scholarly journals Defined neuronal populations drive fatal phenotype in a mouse model of Leigh syndrome

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Irene Bolea ◽  
Alejandro Gella ◽  
Elisenda Sanz ◽  
Patricia Prada-Dacasa ◽  
Fabien Menardy ◽  
...  
Keyword(s):  
Mouse Model ◽  
Critical Role ◽  
Leigh Syndrome ◽  
Early Death ◽  
Epileptic Seizures ◽  
Premature Death ◽  
Neuronal Firing ◽  
Cellular Mechanisms ◽  
Neuronal Populations ◽  
Respiratory Involvement

Mitochondrial deficits in energy production cause untreatable and fatal pathologies known as mitochondrial disease (MD). Central nervous system affectation is critical in Leigh Syndrome (LS), a common MD presentation, leading to motor and respiratory deficits, seizures and premature death. However, only specific neuronal populations are affected. Furthermore, their molecular identity and their contribution to the disease remains unknown. Here, using a mouse model of LS lacking the mitochondrial complex I subunit Ndufs4, we dissect the critical role of genetically-defined neuronal populations in LS progression. Ndufs4 inactivation in Vglut2-expressing glutamatergic neurons leads to decreased neuronal firing, brainstem inflammation, motor and respiratory deficits, and early death. In contrast, Ndufs4 deletion in GABAergic neurons causes basal ganglia inflammation without motor or respiratory involvement, but accompanied by hypothermia and severe epileptic seizures preceding death. These results provide novel insight in the cell type-specific contribution to the pathology, dissecting the underlying cellular mechanisms of MD.

scholarly journals Defined neuronal populations drive fatal phenotype in Leigh Syndrome

2019 ◽  
Author(s):  
Irene Bolea ◽  
Alejandro Gella ◽  
Elisenda Sanz ◽  
Patricia Prada-Dacasa ◽  
Fabien Menardy ◽  
...  
Keyword(s):  
Mitochondrial Disease ◽  
Critical Role ◽  
Leigh Syndrome ◽  
Early Death ◽  
Epileptic Seizures ◽  
Premature Death ◽  
High Energy ◽  
Cellular Mechanisms ◽  
Neuronal Populations ◽  
Respiratory Involvement

AbstractDysfunctions of the mitochondrial energy-generating machinery cause a series of progressive, untreatable and usually fatal diseases collectively known as mitochondrial disease. High energy-requiring organs such as the brain are especially affected, leading to developmental delay, ataxia, respiratory failure, hypotonia, seizures and premature death. While neural affectation is a critical component of the pathology, only discrete neuronal populations are susceptible. However, their molecular identity and their contribution to the disease remain unknown. Mice lacking the mitochondrial Complex I subunit NDUFS4 (Ndufs4KO mice) recapitulate the classical signs of Leigh Syndrome (LS), the most common presentation of mitochondrial disease with predominant CNS affectation. Here, we identify the critical role of two genetically-defined neuronal populations driving the fatal phenotype in Ndufs4KO mice. Selective inactivation of Ndufs4 in Vglut2-expressing glutamatergic neurons causes brainstem inflammation, motor and respiratory deficits, and early death. On the other hand, Ndufs4 deletion in GABAergic neurons leads to basal ganglia inflammation without motor or respiratory involvement, but accompanied by severe refractory epileptic seizures preceding premature death. These results provide novel insight in the cell type-specific contribution to LS pathology and open new avenues to understand the underlying cellular mechanisms of mitochondrial disease.

scholarly journals Author response: Defined neuronal populations drive fatal phenotype in a mouse model of Leigh syndrome

2019 ◽  
Author(s):  
Irene Bolea ◽  
Alejandro Gella ◽  
Elisenda Sanz ◽  
Patricia Prada-Dacasa ◽  
Fabien Menardy ◽  
...  
Keyword(s):  
Mouse Model ◽  
Leigh Syndrome ◽  
Author Response ◽  
Neuronal Populations

scholarly journals Mitochondrial Proteome of Affected Neurons in a Mouse Model of Leigh Syndrome

2019 ◽  
Author(s):  
Alejandro Gella ◽  
Patricia Prada-Dacasa ◽  
Montserrat Carrascal ◽  
Melania González-Torres ◽  
Joaquin Abian ◽  
...  
Keyword(s):  
Mouse Model ◽  
Mitochondrial Disease ◽  
Complex I ◽  
Viral Vector ◽  
Mitochondrial Diseases ◽  
Leigh Syndrome ◽  
Premature Death ◽  
Cell Types ◽  
Supporting Cell ◽  
Pediatric Presentation

AbstractDefects in mitochondrial function lead to severe neuromuscular orphan pathologies known as mitochondrial disease. Among them, Leigh Syndrome is the most common pediatric presentation, characterized by symmetrical brain lesions, hypotonia, motor and respiratory deficits, and premature death. Mitochondrial diseases are characterized by a marked anatomical and cellular specificity. However, the molecular determinants for this susceptibility are currently unknown, hindering the efforts to find an effective treatment. Due to the complex crosstalk between mitochondria and their supporting cell, strategies to assess the underlying alterations in affected cell types in the context of mitochondrial dysfunction are critical. Here, we developed a novel virus-based tool, the AAV-mitoTag viral vector, to isolate mitochondria from genetically-defined cell types. Administration of the AAV-mitoTag in the vestibular neurons of a mouse model of Leigh Syndrome lacking the complex I subunit Ndufs4 allowed us to assess the proteome and acetylome of susceptible neurons in a well characterized model recapitulating the human disease. Our results show a marked reduction of complex-I N-module subunit abundance and an increase in the levels of the assembly factor NDUFA2. Transiently-associated non-mitochondrial proteins such as PKCδ, and the complement subcomponent C1Q were also increased in Ndufs4-deficient mitochondria. Furthermore, lack of Ndufs4 induced pyruvate dehydrogenase (PDH) subunit hyperacetylation, leading to decreased PDH activity. We provide novel insight on the pathways involved in mitochondrial disease, which could underlie potential therapeutic approaches for these pathologies.

scholarly journals CNS Glycosylphosphatidylinositol Deficiency Results in Delayed White Matter Development, Ataxia, and Premature Death in a Novel Mouse Model

2019 ◽  
Author(s):  
Marshall Lukacs ◽  
Rolf W. Stottmann
Keyword(s):  
White Matter ◽  
Mouse Model ◽  
Critical Role ◽  
Premature Death ◽  
Post Translational Modification ◽  
Gpi Anchor ◽  
Wide Range ◽  
Affected Tissue ◽  
White Matter Development ◽  
The Central Nervous System

AbstractThe Glycosylphosphatidylinositol (GPI) anchor is a post-translational modification added to approximately 150 different proteins to facilitate proper membrane anchoring and trafficking to lipid rafts. Biosynthesis and remodeling of the GPI anchor requires the activity of over twenty distinct genes. Defects in the biosynthesis of GPI anchors in humans leads to Inherited Glycosylphosphatidylinositol Deficiency (IGD). IGD patients display a wide range of phenotypes though the central nervous system (CNS) appears to be the most commonly affected tissue. A full understanding of the etiology of these phenotypes has been hampered by the lack of animal models due to embryonic lethality of GPI biosynthesis gene null mutants. Here we model IGD by genetically ablating GPI production in the CNS with a conditional mouse allele of phosphatidylinositol glycan anchor biosynthesis, class A (Piga) and Nestin-Cre. We find that the mutants do not have structural brain defects but do not survive past weaning. The mutants show progressive decline with severe ataxia consistent with defects in cerebellar development. We show the mutants have reduced myelination and defective Purkinje cell development. Surprisingly we found Piga was expressed in a fairly restricted pattern in the early postnatal brain consistent with the defects we observed in our model. Thus, we have generated a novel mouse model of the neurological defects of IGD which demonstrates a critical role for GPI biosynthesis in cerebellar and white matter development.

scholarly journals Protein Kinase C Downregulation upon Rapamycin Treatment Attenuates Neuroinflammation and Mitochondrial Disease

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 889-890
Author(s):  
Anthony Grillo ◽  
Alessandro Bitto ◽  
Matt Kaeberlein
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Critical Role ◽  
Specific Inhibitor ◽  
Mitochondrial Diseases ◽  
Leigh Syndrome ◽  
Premature Death ◽  
Kinase C ◽  
Pkc Β ◽  
Pkc Inhibitors

Abstract Mitochondrial dysfunction causes many poorly understood diseases, such as Leigh Syndrome, that are often caused by dysfunctions in proteins involved in the electron transport chain. My lab previously reported mTOR is pathologically involved in the neurodegenerative phenotype and premature death of mice missing the Complex I subunit Ndufs4 (Ndufs4-/- mice). We discovered treatment with rapamycin extends lifespan, reduces neuroinflammation, and attenuates the neurodegenerative phenotype in these mice, although the mechanisms remain unclear. Rapamycin-treated Ndufs4-/- mice exhibited decreased activation of the mTORC1 pathway. It also deactivated the mTORC2 pathway. We observed that phosphorylation of the canonical protein kinase C (PKC) isoforms (PKC-α, -β, and -γ) decreased more than any other kinases, leading us to hypothesize its deactivation contributes to the observed lifespan extension. To test this, we treated Ndufs4-/- mice with three different PKC inhibitors: the pan-PKC inhibitors GO6983 and GF109203X, and the PKC-β specific inhibitor ruboxistaurin. Similar to rapamycin, all three drugs were able to significantly delay the onset of neurological symptoms (i.e. clasping) and increase survival. We also observed that PKC-β inhibition reduced skin inflammation to suppress the hair loss phenotype displayed by Ndufs4-/- mice at weaning. We further discovered PKC-β inhibition reduces neuroinflammation by deactivating the NF-kB inflammatory pathway. These results suggest that mTORC2 may play a critical role in the etiology of mitochondrial diseases such as Leigh Syndrome.

Depolarization Block of Neurons During Maintenance of Electrographic Seizures

2003 ◽  
Vol 90 (4) ◽  
pp. 2402-2408 ◽  
Author(s):  
Marom Bikson ◽  
Philip J. Hahn ◽  
John E. Fox ◽  
John G.R. Jefferys
Keyword(s):  
Electric Fields ◽  
Sodium Current ◽  
Critical Role ◽  
Hippocampal Slices ◽  
Epileptic Seizures ◽  
Neuronal Firing ◽  
Extracellular Potassium ◽  
Depolarization Block ◽  
Antidromic Stimulation ◽  
Electrographic Seizures

Epileptic seizures are associated with neuronal hyperactivity. Here, however, we investigated whether continuous neuronal firing is necessary to maintain electrographic seizures. We studied a class of “low-Ca2+” ictal epileptiform bursts, induced in rat hippocampal slices, that are characterized by prolonged (2–15 s) interruptions in population spike generation. We found that, during these interruptions, neuronal firing was suppressed rather than desynchronized. Intracellular current injection, application of extracellular uniform electric fields, and antidromic stimulation showed that the source of action potential disruption was depolarization block. The duration of the extracellular potassium transients associated with each ictal burst was not affected by disruptions in neuronal firing. Application of phenytoin or veratridine indicated a critical role for the persistent sodium current in maintaining depolarization block. Our results show that continuous neuronal firing is not necessary for the maintenance of experimental electrographic seizures.

scholarly journals CNS glycosylphosphatidylinositol deficiency results in delayed white matter development, ataxia and premature death in a novel mouse model

2020 ◽  
Vol 29 (7) ◽  
pp. 1205-1217 ◽  
Author(s):  
Marshall Lukacs ◽  
Lauren E Blizzard ◽  
Rolf W Stottmann
Keyword(s):  
White Matter ◽  
Mouse Model ◽  
Critical Role ◽  
Premature Death ◽  
Post Translational Modification ◽  
Gpi Anchor ◽  
Wide Range ◽  
Affected Tissue ◽  
White Matter Development ◽  
The Central Nervous System

Abstract The glycosylphosphatidylinositol (GPI) anchor is a post-translational modification added to approximately 150 different proteins to facilitate proper membrane anchoring and trafficking to lipid rafts. Biosynthesis and remodeling of the GPI anchor requires the activity of over 20 distinct genes. Defects in the biosynthesis of GPI anchors in humans lead to inherited glycosylphosphatidylinositol deficiency (IGD). IGD patients display a wide range of phenotypes though the central nervous system (CNS) appears to be the most commonly affected tissue. A full understanding of the etiology of these phenotypes has been hampered by the lack of animal models due to embryonic lethality of GPI biosynthesis gene null mutants. Here we model IGD by genetically ablating GPI production in the CNS with a conditional mouse allele of phosphatidylinositol glycan anchor biosynthesis, class A (Piga) and Nestin-Cre. We find that the mutants do not have structural brain defects but do not survive past weaning. The mutants show progressive decline with severe ataxia consistent with defects in cerebellar development. We show that the mutants have reduced myelination and defective Purkinje cell development. Surprisingly, we found that Piga was expressed in a fairly restricted pattern in the early postnatal brain consistent with the defects we observed in our model. Thus, we have generated a novel mouse model of the neurological defects of IGD which demonstrates a critical role for GPI biosynthesis in cerebellar and white matter development.

scholarly journals Collagen molecular phenotypic switch between non-neoplastic and neoplastic canine mammary tissues

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masahiko Terajima ◽  
Yuki Taga ◽  
Becky K. Brisson ◽  
Amy C. Durham ◽  
Kotaro Sato ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Mammary Gland ◽  
Mammary Carcinoma ◽  
Cancer Biology ◽  
Type I Collagen ◽  
Critical Role ◽  
Premature Death ◽  
Mammary Tissue ◽  
Type I ◽  
Cross Links

AbstractIn spite of major advances over the past several decades in diagnosis and treatment, breast cancer remains a global cause of morbidity and premature death for both human and veterinary patients. Due to multiple shared clinicopathological features, dogs provide an excellent model of human breast cancer, thus, a comparative oncology approach may advance our understanding of breast cancer biology and improve patient outcomes. Despite an increasing awareness of the critical role of fibrillar collagens in breast cancer biology, tumor-permissive collagen features are still ill-defined. Here, we characterize the molecular and morphological phenotypes of type I collagen in canine mammary gland tumors. Canine mammary carcinoma samples contained longer collagen fibers as well as a greater population of wider fibers compared to non-neoplastic and adenoma samples. Furthermore, the total number of collagen cross-links enriched in the stable hydroxylysine-aldehyde derived cross-links was significantly increased in neoplastic mammary gland samples compared to non-neoplastic mammary gland tissue. The mass spectrometric analyses of type I collagen revealed that in malignant mammary tumor samples, lysine residues, in particular those in the telopeptides, were markedly over-hydroxylated in comparison to non-neoplastic mammary tissue. The extent of glycosylation of hydroxylysine residues was comparable among the groups. Consistent with these data, expression levels of genes encoding lysyl hydroxylase 2 (LH2) and its molecular chaperone FK506-binding protein 65 were both significantly increased in neoplastic samples. These alterations likely lead to an increase in the LH2-mediated stable collagen cross-links in mammary carcinoma that may promote tumor cell metastasis in these patients.

scholarly journals Brain-Specific SNAP-25 Deletion Leads to Elevated Extracellular Glutamate Level and Schizophrenia-Like Behavior in Mice

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Hua Yang ◽  
Mengjie Zhang ◽  
Jiahao Shi ◽  
Yunhe Zhou ◽  
Zhipeng Wan ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Mouse Model ◽  
Glutamate Release ◽  
Critical Role ◽  
Conditional Knockout ◽  
Snare Complex ◽  
Extracellular Glutamate ◽  
Glutamate Level

Several studies have associated reduced expression of synaptosomal-associated protein of 25 kDa (SNAP-25) with schizophrenia, yet little is known about its role in the illness. In this paper, a forebrain glutamatergic neuron-specific SNAP-25 knockout mouse model was constructed and studied to explore the possible pathogenetic role of SNAP-25 in schizophrenia. We showed that SNAP-25 conditional knockout (cKO) mice exhibited typical schizophrenia-like phenotype. A significantly elevated extracellular glutamate level was detected in the cerebral cortex of the mouse model. Compared with Ctrls, SNAP-25 was dramatically reduced by about 60% both in cytoplasm and in membrane fractions of cerebral cortex of cKOs, while the other two core members of SNARE complex: Syntaxin-1 (increased ~80%) and Vamp2 (increased ~96%) were significantly increased in cell membrane part. Riluzole, a glutamate release inhibitor, significantly attenuated the locomotor hyperactivity deficits in cKO mice. Our findings provide in vivo functional evidence showing a critical role of SNAP-25 dysfunction on synaptic transmission, which contributes to the developmental of schizophrenia. It is suggested that a SNAP-25 cKO mouse, a valuable model for schizophrenia, could address questions regarding presynaptic alterations that contribute to the etiopathophysiology of SZ and help to consummate the pre- and postsynaptic glutamatergic pathogenesis of the illness.

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