Distribution of EFHC1 or Myoclonin 1 in mouse neural structures

Abstract

Summary EFHC1, a gene mutated in juvenile myoclonic epilepsy, encodes EFHC1, a protein with three DM10 domains and one EF-hand motif. We recently demonstrated that this molecule is a microtubule-associated protein (MAP) implicated in neuronal migration. Because some controversies persist about the precise localization in the CNS, we studied the neuroanatomical distribution of EFHC1 in mature and developing mouse brain. In the adult, low mRNA expression was detected in several brain structures such as cortex, striatum, hippocampus and cerebellum. At E16, EFHC1 mRNA was shown to be expressed in cortex and not only in cells lining ventricles.Using a purified polyclonal antibody, EFHC1 staining was observed in all cortical layers, in piriform cortex, in hippocampus and in Purkinje cells of cerebellum. In the cortex, the majority of EFHC1 positive cells correspond to neurons, however some glial cells were also stained. In agreement with a previous study, we demonstrated strong EFHC1 expression in cilia of ependymal cells lining cerebral ventricles. Moreover, at E16, the protein was observed at the borders of brain ventricles, in choroid plexus, but also, although to a lesser extent, in piriform and neocortex. In these latter structures, the pattern of expression seems to correspond to the extensions of the radial glia fibers as demonstrated by BLBP immunostaining. Finally, we confirmed that EFHC1 was also expressed and co-localized with the mitotic spindle of neural stem cells.These results confirm that EFHC1 is a protein with a likely low expression level in mouse brain but detectable both in adult and embryonic brain supporting our previous data and Abbreviations: ABC, avidin-biotin-peroxidase complex; BLBP, brain lipid-binding protein; DAB3, 3 -diaminobenzidine; FITC, fluorescein isothiocyanate; GFAP, glial fibrillary acidic protein; IgG, immunoglobulin G; JME, juvenile myoclonic epilepsy; MAP, microtubule-associated protein; MTOC, microtubule-organizing center; NeuN, neuronal nuclei; NGS, normal goat serum; NSC, neural stem cells; PBS, phosphatebuffered saline; PBSG, phosphate-buffered saline with 4.5 g/l glucose; PFA, paraformaldehyde; RRX, rhodamine Red-X; VDCC, voltagedependent calcium channel. Distribution of EFHC1 or Myoclonin 1 in mouse neural structures 197 hypothesis that EFHC1 could play an important role during brain development. As discussed, this opens the door to a new conceptual approach viewing some idiopathic generalized epilepsies as developmental diseases instead of classical channelopathies.

Effect of BMP4 preceded by retinoic acid and co‐culturing ovarian somatic cells on differentiation of mouse embryonic stem cells into oocyte‐like cells

“…Tekt1 is predominantly expressed in the spermatocytes and round spermatids in seminiferous tubules of the mouse testis and participates in nucleation of the flagellar axoneme (Xu et al 2001). Tekt1 is also expressed in some tissues as a structural component of microtubules (Norrander et al 1998;Leon et al 2010). Low mRNA level of Tekt1 was detected in all the experimental groups as well as newborn ovaries.…”

“…; Leon et al . ). Low mRNA level of Tekt1 was detected in all the experimental groups as well as newborn ovaries.…”

Genes and molecular pathways underpinning ciliopathies

“…158), and the D. melanogaster EFHC1 orthologue regulates the morphogenesis of neurons that lack cilia 159 . As in C. elegans , mammalian EFHC1 is expressed by cells with non-motile cilia, including those in the brain 160 . The function of EFHC1 in neurons is unclear but important, as mutations in this protein predispose humans to juvenile epilepsy 157 .…”

juvenile myoclonic epilepsy: efhc1 at the cross-roads ?

“…8,14 Ectopic overexpression of EFHC1 resulted in shorter neurites and a fewer branches and the neurons showed signs of degeneration and eventually underwent apoptotic form of cell death. 8,14 Intriguingly, the overexpression of JME associated EFHC1 mutant proteins did not lead to such abnormal neuronal features, suggesting that the mutations might have affected some of the functional properties of EFHC1 ; one of such functions could be positively regulating the apoptotic process. 7,8 The EFHC1 protein harbors an EF–hand domain and this domain has been shown to bind to calcium.…”