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  1. Article ; Online: AGC1 Deficiency

    Beatriz Pardo / Eduardo Herrada-Soler / Jorgina Satrústegui / Laura Contreras / Araceli del Arco

    International Journal of Molecular Sciences, Vol 23, Iss 528, p

    Pathology and Molecular and Cellular Mechanisms of the Disease

    2022  Volume 528

    Abstract: AGC1/Aralar/Slc25a12 is the mitochondrial carrier of aspartate-glutamate, the regulatory component of the NADH malate-aspartate shuttle (MAS) that transfers cytosolic redox power to neuronal mitochondria. The deficiency in AGC1/Aralar leads to the human ... ...

    Abstract AGC1/Aralar/Slc25a12 is the mitochondrial carrier of aspartate-glutamate, the regulatory component of the NADH malate-aspartate shuttle (MAS) that transfers cytosolic redox power to neuronal mitochondria. The deficiency in AGC1/Aralar leads to the human rare disease named “early infantile epileptic encephalopathy 39” (EIEE 39, OMIM # 612949) characterized by epilepsy, hypotonia, arrested psychomotor neurodevelopment, hypo myelination and a drastic drop in brain aspartate (Asp) and N -acetylaspartate (NAA). Current evidence suggest that neurons are the main brain cell type expressing Aralar. However, paradoxically, glial functions such as myelin and Glutamine (Gln) synthesis are markedly impaired in AGC1 deficiency. Herein, we discuss the role of the AGC1/Aralar-MAS pathway in neuronal functions such as Asp and NAA synthesis, lactate use, respiration on glucose, glutamate (Glu) oxidation and other neurometabolic aspects. The possible mechanism triggering the pathophysiological findings in AGC1 deficiency, such as epilepsy and postnatal hypomyelination observed in humans and mice, are also included. Many of these mechanisms arise from findings in the aralar -KO mice model that extensively recapitulate the human disease including the astroglial failure to synthesize Gln and the dopamine (DA) mishandling in the nigrostriatal system. Epilepsy and DA mishandling are a direct consequence of the metabolic defect in neurons due to AGC1/Aralar deficiency. However, the deficits in myelin and Gln synthesis may be a consequence of neuronal affectation or a direct effect of AGC1/Aralar deficiency in glial cells. Further research is needed to clarify this question and delineate the transcellular metabolic fluxes that control brain functions. Finally, we discuss therapeutic approaches successfully used in AGC1-deficient patients and mice.
    Keywords malate-aspartate shuttle ; AGC1/Aralar deficiency ; mitochondrial disorders ; mitochondrial aspartate-glutamate carrier ; mitochondrial function ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 570
    Language English
    Publishing date 2022-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Calcium Deregulation and Mitochondrial Bioenergetics in GDAP1-Related CMT Disease

    Paloma González-Sánchez / Jorgina Satrústegui / Francesc Palau / Araceli del Arco

    International Journal of Molecular Sciences, Vol 20, Iss 2, p

    2019  Volume 403

    Abstract: The pathology of Charcot-Marie-Tooth (CMT), a disease arising from mutations in different genes, has been associated with an impairment of mitochondrial dynamics and axonal biology of mitochondria. Mutations in ganglioside-induced differentiation- ... ...

    Abstract The pathology of Charcot-Marie-Tooth (CMT), a disease arising from mutations in different genes, has been associated with an impairment of mitochondrial dynamics and axonal biology of mitochondria. Mutations in ganglioside-induced differentiation-associated protein 1 (GDAP1) cause several forms of CMT neuropathy, but the pathogenic mechanisms involved remain unclear. GDAP1 is an outer mitochondrial membrane protein highly expressed in neurons. It has been proposed to play a role in different aspects of mitochondrial physiology, including mitochondrial dynamics, oxidative stress processes, and mitochondrial transport along the axons. Disruption of the mitochondrial network in a neuroblastoma model of GDAP1-related CMT has been shown to decrease Ca2+ entry through the store-operated calcium entry (SOCE), which caused a failure in stimulation of mitochondrial respiration. In this review, we summarize the different functions proposed for GDAP1 and focus on the consequences for Ca2+ homeostasis and mitochondrial energy production linked to CMT disease caused by different GDAP1 mutations.
    Keywords GDAP1 ; recessive mutations ; store operated calcium entry ; mitochondrial location ; calcium regulated cell respiration ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 570
    Language English
    Publishing date 2019-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Exogenous aralar/slc25a12 can replace citrin/slc25a13 as malate aspartate shuttle component in liver

    Luis González-Moreno / Andrea Santamaría-Cano / Alberto Paradela / María Luz Martínez-Chantar / Miguel Á. Martín / Mercedes Pérez-Carreras / Alberto García-Picazo / Jesús Vázquez / Enrique Calvo / Gloria González-Aseguinolaza / Takeyori Saheki / Araceli del Arco / Jorgina Satrústegui / Laura Contreras

    Molecular Genetics and Metabolism Reports, Vol 35, Iss , Pp 100967- (2023)

    2023  

    Abstract: The deficiency of CITRIN, the liver mitochondrial aspartate–glutamate carrier (AGC), is the cause of four human clinical phenotypes, neonatal intrahepatic cholestasis caused by CITRIN deficiency (NICCD), silent period, failure to thrive and dyslipidemia ... ...

    Abstract The deficiency of CITRIN, the liver mitochondrial aspartate–glutamate carrier (AGC), is the cause of four human clinical phenotypes, neonatal intrahepatic cholestasis caused by CITRIN deficiency (NICCD), silent period, failure to thrive and dyslipidemia caused by CITRIN deficiency (FTTDCD), and citrullinemia type II (CTLN2). Clinical symptoms can be traced back to disruption of the malate-aspartate shuttle due to the lack of citrin. A potential therapy for this condition is the expression of aralar, the AGC present in brain, to replace citrin. To explore this possibility we have first verified that the NADH/NAD+ ratio increases in hepatocytes from citrin(−/−) mice, and then found that exogenous aralar expression reversed the increase in NADH/NAD+ observed in these cells. Liver mitochondria from citrin (−/−) mice expressing liver specific transgenic aralar had a small (~ 4–6 nmoles x mg prot−1 x min−1) but consistent increase in malate aspartate shuttle (MAS) activity over that of citrin(−/−) mice. These results support the functional replacement between AGCs in the liver. To explore the significance of AGC replacement in human therapy we studied the relative levels of citrin and aralar in mouse and human liver through absolute quantification proteomics. We report that mouse liver has relatively high aralar levels (citrin/aralar molar ratio of 7.8), whereas human liver is virtually devoid of aralar (CITRIN/ARALAR ratio of 397). This large difference in endogenous aralar levels partly explains the high residual MAS activity in liver of citrin(−/−) mice and why they fail to recapitulate the human disease, but supports the benefit of increasing aralar expression to improve the redox balance capacity of human liver, as an effective therapy for CITRIN deficiency.
    Keywords Mitochondria ; Citrin deficiency ; Aspartate-glutamate carrier ; Malate-aspartate shuttle ; Hepatocyte ; Medicine (General) ; R5-920 ; Biology (General) ; QH301-705.5
    Subject code 610
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: SCaMC-1Like a member of the mitochondrial carrier (MC) family preferentially expressed in testis and localized in mitochondria and chromatoid body.

    Ignacio Amigo / Javier Traba / Jorgina Satrústegui / Araceli del Arco

    PLoS ONE, Vol 7, Iss 7, p e

    2012  Volume 40470

    Abstract: Mitochondrial carriers (MC) form a highly conserved family involved in solute transport across the inner mitochondrial membrane in eukaryotes. In mammals, ATP-Mg/Pi carriers, SCaMCs, form the most complex subgroup with four paralogs, SCaMC-1, -2, -3 and - ...

    Abstract Mitochondrial carriers (MC) form a highly conserved family involved in solute transport across the inner mitochondrial membrane in eukaryotes. In mammals, ATP-Mg/Pi carriers, SCaMCs, form the most complex subgroup with four paralogs, SCaMC-1, -2, -3 and -3L, and several splicing variants. Here, we report the tissue distribution and subcellular localization of a mammalian-specific SCaMC paralog, 4930443G12Rik/SCaMC-1Like (SCaMC-1L), which displays unanticipated new features. SCaMC-1L proteins show higher amino acid substitution rates than its closest paralog SCaMC-1. In mouse, SCaMC-1L expression is restricted to male germ cells and regulated during spermatogenesis but unexpectedly its localization is not limited to mitochondrial structures. In mature spermatids SCaMC-1L is detected in the mitochondrial sheath but in previous differentiation stages appears associated to cytosolic granules which colocalize with specific markers of the chromatoid body (CB) in post-meiotic round spermatids and inter-mitochondrial cement (IMC) in spermatocytes. The origin of this atypical distribution was further investigated by transient expression in cell lines. Similarly to male germ cells, in addition to mitochondrial and cytosolic distribution, a fraction of SCaMC-1L-expressing COS-7 cells display cytosolic SCaMC-1L-aggregates which exhibit aggresomal-like features as the CB. Our results indicate that different regions of SCaMC-1L hinder its import into mitochondria and this apparently favours the formation of cytosolic aggregates in COS-7 cells. This mechanism could be also operational in male germ cells and explain the incorporation of SCaMC-1L into germinal granules.
    Keywords Medicine ; R ; Science ; Q
    Subject code 570
    Language English
    Publishing date 2012-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Ca2+ regulation of mitochondrial function in neurons

    Rueda, Carlos B / Irene Llorente-Folch / Ignacio Amigo / Laura Contreras / Paloma González-Sánchez / Paula Martínez-Valero / Inés Juaristi / Beatriz Pardo / Araceli del Arco / Jorgina Satrústegui

    Biochimica et biophysica acta. 2014 Oct., v. 1837, no. 10

    2014  

    Abstract: Calcium is thought to regulate respiration but it is unclear whether this is dependent on the increase in ATP demand caused by any Ca2+ signal or to Ca2+ itself. [Na+]i, [Ca2+]i and [ATP]i dynamics in intact neurons exposed to different workloads in the ... ...

    Abstract Calcium is thought to regulate respiration but it is unclear whether this is dependent on the increase in ATP demand caused by any Ca2+ signal or to Ca2+ itself. [Na+]i, [Ca2+]i and [ATP]i dynamics in intact neurons exposed to different workloads in the absence and presence of Ca2+ clearly showed that Ca2+-stimulation of coupled respiration is required to maintain [ATP]i levels. Ca2+ may regulate respiration by activating metabolite transport in mitochondria from outer face of the inner mitochondrial membrane, or after Ca2+ entry in mitochondria through the calcium uniporter (MCU). Two Ca2+-regulated mitochondrial metabolite transporters are expressed in neurons, the aspartate–glutamate exchanger ARALAR/AGC1/Slc25a12, a component of the malate–aspartate shuttle, and the ATP-Mg/Pi exchanger SCaMC-3/APC2/Slc25a23, with S0.5 for Ca2+ of 300nM and 3.4μM, respectively. The lack of SCaMC-3 results in a smaller Ca2+-dependent stimulation of respiration only at high workloads, as caused by veratridine, whereas the lack of ARALAR reduced by 46% basal OCR in intact neurons using glucose as energy source and the Ca2+-dependent responses to all workloads: a reduction of about 65–70% in the response to the high workload imposed by veratridine, and completely suppression of the OCR responses to moderate (K+-depolarization) and small (carbachol) workloads, effects reverted by pyruvate supply. For K+-depolarization, this occurs in spite of the presence of large [Ca2+]mit signals and increased formation of mitochondrial NAD(P)H. These results show that ARALAR-MAS is a major contributor of Ca2+-stimulated respiration in neurons by providing increased pyruvate supply to mitochondria. In its absence and under moderate workloads, matrix Ca2+ is unable to stimulate pyruvate metabolism and entry in mitochondria suggesting a limited role of MCU in these conditions. This article was invited for a Special Issue entitled: 18th European Bioenergetic Conference.
    Keywords NAD (coenzyme) ; adenosine triphosphate ; calcium ; carbachol ; energy ; glucose ; metabolism ; metabolites ; mitochondria ; mitochondrial membrane ; neurons ; pyruvic acid ; sodium ; transporters
    Language English
    Dates of publication 2014-10
    Size p. 1617-1624.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 282711-6
    ISSN 0005-2728 ; 0304-4173
    ISSN 0005-2728 ; 0304-4173
    DOI 10.1016/j.bbabio.2014.04.010
    Database NAL-Catalogue (AGRICOLA)

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  6. Article: Glutamate excitotoxicity and Ca2+-regulation of respiration: Role of the Ca2+ activated mitochondrial transporters (CaMCs)

    Rueda, Carlos B / Irene Llorente-Folch / Javier Traba / Ignacio Amigo / Paloma Gonzalez-Sanchez / Laura Contreras / Inés Juaristi / Paula Martinez-Valero / Beatriz Pardo / Araceli del Arco / Jorgina Satrustegui

    Biochimica et biophysica acta. 2016 Aug., v. 1857, no. 8

    2016  

    Abstract: Glutamate elicits Ca2+ signals and workloads that regulate neuronal fate both in physiological and pathological circumstances. Oxidative phosphorylation is required in order to respond to the metabolic challenge caused by glutamate. In response to ... ...

    Abstract Glutamate elicits Ca2+ signals and workloads that regulate neuronal fate both in physiological and pathological circumstances. Oxidative phosphorylation is required in order to respond to the metabolic challenge caused by glutamate. In response to physiological glutamate signals, cytosolic Ca2+ activates respiration by stimulation of the NADH malate–aspartate shuttle through Ca2+-binding to the mitochondrial aspartate/glutamate carrier (Aralar/AGC1/Slc25a12), and by stimulation of adenine nucleotide uptake through Ca2+ binding to the mitochondrial ATP-Mg/Pi carrier (SCaMC-3/Slc25a23). In addition, after Ca2+ entry into the matrix through the mitochondrial Ca2+ uniporter (MCU), it activates mitochondrial dehydrogenases. In response to pathological glutamate stimulation during excitotoxicity, Ca2+ overload, reactive oxygen species (ROS), mitochondrial dysfunction and delayed Ca2+ deregulation (DCD) lead to neuronal death. Glutamate-induced respiratory stimulation is rapidly inactivated through a mechanism involving Poly (ADP-ribose) Polymerase-1 (PARP-1) activation, consumption of cytosolic NAD+, a decrease in matrix ATP and restricted substrate supply. Glutamate-induced Ca2+-activation of SCaMC-3 imports adenine nucleotides into mitochondria, counteracting the depletion of matrix ATP and the impaired respiration, while Aralar-dependent lactate metabolism prevents substrate exhaustion. A second mechanism induced by excitotoxic glutamate is permeability transition pore (PTP) opening, which critically depends on ROS production and matrix Ca2+ entry through the MCU. By increasing matrix content of adenine nucleotides, SCaMC-3 activity protects against glutamate-induced PTP opening and lowers matrix free Ca2+, resulting in protracted appearance of DCD and protection against excitotoxicity in vitro and in vivo, while the lack of lactate protection during in vivo excitotoxicity explains increased vulnerability to kainite-induced toxicity in Aralar +/− mice. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
    Keywords NAD (coenzyme) ; adenine ; adenosine triphosphate ; aspartic acid ; calcium ; cell death ; death ; mice ; mitochondria ; neurons ; oxidative phosphorylation ; permeability ; reactive oxygen species ; toxicity ; transporters
    Language English
    Dates of publication 2016-08
    Size p. 1158-1166.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 282711-6
    ISSN 0005-2728 ; 0304-4173
    ISSN 0005-2728 ; 0304-4173
    DOI 10.1016/j.bbabio.2016.04.003
    Database NAL-Catalogue (AGRICOLA)

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