Nogo-A at CNS paranodes is a ligand of Caspr: possible regulation of K+ channel localization

Abstract

We report Nogo-A as an oligodendroglial component congregating and interacting with the Caspr±F3 complex at paranodes. However, its receptor Nogo-66 receptor (NgR) does not segregate to speci®c axonal domains. CHO cells cotransfected with Caspr and F3, but not with F3 alone, bound speci®cally to substrates coated with Nogo-66 peptide and GST±Nogo-66. Binding persisted even after phosphatidylinositolspeci®c phospholipase C (PI-PLC) removal of GPIlinked F3 from the cell surface, suggesting a direct interaction between Nogo-66 and Caspr. Both Nogo-A and Caspr co-immunoprecipitated with Kv1.1 and Kv1.2, and the developmental expression pattern of both paralleled compared with Kv1.1, implicating a transient interaction between Nogo-A±Caspr and K + channels at early stages of myelination. In pathological models that display paranodal junctional defects (EAE rats, and Shiverer and CGT ±/± mice), distances between the paired labeling of K + channels were shortened signi®cantly and their localization shifted toward paranodes, while paranodal Nogo-A congregation was markedly reduced. Our results demonstrate that Nogo-A interacts in trans with axonal Caspr at CNS paranodes, an interaction that may have a role in modulating axon±glial junction architecture and possibly K + -channel localization during development.

Neuronal Nogo-A upregulation does not contribute to ER stress-associated apoptosis but participates in the regenerative response in the axotomized adult retina

“…Among the different members of the activating transcription factor (ATF) family, only ATF3 was found to be upregulated in agreement with a previous study (Figures 3a and 6g). 22 The relationship between neuronal Nogo-A upregulation, ER stress and neuronal cell death was then analyzed by double immunofluorescence stainings for Nogo-A and CHOP/ GADD153 or the apoptosis marker annexin V, respectively (Figures 3e and f). On 5-day post-axotomy retinal flat-mounts, the large soma-sized RGCs labelled for Nogo-A exhibited a weak or no signal for CHOP/GADD153 (Figure 3e).…”

Abnormal myelination in the spinal cord of PTPα-knockout mice

“…PTPα and F3 form a membrane-spanning co-receptor complex. 7 Given that both neurons and oligodendrocytes express F3, 5,11 we investigated whether these two cell types could also express PTPα. Double-immunofluorescence (IF) labeling was performed on cross sections (Fig.…”

“…Polyclonal antibodies to PTPα, 7 Caspr, 11 and monoclonal antibodies to sodium channels (PAN) (Sigma), were used. Secondary antibodies included goat anti-rabbit IgG (Amersham), goat anti-mouse IgG (Amersham), Cy3-conjugated anti-rabbit IgG (Amersham), and Cy2-conjugated anti-mouse IgG (Amersham).…”

Amyloid precursor protein at node of Ranvier modulates nodal formation

“…Antibodies, peptides, inhibitors, and activators Rabbit polyclonal antibodies against Caspr 43 and monoclonal antibodies against Tenascin-R (596, 619) 44 and Rabbit polyclonal antibodies against APP [15][16][17] were generously from Dr Dennis Selkoe (Harvard University; C7 and C9). Monoclonal antibodies against pan-sodium channel (Sigma), potassium channels Kv1.2 (K14/16), Kvb2 (Upstate), and NF200 (Sigma) were obtained from the respective commercial sources…”

“…These results support the notion that nodal accumulation of APP requires the integrity of distinct axonal domains, as is the case for other compartmentalized axonal proteins. 43 APP deficiency increases the length of NORs Structural maturation of NORs is essential for saltatory conduction, which is completed during the late phase of myelination. [21][22][23] To define whether APP may play a regulatory role in nodal formation, we analyzed nodal structures in the spinal cord of APP KO as well as their WT mice.…”