Temporal and Spatial Mouse Brain Expression of Cereblon, An Ionic Channel Regulator Involved in Human Intelligence

Abstract

A mild form of autosomal recessive, nonsyndromal intellectual disability (ARNSID) in humans is caused by a homozygous nonsense mutation in the cereblon gene (mutCRBN). Rodent crbn protein binds to the intracellular C-terminus of the large conductance Ca(2+)-activated K(+)channel (BK(Ca)). An mRNA variant (human SITE 2 INSERT or mouse strex) of the BK(Ca) gene (KCNMA1) that is normally expressed during embryonic development is aberrantly expressed in mutCRBN human lymphoblastoid cell lines (LCLs) as compared to wild-type (wt) LCLs. The present study analyzes the temporal and spatial distribution of crbn and kcnma1 mRNAs in the mouse brain by the quantitative real-time reverse transcriptase-polymerase chain reaction (qPCR). The spatial expression pattern of endogenous and exogenous crbn proteins is characterized by immunostaining. The results show that neocortical (CTX) crbn and kcnma1 mRNA expression increases from embryonic stages to adulthood. The strex mRNA variant is >3.5-fold higher in embryos and decreases rapidly postnatally. Mouse crbn mRNA is abundant in the cerebellum (CRBM), with less expression in the CTX, hippocampus (HC), and striatum (Str) in adult mice. The intracytoplasmic distribution of endogenous crbn protein in the mouse CRBM, CTX, HC, and Str is similar to the immunostaining pattern described previously for the BK(Ca) channel. Exogenous hemagglutinin (HA) epitope-tagged human wt- and mutCRBN proteins using cDNA transfection in HEK293T cell lines showed the same intracellular expression distribution as endogenous mouse crbn protein. The results suggest that mutCRBN may cause ARNSID by disrupting the developmental regulation of BK(Ca) in brain regions that are critical for memory and learning.

A missense mutation in theCRBNgene that segregates with intellectual disability and self-mutilating behaviour in a consanguineous Saudi family

“…Although little is known about the function of human CRBN, the association of this protein with cognitive deficits suggests that it is involved in fundamental processes of human memory and learning. 6 The direct involvement of CRBN in the assembly and surface expression of large-conductance Ca2 + -activated K + channels (BK Ca ) has already been identified, 17 although the mechanism by which CRBN interacts with the channel is not known. The large conductance, BK Ca channels are expressed in brain neurons where they play an important role in regulating the duration of an action potential, firing frequency and neurotransmitter release.…”

Epigenetic regulation of Kcna3 -encoding Kv1.3 potassium channel by cereblon contributes to regulation of CD4 + T-cell activation

“…CRBN is expressed in the cytoplasm, nucleus, and peripheral membranes of a wide variety of cells and tissues (1,(3)(4)(5). CRBN forms an E3 ubiquitin ligase complex with damaged DNA-binding protein (DDB) 1 and Cul4A, and this complex is involved in limb outgrowth and controls fibroblast growth factor 8 expression in zebrafish and chicks (1).…”

Nuclear cereblon modulates transcriptional activity of Ikaros and regulates its downstream target, enkephalin, in human neuroblastoma cells

“…It has been reported that a decrease in Ikaros mRNA triggers differentiation of neural stem cells into the early stages of neural precursor cells in the mammalian cerebral cortex and retina [34,35]. CRBN is also expressed in the mouse cerebral cortex [36] and retina [7]. Therefore, it is important to perform comparative analysis between Ikaros and CRBN at the mRNA level during development.…”