Epilepsy protein Efhc1/myoclonin1 is expressed in cells with motile cilia but not in neurons or mitotic apparatuses in brain

• Published in: Scientific reports Vol. 10; no. 1; p. 22076
• Main Authors: Suzuki, Toshimitsu, Inoue, Ikuyo, Yamakawa, Kazuhiro
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16-12-2020; Nature Publishing Group; Nature Portfolio
• Subjects: 692/699; 692/699/375; 692/699/375/178; Animals; Calcium-Binding Proteins - biosynthesis; Calcium-Binding Proteins - genetics; Cell division; Cell migration; Cerebral cortex; Cerebral Cortex - metabolism; Choroid plexus; Cilia; Cilia - genetics; Cilia - metabolism; Ependymal cells; Epilepsy; Flagella; Gene Expression Regulation; Humanities and Social Sciences; Mice; Mice, Knockout; Mitosis; Monoclonal antibodies; multidisciplinary; Neurons; Neurons - metabolism; Science; Science (multidisciplinary); Trachea
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-79202-4

EFHC1
gene encodes the myoclonin1 protein, also known as Rib72-1. Pathogenic variants in
EFHC1
have been reported in patients with juvenile myoclonic epilepsy (JME). Although several studies of immunohistological investigations reproducibly showed that the myoclonin1 is expressed in cells with flagella and motile cilia such as sperm, trachea and ependymal cells lining the brain ventricles, whether myoclonin1 is also expressed in neurons still remains controversial. Here we investigated myoclonin1 expression using widely-used polyclonal (mRib72-pAb) and self-made monoclonal (6A3-mAb) anti-myoclonin1 antibodies together with
Efhc1
homozygous knock-out (
Efhc1
−/−
) mice. All of the western blot, immunocytochemical, and immunohistochemical analyses showed that mRib72-pAb crossreacts with several mouse proteins besides myoclonin1, while 6A3-mAb specifically recognized myoclonin1 and detected it only in cells with motile cilia but not in neurons. In dividing cells, mRib72-pAb signals were observed at the midbody (intercellular bridge) and mitotic spindle, but 6A3-mAb did not show any signals at these apparatuses. We further found that the complete elimination of myoclonin1 in
Efhc1
−/−
mouse did not critically affect cell division and migration of neurons in cerebral cortex. These results indicate that myoclonin1 is not expressed in neurons, not a regulator of cell division or neuronal migration during cortical development, but expressed in choroid plexus and ependymal cells and suggest that
EFHC1
mutation-dependent JME is a motile ciliopathy.