Laboratory of neurobiology and neuropharmacologyof aging and neurodegenerative diseases

Department of Experimental and Applied Pharmacology

Viale Taramelli 14

Laboratory coordinators

Collaborators

Current students

Research activities

The primary focus of this laboratory is the study of the cellular and molecular events leading to neurodegeneration in Alzheimer’s disease. The possibility to understand the causes and treat the symptoms of Alzheimer’s disease patients is still a great challenge since the triggering events leading to the selective neurodegeneration observed in Alzheimer’s brains are not completely understood. This lack of understanding of the pathophysiological processes poses an important theoretical challenge for the rational design of pharmacological intervention.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, clinically characterised by a gradual onset of memory loss followed by progressive cognitive and physical deterioration. Post mortem evaluation of brain tissue from AD patients shows a distinctive neuropathology with the extensive presence of neurofibrillary tangles (mainly composed by a cytoskeletal protein named tau) and neuritic or senile plaques, characterised by the accumulation of proteins in the form of β pleated sheet fibrils. The major component of senile plaques is the β amyloid (Aβ) peptide, which is derived by proteolytic processing by a larger protein named the Amyloid Precursor Protein (APP). Currently one of the leading, although controversial, hypothesis for the pathogenesis of AD is focused on the potential toxic role of an excessive production of Aβ . As a working hypothesis a number of investigators favor the “amyloid cascade” (1, 2) which considers Aβ formation as an early event of Alzheimer's pathogenesis.  Such peptide is derived from the proteolytic metabolism of a larger protein named the amyloid precursor protein (APP). Until today the major obstacle to an effective therapeutic strategy is the lack of understanding of the mechanisms that regulate the production of Aβ and the factors that induce its conformational transition into amyloid fibrils as well as the mechanism of cellular toxicity induced by Aβ and/or amyloid fibrils. Our studies have the aim of characterising the correlation between the excessive production of  Aβ, its aggregation into amyloid fibrils and the resulting cellular toxicity. We aim at the definition of novel therapeutic strategies either related to the pharmacoogical modulation of Aβ production or the process of fibrillogenesis and cellular toxicity.

A second unit of the Lab focuses the research on the mechanisms fo memory and cognition, and in particular on the chenges underlying aging related changes in these brain functions. The long term changes associated with memory consolidation are only partialy dependent on trascriptional events. There are in fact post transcriptional mechanisms that allow for a fine and localized control of the biochemical mechanisms taking place in those synapse activated during learning. In particular literature data suggest the importance of the process of mRNA stabilization. The proteins identified so far that can act as mRNA stabilizers are those called ELAV-like. These proteins are highly conserved in evolution and bind preferentially A U rich elements (ARE) on the mRNA molecule. It has been reported that the ELAV-lik proteins can bind and increase the stability of mRNAs containing ARE elements. In mammals there are three of these proteins HuB, HuC e HuD that are specifcicaly expressed in the brain and recent studies have demonstrated that the neuronal ELAV-like proteins are involved in memory processes. (3).

Lines of research:

Studies on neuroprotective strategies based on the “amyloid cascade hypothesis”

Although a principal morphological marker in the disease, the role of Aβ has been controversial and studies of biological activities of Aβ suggest that it may increase neuronal risk for degeneration and may be directly neurotoxic when aggregated into fibrils. Thus, the important pathologic properties of this protein, such as neurotoxicity and resistance to proteolytic degradation, depend on the ability of Aβ to form β-sheet structures or amyloid fibrils.

One strategy for developing possible drugs to treat AD is to screen for molecules that inhibit Aβ aggregation and, possibly, interfere with its toxicity, with the aim to establish general requirements for the design of therapeutic agents against Aβ overproduction, aggregate formation, deposition and neurotoxicity in AD brains.

Pharmacological intervention on the amyloid precursor protein metabolism

The proteolytic metabolism of the Amyloid Precursor Protein (APP) is complex and can be regulated by several protease activities. The pathways that generate Aβ are regulated by the sequential action of two enzymes, named β and γ-secretase. Alpha secretase, instead, cleaves APP within the Aβ sequence and releases a soluble N-terminal fragment, termed soluble APPα , a process that constitutes the so called non amyloidogenic pathway. Several studies in the field of AD research, over the past 15 years have indicated that an aberrant proteolytic metabolism of APP can be held responsible for the excessive production of of beta amyloid, resulting in a neurotoxic effect. Interestingly the collected informations lead to the notion that APP metabolism may be amenable to pharmacological modulation (1, 2) and may be controlled by classical neurotransmitters, and hormones (4), as well as drugs inhibiting acetylcholinesterase activity (Racchi et al., 2001). The alterations in neurotransmission in the AD brain can affect also multiple signal-transduction mechanisms that are directly involved in the metabolic fate of APP. One of the most consistent findings is the alteration of protein kinase C (PKC), whose level, activity and subcellular distribution have been found to be altered (5). Although PKC activity is thought to be central in the regulated metabolism of APP a number of intracellular pathways interact to form a complex signalling network where at least four major kinase systems are involved, and thus a complex network of second messengers is involved in the regulation of APP metabolism. Such network of signal transduction molecules is an extraordinary tool for the dissection of multiple possibilities of pharmacological modulation. The purpose of these studies is aimed at the pharmacological regulation of APP metabolism with the final goal to reduce the formation of Aβ, a potentially neurotoxic peptide or possibily to support the production of soluble APPα, a potentially neuroprotective molecule whose definite physiological role has yet to be defined.

Characterization of the role of ELAV-like proteins in the molecular mechanisms related to memory.

The view that memory is encoded by variations in the strength of synapses implies that long-term biochemical changes take place within subcellular microdomains of neurons. These changes are thought ultimately to be an effect of transcriptional regulation of specific genes. Localized changes, however, cannot be fully explained by a purely transcriptional control of gene expression. The only proteins reported to act by increasing the stability and rate of translation of some specific mRNAs are the ELAV-like proteins (ELPs). HuB, HuC and HuD are neuron-specific, while HuR is ubiquitary. We reported that neuronal ELPs increase in the hippocampus of mice that have learned a spatial task (3). This increase was also accompanied by enhanced expression of the GAP-43 gene, known to be regulated mainly post-transcriptionally and whose mRNA we demonstrated to be an in vivo ELAV-like target. Antisense-mediated knockdown of HuC impaired spatial learning performance in mice and induced a concomitant downregulation of GAP-43 expression. We are presently investigating the specific role played by HuD during the enconding phase of memory formation and the possible involvement of cortical areas in this mechanism. In addition, we are performing experiments in another specie (the rat) using a different learning paradigm to demonstrate the generality of the process. Neuronal ELAV-like proteins could then exert learning-induced post-transcriptional control of an array of target genes uniquely suited to subserve substrates of memory storage.

Funds for research

CNR, FAR, MIUR, Progetti di Ateneo, Human Frontier Science Program, Ministero della Sanità, Alzheimer Association USA, Telethon, Astra-Zeneca, Bayer, Chiesi, Pfizer, Sanofi-Synthelabo, FIRB

Educational activities (Academic courses)

          Communicate with us at:  racchi@unipv.it ; govonis@unipv.it ; alessia.pascale@unipv.it

Editorial activities    Dementia Update    

Recent publications (see also PubMed for others)

Cavazzin C, Bonvicini C, Nocera A, Racchi M, Kasahara J, Tardito D, Gennarelli M, Govoni S, Racagni G, Popoli M.   Expression and phosphorylation of delta-CaM kinase II in cultured Alzheimer fibroblasts. Neurobiol Aging. 2004 Oct;25(9):1187-96.   

Racchi M, Mazzucchelli M, Porrello E, Lanni C, Govoni S.   Acetylcholinesterase inhibitors: novel activities of old molecules. Pharmacol Res. 2004 Oct;50(4):441-51.   

Govoni S.   Alzheimer's disease: facing the biological complexity to treat the disease. Pharmacol Res. 2004 Oct;50(4):381-3. No abstract available.   

Lanni C, Mazzucchelli M, Porrello E, Govoni S, Racchi M.   Differential involvement of protein kinase C alpha and epsilon in the regulated secretion of soluble amyloid precursor protein. Eur J Biochem. 2004 Jul;271(14):3068-75.   

Amadio M, Govoni S, Alkon DL, Pascale A.   Emerging targets for the pharmacology of learning and memory. Pharmacol Res. 2004 Aug;50(2):111-22.   

Racchi M, Leone M, Porrello E, Rigamonti A, Govoni S, Sironi M, Montomoli C, Bussone G.   Familial migraine with aura: association study with 5-HT1B/1D, 5-HT2C, and hSERT polymorphisms. Headache. 2004 Apr;44(4):311-7.  

Pascale A, Alkon DL, Grimaldi M.   Translocation of protein kinase C-betaII in astrocytes requires organized actin cytoskeleton and is not accompanied by synchronous RACK1 relocation. Glia. 2004 Apr 15;46(2):169-82.   

Daglia M, Racchi M, Papetti A, Lanni C, Govoni S, Gazzani G.   In vitro and ex vivo antihydroxyl radical activity of green and roasted coffee. J Agric Food Chem. 2004 Mar 24;52(6):1700-4.   

Pascale A, Gusev PA, Amadio M, Dottorini T, Govoni S, Alkon DL, Quattrone A.   Increase of the RNA-binding protein HuD and posttranscriptional up-regulation of the GAP-43 gene during spatial memory. Proc Natl Acad Sci U S A. 2004 Feb 3;101(5):1217-22. Epub 2004 Jan 26.   

D'Agata V, Schreurs BG, Pascale A, Zohar O, Cavallaro S.   Down regulation of cerebellar memory related gene-1 following classical conditioning. Genes Brain Behav. 2003 Aug;2(4):231-7.    

Mazzucchelli M, Porrello E, Villetti G, Pietra C, Govoni S, Racchi M.   Characterization of the effect of ganstigmine (CHF2819) on amyloid precursor protein metabolism in SH-SY5Y neuroblastoma cells. J Neural Transm. 2003 Aug;110(8):935-47.   

Racchi M, Mazzucchelli M, Pascale A, Sironi M, Govoni S.   Role of protein kinase Calpha in the regulated secretion of the amyloid precursor protein. Mol Psychiatry. 2003 Feb;8(2):209-16.    

Racchi M, Balduzzi C, Corsini E.   Dehydroepiandrosterone (DHEA) and the aging brain: flipping a coin in the "fountain of youth". CNS Drug Rev. 2003 Spring;9(1):21-40. Review.   

Racchi M, Govoni S.   The pharmacology of amyloid precursor protein processing. Exp Gerontol. 2003 Jan-Feb;38(1-2):145-57. Review.    

Zhao WQ, Chen GH, Chen H, Pascale A, Ravindranath L, Quon MJ, Alkon DL.   Secretion of Annexin II via activation of insulin receptor and insulin-like growth factor receptor. J Biol Chem. 2003 Feb 7;278(6):4205-15. Epub 2002 Nov 12.

Ling X, Martins RN, Racchi M, Craft S, Helmerhorst E. Amyloid beta antagonizes insulin promoted secretion of the amyloid beta protein precursor. J Alzheimers Dis. 2002 Oct;4(5):369-74.

Uberti D, Carsana T, Bernardi E, Rodella L, Grigolato P, Lanni C, Racchi M, Govoni S, Memo M. Selective impairment of p53-mediated cell death in fibroblasts from sporadic Alzheimer's disease patients. J Cell Sci. 2002 Aug 1;115(Pt 15):3131-8.

Govoni S, Lanni C, Racchi M. Advances in understanding the pathogenetic mechanisms of Alzheimer's disease. Funct Neurol. 2001;16(4 Suppl):17-30. Review.

Racchi M, Daglia M, Lanni C, Papetti A, Govoni S, Gazzani G. Antiradical activity of water soluble components in common diet vegetables. J Agric Food Chem. 2002 Feb 27;50(5):1272-7.

Corsini E, Lucchi L, Meroni M, Racchi M, Solerte B, Fioravanti M, Viviani B, Marinovich M, Govoni S, Galli CL. In vivo dehydroepiandrosterone restores age-associated defects in the protein kinase C signal transduction pathway and related functional responses. J Immunol. 2002 Feb 15;168(4):1753-8.

Racchi M, Govoni S, Solerte SB, Galli CL, Corsini E. Dehydroepiandrosterone and the relationship with aging and memory: a possible link with protein kinase C functional machinery. Brain Res Brain Res Rev. 2001 Nov;37(1-3):287-93. Review.

Racchi M, Sironi M, Caprera A, Konig G, Govoni S. Short- and long-term effect of acetylcholinesterase inhibition on the expression and metabolism of the amyloid precursor protein. Mol Psychiatry. 2001 Sep;6(5):520-8.

Quattrone A, Pascale A, Nogues X, Zhao W, Gusev P, Pacini A, Alkon DL. Posttranscriptional regulation of gene expression in learning by the neuronal ELAV-like mRNA-stabilizing proteins. Proc Natl Acad Sci U S A. 2001 Sep 25;98(20):11668-73.

Corsini E, Viviani B, Lucchi L, Marinovich M, Racchi M, Galli CL. Ontogenesis of protein kinase C betaII and its anchoring protein RACK1 in the maturation of alveolar macrophage functional responses. Immunol Lett. 2001 Mar 1;76(2):89-93.

Solano DC, Sironi M, Bonfini C, Solerte SB, Govoni S, Racchi M. Insulin regulates soluble amyloid precursor protein release via phosphatidyl inositol 3 kinase-dependent pathway. FASEB J. 2000 May;14(7):1015-22.

Brandi ML, Becherini L, Gennari L, Racchi M, Bianchetti A, Nacmias B, Sorbi S, Mecocci P, Senin U, Govoni S. Association of the estrogen receptor alpha gene polymorphisms with sporadic Alzheimer's disease. Biochem Biophys Res Commun. 1999 Nov 19;265(2):335-8.

Racchi M, Govoni S. Rationalizing a pharmacological intervention on the amyloid precursor protein metabolism. Trends Pharmacol Sci. 1999 Oct;20(10):418-23. Review.

Corsini E, Battaini F, Lucchi L, Marinovich M, Racchi M, Govoni S, Galli CL. A defective protein kinase C anchoring system underlying age-associated impairment in TNF-alpha production in rat macrophages. J Immunol. 1999 Sep 15;163(6):3468-73.

Pascale A, Bhagavan S, Nelson TJ, Neve RL, McPhie DL, Etcheberrigaray R. Enhanced BK-induced calcium responsiveness in PC12 cells expressing the C100 fragment of the amyloid precursor protein. Brain Res Mol Brain Res. 1999 Oct 1;72(2):205-13.

Racchi M, Solano DC, Sironi M, Govoni S. Activity of alpha-secretase as the common final effector of protein kinase C-dependent and -independent modulation of amyloid precursor protein metabolism. J Neurochem. 1999 Jun;72(6):2464-70.

Solerte SB, Fioravanti M, Racchi M, Trabucchi M, Zanetti O, Govoni S. Menopause and estrogen deficiency as a risk factor in dementing illness: hypothesis on the biological basis. Maturitas. 1999 Jan 4;31(2):95-101. Review.

Gasparini L, Benussi L, Bianchetti A, Binetti G, Curti D, Govoni S, Moraschi S, Racchi M, Trabucchi M. Energy metabolism inhibition impairs amyloid precursor protein secretion from Alzheimer's fibroblasts. Neurosci Lett. 1999 Mar 26;263(2-3):197-200.

Vestling M, Cedazo-Minguez A, Adem A, Wiehager B, Racchi M, Lannfelt L, Cowburn RF. Protein kinase C and amyloid precursor protein processing in skin fibroblasts from sporadic and familial Alzheimer's disease cases. Biochim Biophys Acta. 1999 Mar 30;1453(3):341-50.

Racchi M, Johnston JA, Flood FM, Cowburn RF, Govoni S. Amyloid precursor protein metabolism in fibroblasts from individuals with one, two or three copies of the amyloid precursor protein (APP) gene. Biochem J. 1999 Mar 15;338 ( Pt 3):777-82.

Battaini F, Pascale A, Lucchi L, Pasinetti GM, Govoni S. Protein kinase C anchoring deficit in postmortem brains of Alzheimer's disease patients. Exp Neurol. 1999 Oct;159(2):559-64.

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