Sabrina Paratore

Cutting edge: MHC class I-Ly49 interaction regulates neuronal function.

MHC class I molecules (MHC-I) have been implicated in nervous system development in the mouse. In this study we present evidence for the interaction of MHC-I with the NK cell receptor Ly49 in primary cortical neuronal cultures. We show that MHC-I and Ly49 are expressed on neuronal soma and axon surfaces, with Ly49 also present on dendrites. Anti-MHC-I Abs reduce synapsin-I expression and enhance neurite outgrowth and neuronal death. Conversely, anti-Ly49 mAbs increase synapsin-I expression, reduce neurite outgrowth, and promote neuron viability. Because we show that Ly49 genes are selectively expressed in the adult brain, these findings suggest an unsuspected role for the MHC-I-Ly49 interaction in the development and function of the brain.

A natural antisense transcript against Rad18, specifically expressed in neurons and upregulated during β‐amyloid‐induced apoptosis

Apoptosis, the main form of programmed cell death, is associated to a complex and dynamic transcriptional and post‐transcriptional programme. By microarray analysis, we have previously implicated 241 genes differentially expressed in rat cortical neurons exposed to β‐amyloid (Aβ) protein, the major constituent of amyloid plaques in Alzheimers disease. A large number of identified genes have no name or known function. In the present study, we have investigated one of these genes that encodes for a natural antisense transcript against Rad18 (NAT‐Rad18). Real‐time quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) confirmed differential expression of this transcript in cortical neurons exposed to Aβ. In situ hybridization, qRT‐PCR and immunohistochemistry were used to assess the regional and cellular distribution of NAT‐Rad18 in adult rat brain. These experiments showed a widespread distribution of NAT‐Rad18, with the highest levels in the cerebellum, brainstem and cortex, where it was specifically expressed by neurons. NAT‐Rad18 was also strongly expressed in epithelial cells of choroid plexus and cerebral vessels. At the cellular level, expression of Rad18 was counterbalanced by that of its natural antisense transcript, as shown by both in situ hybridization and immunohistochemistry. These experiments suggest the existence of a NAT that exerts a post‐transcriptional control over Rad18.

Genomic analysis: Toward a new approach in breast cancer management

Breast cancer is a clinically heterogeneous and complex disease that can affect differently individuals with seemingly identical clinicopathologic parameters. This heterogeneity is strictly linked to individuals and tumors genetic variability. Currently, the development of high-throughput technologies are proving novel tools to tackle this complexity. By DNA microarray technology, genomic analysis has been used successfully for breast carcinomas stratification into molecular subgroups with relevant implications for clinical outcomes, and detection of prognostic/treatment predictive signatures. Indeed, DNA microarray has rapidly improved becoming a powerful diagnostic tool. Information derived from these assays allows clinicians to estimate the risk for distant recurrence, and predict accurately which patients are likely to benefit from adjuvant therapy. This review will describe the state-of-the-art of genomic analysis in breast cancer and introduce the clinicians to a genomic approach to cancer management, illustrating how it can help in defying a better diagnosis, prognosis and therapeutic treatment.

CXCR4 and CXCL12 immunoreactivities differentiate primary non-small-cell lung cancer with or without brain metastases

Synchronous or metachronous brain metastases (BMs) occur in about 33% of patients affected by non-small-cell lung cancer (NSCLC). To date, no reliable biological marker is able to identify patients who will develop BMs. In the present study, using a quantitative double-labeling immunofluorescence analysis, we evaluated the expression of chemokine CXCL12 and its receptor, CXCR4, in primary NSCLC histological specimens of patients with and without BMs. The immunoreactivity of CXCL12 and CXCR4 was significantly higher in NSCLC samples of patients with BMs. We performed Receiver Operating Characteristics (ROC) analysis in order to define optimal cut-off values for CXCL12 and CXCR4 immunoreactivity that could discriminate between NSCLC patients without and with BMs. ROC curves showed a good diagnostic accuracy and adequate predictive power for both CXCL12 and CXCR4. These findings suggest a possible role for the CXCL12/CXCR4 axis in the metastatic evolution of NSCLC, and its potential use as prognostic markers and drug targets.

Early genomics of learning and memory: a review

The characterization of the molecular mechanisms whereby our brain codes, stores and retrieves memories remains a fundamental puzzle in neuroscience. Despite the knowledge that memory storage involves gene induction, the identification and characterization of the effector genes has remained elusive. The completion of the Human Genome Project and a variety of new technologies are revolutionizing the way these mechanisms can be explored. This review will examine how a genomic approach can be used to dissect and analyze the complex dynamic interactions involved in gene regulation during learning and memory. This innovative approach is providing information on a new class of genes associated with learning and memory in health and disease and is elucidating new molecular targets and pathways whose pharmacological modulation may allow new therapeutic approaches for improving cognition.

Gastric Inhibitory Polypeptide and its Receptor are Expressed in the Central Nervous System and Support Neuronal Survival

The development of neuronal apoptosis depends on an intrinsic transcriptional program. By DNA microarray technology, we have previously implicated a number of genes in different paradigms of neuronal apoptosis. In the present study, we investigated the spatiotemporal pattern of expression of two of these genes, gastric inhibitory polypeptide (Gip) and its receptor (Gipr) in the rat central nervous system. The levels of their transcripts were measured with real-time quantitative polymerase chain reaction and in situ-hybridization. Widespread expression of Gip and Gipr was found in adult rat brain, whereas during postnatal cerebellum development, they were highly expressed in the external and internal granule layer, and in Purkinje cells. To investigate the possible biological function of Gip we examined its effects in vitro. Addition of Gip to cultured cerebellar granule neurons reduced the extent of apoptotic death induced by switching the growing medium from 25 to 5 mM K+. This neurotrophic effect was mimicked by that of PACAP38 and IGF1. We conclude that Gip acts as an endogenous neurotrophic factor and supports neuronal survival.

Identification of Pharmacological Targets in Amyotrophic Lateral Sclerosis Through Genomic Analysis of Deregulated Genes and Pathways

Amyotrophic Lateral Sclerosis (ALS) is a progressive and disabling neurodegenerative disorder characterized by upper and lower motor neuron loss, leading to respiratory insufficiency and death after 3-5 years. Riluzole is currently the only FDA approved drug for ALS, but it has only modest effects on survival. The majority of ALS cases are sporadic and probably associated to a multifactorial etiology. With the completion of genome sequencing in humans and model organisms, together with the advent of DNA microarray technology, the transcriptional cascades and networks underlying neurodegeneration in ALS are being elucidated providing new potential pharmacological targets. The main challenge now is the effective screening of the myriad of targets to identify those with the most therapeutic utility. The present review will illustrate how the identification, prioritization and validation of preclinical therapeutics can be achieved through genomic analysis of critical pathways and networks deregulated in ALS pathology.

Genes and pathways differentially expressed in the brains of Fxr2 knockout mice.

Fragile X syndrome is a common inherited form of mental retardation and originates from the absence of expression of the FMR1 gene. This gene and its two homologues, FXR1 and FXR2, encode for a family of fragile X related (FXR) proteins with similar tissue distribution, together with sequence and functional homology. Based on these characteristics, it has been suggested that these proteins might partly complement one another. To unravel the function of Fxr2 protein, the expression pattern of 12,588 genes was studied in the brains of wild-type and Fxr2 knockout mice, an animal model which shows behavioral abnormalities partly similar to those observed in Fmr1-knockout mice. By genome expression profiling and stringent significance tests we identify genes and gene groups de-regulated in the brains of Fxr2 knockout mice. Differential expression of candidate genes was validated by real-time PCR, in situ hybridization, immunohistochemistry and western blot analysis. A number of differentially expressed genes associated with the Fxr2 phenotype have been previously involved in other memory or cognitive disorders.

Drug Target Identification for Neuronal Apoptosis Through a Genome Scale Screening

During normal nervous system development, physiologically appropriate neuronal apoptosis contributes to a sculpting process that removes approximately one-half of all neurons born during neurogenesis. However, neuronal apoptosis subsequent to this developmental window is physiologically inappropriate for most systems and can contribute to neurodegenerative diseases. Neuronal apoptosis is characterized by specific morphological events and requires the activation of an intrinsic transcriptional program. With the completion of genome sequencing in humans and model organisms, and the advent of DNA microarray technology, the transcriptional cascades and networks regulating neuronal apoptosis are being elucidated providing new potential pharmacological targets. This review will introduce the reader to this genomic approach and illustrate with a few examples a methodological strategy for the rational selection of pharmacological targets and the development of neuroprotective agents.