data were obtained from middle-aged (15 mo) and senescent (24 mo) Sprague-Dawley rats either 1 or 3 mo after the initiation of one-kidney figure-8 renal wrap (Grollman) hypertension. Peak left ventricular (LV) function assessed during acute volume expansion was not markedly affected 1 mo after induction of hypertension with the exception of a decrement in the acceleration of aortic flow (dF/dt) in the senescent hypertensive group. Three months after the surgery was performed, peak LV function (stroke index, stroke volume/g LV, and dF/dt) was depressed in the senescent hypertensive rats, compared with the controls. In contrast, these indexes in the 15-mo-old rats were similar in the experimental and control groups after either 1 or 3 mo of hypertension. Developed pressure, however, was not compromised by hypertension at either age. Cardiocyte hypertrophy due to pressure overload occurred in both age groups but to a greater extent in the senescent group. This cellular response did not cause an absolute increase in LV mass and was associated with endomyocardial foci of cellular degeneration and fibrosis suggestive of cell loss. Mitochondria-to-myofibril volume ratios were not significantly altered in the experimental groups at either age, thus the cellular hypertrophy in these rats was characterized by uniform organelle growth. These data support two important conclusions regarding late onset hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

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Mitophagy as a stress response in mammalian cells and in respiring S. cerevisiae

Biochemical Society Transactions ◽

10.1042/bst20150278 ◽

2016 ◽

Vol 44 (2) ◽

pp. 541-545 ◽

Cited By ~ 7

Author(s):

Hagai Abeliovich ◽

Jörn Dengjel

Keyword(s):

Mammalian Cells ◽

Late Onset ◽

Specific Form ◽

Mitochondrial Quality Control ◽

Evolutionarily Conserved ◽

Autophagic Degradation ◽

Relationship Of ◽

To Receive ◽

The Relationship ◽

Significant Attention

The degradation of malfunctioning or superfluous mitochondria in the lysosome/vacuole is an important housekeeping function in respiring eukaryotic cells. This clearance is thought to occur by a specific form of autophagic degradation called mitophagy, and plays a role in physiological homoeostasis as well as in the progression of late-onset diseases. Although the mechanism of bulk degradation by macroautophagy is relatively well established, the selective autophagic degradation of mitochondria has only recently begun to receive significant attention. In this mini-review, we introduce mitophagy as a form of mitochondrial quality control and proceed to provide specific examples from yeast and mammalian systems. We then discuss the relationship of mitophagy to mitochondrial stress, and provide a broad mechanistic overview of the process with an emphasis on evolutionarily conserved pathways.

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Sulfate suicide selection of Dictyostelium discoideum mutants defective in protein glycosylation

Molecular and Cellular Biology ◽

10.1128/mcb.6.8.2820-2827.1986 ◽

1986 ◽

Vol 6 (8) ◽

pp. 2820-2827

Author(s):

J A Boose ◽

E J Henderson

Keyword(s):

Dictyostelium Discoideum ◽

Developmental Regulation ◽

Selection Procedure ◽

Protein Glycosylation ◽

Temperature Sensitive ◽

Restrictive Temperature ◽

Metabolic Labeling ◽

Replica Plating ◽

Oligosaccharide Processing ◽

Glycoprotein Processing

The assembly and processing of glycoprotein-linked oligosaccharides in Dictyostelium discoideum has been shown to generate a wide array of glycan structures which undergo dramatic developmental regulation. As late steps in processing of these oligosaccharides involve sulfation, a sulfate suicide selection procedure was developed to select for temperature-sensitive glycoprotein-processing mutants. Of 673 clones derived from the survivors of suicide selection, 99 were classified by replica-plating fluorography as temperature sensitive for sulfate transport or incorporation. Of these, 74 were unable to complete the developmental program to the fruiting body stage at the restrictive temperature, 29 being blocked in some aspect of aggregation and 45 being blocked at some postaggregation stage. Quantitative metabolic labeling experiments with representative clones showed that they incorporated wild-type levels of [35S]methionine but reduced levels of sulfate at the restrictive temperature. The specific incorporation patterns in the mutants suggest that distinct oligosaccharide-processing steps are involved in different developmental events.

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Sulfate suicide selection of Dictyostelium discoideum mutants defective in protein glycosylation.

Molecular and Cellular Biology ◽

10.1128/mcb.6.8.2820 ◽

1986 ◽

Vol 6 (8) ◽

pp. 2820-2827 ◽

Cited By ~ 3

Author(s):

J A Boose ◽

E J Henderson

Keyword(s):

Dictyostelium Discoideum ◽

Developmental Regulation ◽

Selection Procedure ◽

Protein Glycosylation ◽

Temperature Sensitive ◽

Restrictive Temperature ◽

Metabolic Labeling ◽

Replica Plating ◽

Oligosaccharide Processing ◽

Glycoprotein Processing

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Pattern separation and tuning shift in human sensory cortex underlie fear memory

10.1101/2021.08.27.457990 ◽

2021 ◽

Author(s):

Yuqi You ◽

Lucas R. Novak ◽

Kevin Clancy ◽

Wen Li

Keyword(s):

Late Onset ◽

Piriform Cortex ◽

Fear Memory ◽

Pattern Separation ◽

Sensory Cortex ◽

Evolutionarily Conserved ◽

Sensory Encoding ◽

Underlying Mechanisms ◽

Cortical System

ABSTRACTAnimal research has recognized the role of the sensory cortex in fear memory and two key underlying mechanisms—pattern separation and tuning shift. We interrogated these mechanisms in the human sensory cortex in an olfactory differential conditioning study with a delayed (9-day) retention test. Combining affective appraisal and olfactory psychophysics with functional magnetic resonance imaging (fMRI) multivoxel pattern analysis and voxel-based tuning analysis over a linear odor-morphing continuum, we confirmed affective and perceptual learning and memory and demonstrated associative plasticity in the human olfactory (piriform) cortex. Specifically, the piriform cortex exhibited immediate and lasting enhancement in pattern separation (between the conditioned stimuli/CS and neighboring non-CS) and late-onset yet lasting tuning shift towards the CS, especially in anxious individuals. These findings highlight an evolutionarily conserved sensory cortical system of fear memory, which can underpin sensory encoding of fear/threat and confer a sensory mechanism to the neuropathophysiology of anxiety.

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Cardiomyopathy associated with the Ala143Thr variant of the α-galactosidase A gene

Heart ◽

10.1136/heartjnl-2019-315933 ◽

2020 ◽

Vol 106 (8) ◽

pp. 609-615 ◽

Cited By ~ 3

Author(s):

Kati Valtola ◽

Juanita Nino-Quintero ◽

Marja Hedman ◽

Line Lottonen-Raikaslehto ◽

Tomi Laitinen ◽

...

Keyword(s):

Endomyocardial Biopsy ◽

Late Onset ◽

Light And Electron Microscopy ◽

Pacemaker Implantation ◽

Index Patient ◽

Left Ventricular ◽

Incomplete Penetrance ◽

Gadolinium Enhancement ◽

Positron Emission ◽

Pet Ct

ObjectiveTo investigate whether the Ala143Thr variant of the α-galactosidase A gene (A143T/GLA), with conflicting interpretations of pathogenicity, is associated with Fabry cardiomyopathy.MethodsThe index patient, a woman in her 60s with cardiomyopathy, was screened for variants in 59 cardiomyopathy-related genes. A143T/GLA, the only rare variant found, was screened in 10 relatives. GLA activity and lyso-Gb3 levels were measured and echocardiography was performed in 8 of 9 subjects carrying A143T/GLA. Cardiac magnetic resonance (CMR) imaging and 18F-fluorodeoxyglucose (FDG) positron emission tomography/CT (PET/CT) were performed in four adult A143T/GLA carriers. Endomyocardial biopsy was obtained from two adult A143T/GLA carrying sons of the index patient.ResultsThe index patient and her elder son had a pacemaker implantation because of sick sinus syndrome and atrioventricular block. GLA activities were decreased to 25%–40% of normal in both sons and one granddaughter. Lyso-Gb3 levels were elevated in both sons. In CMR, the index patient and her two sons had left ventricular (LV) hypertrophy and/or dilatation. The elder son had late gadolinium enhancement, high CMR-derived T1 time and positive FDG signal in PET/CT in the basal inferolateral LV wall. The younger son had low T1 time and the mother had positive FDG signal in PET/CT in the basal inferolateral LV wall. Endomyocardial biopsy of both sons showed myocardial accumulation compatible with glycolipids in light and electron microscopy, staining with anti-Gb3 antibody available for the younger son. Five female relatives with A143T/GLA had no cardiomyopathy in cardiac imaging.ConclusionsA143T/GLA is likely a late-onset Fabry cardiomyopathy causing variant with incomplete penetrance.

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Monitoring Protein Dynamics in Protein O-Mannosyltransferase Mutants In Vivo by Tandem Fluorescent Protein Timers

Molecules ◽

10.3390/molecules23102622 ◽

2018 ◽

Vol 23 (10) ◽

pp. 2622 ◽

Cited By ~ 6

Author(s):

Joan Castells-Ballester ◽

Ewa Zatorska ◽

Matthias Meurer ◽

Patrick Neubert ◽

Anke Metschies ◽

...

Keyword(s):

Protein Dynamics ◽

Secretory Pathway ◽

Fluorescent Protein ◽

Model Organism ◽

Protein Glycosylation ◽

Major Protein ◽

Specific Substrate ◽

Evolutionarily Conserved ◽

The Impact

For proteins entering the secretory pathway, a major factor contributing to maturation and homeostasis is glycosylation. One relevant type of protein glycosylation is O-mannosylation, which is essential and evolutionarily-conserved in fungi, animals, and humans. Our recent proteome-wide study in the eukaryotic model organism Saccharomyces cerevisiae revealed that more than 26% of all proteins entering the secretory pathway receive O-mannosyl glycans. In a first attempt to understand the impact of O-mannosylation on these proteins, we took advantage of a tandem fluorescent timer (tFT) reporter to monitor different aspects of protein dynamics. We analyzed tFT-reporter fusions of 137 unique O-mannosylated proteins, mainly of the secretory pathway and the plasma membrane, in mutants lacking the major protein O-mannosyltransferases Pmt1, Pmt2, or Pmt4. In these three pmtΔ mutants, a total of 39 individual proteins were clearly affected, and Pmt-specific substrate proteins could be identified. We observed that O-mannosylation may cause both enhanced and diminished protein abundance and/or stability when compromised, and verified our findings on the examples of Axl2-tFT and Kre6-tFT fusion proteins. The identified target proteins are a valuable resource towards unraveling the multiple functions of O-mannosylation at the molecular level.

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A novel hypomorphic mutation in STIM1 results in a late-onset immunodeficiency

Journal of Allergy and Clinical Immunology ◽

10.1016/j.jaci.2015.03.009 ◽

2015 ◽

Vol 136 (3) ◽

pp. 816-819.e4 ◽

Cited By ~ 31

Author(s):

Heidi Schaballie ◽

Rémy Rodriguez ◽

Emmanuel Martin ◽

Leen Moens ◽

Glynis Frans ◽

...

Keyword(s):

Late Onset ◽

Hypomorphic Mutation

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hrT is required for cardiovascular development in zebrafish

Development ◽

10.1242/dev.129.21.5093 ◽

2002 ◽

Vol 129 (21) ◽

pp. 5093-5101 ◽

Cited By ~ 1

Author(s):

Daniel P. Szeto ◽

Kevin J. P. Griffin ◽

David Kimelman

Keyword(s):

Late Onset ◽

Cardiovascular Development ◽

Lateral Plate ◽

T Box ◽

Vascular Morphogenesis ◽

Developing Heart ◽

Evolutionarily Conserved ◽

Heart Formation ◽

Cardiovascular Cells

The recently identified zebrafish T-box gene hrT is expressed in the developing heart and in the endothelial cells forming the dorsal aorta. Orthologs of hrT are expressed in cardiovascular cells fromDrosophila to mouse, suggesting that the function of hrT is evolutionarily conserved. The role of hrT in cardiovascular development, however, has not thus far been determined in any animal model. Using morpholino antisense oligonucleotides, we show that zebrafish embryos lacking hrT function have dysmorphic hearts and an absence of blood circulation. Although the early events in heart formation were normal inhrT morphant embryos, subsequently the hearts failed to undergo looping, and late onset defects in chamber morphology and gene expression were observed. In particular, we found that the loss of hrT function led to a dramatic upregulation of tbx5, a gene required for normal heart morphogenesis. Conversely, we show that overexpression of hrT causes a significant downregulation of tbx5, indicating that one key role ofhrT is to regulate the levels of tbx5. Secondly, we found that HrT is required to inhibit the expression of the blood lineage markersgata1 and gata2 in the most posterior lateral plate mesoderm. Finally, we show that HrT is required for vasculogenesis in the trunk, leading to similar vascular defects to those observed in midline mutants such as floating head. hrT expression in the vascular progenitors depends upon midline mesoderm, indicating that this expression is one important component of the response to a midline-derived signal during vascular morphogenesis.

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