The Complement Regulator Susd4 Influences Nervous-System Function and Neuronal Morphology in Mice

Hongling Zhu; Laura E Meissner; Colleen Byrnes; Galina Tuymetova; Cynthia J Tifft; Richard L Proia

doi:10.1016/j.isci.2020.100957

The Complement Regulator Susd4 Influences Nervous-System Function and Neuronal Morphology in Mice

iScience. 2020 Mar 27;23(3):100957. doi: 10.1016/j.isci.2020.100957. Epub 2020 Feb 28.

Authors

Hongling Zhu¹, Laura E Meissner², Colleen Byrnes¹, Galina Tuymetova¹, Cynthia J Tifft³, Richard L Proia⁴

Affiliations

¹ Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
² Office of the Clinical Director and Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
³ Office of the Clinical Director and Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address: cynthiat@mail.nih.gov.
⁴ Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA. Electronic address: proia@nih.gov.

Abstract

The SUSD4 (Sushi domain-containing protein 4) gene encodes a complement inhibitor that is frequently deleted in 1q41q42 microdeletion syndrome, a multisystem congenital disorder that includes neurodevelopmental abnormalities. To understand SUSD4's role in the mammalian nervous system, we analyzed Susd4 knockout (KO) mice. Susd4 KO mice exhibited significant defects in motor performance and significantly higher levels of anxiety-like behaviors. Susd4 KO brain had abnormal "hairy" basket cells surrounding Purkinje neurons within the cerebellum and significantly reduced dendritic spine density in hippocampal pyramidal neurons. Neurons and oligodendrocyte lineage cells of wild-type mice were found to express Susd4 mRNA. Protein expression of the complement component C1q was increased in the brains of Susd4 KO mice. Our data indicate that SUSD4 plays an important role in neuronal functions, possibly via the complement pathway, and that SUSD4 deletion may contribute to the nervous system abnormalities in patients with 1q41q42 deletions.

Keywords: Behavioral Neuroscience; Cellular Neuroscience; Components of the Immune System; Neuroscience.

Published by Elsevier Inc.