CNR - Institute of Neuroscience CNR
Institute of Neuroscience
 

Project

Neuronal nicotinic receptors as targets in pathology

Neuronal nicotinic acetylcholine receptors (nAChRs) are ubiquitous signalling molecules and therefore involved in a wide variety of diseases affecting neuronal and non-neuronal tissues. Our research concentrates on two aspects: the role of nAChRs in degenerative brain diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD), and their role in diseases characterised by particular mutations in the genes encoding the subunits of nAChRs. In particular in brain disease, smoking addiction and tumors. As we believe that a pharmacological approach to these pathologies could be useful therapeutically, we also synthesise and investigate novel nAChR-specific drugs.

nACHRs in AD and PD

Nicotinic transmission participates in many cognitive processes; lesions of the forebrain cholinergic system lead to cognitive deficits that can be reversed by nicotine; brain cholinergic function is impaired in patients with AD and the incidence of AD and PD is reduced in smokers; these and other findings have contributed to the formulation of a cholinergic hypothesis to explain the cognitive defects associated with the neurodegenerative disorders (reviewed in Gotti and Clementi, 2004).

 

In the early stage AD is characterised by a decreased number of brain nAChRs in the absence of a general decrease in the number of neurons, and we have demonstrated that there is a selective reduction in the alpha4beta2 subtype in the cortex of AD patients (reviewed in Gotti and Clementi, 2004).

Experimental rodent and monkey models of PD (Quik et al 2005), and studies of human patients (Gotti et al 2006) have shown that there is a selective decrease in the number of alpha6- alpha4- and beta2-containing receptors in the striatum and a decrease in the number of alpha4-containing receptors in the cerebral cortex (see Figure; Gotti et al., 2006).

Future studies will consider the effects of smoking and other chronic drug treatments on nAChR subtype composition and distribution in the human brain areas and the possible use of selective nicotinic drugs to modulate their function.

nAChRs and neuroprotection

The hypothesis that nAChRs play a neuroprotective role during brain aging has received direct support from the studies showing that aged beta2 Ko mice are affected by region-specific structural alterations in cortical areas (including the loss of neocortical and hippocampal neurons, and astro- and microgliosis) and impaired cognitive performance. Furthermore, in vivo and in culture cell, nicotine protects striatal, hippocampal and cortical neurons against the neurotoxicity induced by excitotoxic amino acids, as well as the toxicity caused by beta-amyloid, the major component of senile plaques. The cellular and molecular mechanisms of nicotinic neuroprotection are not well understood, nicotine and nicotinic agents could operate by activating nAChRs, thus increasing calcium influx, trophic factors and calcium binding protein levels and activating intracellular anti-apoptotic cascades. We have also suggested that an important target is the intracellular traffic of nAChRs.

Our aim is to clarify further the molecular mechanisms of nicotine-mediated neuroprotection, and to find nicotinic agents that are specific for the modulation of different nAChR subtypes.

nAChRs and epilepsy

Recent advances in genetic analysis have led to the identification of particular mutations in the genes encoding the subunits of nAChRs that are associated with a form of sleep-related epilepsy called autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) with familial occurrence.

We have recently contributed to the study of an inducible mouse model of ADNFLE carrying the V287L mutation of the beta2 subunit of nAChR, and found that silencing the transgene expression during brain development is sufficient to prevent the occurrence of the epileptic seizures in adult mutant mice. This indicates that beta2* receptors play a major role in the formation of neuronal networks during development (Manfredi et al, 2009).

With the use of this mouse model we will investigate the possible use of subtype-selective nicotinic agent for the control of ADNFLE.

The role of nAChr subunits in pathology

Recent genetical analysis of groups that are more prone to develop nicotine addiction and lung tumors have suggested that the presence in nAChRs of some mutated nicotinic subunits, in particular alpha 5 and alpha 3, may plays an important role in the pathogenesis of these diseases. This could be due to a modification of the receptor function, or to an abnormal localisation of the modified receptors in particular cell types, or to ectopic intracellular localisation, or to the association with different signal transduction pathways. We will further investigate these aspects and try to synthethise new subtypes specific drugs that could modulate these pathological functions.

nAChRs as new pharmacological targets

The findings that native receptors are much more heterogeneous than previously thought, that drug sensitivity may be species specific and vary from full to partial agonism or antagonism, that mutated receptors could respond differently to drugs, that particular nAChR subtypes are preferentially involved in many different diseases, have increased the complexity of studying drug specificity and opened up new possibilities for a pharmacological approach.

Using the powerful new approaches of medicinal chemistry, in collaboration with the Institutes of Medicinal Chemistry of the University of Milan and Genoa, we have generated a number of ligands starting from the structure of epibatidine, cytisine, nicotine and neurotoxins (reviewed in Gotti et al., 2006; Bolchi et al., 2011, Dellanoce et al., 2011, Pucci et al., 2011). These drugs have been characterised using complementary approaches ranging from molecular and cell biology and morphology, biochemistry and electrophysiology, and from in vitro functional assays to behavioural studies.

Our goal is to generate subtype specific agonists and antagonists, allosteric modulators and drugs capable of affecting the cellular life of nicotinic receptors and of their patholohgically mutated analogs.

Publications

  • Bolchi C, Gotti C, Binda M, Fumagalli L, Pucci L, Pistillo F, Vistoli G, Valoti E, Pallavicini M (2011) Unichiral 2-(2'-pyrrolidinyl)-1,4-benzodioxanes: the 2R,2'S diastereomer of the N-methyl-7-hydroxy analogue is a potent ?4?2- and ?6?2-nicotinic acetylcholine receptor partial agonist. J. Med. Chem. 54:7588-601.
  • Pucci L, Grazioso G, Dallanoce C, Rizzi L, De Micheli C, Clementi F, Bertrand S, Bertrand D, Longhi R, De Amici M, Gotti C (2011) Engineering of ?-conotoxin MII-derived peptides with increased selectivity for native ?6?2* nicotinic acetylcholine receptors. FASEB J. 25:3775-89.
  • Dallanoce C, Magrone P, Matera C, Frigerio F, Grazioso G, De Amici M, Fucile S, Piccari V, Frydenvang K, Pucci L, Gotti C, Clementi F, De Micheli C (2011) Design, synthesis, and pharmacological characterization of novel spirocyclic quinuclidinyl-?2-isoxazoline derivatives as potent and selective agonists of ?7 nicotinic acetylcholine receptors. ChemMedChem 6:889-903.
  • Manfredi I, Zani AD, Rampoldi L, Pegorini S, Bernascone I, Moretti M, Gotti C, Croci L, Consalez GG, Ferini-Strambi L, Sala M, Pattini L, Casari G (2009) Expression of mutant beta2 nicotinic receptors during development is crucial for epileptogenesis. Hum. Mol. Genet. 18:1075-88.
  • Gotti C, Moretti M, Bohr I, Ziabreva I, Vailati S, Longhi R, Riganti L, Gaimarri A, McKeith IG, Perry RH, Aarsland D, Larsen JP, Sher E, Beattie R, Clementi F, Court JA (2006) Selective nicotinic acetylcholine receptor subunit deficits identified in Alzheimer's disease, Parkinson's disease and dementia with Lewy bodies by immunoprecipitation. Neurobiol. Dis. 23:481-9.
  • Gotti C, Riganti L, Vailati S, Clementi F (2006) Brain neuronal nicotinic receptors as new targets for drug discovery. Curr. Pharm. Des. 12:407-28.
  • Gotti C, Clementi F (2004) Neuronal nicotinic receptors: from structure to pathology. Prog. Neurobiol. 74:363-96.
  • Quik M, Vailati S, Bordia T, Kulak JM, Fan H, McIntosh JM, Clementi F, Gotti C (2005) Subunit composition of nicotinic receptors in monkey striatum: effect of treatments with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine or L-DOPA. Mol. Pharmacol. 67:32-41.

Grants

European Community

Fondazione Cariplo

MIUR COFIN

MIUR FIRB

Collaborations

  • D. Bertrand, HiQScreen, Sarl, Geneva, Switzerland.
  • G. Casari, San Raffaele Scientific Institute, Milan, Italy.
  • C. De Micheli, M. De Amici, M. Pallavicini, Università degli Studi di Milano, Milan, Italy.
  • S. Fucile, Università di Roma “La Sapienza”, Rome, Italy.
  • R. Longhi, CNR, Istituto Riconoscimento Molecolare, Milano, Italy.
  • M. Quik, The Parkinson Inst., Sunnyvale, CA, USA.
  • M.E. Sala, Università di Milano, Milan, Italy.
  • F. Sparatore, Università di Genova, Genoa, Italy.
  • M. Zoli, Università di Modena e Reggio Emilia, Modena, Italy.

 

PI photo

Francesco Clementi

Contact information

email  E-mail

email  +39 02 5031 6962

Participating staff

Cecilia Gotti

Milena Moretti

Irene Manfredi

Francesco Pistillo