Microglia activation and neuroinflammation have been extensively studied in murine models of neur... more Microglia activation and neuroinflammation have been extensively studied in murine models of neurodegenerative diseases; however, to overcome the genetic differences between species, a human cell model of microglia able to recapitulate the activation profiles described in patients is needed. Here we developed human models of Parkinson’s like neuroinflammation by using the human microglia clone 3 (HMC3) cells, whose activation profile in response to classic inflammatory stimuli has been controversial and reported only at mRNA levels so far. In fact, we showed the increased expression of the pro-inflammatory markers iNOS, Caspase 1, IL-1β, in response to IFN-γ plus high glucose, a non-specific disease stimulus that emphasized the dynamic polarization and heterogenicity of the microglial population. More specifically, we demonstrated the polarization of HMC3 cells through the upregulation of iNOS expression and nitrite production in response to the Parkinson’s like stimuli, 6-hydroxido...
The interest on Purine Nucleoside Phosphorylase (PNP), Superoxide Dismutase 1 (SOD1) and α-synucl... more The interest on Purine Nucleoside Phosphorylase (PNP), Superoxide Dismutase 1 (SOD1) and α-synuclein derived from the fact that they are all involved in brain neuropathology.Mutations in the gene codifying for PNP induce PNP deficiency, a neurodevelopmental disorder characterized by immunodeficiency; SOD1 and alpha-synuclein are involved in amyotrophic lateral sclerosis and Parkison’s disease respectively, both characterized by the presence of protein aggregates, neurodegeneration and neuroinflammation. Because in all these neurological diseases there is a strong involvement of immune cells, we focused on the role of glial cell secretion. Here we obtained data on PNP release by glial cells and we could speculate that, by releasing this enzyme, these cells may support neuronal activity, by maintaining the homeostasis of the purinergic system. In particular, since cerebellar neurons displayed a low content and reduced capability of releasing PNP, we hypothesize that glial PNP is parti...
Amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) is a progressive and ultimately f... more Amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) is a progressive and ultimately fatal disease spectrum characterised by 43-kDa TAR DNA-binding protein (TDP-43) pathology. Current disease modifying drugs have modest effects and novel therapies are sorely needed. We previously showed that deletion of glycogen synthase kinase-3 (GSK3) suppresses TDP-43-mediated motor neuron degeneration in Drosophila. Here, we investigated the potential of GSK3 inhibition to ameliorate TDP43-mediated toxicity in mammalian neurons. Expression of TDP-43 was found to both activate GSK3 and promote caspase mediated cleavage of TDP-43. Inhibition of GSK3 reduced the abundance of full-length and cleaved TDP-43 in rodent neurons expressing wild-type or disease-associated mutant TDP-43 and also ameliorated neurotoxicity. Our results suggest that TDP-43 turnover is promoted by GSK3 inhibition in a caspase-dependent manner, and that targeting GSK3 activity could have therapeutic value.
Microglial cells, the immune cells of the central nervous system (CNS), play a crucial role for t... more Microglial cells, the immune cells of the central nervous system (CNS), play a crucial role for the proper brain development and function and in CNS homeostasis. While in physiological conditions, microglia continuously check the state of brain parenchyma, in pathological conditions, microglia can show different activated phenotypes: In the early phases, microglia acquire the M2 phenotype, increasing phagocytosis and releasing neurotrophic and neuroprotective factors. In advanced phases, they acquire the M1 phenotype, becoming neurotoxic and contributing to neurodegeneration. Underlying this phenotypic change, there is a switch in the expression of specific microglial genes, in turn modulated by epigenetic changes, such as DNA methylation, histones post-translational modifications and activity of miRNAs. New roles are attributed to microglial cells, including specific communication with neurons, both through direct cell–cell contact and by release of many different molecules, either...
Aspartate-Glutamate Carrier 1 (AGC1) deficiency is a rare neurological disease caused by mutation... more Aspartate-Glutamate Carrier 1 (AGC1) deficiency is a rare neurological disease caused by mutations in the solute carrier family 25, member 12 (SLC25A12) gene, encoding for the mitochondrial aspartate-glutamate carrier isoform 1 (AGC1), a component of the malate–aspartate NADH shuttle (MAS), expressed in excitable tissues only. AGC1 deficiency patients are children showing severe hypotonia, arrested psychomotor development, seizures and global hypomyelination. While the effect of AGC1 deficiency in neurons and neuronal function has been deeply studied, little is known about oligodendrocytes and their precursors, the brain cells involved in myelination. Here we studied the effect of AGC1 down-regulation on oligodendrocyte precursor cells (OPCs), using both in vitro and in vivo mouse disease models. In the cell model, we showed that a reduced expression of AGC1 induces a deficit of OPC proliferation leading to their spontaneous and precocious differentiation into oligodendrocytes. Inte...
Overcoming the lack of effective treatments and the continuous clinical trial failures in neurode... more Overcoming the lack of effective treatments and the continuous clinical trial failures in neurodegenerative drug discovery might require a shift from the prevailing paradigm targeting pathogenesis to the one targeting simultaneously neuroprotection and neuroregeneration. In the studies reported herein, we sought to identify small molecules that might exert neuroprotective and neuroregenerative potential as tools against neurodegenerative diseases. In doing so, we started from the reported neuroprotective/neuroregenerative mechanisms of psychotropic drugs featuring a tricyclic alkylamine scaffold. Thus, we designed a focused-chemical library of 36 entries aimed at exploring the structural requirements for efficient neuroprotective/neuroregenerative cellular activity, without the manifestation of toxicity. To this aim, we developed a synthetic protocol which overcame the limited applicability of previously reported procedures. Next, we evaluated the synthesized compounds through a phe...
In the version of this article initially published, the footnote number 17 was missing from the a... more In the version of this article initially published, the footnote number 17 was missing from the author list for the two authors who contributed equally. Also, the authors have added a middle initial for author Justin R. Fallon and an acknowledgement to the Babraham Institute Imaging Facility and Sequencing Core Facility. The errors have been corrected in the HTML and PDF versions of the article.
Amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) constitutes a devastating disease... more Amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) constitutes a devastating disease spectrum characterized by 43-kDa TAR DNA-binding protein (TDP-43) pathology. Understanding how TDP-43 contributes to neurodegeneration will help direct therapeutic efforts. Here we have created a TDP-43 knock-in mouse with a human-equivalent mutation in the endogenous mouse Tardbp gene. TDP-43mice demonstrate cognitive dysfunction and a paucity of parvalbumin interneurons. Critically, TDP-43 autoregulation is perturbed, leading to a gain of TDP-43 function and altered splicing of Mapt, another pivotal dementia-associated gene. Furthermore, a new approach to stratify transcriptomic data by phenotype in differentially affected mutant mice revealed 471 changes linked with improved behavior. These changes included downregulation of two known modifiers of neurodegeneration, Atxn2 and Arid4a, and upregulation of myelination and translation genes. With one base change in murine Tardbp, this st...
Purine nucleoside phosphorylase (PNP), a crucial enzyme in purine metabolism which converts ribon... more Purine nucleoside phosphorylase (PNP), a crucial enzyme in purine metabolism which converts ribonucleosides into purine bases, has mainly been found inside glial cells. Since we recently demonstrated that PNP is released from rat C6 glioma cells, we then wondered whether this occurs in normal brain cells. Using rat primary cultures of microglia, astrocytes and cerebellar granule neurons, we found that in basal condition all these cells constitutively released a metabolically active PNP with Km values very similar to those measured in C6 glioma cells. However, the enzyme expression/release was greater in microglia or astrocytes that in neurons. Moreover, we exposed primary brain cell cultures to pro-inflammatory agents such as lipopolysaccharide (LPS) or ATP alone or in combination. LPS alone caused an increased interleukin-1β (IL-1β) secretion mainly from microglia and no modification in the PNP release, even from neurons in which it enhanced cell death. In contrast, ATP administere...
The mitochondrial aspartate-glutamate carrier isoform 1 (AGC1) catalyzes a Ca(2+)-stimulated expo... more The mitochondrial aspartate-glutamate carrier isoform 1 (AGC1) catalyzes a Ca(2+)-stimulated export of aspartate to the cytosol in exchange for glutamate, and is a key component of the malate-aspartate shuttle which transfers NADH reducing equivalents from the cytosol to mitochondria. By sustaining the complete glucose oxidation, AGC1 is thought to be important in providing energy for cells, in particular in the CNS and muscle where this protein is mainly expressed. Defects in the AGC1 gene cause AGC1 deficiency, an infantile encephalopathy with delayed myelination and reduced brain N-acetylaspartate (NAA) levels, the precursor of myelin synthesis in the CNS. Here, we show that undifferentiated Neuro2A cells with down-regulated AGC1 display a significant proliferation deficit associated with reduced mitochondrial respiration, and are unable to synthesize NAA properly. In the presence of high glutamine oxidation, cells with reduced AGC1 restore cell proliferation, although oxidative ...
Microglia activation and neuroinflammation have been extensively studied in murine models of neur... more Microglia activation and neuroinflammation have been extensively studied in murine models of neurodegenerative diseases; however, to overcome the genetic differences between species, a human cell model of microglia able to recapitulate the activation profiles described in patients is needed. Here we developed human models of Parkinson’s like neuroinflammation by using the human microglia clone 3 (HMC3) cells, whose activation profile in response to classic inflammatory stimuli has been controversial and reported only at mRNA levels so far. In fact, we showed the increased expression of the pro-inflammatory markers iNOS, Caspase 1, IL-1β, in response to IFN-γ plus high glucose, a non-specific disease stimulus that emphasized the dynamic polarization and heterogenicity of the microglial population. More specifically, we demonstrated the polarization of HMC3 cells through the upregulation of iNOS expression and nitrite production in response to the Parkinson’s like stimuli, 6-hydroxido...
The interest on Purine Nucleoside Phosphorylase (PNP), Superoxide Dismutase 1 (SOD1) and α-synucl... more The interest on Purine Nucleoside Phosphorylase (PNP), Superoxide Dismutase 1 (SOD1) and α-synuclein derived from the fact that they are all involved in brain neuropathology.Mutations in the gene codifying for PNP induce PNP deficiency, a neurodevelopmental disorder characterized by immunodeficiency; SOD1 and alpha-synuclein are involved in amyotrophic lateral sclerosis and Parkison’s disease respectively, both characterized by the presence of protein aggregates, neurodegeneration and neuroinflammation. Because in all these neurological diseases there is a strong involvement of immune cells, we focused on the role of glial cell secretion. Here we obtained data on PNP release by glial cells and we could speculate that, by releasing this enzyme, these cells may support neuronal activity, by maintaining the homeostasis of the purinergic system. In particular, since cerebellar neurons displayed a low content and reduced capability of releasing PNP, we hypothesize that glial PNP is parti...
Amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) is a progressive and ultimately f... more Amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) is a progressive and ultimately fatal disease spectrum characterised by 43-kDa TAR DNA-binding protein (TDP-43) pathology. Current disease modifying drugs have modest effects and novel therapies are sorely needed. We previously showed that deletion of glycogen synthase kinase-3 (GSK3) suppresses TDP-43-mediated motor neuron degeneration in Drosophila. Here, we investigated the potential of GSK3 inhibition to ameliorate TDP43-mediated toxicity in mammalian neurons. Expression of TDP-43 was found to both activate GSK3 and promote caspase mediated cleavage of TDP-43. Inhibition of GSK3 reduced the abundance of full-length and cleaved TDP-43 in rodent neurons expressing wild-type or disease-associated mutant TDP-43 and also ameliorated neurotoxicity. Our results suggest that TDP-43 turnover is promoted by GSK3 inhibition in a caspase-dependent manner, and that targeting GSK3 activity could have therapeutic value.
Microglial cells, the immune cells of the central nervous system (CNS), play a crucial role for t... more Microglial cells, the immune cells of the central nervous system (CNS), play a crucial role for the proper brain development and function and in CNS homeostasis. While in physiological conditions, microglia continuously check the state of brain parenchyma, in pathological conditions, microglia can show different activated phenotypes: In the early phases, microglia acquire the M2 phenotype, increasing phagocytosis and releasing neurotrophic and neuroprotective factors. In advanced phases, they acquire the M1 phenotype, becoming neurotoxic and contributing to neurodegeneration. Underlying this phenotypic change, there is a switch in the expression of specific microglial genes, in turn modulated by epigenetic changes, such as DNA methylation, histones post-translational modifications and activity of miRNAs. New roles are attributed to microglial cells, including specific communication with neurons, both through direct cell–cell contact and by release of many different molecules, either...
Aspartate-Glutamate Carrier 1 (AGC1) deficiency is a rare neurological disease caused by mutation... more Aspartate-Glutamate Carrier 1 (AGC1) deficiency is a rare neurological disease caused by mutations in the solute carrier family 25, member 12 (SLC25A12) gene, encoding for the mitochondrial aspartate-glutamate carrier isoform 1 (AGC1), a component of the malate–aspartate NADH shuttle (MAS), expressed in excitable tissues only. AGC1 deficiency patients are children showing severe hypotonia, arrested psychomotor development, seizures and global hypomyelination. While the effect of AGC1 deficiency in neurons and neuronal function has been deeply studied, little is known about oligodendrocytes and their precursors, the brain cells involved in myelination. Here we studied the effect of AGC1 down-regulation on oligodendrocyte precursor cells (OPCs), using both in vitro and in vivo mouse disease models. In the cell model, we showed that a reduced expression of AGC1 induces a deficit of OPC proliferation leading to their spontaneous and precocious differentiation into oligodendrocytes. Inte...
Overcoming the lack of effective treatments and the continuous clinical trial failures in neurode... more Overcoming the lack of effective treatments and the continuous clinical trial failures in neurodegenerative drug discovery might require a shift from the prevailing paradigm targeting pathogenesis to the one targeting simultaneously neuroprotection and neuroregeneration. In the studies reported herein, we sought to identify small molecules that might exert neuroprotective and neuroregenerative potential as tools against neurodegenerative diseases. In doing so, we started from the reported neuroprotective/neuroregenerative mechanisms of psychotropic drugs featuring a tricyclic alkylamine scaffold. Thus, we designed a focused-chemical library of 36 entries aimed at exploring the structural requirements for efficient neuroprotective/neuroregenerative cellular activity, without the manifestation of toxicity. To this aim, we developed a synthetic protocol which overcame the limited applicability of previously reported procedures. Next, we evaluated the synthesized compounds through a phe...
In the version of this article initially published, the footnote number 17 was missing from the a... more In the version of this article initially published, the footnote number 17 was missing from the author list for the two authors who contributed equally. Also, the authors have added a middle initial for author Justin R. Fallon and an acknowledgement to the Babraham Institute Imaging Facility and Sequencing Core Facility. The errors have been corrected in the HTML and PDF versions of the article.
Amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) constitutes a devastating disease... more Amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) constitutes a devastating disease spectrum characterized by 43-kDa TAR DNA-binding protein (TDP-43) pathology. Understanding how TDP-43 contributes to neurodegeneration will help direct therapeutic efforts. Here we have created a TDP-43 knock-in mouse with a human-equivalent mutation in the endogenous mouse Tardbp gene. TDP-43mice demonstrate cognitive dysfunction and a paucity of parvalbumin interneurons. Critically, TDP-43 autoregulation is perturbed, leading to a gain of TDP-43 function and altered splicing of Mapt, another pivotal dementia-associated gene. Furthermore, a new approach to stratify transcriptomic data by phenotype in differentially affected mutant mice revealed 471 changes linked with improved behavior. These changes included downregulation of two known modifiers of neurodegeneration, Atxn2 and Arid4a, and upregulation of myelination and translation genes. With one base change in murine Tardbp, this st...
Purine nucleoside phosphorylase (PNP), a crucial enzyme in purine metabolism which converts ribon... more Purine nucleoside phosphorylase (PNP), a crucial enzyme in purine metabolism which converts ribonucleosides into purine bases, has mainly been found inside glial cells. Since we recently demonstrated that PNP is released from rat C6 glioma cells, we then wondered whether this occurs in normal brain cells. Using rat primary cultures of microglia, astrocytes and cerebellar granule neurons, we found that in basal condition all these cells constitutively released a metabolically active PNP with Km values very similar to those measured in C6 glioma cells. However, the enzyme expression/release was greater in microglia or astrocytes that in neurons. Moreover, we exposed primary brain cell cultures to pro-inflammatory agents such as lipopolysaccharide (LPS) or ATP alone or in combination. LPS alone caused an increased interleukin-1β (IL-1β) secretion mainly from microglia and no modification in the PNP release, even from neurons in which it enhanced cell death. In contrast, ATP administere...
The mitochondrial aspartate-glutamate carrier isoform 1 (AGC1) catalyzes a Ca(2+)-stimulated expo... more The mitochondrial aspartate-glutamate carrier isoform 1 (AGC1) catalyzes a Ca(2+)-stimulated export of aspartate to the cytosol in exchange for glutamate, and is a key component of the malate-aspartate shuttle which transfers NADH reducing equivalents from the cytosol to mitochondria. By sustaining the complete glucose oxidation, AGC1 is thought to be important in providing energy for cells, in particular in the CNS and muscle where this protein is mainly expressed. Defects in the AGC1 gene cause AGC1 deficiency, an infantile encephalopathy with delayed myelination and reduced brain N-acetylaspartate (NAA) levels, the precursor of myelin synthesis in the CNS. Here, we show that undifferentiated Neuro2A cells with down-regulated AGC1 display a significant proliferation deficit associated with reduced mitochondrial respiration, and are unable to synthesize NAA properly. In the presence of high glutamine oxidation, cells with reduced AGC1 restore cell proliferation, although oxidative ...
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Papers by Francesca Massenzio