Catia Diogo - Academia.edu (original) (raw)

Papers by Catia Diogo

Research paper thumbnail of The Silybin-Phospholipids-Vitamin E Complex Protects Against Fatty Degeneration, Nitrosative and Oxidative Stress in Rat Models of Liver Steatosis

Research paper thumbnail of Biochemical mechanisms in drug-induced liver injury: certainties and doubts

World journal of gastroenterology : WJG, Jan 21, 2009

Drug-induced liver injury is a significant and still unresolved clinical problem. Limitations to ... more Drug-induced liver injury is a significant and still unresolved clinical problem. Limitations to knowledge about the mechanisms of toxicity render incomplete the detection of hepatotoxic potential during preclinical development. Several xenobiotics are lipophilic substances and their transformation into hydrophilic compounds by the cytochrome P-450 system results in production of toxic metabolites. Aging, preexisting liver disease, enzyme induction or inhibition, genetic variances, local O(2) supply and, above all, the intrinsic molecular properties of the drug may affect this process. Necrotic death follows antioxidant consumption and oxidation of intracellular proteins, which determine increased permeability of mitochondrial membranes, loss of potential, decreased ATP synthesis, inhibition of Ca(2+)-dependent ATPase, reduced capability to sequester Ca(2+) within mitochondria, and membrane bleb formation. Conversely, activation of nucleases and energetic participation of mitochondr...

Research paper thumbnail of Mitochondrial toxicity of the phyotochemicals daphnetoxin and daphnoretin – Relevance for possible anti-cancer application

Toxicology in Vitro, 2009

Daphnetoxin is a daphnane type orthoester diterpene found exclusively in plants of the family Thy... more Daphnetoxin is a daphnane type orthoester diterpene found exclusively in plants of the family Thymelaeaceae while daphnoretin, a bis-coumarin derivative that is the major constituent of the bark of some plants of this family, can also be found in Leguminosae and Rutaceae. These two compounds are recognized to have different biological effects, including a possible anti-cancer activity. The subject of the present research was to compare their mitochondrial toxicity and also investigate a possible selectivity towards tumor cell lines. Wistar rat liver mitochondria and three distinct cell lines were used to investigate compound-induced toxicity. The results indicate that both test compounds are toxic to isolated mitochondrial fractions, especially when used at concentrations higher than 100 lM. However, daphnetoxin presented the highest toxicity including increased proton leak in the inner mitochondrial membrane, increased induction of the mitochondrial permeability transition pore, inhibition of ATP synthase and inhibition of the mitochondrial respiratory chain. Both compounds also inhibited cell proliferation, regardless of the cell line used. Up to the maximal concentration tested in cells, no mitochondrial effects were detected by vital epifluorescence imaging, indicating that inhibition of cell proliferation may also originate from mitochondrial-independent mechanisms. The results warrant careful assessment of toxicity vs. pharmacology benefits of both molecules.

Research paper thumbnail of Disrupted ATP synthase activity and mitochondrial hyperpolarisation-dependent oxidative stress is associated with p66Shc phosphorylation in fibroblasts of NARP patients

The International Journal of Biochemistry & Cell Biology, 2013

a b s t r a c t p66Shc is an adaptor protein involved in cell proliferation and differentiation t... more a b s t r a c t p66Shc is an adaptor protein involved in cell proliferation and differentiation that undergoes phosphorylation at Ser36 in response to oxidative stimuli, consequently inducing a burst of reactive oxygen species (ROS), mitochondrial disruption and apoptosis. Its role during several pathologies suggests that p66Shc mitochondrial signalling can perpetuate a primary mitochondrial defect, thus contributing to the pathophysiology of that condition. Here, we show that in the fibroblasts of neuropathy, ataxia and retinitis pigmentosa (NARP) patients, the p66Shc phosphorylation pathway is significantly induced in response to intracellular oxidative stress related to disrupted ATP synthase activity and mitochondrial membrane hyperpolarisation. We postulate that the increased phosphorylation of p66Shc at Ser36 is partially responsible for further increasing ROS production, resulting in oxidative damage of proteins. Oxidative stress and p66Shc phosphorylation at Ser36 may be mitigated by antioxidant administration or the use of a p66Shc phosphorylation inhibitor.

Research paper thumbnail of Cardiac mitochondrial dysfunction during hyperglycemia—The role of oxidative stress and p66Shc signaling

The International Journal of Biochemistry & Cell Biology, 2013

Diabetes mellitus is a chronic disease caused by a deficiency in the production of insulin and/or... more Diabetes mellitus is a chronic disease caused by a deficiency in the production of insulin and/or by the effects of insulin resistance. Insulin deficiency leads to hyperglycemia which is the major initiator of diabetic cardiovascular complications escalating with time and driven by many complex biochemical and molecular processes. Four hypotheses, which propose mechanisms of diabetes-associated pathophysiology, are currently considered. Cardiovascular impairment may be caused by an increase in polyol pathway flux, by intracellular advanced glycation end-products formation or increased flux through the hexosamine pathway. The latter of these mechanisms involves activation of the protein kinase C.

Research paper thumbnail of Physical exercise prevents and mitigates non-alcoholic steatohepatitis-induced liver mitochondrial structural and bioenergetics impairments

Mitochondrion, 2014

Exercise is considered a non-pharmacological tool against several lifestyle disorders in which mi... more Exercise is considered a non-pharmacological tool against several lifestyle disorders in which mitochondrial dysfunction is involved. The present study aimed to analyze the preventive (voluntary physical activity-VPA) and therapeutic (endurance training-ET) role of exercise against non-alcoholic steatohepatitis (NASH)-induced liver mitochondrial dysfunction. Sixty male Sprague-Dawley rats were divided into standard-diet sedentary (SS, n=20), standard-diet VPA (SVPA, n=10), high-fat diet sedentary (HS, n=20) and high-fat diet VPA (HVPA, n=10). After 9weeks of diet-treatment, half of SS and HS animals were engaged in an ET program (SET and HET) for 8weeks, 5days/week and 60min/day. Liver mitochondrial oxygen consumption and transmembrane-electric potential (ΔΨ) were evaluated in the presence of glutamate-malate (G/M), palmitoyl-malate (P/M) and succinate (S/R). Mitochondrial enzymes activity, lipid and protein oxidation, oxidative phosphorylation (OXPHOS) subunits, cytochrome c, adenine nucleotide translocator (ANT) and uncoupling protein-2 (UCP2) content were assessed. HS groups show the histological features of NASH in parallel with decreased ΔΨ and respiratory control (RCR) and ADP/O ratios (G/M and P/M). A state 3 decrease (G/M and S/R), FCCP-induced uncoupling respiration (S/R) and ANT content were also observed. Both exercise types counteracted oxygen consumption (RCR, ADP/O and FCCP-uncoupling state) impairments and improved ΔΨ (lag-phase). In conclusion, exercise prevented or reverted (VPA and ET, respectively) the bioenergetic impairment induced by NASH, but only ET positively remodeled NASH-induced liver structural damage and abnormal mitochondria. It is possible that alterations in inner membrane integrity and fatty acid oxidation may be related to the observed phenotypes induced by exercise.

Research paper thumbnail of r-Sm14 - pRSETA efficacy in experimental animals

Memórias do Instituto Oswaldo Cruz, 2001

Research paper thumbnail of Immunoreactivity of a cytokeratin-related polypeptide from adult Schistosoma mansoni

International Journal for Parasitology, 1994

A saline extract (SE) derived from living adult Schistosoma mansoni confers high levels of resist... more A saline extract (SE) derived from living adult Schistosoma mansoni confers high levels of resistance to challenge infection in mice and rabbits. We have carried out a number of experiments to analyse the composition of SE and to define the proteins that are rapidly released from the parasite. One of these proteins, with apparent molecular mass of 62 kDa, is recognized by polyclonal and monoclonal antibodies raised against high molecular mass cytokeratins from human epidermal cells. Immunocytochemical studies revealed a tegumental staining using the anti-cytokeratin antibody. Moreover, sera from schistosomiasis patients, as well as those from animals immunized with SE, were able to recognize this 62 kDa polypeptide as shown by immunoblot assays. These results suggest the existence of cytokeratin-containing filaments in the schistosome.

Research paper thumbnail of Biliary proteins and their redox status changes in gallstone patients

European Journal of Clinical Investigation, 2009

Background Proteins might act as pronucleating agents of cholesterol crystallization in bile. How... more Background Proteins might act as pronucleating agents of cholesterol crystallization in bile. However, little is known about the redox status of biliary proteins in humans and their interaction with crystallization of biliary cholesterol.

Research paper thumbnail of Drug-induced Cardiac Mitochondrial Toxicity and Protection: From Doxorubicin to Carvedilol

Current Pharmaceutical Design, 2011

Mitochondria have long been involved in several cellular processes beyond its role in energy prod... more Mitochondria have long been involved in several cellular processes beyond its role in energy production. The importance of this organelle for cardiac tissue homeostasis has been greatly investigated and its impairment can lead to cell death and consequent organ failure. Several compounds have been described in the literature as having direct effects on cardiac mitochondria which can provide a mechanistic explanation for their toxicological or pharmacological effects. The present review describes one classic example of druginduced cardiac mitochondrial toxicity and another case of drug-induced mitochondrial protection. For the former, we present the case of doxorubicin, an anticancer agent whose treatment is associated with a cumulative and dose-dependent cardiomyopathy with a mitochondrial etiology. Following this, we present the case of carvedilol, a -blocker with intrinsic antioxidant activity, which has been described to protect cardiac mitochondria from oxidative injury. The final part of the review integrates information from the previous chapters, demonstrating how carvedilol can contribute to reduce doxorubicin toxicity on cardiac mitochondria. The two referred examples result in important take-home messages: a) drug-induced cardiac mitochondrial dysfunction is an important contributor for drug-associated organ failure, b) protection of mitochondrial function is involved in the beneficial impact of some clinically-used drugs and c) a more accurate prediction of toxic vs. beneficial effects should be an important component of drug development by the pharmaceutical industry.

Research paper thumbnail of Mitochondria in Chronic Liver Disease

Current Drug Targets, 2011

Mitochondria are the main energy source in hepatocytes and play a major role in extensive oxidati... more Mitochondria are the main energy source in hepatocytes and play a major role in extensive oxidative metabolism and normal function of the liver. This key role also assigns mitochondria a gateway function in the center of signaling pathways that mediate hepatocyte injury, because impaired mitochondrial functions affect cell survival and contribute to the onset and perpetuation of liver diseases. Altered mitochondrial functions have indeed been documented in a variety of chronic liver diseases including alcohol-induced liver disease, nonalcoholic fatty liver disease, viral hepatitis, primary and secondary cholestasis, hemochromatosis, and Wilson's disease. Major changes include impairment of the electron transport chain and/or oxidative phosphorylation leading to decreased oxidative metabolism of various substrates, decreased ATP synthesis, and reduced hepatocyte tolerance towards stressing insults. Functional impairment of mitochondria is often accompanied by structural changes, resulting in organelle swelling and formation of inclusions in the mitochondrial matrix. Adequate mitochondrial functions in hepatocytes are maintained by mitochondrial proliferation and/or increased activity of critical enzymes. The assessment of mitochondrial functions in vivo can be a useful tool in liver diseases for diagnostic and prognostic purposes, and also for the evaluation of (novel) therapeutic interventions.

Research paper thumbnail of Berberine as a Promising Safe Anti-Cancer Agent- Is there a Role for Mitochondria?

Current Drug Targets, 2011

Metabolic regulation is largely dependent on mitochondria, which play an important role in energy... more Metabolic regulation is largely dependent on mitochondria, which play an important role in energy homeostasis. Imbalance between energy intake and expenditure leads to mitochondrial dysfunction, characterized by a reduced ratio of energy production (ATP production) to respiration. Due to the role of mitochondrial factors/events in several apoptotic pathways, the possibility of targeting that organelle in the tumor cell, leading to its elimination is very attractive, although the safety issue is problematic. Berberine, a benzyl-tetra isoquinoline alkaloid extracted from plants of the Berberidaceae family, has been extensively used for many centuries, especially in the traditional Chinese and Native American medicine. Several evidences suggest that berberine possesses several therapeutic uses, including anti-tumoral activity. The present review supplies evidence that berberine is a safe anti-cancer agent, exerting several effects on mitochondria, including inhibition of mitochondrial Complex I and interaction with the adenine nucleotide translocator which can explain several of the described effects on tumor cells.

Research paper thumbnail of Schistosoma mansoni Fatty Acid Binding Protein:  Specificity and Functional Control as Revealed by Crystallographic Structure † , ‡

Biochemistry, 2004

Schistosoma mansoni fatty acid binding protein (Sm14) was crystallized with bound oleic acid (OLA... more Schistosoma mansoni fatty acid binding protein (Sm14) was crystallized with bound oleic acid (OLA) and arachidonic acid (ACD), and their structures were solved at 1.85 and 2.4 Å resolution, respectively. Sm14 is a vaccine target for schistosomiasis, the second most prevalent parasitic disease in humans. The parasite is unable to synthesize fatty acids depending on the host for these nutrients. Moreover, arachidonic acid (ACD) is required to synthesize prostaglandins employed by schistosomes to evade the host's immune defenses. In the complex, the hydrocarbon tail of bound OLA assumes two conformations, whereas ACD adopts a unique hairpin-looped structure. ACD establishes more specific interactions with the protein, among which the most important is a π-cation bond between Arg78 and the double bond at C8. Comparison with homologous fatty acid binding proteins suggests that the binding site of Sm14 is optimized to fit ACD. To test the functional implications of our structural data, the affinity of Sm14 for 1,8-anilinonaphthalenesulfonic acid (ANS) has been measured; moreover the binding constants of six different fatty acids were determined from their ability to displace ANS. OLA and ACD exhibited the highest affinities. To determine the rates of fatty acid binding and dissociation we carried out stopped flow kinetic experiments monitoring displacement by (and of) ANS. The binding rate constant of ligands is controlled by a slow pH dependent conformational change, which we propose to have physiological relevance. † Funding was received by the University of Rome "La Sapienza" (Progetto Ateneo 60%sanno 2003) and by the Ministero dell'Università e della Ricerca Scientifica e Tecnologica of Italy (PRIN 2003). Elettra (Trieste, Italy) provided generous fellowships to K.A.J. and P.B. ‡ Sm14-ACD and Sm14-OLA have been deposited with PDB codes 1VYF and 1VYG, respectively.

Research paper thumbnail of Preliminary analysis of Sm14 in distinct fractions of Schistosoma mansoni adult worm extract

Memorias Do Instituto Oswaldo Cruz, 2001

In previous studies it was shown that the recombinant molecule, r-Sm14, induces high levels of pr... more In previous studies it was shown that the recombinant molecule, r-Sm14, induces high levels of protection against Schistosoma mansoni infection in two outbred animal models and immune crossprotection against infection by Fasciola hepatica in Swiss outbred mice. r-Sm14 was derived from a living worm extract, called SE, and is being developed as the molecular basis of an anti-helminth bivalent vaccine

Research paper thumbnail of The Silybin-Phospholipids-Vitamin E Complex Protects Against Fatty Degeneration, Nitrosative and Oxidative Stress in Rat Models of Liver Steatosis

Research paper thumbnail of Biochemical mechanisms in drug-induced liver injury: certainties and doubts

World journal of gastroenterology : WJG, Jan 21, 2009

Drug-induced liver injury is a significant and still unresolved clinical problem. Limitations to ... more Drug-induced liver injury is a significant and still unresolved clinical problem. Limitations to knowledge about the mechanisms of toxicity render incomplete the detection of hepatotoxic potential during preclinical development. Several xenobiotics are lipophilic substances and their transformation into hydrophilic compounds by the cytochrome P-450 system results in production of toxic metabolites. Aging, preexisting liver disease, enzyme induction or inhibition, genetic variances, local O(2) supply and, above all, the intrinsic molecular properties of the drug may affect this process. Necrotic death follows antioxidant consumption and oxidation of intracellular proteins, which determine increased permeability of mitochondrial membranes, loss of potential, decreased ATP synthesis, inhibition of Ca(2+)-dependent ATPase, reduced capability to sequester Ca(2+) within mitochondria, and membrane bleb formation. Conversely, activation of nucleases and energetic participation of mitochondr...

Research paper thumbnail of Mitochondrial toxicity of the phyotochemicals daphnetoxin and daphnoretin – Relevance for possible anti-cancer application

Toxicology in Vitro, 2009

Daphnetoxin is a daphnane type orthoester diterpene found exclusively in plants of the family Thy... more Daphnetoxin is a daphnane type orthoester diterpene found exclusively in plants of the family Thymelaeaceae while daphnoretin, a bis-coumarin derivative that is the major constituent of the bark of some plants of this family, can also be found in Leguminosae and Rutaceae. These two compounds are recognized to have different biological effects, including a possible anti-cancer activity. The subject of the present research was to compare their mitochondrial toxicity and also investigate a possible selectivity towards tumor cell lines. Wistar rat liver mitochondria and three distinct cell lines were used to investigate compound-induced toxicity. The results indicate that both test compounds are toxic to isolated mitochondrial fractions, especially when used at concentrations higher than 100 lM. However, daphnetoxin presented the highest toxicity including increased proton leak in the inner mitochondrial membrane, increased induction of the mitochondrial permeability transition pore, inhibition of ATP synthase and inhibition of the mitochondrial respiratory chain. Both compounds also inhibited cell proliferation, regardless of the cell line used. Up to the maximal concentration tested in cells, no mitochondrial effects were detected by vital epifluorescence imaging, indicating that inhibition of cell proliferation may also originate from mitochondrial-independent mechanisms. The results warrant careful assessment of toxicity vs. pharmacology benefits of both molecules.

Research paper thumbnail of Disrupted ATP synthase activity and mitochondrial hyperpolarisation-dependent oxidative stress is associated with p66Shc phosphorylation in fibroblasts of NARP patients

The International Journal of Biochemistry & Cell Biology, 2013

a b s t r a c t p66Shc is an adaptor protein involved in cell proliferation and differentiation t... more a b s t r a c t p66Shc is an adaptor protein involved in cell proliferation and differentiation that undergoes phosphorylation at Ser36 in response to oxidative stimuli, consequently inducing a burst of reactive oxygen species (ROS), mitochondrial disruption and apoptosis. Its role during several pathologies suggests that p66Shc mitochondrial signalling can perpetuate a primary mitochondrial defect, thus contributing to the pathophysiology of that condition. Here, we show that in the fibroblasts of neuropathy, ataxia and retinitis pigmentosa (NARP) patients, the p66Shc phosphorylation pathway is significantly induced in response to intracellular oxidative stress related to disrupted ATP synthase activity and mitochondrial membrane hyperpolarisation. We postulate that the increased phosphorylation of p66Shc at Ser36 is partially responsible for further increasing ROS production, resulting in oxidative damage of proteins. Oxidative stress and p66Shc phosphorylation at Ser36 may be mitigated by antioxidant administration or the use of a p66Shc phosphorylation inhibitor.

Research paper thumbnail of Cardiac mitochondrial dysfunction during hyperglycemia—The role of oxidative stress and p66Shc signaling

The International Journal of Biochemistry & Cell Biology, 2013

Diabetes mellitus is a chronic disease caused by a deficiency in the production of insulin and/or... more Diabetes mellitus is a chronic disease caused by a deficiency in the production of insulin and/or by the effects of insulin resistance. Insulin deficiency leads to hyperglycemia which is the major initiator of diabetic cardiovascular complications escalating with time and driven by many complex biochemical and molecular processes. Four hypotheses, which propose mechanisms of diabetes-associated pathophysiology, are currently considered. Cardiovascular impairment may be caused by an increase in polyol pathway flux, by intracellular advanced glycation end-products formation or increased flux through the hexosamine pathway. The latter of these mechanisms involves activation of the protein kinase C.

Research paper thumbnail of Physical exercise prevents and mitigates non-alcoholic steatohepatitis-induced liver mitochondrial structural and bioenergetics impairments

Mitochondrion, 2014

Exercise is considered a non-pharmacological tool against several lifestyle disorders in which mi... more Exercise is considered a non-pharmacological tool against several lifestyle disorders in which mitochondrial dysfunction is involved. The present study aimed to analyze the preventive (voluntary physical activity-VPA) and therapeutic (endurance training-ET) role of exercise against non-alcoholic steatohepatitis (NASH)-induced liver mitochondrial dysfunction. Sixty male Sprague-Dawley rats were divided into standard-diet sedentary (SS, n=20), standard-diet VPA (SVPA, n=10), high-fat diet sedentary (HS, n=20) and high-fat diet VPA (HVPA, n=10). After 9weeks of diet-treatment, half of SS and HS animals were engaged in an ET program (SET and HET) for 8weeks, 5days/week and 60min/day. Liver mitochondrial oxygen consumption and transmembrane-electric potential (ΔΨ) were evaluated in the presence of glutamate-malate (G/M), palmitoyl-malate (P/M) and succinate (S/R). Mitochondrial enzymes activity, lipid and protein oxidation, oxidative phosphorylation (OXPHOS) subunits, cytochrome c, adenine nucleotide translocator (ANT) and uncoupling protein-2 (UCP2) content were assessed. HS groups show the histological features of NASH in parallel with decreased ΔΨ and respiratory control (RCR) and ADP/O ratios (G/M and P/M). A state 3 decrease (G/M and S/R), FCCP-induced uncoupling respiration (S/R) and ANT content were also observed. Both exercise types counteracted oxygen consumption (RCR, ADP/O and FCCP-uncoupling state) impairments and improved ΔΨ (lag-phase). In conclusion, exercise prevented or reverted (VPA and ET, respectively) the bioenergetic impairment induced by NASH, but only ET positively remodeled NASH-induced liver structural damage and abnormal mitochondria. It is possible that alterations in inner membrane integrity and fatty acid oxidation may be related to the observed phenotypes induced by exercise.

Research paper thumbnail of r-Sm14 - pRSETA efficacy in experimental animals

Memórias do Instituto Oswaldo Cruz, 2001

Research paper thumbnail of Immunoreactivity of a cytokeratin-related polypeptide from adult Schistosoma mansoni

International Journal for Parasitology, 1994

A saline extract (SE) derived from living adult Schistosoma mansoni confers high levels of resist... more A saline extract (SE) derived from living adult Schistosoma mansoni confers high levels of resistance to challenge infection in mice and rabbits. We have carried out a number of experiments to analyse the composition of SE and to define the proteins that are rapidly released from the parasite. One of these proteins, with apparent molecular mass of 62 kDa, is recognized by polyclonal and monoclonal antibodies raised against high molecular mass cytokeratins from human epidermal cells. Immunocytochemical studies revealed a tegumental staining using the anti-cytokeratin antibody. Moreover, sera from schistosomiasis patients, as well as those from animals immunized with SE, were able to recognize this 62 kDa polypeptide as shown by immunoblot assays. These results suggest the existence of cytokeratin-containing filaments in the schistosome.

Research paper thumbnail of Biliary proteins and their redox status changes in gallstone patients

European Journal of Clinical Investigation, 2009

Background Proteins might act as pronucleating agents of cholesterol crystallization in bile. How... more Background Proteins might act as pronucleating agents of cholesterol crystallization in bile. However, little is known about the redox status of biliary proteins in humans and their interaction with crystallization of biliary cholesterol.

Research paper thumbnail of Drug-induced Cardiac Mitochondrial Toxicity and Protection: From Doxorubicin to Carvedilol

Current Pharmaceutical Design, 2011

Mitochondria have long been involved in several cellular processes beyond its role in energy prod... more Mitochondria have long been involved in several cellular processes beyond its role in energy production. The importance of this organelle for cardiac tissue homeostasis has been greatly investigated and its impairment can lead to cell death and consequent organ failure. Several compounds have been described in the literature as having direct effects on cardiac mitochondria which can provide a mechanistic explanation for their toxicological or pharmacological effects. The present review describes one classic example of druginduced cardiac mitochondrial toxicity and another case of drug-induced mitochondrial protection. For the former, we present the case of doxorubicin, an anticancer agent whose treatment is associated with a cumulative and dose-dependent cardiomyopathy with a mitochondrial etiology. Following this, we present the case of carvedilol, a -blocker with intrinsic antioxidant activity, which has been described to protect cardiac mitochondria from oxidative injury. The final part of the review integrates information from the previous chapters, demonstrating how carvedilol can contribute to reduce doxorubicin toxicity on cardiac mitochondria. The two referred examples result in important take-home messages: a) drug-induced cardiac mitochondrial dysfunction is an important contributor for drug-associated organ failure, b) protection of mitochondrial function is involved in the beneficial impact of some clinically-used drugs and c) a more accurate prediction of toxic vs. beneficial effects should be an important component of drug development by the pharmaceutical industry.

Research paper thumbnail of Mitochondria in Chronic Liver Disease

Current Drug Targets, 2011

Mitochondria are the main energy source in hepatocytes and play a major role in extensive oxidati... more Mitochondria are the main energy source in hepatocytes and play a major role in extensive oxidative metabolism and normal function of the liver. This key role also assigns mitochondria a gateway function in the center of signaling pathways that mediate hepatocyte injury, because impaired mitochondrial functions affect cell survival and contribute to the onset and perpetuation of liver diseases. Altered mitochondrial functions have indeed been documented in a variety of chronic liver diseases including alcohol-induced liver disease, nonalcoholic fatty liver disease, viral hepatitis, primary and secondary cholestasis, hemochromatosis, and Wilson's disease. Major changes include impairment of the electron transport chain and/or oxidative phosphorylation leading to decreased oxidative metabolism of various substrates, decreased ATP synthesis, and reduced hepatocyte tolerance towards stressing insults. Functional impairment of mitochondria is often accompanied by structural changes, resulting in organelle swelling and formation of inclusions in the mitochondrial matrix. Adequate mitochondrial functions in hepatocytes are maintained by mitochondrial proliferation and/or increased activity of critical enzymes. The assessment of mitochondrial functions in vivo can be a useful tool in liver diseases for diagnostic and prognostic purposes, and also for the evaluation of (novel) therapeutic interventions.

Research paper thumbnail of Berberine as a Promising Safe Anti-Cancer Agent- Is there a Role for Mitochondria?

Current Drug Targets, 2011

Metabolic regulation is largely dependent on mitochondria, which play an important role in energy... more Metabolic regulation is largely dependent on mitochondria, which play an important role in energy homeostasis. Imbalance between energy intake and expenditure leads to mitochondrial dysfunction, characterized by a reduced ratio of energy production (ATP production) to respiration. Due to the role of mitochondrial factors/events in several apoptotic pathways, the possibility of targeting that organelle in the tumor cell, leading to its elimination is very attractive, although the safety issue is problematic. Berberine, a benzyl-tetra isoquinoline alkaloid extracted from plants of the Berberidaceae family, has been extensively used for many centuries, especially in the traditional Chinese and Native American medicine. Several evidences suggest that berberine possesses several therapeutic uses, including anti-tumoral activity. The present review supplies evidence that berberine is a safe anti-cancer agent, exerting several effects on mitochondria, including inhibition of mitochondrial Complex I and interaction with the adenine nucleotide translocator which can explain several of the described effects on tumor cells.

Research paper thumbnail of Schistosoma mansoni Fatty Acid Binding Protein:  Specificity and Functional Control as Revealed by Crystallographic Structure † , ‡

Biochemistry, 2004

Schistosoma mansoni fatty acid binding protein (Sm14) was crystallized with bound oleic acid (OLA... more Schistosoma mansoni fatty acid binding protein (Sm14) was crystallized with bound oleic acid (OLA) and arachidonic acid (ACD), and their structures were solved at 1.85 and 2.4 Å resolution, respectively. Sm14 is a vaccine target for schistosomiasis, the second most prevalent parasitic disease in humans. The parasite is unable to synthesize fatty acids depending on the host for these nutrients. Moreover, arachidonic acid (ACD) is required to synthesize prostaglandins employed by schistosomes to evade the host's immune defenses. In the complex, the hydrocarbon tail of bound OLA assumes two conformations, whereas ACD adopts a unique hairpin-looped structure. ACD establishes more specific interactions with the protein, among which the most important is a π-cation bond between Arg78 and the double bond at C8. Comparison with homologous fatty acid binding proteins suggests that the binding site of Sm14 is optimized to fit ACD. To test the functional implications of our structural data, the affinity of Sm14 for 1,8-anilinonaphthalenesulfonic acid (ANS) has been measured; moreover the binding constants of six different fatty acids were determined from their ability to displace ANS. OLA and ACD exhibited the highest affinities. To determine the rates of fatty acid binding and dissociation we carried out stopped flow kinetic experiments monitoring displacement by (and of) ANS. The binding rate constant of ligands is controlled by a slow pH dependent conformational change, which we propose to have physiological relevance. † Funding was received by the University of Rome "La Sapienza" (Progetto Ateneo 60%sanno 2003) and by the Ministero dell'Università e della Ricerca Scientifica e Tecnologica of Italy (PRIN 2003). Elettra (Trieste, Italy) provided generous fellowships to K.A.J. and P.B. ‡ Sm14-ACD and Sm14-OLA have been deposited with PDB codes 1VYF and 1VYG, respectively.

Research paper thumbnail of Preliminary analysis of Sm14 in distinct fractions of Schistosoma mansoni adult worm extract

Memorias Do Instituto Oswaldo Cruz, 2001

In previous studies it was shown that the recombinant molecule, r-Sm14, induces high levels of pr... more In previous studies it was shown that the recombinant molecule, r-Sm14, induces high levels of protection against Schistosoma mansoni infection in two outbred animal models and immune crossprotection against infection by Fasciola hepatica in Swiss outbred mice. r-Sm14 was derived from a living worm extract, called SE, and is being developed as the molecular basis of an anti-helminth bivalent vaccine