Jole Fiorito

Synaptic Therapy in Alzheimer’s Disease: A CREB-centric Approach

Therapeutic attempts to cure Alzheimer’s disease (AD) have failed, and new strategies are desperately needed. Motivated by this reality, many laboratories (including our own) have focused on synaptic dysfunction in AD because synaptic changes are highly correlated with the severity of clinical dementia. In particular, memory formation is accompanied by altered synaptic strength, and this phenomenon (and its dysfunction in AD) has been a recent focus for many laboratories. The molecule cyclic adenosine monophosphate response element-binding protein (CREB) is at a central converging point of pathways and mechanisms activated during the processes of synaptic strengthening and memory formation, as CREB phosphorylation leads to transcription of memory-associated genes. Disruption of these mechanisms in AD results in a reduction of CREB activation with accompanying memory impairment. Thus, it is likely that strategies aimed at these mechanisms will lead to future therapies for AD. In this review, we will summarize literature that investigates 5 possible therapeutic pathways for rescuing synaptic dysfunction in AD: 4 enzymatic pathways that lead to CREB phosphorylation (the cyclic adenosine monophosphate cascade, the serine/threonine kinases extracellular regulated kinases 1 and 2, the nitric oxide cascade, and the calpains), as well as histone acetyltransferases and histone deacetylases (2 enzymes that regulate the histone acetylation necessary for gene transcription).

Synthesis of Quinoline Derivatives: Discovery of a Potent and Selective Phosphodiesterase 5 Inhibitor for the Treatment of Alzheimer's disease

Phosphodiesterase type 5 (PDE5) mediates the degradation of cGMP in a variety of tissues including brain. Recent studies have demonstrated the importance of the nitric oxide/cGMP/cAMP-responsive element-binding protein (CREB) pathway to the process of learning and memory. Thus, PDE5 inhibitors (PDE5Is) are thought to be promising new therapeutic agents for the treatment of Alzheimers disease (AD), a neurodegenerative disorder characterized by memory loss. To explore this possibility, a series of quinoline derivatives were synthesized and evaluated. We found that compound 7a selectively inhibits PDE5 with an IC(50) of 0.27 nM and readily crosses the blood brain barrier. In an in vivo mouse model of AD, compound 7a rescues synaptic and memory defects. Quinoline-based, CNS-permeant PDE5Is have potential for AD therapeutic development.

Haloperidol metabolite II prodrug: Asymmetric synthesis and biological evaluation on rat C6 glioma cells

In a previous work we reported the antiproliferative effects of (±)-MRJF4, a novel haloperidol metabolite II (HP-mII) (a sigma-1 antagonist and sigma-2 agonist) prodrug, obtained through conjugation to 4-phenylbutyric acid (PhBA) [a histone deacetylase inhibitor (HDACi)] via an ester bond. As a continuation of this work, here we report the asymmetric synthesis of compounds (R)-(+)-MRJF4 and (S)-(-)-MRJF4 and the evaluation of their biological activity on rat C6 glioma cells, derived from glioblastoma multiforme (GBM), which is the most common and deadliest central nervous system (CNS) invasive malignancy. Favourable physicochemical properties, high permeability in the parallel artificial membrane permeability assay (PAMPA), good enzymatic and chemical stability, in vivo anticancer activity, associated with the capacity to reduce cell viability and to increase cell death by apoptosis, render compound (R)-(+)-MRJF4 a promising candidate for the development of a useful therapeutic for gliomas therapy.

PDE5 Exists in Human Neurons and is a Viable Therapeutic Target for Neurologic Disease

Phosphodiesterase 5 (PDE5) is a critical component of the cGMP-PKG axis of cellular signaling in neurons, and inhibition of PDE5 has been shown to be therapeutic in a wide range of neurologic conditions in animal models. However, enthusiasm for PDE5 inhibitors in humans is limited by data suggesting that PDE5 may not exist in human neurons. Here, we first show that past attempts to quantify PDE5 mRNA were flawed due to the use of incorrect primers, and that when correct primers are used, PDE5 mRNA is detectable in human brain tissue. We then show that PDE5 protein exists in human brain by western blot and ELISA. Most importantly, we performed immunohistochemistry and demonstrate that PDE5 is present in human neurons. We hope that this work will trigger a renewed interest in the development of PDE5 inhibitors for neurologic disease.

Identification of a Novel 1,2,3,4-Tetrahydrobenzo[b][1,6]naphthyridine Analogue as a Potent Phosphodiesterase 5 Inhibitor with Improved Aqueous Solubility for the Treatment of Alzheimer’s Disease

Phosphodiesterase 5 (PDE5) hydrolyzes cyclic guanosine monophosphate (cGMP) leading to increased levels of the cAMP response element binding protein (CREB), a transcriptional factor involved with learning and memory processes. We previously reported potent quinoline-based PDE5 inhibitors (PDE5Is) for the treatment of Alzheimers disease (AD). However, the low aqueous solubility rendered them undesirable drug candidates. Here we report a series of novel PDE5Is with two new scaffolds, 1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridine and 2,3-dihydro-1H-pyrrolo[3,4-b]quinolin-1-one. Among them, compound 6c, 2-acetyl-10-((3-chloro-4-methoxybenzyl)amino)-1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridine-8-carbonitrile, the most potent compound, has an excellent in vitro IC50 (0.056 nM) and improved aqueous solubility as well as good efficacy in a mouse model of AD. Furthermore, we are proposing two plausible binding modes obtained through in silico docking, which provide insights into the structural basis of the activity of the two series of compounds reported herein.

Effect of MRJF4 on C6 Glioma Cells Proliferation and Migration

BACKGROUND MRJF4, a novel haloperidol metabolite II prodrug, was obtained through the esterification of the secondary hydroxyl group of haloperidol metabolite II with 4-phenylbutyric acid. The activities of (±)-MRJF4 and its two enantiomers [(+)-MRJF4 and (-)-MRJF4] as tumor specific inducers of pro-apoptotic genes were evaluated on malignant C6 glioma cells. In particular, changes in Nf-κB signaling pathway, activity of nitric oxide synthases (NOS), metalloproteinases (MMPs), and membrane adhesion proteins were investigated. RESULTS IκBα reduced phosphorylation and iNOS lowered activity could be correlated with the previously demonstrated decreased proliferation and tumor progression of C6 cells upon 24 h of treatment with all the three compounds. Integrin β1 decreased expression, at the same experimental time, seems to support lower C6 cells migrative capability and the consequent reduced invasiveness of these cells upon treatment with (±)-MRJF4 and its enantiomers. CONCLUSION These results suggest that this multi-target prodrug and its two enantiomers might be a valuable clinical tool for the treatment of metastatic glioblastoma.

Molecular Mechanisms of Learning and Memory

Abstract Learning and memory are two closely related phenomena that allow living beings to acquire new knowledge of the world and to retain it. They shape the individual personality and relationship with the world outside. Memory’s molecular mechanisms are highly conserved among different species ranging from Drosophila to humans. In this chapter, we will address questions such as how the brain memorizes new information, and what memories are made of. To answer these questions, we will examine the cellular, electrophysiological, and molecular processes underlying hippocampus-dependent declarative memory with a focus on the role of the transcription factor, cAMP responsive element-binding protein, and histone acetylation in this process.