Please cite this article in press as: J. Semmler, et al., Pacsin 2 is required for the maintenance of a normal cardiac function in the developing mouse heart, Pharmacol Res (2017), https://doi.org/10.1016/j.phrs.2017.10.004 ARTICLE IN PRESS G Model YPHRS-3704; No. of Pages 11 Pharmacological Research xxx (2017) xxx–xxx Contents lists available at ScienceDirect Pharmacological Research journal homepage: www.elsevier.com/locate/yphrs Invited Perspective Pacsin 2 is required for the maintenance of a normal cardiac function in the developing mouse heart Judith Semmler a , Jan Kormann b , Sureshkumar Perumal Srinivasan a , Annette Köster a , Daniel Sälzer b , Michael Reppel a,c , Jürgen Hescheler a , Markus Plomann b , Filomain Nguemo a,∗ a Institute of Neurophysiology, University of Cologne, 50931 Cologne, Germany b Institute of Biochemistry, University of Cologne, 50931 Cologne, Germany c Department of Cardiology, University of Lübeck, Lübeck, Germany a r t i c l e i n f o Article history: Received 10 October 2016 Received in revised form 26 June 2017 Accepted 15 October 2017 Available online xxx Keywords: Pacsin 2 Knockout mouse Developing heart Myocardial function AV conduction Ion channels a b s t r a c t The Pacsin proteins (Pacsin 1, 2 and 3) play an important role in intracellular trafficking and thereby signal transduction in many cells types. This study was designed to examine the role of Pacsin 2 in car- diac development and function. We investigated the development and electrophysiological properties of Pacsin 2 knockout (P2KO) hearts and single cardiomyocytes isolated from 11.5 and 15.5 days old fetal mice. Immunofluorescence experiments confirmed the lack of Pacsin 2 protein expression in P2KO car- diac myocytes in comparison to wildtype (WT). Western blotting demonstrates low expression levels of connexin 43 and T-box 3 proteins in P2KO compared to wildtype (WT). Electrophysiology measurements including online Multi-Electrode Array (MEA) based field potential (FP) recordings on isolated whole heart of P2KO mice showed a prolonged AV-conduction time. Patch clamp measurements of P2KO car- diomyocytes revealed differences in action potential (AP) parameters and decreased pacemaker funny channel (I f ), as well as L-type Ca 2+ channel (I CaL ), and sodium channel (I Na ). These findings demonstrate that Pacsin 2 is necessary for cardiac development and function in mouse embryos, which will enhance our knowledge to better understand the genesis of cardiovascular diseases. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction Understanding the factors and networks of signals that regu- late the formation and function of the heart can provide significant insight into both development and disease. The Pacsin (protein kinase C and casein kinase 2 substrate in neurons) proteins, also called syndapins, comprise a subfamily of the Bin-Amphiphysin- Rvs- (BAR-) protein superfamily mediating membrane deformation required for the generation of carriers in intracellular transport pro- cesses and/or regulating the transport of specific cargo proteins (for review see Safari and Suetsugu [1]). Of the three family mem- bers, termed Pacsin 1–3, Pacsin 2 shows a broad tissue distribution, while Pacsin 1 is mainly expressed in neuronal tissue and Pacsin 3 restricted to muscle, heart and lung [2]. All Pacsins share an N- terminal Fes-Cip4 homology-BAR (F-BAR) domain, followed by an ∗ Corresponding author at: Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Robert Koch Str. 39, 50931 Cologne, Germany. E-mail address: filo.nguemo@uni-koeln.de (F. Nguemo). unstructured linker region and a C-terminal SH3 domain, which is crucial for binding to proline-rich regions of specific interaction partners. Thus, all Pacsins bind to dynamin and to the neuronal Wiskott-Aldrich-syndrome protein (N-WASP) to activate the Arp 2/3 complex, linking actin remodeling processes to endocytic sites [3]. Two recent studies elucidated a role for Pacsin 2 in caveolin- dependent endocytosis [4,5]. Pacsin 2 binds directly to caveolin1 via its F-BAR domain and is thought to recruit dynamin to caveo- lae scission sites. In addition to its localization at caveolae and at vesicles, Pacsin 2 is also found at tubular structures [2,6]. Pacsin 1 and 2 also bind to Eps15 homology domain (EHD) proteins, which are dynamin-like ATPases, with an N-terminal G- domain and a C-terminal EH-domain [7]. EHD proteins interact via the EH domain with the NPF motifs present in the linker regions of Pacsin 1 and 2. EHD proteins were previously shown to par- ticipate in distinct clathrin-dependent and independent endocytic and recycling processes [8,9]. Furthermore, in a recent study EHD proteins were identified as direct interactors of ankyrin B in car- diomyocytes which regulate its localization and thereby membrane excitability [10]. https://doi.org/10.1016/j.phrs.2017.10.004 1043-6618/© 2017 Elsevier Ltd. All rights reserved.