Tetraspanin Protein CD9 Is a Novel Paranodal Component Regulating Paranodal Junctional Formation

Abstract

The axoglial paranodal junction is essential for the proper localization of ion channels around the node of Ranvier. The integrity of this junction is important for nerve conduction. Although recent studies have made significant progress in understanding the molecular composition of the paranodal junction, it is not known how these membrane components are distributed to the appropriate sites and interact with each other. Here we show that CD9, a member of the tetraspanin family, is present at the paranode. CD9 is concentrated in the paranode as myelination proceeds, but CD9 clusters become diffuse, associated with disruption of the paranode, in cerebroside sulfotransferase-deficient mice. Immunohistochemical and Western blot analysis showed that CD9 is distributed predominantly in the PNS. Ablation of CD9 in mutant mice disrupts junctional attachment at the paranode and alters the paranodal components contactinassociated protein (also known as Paranodin) and neurofascin 155, although the frequency of such abnormalities varies among individuals and individual axons even in the same mouse. Electron micrographs demonstrated that compact myelin sheaths were also affected in the PNS. Therefore, CD9 is a myelin protein important for the formation of paranodal junctions. CD9 also plays a role in the formation of compact myelin in the PNS.

Cumulus cell gene expression following the LH surge in bovine preovulatory follicles: potential early markers of oocyte competence

“…Following the LH surge, we showed up the overexpression of several neuronal-related genes such as THBS1 (Liauw et al 2008), FGF2 (Chen et al 2010), MYO1D (Brown & Bridgman 2004), SYNPO (Vlachos et al 2009), and CD9 (Ishibashi et al 2004;Figs 2 and 4). Strikingly, the common functions ensured by these genes were mainly neuron plasticity, neurogenesis (including the dendrogenesis and the axogenesis), and synaptogenesis.…”

How to make an oligodendrocyte

“…Such cardinal stages of oligodendroglial development are characterized by distinct signal effectors and transcription factors that regulate the expression of multiple stage-specific marker genes (Ahmed et al, 2009;Cahoy et al, 2008;Nishiyama et al, 2009;Sim et al, 2011;Young, 2011;Zhang, 2001;Zhang et al, 2014;Zuchero and Barres, 2013). At each stage, cells can be identified and isolated on the basis of temporally regulated surface antigens, which permit the selection of cells of defined mitotic and differentiation potential (Ishibashi et al, 2004;Nishiyama et al, 2009;Yuan et al, 2011;Zhang, 2001;Zhao et al, 2012). These discrete stages exhibit distinct miRNA profiles as well, that may serve to regulate translation, and thus sharpen phenotypic transitions during lineage progression (Barca-Mayo and Lu, 2012;Dugas et al, 2010;He et al, 2012;Lau et al, 2008;Mallanna and Rizzino, 2010;Shenoy and Blelloch, 2014;Shi et al, 2010;Zhao et al, 2010).…”

A tetraspanin regulates septate junction formation in Drosophila midgut

“…Some tetraspanins have been reported to be involved in the regulation of cell-cell adhesion (Chattopadhyay et al, 2003;Ishibashi et al, 2004;Shigeta et al, 2003). A mammalian tetraspanin, CD151, regulates epithelial cell-cell adhesion through PKC-and Cdc42-dependent actin reorganization (Shigeta et al, 2003), or through complex formation with α3β1 integrin (Chattopadhyay et al, 2003).…”

“…Tetraspanins are believed to play a role in membrane compartmentalization and are involved in many biological processes, including cell migration, cell fusion and lymphocyte activation, as well as viral and parasitic infections (Charrin et al, 2014(Charrin et al, , 2009Hemler, 2005;Yanez-Mo et al, 2009). Several tetraspanins regulate cell-cell adhesion (Chattopadhyay et al, 2003;Ishibashi et al, 2004;Shigeta et al, 2003) but none are known to be involved in the formation of epithelial occluding junctions. In the Drosophila genome, there are 37 tetraspanin family members (Charrin et al, 2014;Fradkin et al, 2002;Hemler, 2005;Todres et al, 2000), and some have been characterized by genetic analyses.…”