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Laboratory of Neuropsychopharmacology and Functional Neurogenomics  

Lab Prof. Popoli

 

Head
Maurizio Popoli      Associate Professor  maurizio.popoli@unimi.it 

Team
Laura Musazzi, Assistant Professor laura.musazzi@unimi.it
Alessandro Ieraci, Research Associate alessandro.ieraci@unimi.it
Alessandra Mallei, Research Associate alessandra.mallei@unimi.it
Nathalie Sala, Ph.D student nathalie.sala@unimi.it
Mara Seguini, Research Associate mara.seguini@guest.unimi.it
Daniela Tardito, Research Assistant daniela.tardito@unimi.it
Paolo Tornese, Ph.D student paolo.tornese@unimi.it
Giulia Treccani, Research Associate giulia.treccani@unimi.it

 

Research lines

Investigation of the action of behavioral stress at synaptic level. Regulation of synaptic function, neuroplasticity and gene expression with regard to acute/chronic stress, pathogenesis of neuropsychiatric/neurodegenerative disorders, mechanisms of psychotropic drugs. Genome-wide studies of animal models of pathology and response/resistance to drugs (transcriptomics, proteomics, epigenetics, miRNomics). Special attention is given to the identification of new targets for diagnosis or treatment that may improve efficacy and alleviate adverse effects.

 

Study of the effects of behavioral stress and psychotropic drugs on glutamatergic transmission and neuronal architecture

Stress is the major environmental risk factor for neuropsychiatric disorders. Dysfunction of the glutamate system is considered a core feature of stress-related disorders, including mood and anxiety disorders. Indeed, a number of studies have shown that glutamatergic transmission and neuronal architecture are altered both in the brain of depressed patients and in animal models of disease. Our group has demonstrated that acute stress enhances glutamate release in prefrontal and frontal cortex, by rapid non-genomic action of glucocorticoids, which increase the pool of glutamate vesicles ready for release. Moreover, chronic treatment with antidepressants blocks the enhancement of glutamate release induced by acute stress; this effect is probably related to the antidepressant/anxiolytic action of these drugs. The main objectives of this research are: (1) Dissection of cellular/molecular rapid (non-genomic) effects of stress and glucocorticoids on glutamate synapses, using functional, molecular, morphological and imaging approaches; (2) Study of the effects of prolonged stress on glutamate synapses and neuronal architecture. We are also studying the molecular mechanisms whereby antidepressants and new fast-acting drugs, such as ketamine, modulate glutamate transmission and behavior. This line of research is carried out in collaboration with other Italian (Universities of Genova, Trieste, Brescia, HSR), European (Aarhus, Denmark) and USA groups (Cornell, Yale, Rockefeller University).

 

Study of epigenetic changes induced by stress physical exercise and psychotropic drugs.

Regular physical activity has been associated with improvement in cognitive functions, mood and stress-coping capabilities both in humans and rodents. The resulting positive effects of physical exercise led to proposing running as an adjunct non-drug treatment for neurological and psychiatric disorders. Beneficial effects of physical activity have been associated with changes in hippocampal plasticity and elevated expression of Brain-Derived Neurotrophic factor (BDNF). On the contrary, stressful experiences in general reduce expression of neurotrophic factors and promote hippocampal atrophy, suggesting a possible mechanism whereby exercise may counteract the effect of stress. However, the molecular mechanisms underpinning these various effects remain poorly understood. Recently, we have demonstrated that physical exercise and antidepressant drugs promote dendritic translocation of specific BDNF mRNA in rodents, while stress blocks this translocation. Main goal of this project is to understand the role of epigenetic mechanisms in the transcriptional modulation of neurotrophic factors in the brain, in response to physical activity and stressful events in wild type and genetically modify mice.

 

Global epigenetic analysis of an animal model for neuropsychiatric disorders with gene–environment interaction

It is widely accepted that chronic stress, in particular chronic psychosocial stress, is involved in the pathophysiology of neuropsychiatric disorders, such as depression, anxiety, posttraumatic stress disorder, and schizophrenia. The main source of stress stimuli in humans is of a social nature; however, the conventional animal models of stress, including forced immobility and inescapable footshock, do not mimic real life. In this context, modeling the establishment of social hierarchy (dominant vs. subordinate relationship) represent high “face validity” with respect to human social life. Aim of this project is to perform a global epigenetic analysis of transgenic mice carrying the human polymorphism (Val66Met) of BDNF gene (BDNFMet), subjected to social defeat stress. BDNFMet mice recapitulate many phenotypic features of humans carrying the Met allele. We investigate epigenetic changes by using chromatin immunoprecipitation (ChiP) with specific antibodies directed against DNA-bound histones methylated or acetylated on several different residues, and characterizing the gene promoters that are activated or repressed. This is carried out at the level of candidate genes, by analyzing with qPCR the promoter sequences binding to different methylated or acetylated histones, or at genome-wide level, by using next generation sequencing (ChiP-Seq). Main result of this project will be the identification of genes whose function is altered by the presence of the human BDNF polymorphism and by psychosocial stress in the identified context of genetic vulnerability. Preliminary studies conducted in our laboratory demonstrated a reduced expression of specific BDNF mRNA isoforms, brought about by epigenetic modifications at BDNF promoters, and impaired dendritic trafficking of one of these mRNAs in BDNFMet mice. With this project our group participates to the in-BDNF consortium (http://www.in-BDNF.it).

 

Role of BDNF in food intake and obesity

Obesity, and its related medical complications, is one of major worldwide health problems, with no currently available pharmacological treatment. Body weight is finely regulated by the balance between caloric food intake and energy expenditure. Food intake is a complex behavior coordinated in the brain not only by homeostatic mechanisms balancing nutritional requirements and caloric status but also by hedonic factors that regulate the sense of pleasure and reward derived from consuming palatable food. Strong evidence supports a role for BDNF in the regulation of food intake, hedonic feeding and metabolism. However, the molecular and cellular mechanisms whereby BDNF modulates food intake are mostly unknown. Human BDNF Va66Met polymorphism has been correlated not only with the pathophysiology of cognitive and affective functions, but also with eating disorders and metabolism. To uncover the role of BDNF in brain changes that result in hyperphagia, metabolic dysfunction and obesity, we are currently studying the effects of environmental factors able to modify food intake (diet, stress) and metabolism (physical exercise) in BDNFMet mutant mice.

 

Role of microRNAs in the pathophysiology of neuropsychiatric disorders and in the action of psychotropic drugs

The microRNAs (miRNAs) are small (~ 22 nts) non-coding RNAs with a key role in the regulation of the genome. Several studies have shown that miRNAs are involved in the modulation of numerous physiological and pathological processes in the whole organism. In recent years, growing evidence has shown an important role of miRNAs in the development and homeostasis of the central nervous system. It has been reported that miRNAs constitute a key element in synaptic development and function as well as in the local control of protein expression, with important implications in processes such as neurogenesis, differentiation and neuronal survival. Moreover, some studies showed alteration of miRNAs in neuropsychiatric diseases. The main objective of our research is to investigate the role of miRNAs in the action of antidepressant drugs as well as in the pathophysiology of neuropsychiatric disorders through the use of animal models and pharmacological and molecular approaches. This line of research is carried out in collaboration with other Italian groups (IRCCS San Giovanni di Dio-Fatebenefratelli di Brescia, University of Trieste, National Research Council).

 

Techniques

Molecular Biology: qPCR, Chromatin Immunoprecipitation (ChIP), ChIP-qPCR, ChIP-Seq, TLDA cards for miRNA, Subcellular fractionation. Preparation of constructs for transfections or gene reporter assays.

Cellular biology: Preparation of subcellular fractions, purification of synaptic terminals by Percoll gradients. Measurement of basal/evoked release of endogenous or labeled neurotransmitters from purified synaptic terminals in superfusion.

Proteomics: Western Blotting, 2D electrophoresis, 2D maps analysis. Analysis of protei-protein interaction by co-immunoprecipitation.

Cell Culture: Cell lines and neuronal primary cultures, hippocampal organotypic cultures, transient and stable transfection, RNAi silencing.

Optical methods: Confocal microscopy, Immunohisto/cytochemistry, immunofluorescence, Golgi stain, Sholl analysis, TIRF microscopy.

Bioinformatic analysis (Gene Ontology, pathway and network analysis, miRNA target analysis)

Animals and behavior: Acute/chronic drug administration, cannulae implantation for ICV, maintenance of transgenic colonies, GxE animal model of anxiety and depression, chronic unpredictable mild stress, footshock stress, Porsolt test, Social defeat stress, voluntary physical activity, behavioral tests for anxiety and depression 

 

Selected publications

  1. Nava N, Treccani G, Alabsi A, Kaastrup Mueller H, Elfving B, PopoliM, Wegener G, Nyengaard JR. (2015) Temporal Dynamics of Acute Stress-Induced Dendritic Remodeling in Medial Prefrontal Cortex and the Protective Effect of Desipramine. Cereb Cortex (Epub ahead of print).
  2. Mallei A, Baj G, Ieraci A, Corna S, Musazzi L, Lee FS, Tongiorgi E, Popoli M. (2015) Expression and dendritic trafficking of BDNF-6 splice variant are impaired in knock-in mice carrying human BDNF Val66Met polymorphism. Int J Neuropsychopharmacol (Epub ahead of print).
  3. Ieraci A, Mallei A, Musazzi L, Popoli M. (2015) Physical exercise and acute restraint stress differentially modulate hippocampal Brain-Derived Neurotrophic Factor transcripts and epigenetic mechanisms in mice. Hippocampus25:1380-92.
  4. Nava N, Treccani G, Liebenberg N, Chen F, Popoli M, Wegener G, Nyengaard JR. (2015) Chronic desipramine prevents acute stress-induced reorganization of medial prefrontal cortex architecture by blocking glutamate vesicle accumulation and excitatory synapse increase.Int J Neuropsychopharmacol 18:3.
  5. Popoli M, Sanacora G, Diamond D, Editors (2014) “Stress at the synapse. Synaptic stress and pathogenesis of neuropsychiatric disorders”, Springer, New York, NY.
  6. Treccani G, Musazzi L, Perego C, Milanese M, Nava N, Bonifacino T, Lamanna J, Malgaroli A, Drago F, Racagni G, Nyengaard JR, Wegener G, Bonanno G, Popoli M. (2014) Stress and corticosterone rapidly increase the readily releasable pool of glutamate vesicles in synaptic terminals of prefrontal and frontal cortex. Mol Psychiatry 19:433–443.
  7. Musazzi L, Treccani G, Popoli M. (2013) The action of antidepressants on the glutamate system: regulation of glutamate release and glutamate receptors. Biol Psychiatry 73:1180-1188.
  8. Tardito D, Mallei A, Popoli M. (2013) Lost in translation. New unexplored avenues for neuropsychopharmacology: epigenetics and microRNAs. Exp Opin Invest Drugs 22:217-33.
  9. Baj G, D’Alessandro V, Musazzi L, Mallei A, Tardito D, Sartori CR, Sciancalepore M, Langone F, Popoli M, Tongiorgi E. (2012) Physical exercise and antidepressants enhance BDNF targeting in hippocampal CA3 dendrites: further evidence of a spatial code for BDNF splice variants. Neuropsychopharmacol 37:1600-11.
  10. Popoli M, Yan Z, McEwen BS, Sanacora G. (2012) The stressed synapse: the impact of behavioral stress and glucocorticoids on glutamate transmission. Nature Rev Neurosci 13:22-37.

 

Links:

https://bbrfoundation.org/brain-matters-discoveries/narsad-grantees-further-understanding-of-how-stress-can-lead-to-depression

http://www.springer.com/biomed/neuroscience/book/978-1-4939-1055-7

http://users2.unimi.it/fens_stress/index.html

http://eng.disfeb.unimi.it/ecm/home/research/research-labs/laboratory-of-neuropsychopharmacology-and-functional-neurogenomics

http://www.in-BDNF.it

https://sites.google.com/site/sciencevenatnight/past-events/synaptic-stress

http://www.nature.com/nrn/journal/v13/n1/full/nrn3138.html

 

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