Olga Criado - Academia.edu (original) (raw)

Papers by Olga Criado

Research paper thumbnail of Laforin ddr157supp

Research paper thumbnail of Expression of the β-chain of C4b-binding protein in human ovary

Molecular Immunology, 1998

Research paper thumbnail of Laforin, a dual specificity phosphatase involved in Lafora disease, regulates insulin response and whole-body energy balance in mice

Human Molecular Genetics, 2011

Laforin is a dual specificity protein phosphatase involved in Lafora disease (LD), a fatal form o... more Laforin is a dual specificity protein phosphatase involved in Lafora disease (LD), a fatal form of progressive myoclonus epilepsy characterized by neurodegeneration and the presence of intracellular polyglucosan inclusions (Lafora bodies) in different tissues. In this work, we describe that mice lacking laforin (epm2a2/2) have enhanced insulin response leading to altered whole-body energy balance. This enhanced insulin response overactivates the Akt pathway which increases glucose uptake in the heart, resulting in increased glycogen levels and the formation of polyglucosan inclusions. In addition, enhanced insulin response resulted in increased liver lipid biosynthesis, resulting in hepatic steatosis. On the contrary, overexpression in rat hepatoma FTO2B cells of native laforin but not of a form lacking phosphatase activity (C266S) resulted in attenuation of insulin signaling. These results define laforin as a new regulator of insulin sensitivity, which provides novel insights into LD pathogenesis and identifies this phosphatase as a potential novel component of the insulin signaling cascade.

Research paper thumbnail of Laforin, the most common protein mutated in Lafora disease, regulates autophagy

Human Molecular Genetics, 2010

Lafora disease (LD) is an autosomal recessive, progressive myoclonus epilepsy, which is character... more Lafora disease (LD) is an autosomal recessive, progressive myoclonus epilepsy, which is characterized by the accumulation of polyglucosan inclusion bodies, called Lafora bodies, in the cytoplasm of cells in the central nervous system and in many other organs. However, it is unclear at the moment whether Lafora bodies are the cause of the disease, or whether they are secondary consequences of a primary metabolic alteration.

Research paper thumbnail of Structural and functional analysis of mutations in alkaptonuria

Human Molecular Genetics, 2000

Alkaptonuria (AKU), the prototypic inborn error of metabolism, was the first human disease to be ... more Alkaptonuria (AKU), the prototypic inborn error of metabolism, was the first human disease to be interpreted as a Mendelian trait by Garrod and Bateson at the beginning of last century. AKU results from impaired function of homogentisate dioxygenase (HGO), an enzyme required for the catabolism of phenylalanine and tyrosine. With the novel 7 AKU and 22 fungal mutations reported here, a total of 84 mutations impairing this enzyme have been found in the HGO gene from humans and model organisms. Forty-three of these mutations result in single amino acid substitutions. This mutational information is analysed here in the context of the HGO structure and function using kinetic assays performed using purified AKU mutant enzymes and the crystal structure of human HGO. HGO is a topologically complex structure which assembles as a functional hexamer arranged as a dimer of trimers. We show how the intricate pattern of intra-and inter-subunit interactions and the extensive surfaces required for subunit folding and association of this oligomeric enzyme can be inactivated at multiple levels by single-residue substitutions. This explains, in part, the predominance of missense mutations (67%) in AKU.

Research paper thumbnail of Lafora bodies and neurological defects in malin-deficient mice correlate with impaired autophagy

Human Molecular Genetics, 2012

Lafora disease (LD), a fatal neurodegenerative disorder characterized by the presence of intracel... more Lafora disease (LD), a fatal neurodegenerative disorder characterized by the presence of intracellular inclusions called Lafora bodies (LBs), is caused by loss-of-function mutations in laforin or malin. Previous studies suggested a role of these proteins in the regulation of glycogen biosynthesis, in glycogen dephosphorylation and in the modulation of the intracellular proteolytic systems. However, the contribution of each of these processes to LD pathogenesis is unclear. We have generated a malin-deficient (Epm2b2/2) mouse with a phenotype similar to that of LD patients. By 3 -6 months of age, Epm2b2/2 mice present neurological and behavioral abnormalities that correlate with a massive presence of LBs in the cortex, hippocampus and cerebellum. Sixteen-day-old Epm2b2/2 mice, without detectable LBs, show an impairment of macroautophagy (hereafter called autophagy), which remains compromised in adult animals. These data demonstrate similarities between the Epm2a2/2 and Epm2b2/2 mice that provide further insights into LD pathogenesis. They illustrate that the dysfunction of autophagy is a consequence of the lack of laforin-malin complexes and a common feature of both mouse models of LD. Because this dysfunction precedes other pathological manifestations, we propose that decreased autophagy plays a primary role in the formation of LBs and it is critical in LD pathogenesis.

Research paper thumbnail of Laforin, a dual-specificity phosphatase involved in Lafora disease, is phosphorylated at Ser 25 by AMP-activated protein kinase

Biochemical Journal, 2011

Lafora progressive myoclonus epilepsy [LD (Lafora disease)] is a fatal autosomal recessive neurod... more Lafora progressive myoclonus epilepsy [LD (Lafora disease)] is a fatal autosomal recessive neurodegenerative disorder caused by loss-of-function mutations in either the EPM2A gene, encoding the dual-specificity phosphatase laforin, or the EPM2B gene, encoding the E3-ubiquitin ligase malin. Previously, we and others showed that laforin and malin form a functional complex that regulates multiple aspects of glycogen metabolism, and that the interaction between laforin and malin is enhanced by conditions activating AMPK (AMP-activated protein kinase). In the present study, we demonstrate that laforin is a phosphoprotein, as indicated by two-dimensional electrophoresis, and we identify Ser 25 as the residue involved in this modification. We also show that Ser 25 is phosphorylated both in vitro and in vivo by AMPK. Lastly, we demonstrate that this residue plays a critical role for both the phosphatase activity and the ability of laforin to interact with itself and with previously established binding partners. The results of the present study suggest that phosphorylation of laforin-Ser 25 by AMPK provides a mechanism to modulate the interaction between laforin and malin. Regulation of this complex is necessary to maintain normal glycogen metabolism. Importantly, Ser 25 is mutated in some LD patients (S25P), and our results begin to elucidate the mechanism of disease in these patients.

Research paper thumbnail of The Molecular Basis of 3-Methylcrotonylglycinuria, a Disorder of Leucine Catabolism

The American Journal of Human Genetics, 2001

3-Methylcrotonylglycinuria is an inborn error of leucine catabolism and has a recessive pattern o... more 3-Methylcrotonylglycinuria is an inborn error of leucine catabolism and has a recessive pattern of inheritance that results from the deficiency of 3-methylcrotonyl-CoA carboxylase (MCC). The introduction of tandem mass spectrometry in newborn screening has revealed an unexpectedly high incidence of this disorder, which, in certain areas, appears to be the most frequent organic aciduria. MCC, an heteromeric enzyme consisting of a (biotin-containing) and b subunits, is the only one of the four biotin-dependent carboxylases known in humans that has genes that have not yet been characterized, precluding molecular studies of this disease. Here we report the characterization, at the genomic level and at the cDNA level, of both the MCCA gene and the MCCB gene, encoding the MCCa and MCCb subunits, respectively. The 19-exon MCCA gene maps to 3q25-27 and encodes a 725-residue protein with a biotin attachment site; the 17-exon MCCB gene maps to 5q12-q13 and encodes a 563-residue polypeptide. We show that disease-causing mutations can be classified into two complementation groups, denoted "CGA" and "CGB." We detected two MCCA missense mutations in CGA patients, one of which leads to absence of biotinylated MCCa. Two MCCB missense mutations and one splicing defect mutation leading to early MCCb truncation were found in CGB patients. A fourth MCCB mutation also leading to early MCCb truncation was found in two nonclassified patients. A fungal model carrying an mccA null allele has been constructed and was used to demonstrate, in vivo, the involvement of MCC in leucine catabolism. These results establish that 3-methylcrotonylglycinuria results from loss-of-function mutations in the genes encoding the a and b subunits of MCC and complete the genetic characterization of the four human biotin-dependent carboxylases.

Research paper thumbnail of Laforin ddr157supp

Research paper thumbnail of Expression of the β-chain of C4b-binding protein in human ovary

Molecular Immunology, 1998

Research paper thumbnail of Laforin, a dual specificity phosphatase involved in Lafora disease, regulates insulin response and whole-body energy balance in mice

Human Molecular Genetics, 2011

Laforin is a dual specificity protein phosphatase involved in Lafora disease (LD), a fatal form o... more Laforin is a dual specificity protein phosphatase involved in Lafora disease (LD), a fatal form of progressive myoclonus epilepsy characterized by neurodegeneration and the presence of intracellular polyglucosan inclusions (Lafora bodies) in different tissues. In this work, we describe that mice lacking laforin (epm2a2/2) have enhanced insulin response leading to altered whole-body energy balance. This enhanced insulin response overactivates the Akt pathway which increases glucose uptake in the heart, resulting in increased glycogen levels and the formation of polyglucosan inclusions. In addition, enhanced insulin response resulted in increased liver lipid biosynthesis, resulting in hepatic steatosis. On the contrary, overexpression in rat hepatoma FTO2B cells of native laforin but not of a form lacking phosphatase activity (C266S) resulted in attenuation of insulin signaling. These results define laforin as a new regulator of insulin sensitivity, which provides novel insights into LD pathogenesis and identifies this phosphatase as a potential novel component of the insulin signaling cascade.

Research paper thumbnail of Laforin, the most common protein mutated in Lafora disease, regulates autophagy

Human Molecular Genetics, 2010

Lafora disease (LD) is an autosomal recessive, progressive myoclonus epilepsy, which is character... more Lafora disease (LD) is an autosomal recessive, progressive myoclonus epilepsy, which is characterized by the accumulation of polyglucosan inclusion bodies, called Lafora bodies, in the cytoplasm of cells in the central nervous system and in many other organs. However, it is unclear at the moment whether Lafora bodies are the cause of the disease, or whether they are secondary consequences of a primary metabolic alteration.

Research paper thumbnail of Structural and functional analysis of mutations in alkaptonuria

Human Molecular Genetics, 2000

Alkaptonuria (AKU), the prototypic inborn error of metabolism, was the first human disease to be ... more Alkaptonuria (AKU), the prototypic inborn error of metabolism, was the first human disease to be interpreted as a Mendelian trait by Garrod and Bateson at the beginning of last century. AKU results from impaired function of homogentisate dioxygenase (HGO), an enzyme required for the catabolism of phenylalanine and tyrosine. With the novel 7 AKU and 22 fungal mutations reported here, a total of 84 mutations impairing this enzyme have been found in the HGO gene from humans and model organisms. Forty-three of these mutations result in single amino acid substitutions. This mutational information is analysed here in the context of the HGO structure and function using kinetic assays performed using purified AKU mutant enzymes and the crystal structure of human HGO. HGO is a topologically complex structure which assembles as a functional hexamer arranged as a dimer of trimers. We show how the intricate pattern of intra-and inter-subunit interactions and the extensive surfaces required for subunit folding and association of this oligomeric enzyme can be inactivated at multiple levels by single-residue substitutions. This explains, in part, the predominance of missense mutations (67%) in AKU.

Research paper thumbnail of Lafora bodies and neurological defects in malin-deficient mice correlate with impaired autophagy

Human Molecular Genetics, 2012

Lafora disease (LD), a fatal neurodegenerative disorder characterized by the presence of intracel... more Lafora disease (LD), a fatal neurodegenerative disorder characterized by the presence of intracellular inclusions called Lafora bodies (LBs), is caused by loss-of-function mutations in laforin or malin. Previous studies suggested a role of these proteins in the regulation of glycogen biosynthesis, in glycogen dephosphorylation and in the modulation of the intracellular proteolytic systems. However, the contribution of each of these processes to LD pathogenesis is unclear. We have generated a malin-deficient (Epm2b2/2) mouse with a phenotype similar to that of LD patients. By 3 -6 months of age, Epm2b2/2 mice present neurological and behavioral abnormalities that correlate with a massive presence of LBs in the cortex, hippocampus and cerebellum. Sixteen-day-old Epm2b2/2 mice, without detectable LBs, show an impairment of macroautophagy (hereafter called autophagy), which remains compromised in adult animals. These data demonstrate similarities between the Epm2a2/2 and Epm2b2/2 mice that provide further insights into LD pathogenesis. They illustrate that the dysfunction of autophagy is a consequence of the lack of laforin-malin complexes and a common feature of both mouse models of LD. Because this dysfunction precedes other pathological manifestations, we propose that decreased autophagy plays a primary role in the formation of LBs and it is critical in LD pathogenesis.

Research paper thumbnail of Laforin, a dual-specificity phosphatase involved in Lafora disease, is phosphorylated at Ser 25 by AMP-activated protein kinase

Biochemical Journal, 2011

Lafora progressive myoclonus epilepsy [LD (Lafora disease)] is a fatal autosomal recessive neurod... more Lafora progressive myoclonus epilepsy [LD (Lafora disease)] is a fatal autosomal recessive neurodegenerative disorder caused by loss-of-function mutations in either the EPM2A gene, encoding the dual-specificity phosphatase laforin, or the EPM2B gene, encoding the E3-ubiquitin ligase malin. Previously, we and others showed that laforin and malin form a functional complex that regulates multiple aspects of glycogen metabolism, and that the interaction between laforin and malin is enhanced by conditions activating AMPK (AMP-activated protein kinase). In the present study, we demonstrate that laforin is a phosphoprotein, as indicated by two-dimensional electrophoresis, and we identify Ser 25 as the residue involved in this modification. We also show that Ser 25 is phosphorylated both in vitro and in vivo by AMPK. Lastly, we demonstrate that this residue plays a critical role for both the phosphatase activity and the ability of laforin to interact with itself and with previously established binding partners. The results of the present study suggest that phosphorylation of laforin-Ser 25 by AMPK provides a mechanism to modulate the interaction between laforin and malin. Regulation of this complex is necessary to maintain normal glycogen metabolism. Importantly, Ser 25 is mutated in some LD patients (S25P), and our results begin to elucidate the mechanism of disease in these patients.

Research paper thumbnail of The Molecular Basis of 3-Methylcrotonylglycinuria, a Disorder of Leucine Catabolism

The American Journal of Human Genetics, 2001

3-Methylcrotonylglycinuria is an inborn error of leucine catabolism and has a recessive pattern o... more 3-Methylcrotonylglycinuria is an inborn error of leucine catabolism and has a recessive pattern of inheritance that results from the deficiency of 3-methylcrotonyl-CoA carboxylase (MCC). The introduction of tandem mass spectrometry in newborn screening has revealed an unexpectedly high incidence of this disorder, which, in certain areas, appears to be the most frequent organic aciduria. MCC, an heteromeric enzyme consisting of a (biotin-containing) and b subunits, is the only one of the four biotin-dependent carboxylases known in humans that has genes that have not yet been characterized, precluding molecular studies of this disease. Here we report the characterization, at the genomic level and at the cDNA level, of both the MCCA gene and the MCCB gene, encoding the MCCa and MCCb subunits, respectively. The 19-exon MCCA gene maps to 3q25-27 and encodes a 725-residue protein with a biotin attachment site; the 17-exon MCCB gene maps to 5q12-q13 and encodes a 563-residue polypeptide. We show that disease-causing mutations can be classified into two complementation groups, denoted "CGA" and "CGB." We detected two MCCA missense mutations in CGA patients, one of which leads to absence of biotinylated MCCa. Two MCCB missense mutations and one splicing defect mutation leading to early MCCb truncation were found in CGB patients. A fourth MCCB mutation also leading to early MCCb truncation was found in two nonclassified patients. A fungal model carrying an mccA null allele has been constructed and was used to demonstrate, in vivo, the involvement of MCC in leucine catabolism. These results establish that 3-methylcrotonylglycinuria results from loss-of-function mutations in the genes encoding the a and b subunits of MCC and complete the genetic characterization of the four human biotin-dependent carboxylases.