Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/29803
Title: PROTEIN 4.1G IN CENTRAL NERVOUS SYSTEM: EXPRESSION AND PROMOTION OF CELLULAR ARBORIZATION AND TIGHT JUNCTION FORMATION
Authors: XIA WENHAO
Keywords: 4.1G, CNS, microglia, oligodendrocyte, cellular arborization, tight junction
Issue Date: 21-Jan-2011
Source: XIA WENHAO (2011-01-21). PROTEIN 4.1G IN CENTRAL NERVOUS SYSTEM: EXPRESSION AND PROMOTION OF CELLULAR ARBORIZATION AND TIGHT JUNCTION FORMATION. ScholarBank@NUS Repository.
Abstract: 4.1G belongs to the membrane-associated band 4.1 protein family, which plays important roles in establishing and maintaining the links between transmembrane proteins and the cytoskeleton. To date, the expression and functions of 4.1G in the central nervous system (CNS) have not been fully elucidated. In the present study, expression and biological functions of 4.1G in the rat CNS and in cultured oligodendrocyte cell line OLN-93 were investigated. 4.1G cDNAs were cloned from rat cDNA libraries by using polymerase chain reaction. An exclusion of exons encoding the 4.1G spectrin-actin binding domain was found. Besides, four other alternative splicing variants that were mainly different in the exons encoding 4.1G U3 regions were also cloned. In situ hybridization revealed a splicing variants-specific distribution of 4.1G mRNAs in CNS (glial localization vs neuronal localization). Specific polyclonal antibodies against 4.1G U1 or U3 regions were also generated. Immunoblotting and immunoprecipitation revealed rat CNS 4.1G protein isoforms with molecular weights ranging from ~80 to ~180 kDa. Immunoperoxidase and immunofluorescence double labeling study demonstrated the expression of 4.1G in microglia, some oligodendrocytes, and a selected group of neurons in spinal cord. In subconfluent OLN-93 cell culture, overexpression of full-length 4.1G and C-terminal-domain-deleted 4.1G, but not the four-point-one-erzin-radixin-moesin (FERM)-domain-deleted 4.1G, promoted cellular arborization. Whereas in confluent cells, endogenous 4.1G was localized to the cytoplasmic periphery together with tight junction protein ZO-1, and FERM domain of 4.1G seemed essential for the recruitment of the protein to the periphery. Calcium switch experiment demonstrated that 4.1G promoted tight junction formation, whereas siRNA knockdown of endogenous 4.1G inhibited tight junction formation among confluent OLN-93 cells. Together, these results suggest functional roles of 4.1G in cellular arborization and tight junction formation, as well as neuron/glia interactions.
URI: http://scholarbank.nus.edu.sg/handle/10635/29803
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