NGL-1/LRRC4C Deletion Moderately Suppresses Hippocampal Excitatory Synapse Development and Function in an Input-Independent Manner

Abstract

Netrin-G ligand-1 (NGL-1), also known as LRRC4C, is a postsynaptic densities (PSDs)-95-interacting postsynaptic adhesion molecule that interacts trans-synaptically with presynaptic netrin-G1. NGL-1 and its family member protein NGL-2 are thought to promote excitatory synapse development through largely non-overlapping neuronal pathways. While NGL-2 is critical for excitatory synapse development in specific dendritic segments of neurons in an input-specific manner, whether NGL-1 has similar functions is unclear. Here, we show that Lrrc4c deletion in male mice moderately suppresses excitatory synapse development and function, but surprisingly, does so in an input-independent manner. While NGL-1 is mainly detected in the stratum lacunosum moleculare (SLM) layer of the hippocampus relative to the stratum radiatum (SR) layer, NGL-1 deletion leads to decreases in the number of PSDs in both SLM and SR layers in the ventral hippocampus. In addition, both SLM and SR excitatory synapses display suppressed short-term synaptic plasticity in the ventral hippocampus. These morphological and functional changes are either absent or modest in the dorsal hippocampus. The input-independent synaptic changes induced by Lrrc4c deletion involve abnormal translocation of NGL-2 from the SR to SLM layer. These results suggest that Lrrc4c deletion moderately suppresses hippocampal excitatory synapse development and function in an input-independent manner.

NGL-1/LRRC4C-Mutant Mice Display Hyperactivity and Anxiolytic-Like Behavior Associated With Widespread Suppression of Neuronal Activity

“…The Lrrc4c –/– mice used in this study have been previously described (Choi et al, 2019). Briefly, Lrrc4c –/– mice (LRRC4C TM 1Lex ), obtained from The Mutant Mouse Resource and Research Center (MMRRC), were generated by introducing an NGL-1 targeting vector into 129/SvEvBrd-derived embryonic stem (ES) cells by homologous recombination, thereby replacing the third exon of the Lrrc4c gene encoding NGL-1 with a β-geo (LacZ/neo) cassette.…”

“…NGL-1, NGL-2, and NGL-3 interact intracellularly with PSD-95, an abundant post-synaptic scaffolding protein (Sheng and Sala, 2001; Sheng and Hoogenraad, 2007; Sheng and Kim, 2011), and extracellularly with the presynaptic adhesion molecules, netrin-G1, netrin-G2, and LAR family receptor tyrosine phosphatases, respectively (Nakashiba et al, 2000, 2002; Yin et al, 2002; Lin et al, 2003; Kim et al, 2006; Woo et al, 2009a; Kwon et al, 2010; Seiradake et al, 2011). It has been suggested that the synaptic adhesions mediated by netrin-G1-NGL-1 and netrin-G2-NGL-2 complexes contribute to the development of distinct populations of neuronal synapses and neural circuits, based on the largely non-overlapping distribution of these two sets of proteins in distinct brain regions, synapses, and circuits (Nakashiba et al, 2002; Yin et al, 2002; Niimi et al, 2007; Nishimura-Akiyoshi et al, 2007; Woo et al, 2009b; Matsukawa et al, 2014; Choi et al, 2019). It is therefore expected that these two adhesion complexes may differentially influence distinct neural circuits and behaviors.…”

“…In vivo functions of NGLs in the regulation of neuronal synapses and behaviors have also been investigated, primarily using transgenic mice lacking NGL isoforms. NGL-1-mutant mice display suppressed excitatory synapse development and short-term plasticity in the hippocampus (Matsukawa et al, 2014; Choi et al, 2019). NGL-2-mutant mice show input-specific decreases in the development and function of hippocampal synapses (Denardo et al, 2012; Matsukawa et al, 2014; Um et al, 2018) and autistic-like social deficits and repetitive behaviors that are responsive to N -methyl- D -aspartate (NMDA) receptor activation (Um et al, 2018).…”

Homozygous Missense Variants in NTNG2, Encoding a Presynaptic Netrin-G2 Adhesion Protein, Lead to a Distinct Neurodevelopmental Disorder

“…31 LRRC4C and LRRC4 have both been shown to be important in hippocampal synapse formation and function. 32,33 The marked findings of severe intellectual disability and autistic features in our cohort are particularly intriguing given the unique role of NTNG2 in vertebrates. As we previously mentioned, netrin-g family members express in distinct, non-overlapping, and complementary neuronal circuits, suggesting a role in establishing appropriate neuronal patterning.…”

“…Medical Genetics Research Centre, Shahid Sadoughi University of Medical Sciences, Yazd, Iran; 11 Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; 12 Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; 13 Department of Medical Genetics, Kanuni Sultan Suleyman Training and Research Hospital, Istanbul, 34303, Turkey; 14 Department of Paediatric Neurology, Golestan Medical, Educational, and Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6163764648, Iran; 15 Pediatric Neurology and Metabolic Division, Cairo University Children Hospital, Egypt; 16 Department of Pediatric Neurology, ICH and SSF Hospital Mirpur, Dhaka, 1216, Bangladesh; 17 Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6500 HB, Nijmegen, the Netherlands; 18 CAPES Foundation, Ministry of Education of Brazil, 549 Brasília, Brazil; 19 Department of Radiology, Boston Children's Hospital, Boston, MA 02115, USA; 20 Hasti Genetic Counseling Center of Welfare Organization of Southern Khorasan, Birjand, Iran; 21 Genome Research Division, Human Genetics Department, Radboud University Medical Center, 6500 HB, Nijmegen, the Netherlands; 22 Health Research Institute, Diabetes Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 23 GeneDx, Gaithersburg, MD 20877, USA; 24 Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; 25 Department of Neurology, Faculty of Medicine, Bam University of Medical Sciences, Bam, Iran; 26 Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA; 27 Laboratory for Pediatric Brain Disease, Howard Hughes Medical Institute, Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA; 28 Department of Medical Genetics, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6135715794, Iran; 29 Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; 30 Texas Children's Hospital, Houston, TX 77030, USA 31 Present address: Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York City, NY 10029, USA32 These authors contributed equally to this work *Correspondence: r.maroofian@ucl.ac.uk https://doi.org/10.1016/j.ajhg.2019.09.025.…”