Brief report Molecular cytogenetic interphase analysis of Phosphoinositide-specific Phospholipase C β1 gene in paraffin-embedded brain samples of major depression patients Vincenza Rita Lo Vasco a, ⁎, Patrizia Polonia b a Dipartimento Organi di Senso, Sapienza University of Rome, Italy b Dipartimento di Scienze Ginecologiche e della Riproduzione Umana, Padova university Hospital, Italy article info abstract Article history: Received 19 July 2011 Received in revised form 25 July 2011 Accepted 25 July 2011 Available online 31 August 2011 Mood disorders represent a major medical need, as their chronic treatments are not effective in all patients. Literature data suggested that phosphoinositides (PI) signal transduction pathway and related molecules such as the Phosphoinositide-specific Phospholipase C (PI-PLC) enzymes, might be involved in the pathophysiology of mood disorders, including major depression. By using interphase fluorescent in situ hybridization methodology, we analyzed PLCB1 gene, which codifies for the PI-PLC β1 enzyme, in paraffin embedded samples of orbito-frontal cortex of 15 patients affected with major depression and in 15 normal controls. No deletions of PLCB1 were identified with the methodology used, which allows to exclude wide gene deletions. The results, the technical aspects of the FISH methodology, and its limitations are discussed. © 2011 Elsevier B.V. All rights reserved. Keywords: Genetics Major depression Signaling I-FISH Phospholipase C beta1 1. Introduction Different signaling pathways play a role in the pathophys- iology of mood disorders, such as the cyclic AMP, phosphoinosi- tides (PI), mitogen activated protein kinase (MAPK), and glycogen synthase kinase cascades (Tanis and Duman, 2007). Involvement of PI in lithium's therapeutic effect was suggested. Lithium modifies PI activity in the nervous system of animal models, as well as in cultured and human cells (Jope et al., 1996), reducing the activity of phosphatidylinositol-specific phospholipase C (PI-PLC) enzymes (Ebstein et al., 1988). Moreover, brain regionally selective deficits in G-protein function associated with PI signaling were reported in subjects presenting with major depression (Pacheco and Jope, 1996). Abnormalities in nerve cell myo-inositol levels and/or PI-cycle regulation seem to be involved in the pathophysiology of psychiatric disorders also including major depression. Interest- ingly, the metabolism of myo-inositol is strictly related to the PI-cycle (Kim et al., 2005). In particular, a role for PI-PLC β1 in mood disorders was suggested (Kim et al., 2005). PLCB1 (OMIM *607120), the gene codifying for PI-PLC β1 enzyme, is constituted from 36 small exons and introns, and was located on the short arm of human chromosome 20 (20p12, nearby markers D20S917 and D20S177) (Peruzzi et al., 2000), a region occasionally rearranged in mental illnesses (Fanous et al., 2008; Hovatta et al., 1998). In order to analyze the deletion of PLCB1 gene in major depression affected patients, we used fluorescence in situ hybridization (FISH) technique, a molecular cytogenetic method currently used to detect and localize the presence of specific nucleic acid sequences, such as DNA on chromosomes or RNA/DNA in tissues (Lengauer et al., 1990; van Dekken et al., 1990). In FISH methodology, fluorescent probes bind those sequences of the nucleic acid with which they share high degree of similarity, allowing the formation of a hybrid, fluorescent molecule. Fluorescence microscopy allows to detect the fluo- rescent probe bound to the nucleic acid, whose signal is often Journal of Affective Disorders 136 (2012) 177–180 ⁎ Corresponding author at: Department of Organi di Senso, Faculty of Medicine and Odontoiatry, University of Rome “Sapienza”, viale del Policlinico, 155-00185 Rome, Italy. Tel.: +39 0649976814; fax: +39 0649976817. E-mail address: ritalovasco@hotmail.it (V.R. Lo Vasco). 0165-0327/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2011.07.023 Contents lists available at SciVerse ScienceDirect Journal of Affective Disorders journal homepage: www.elsevier.com/locate/jad