TY - JOUR
T1 - Variability of distribution of Ca2+/calmodulin-dependent kinase II at mixed synapses on the mauthner cell
T2 - Colocalization and association with connexin 35
AU - Flores, Carmen E.
AU - Cachope, Roger
AU - Nannapaneni, Srikant
AU - Ene, Smaranda
AU - Nairn, Angus C.
AU - Pereda, Alberto E.
PY - 2010/7/14
Y1 - 2010/7/14
N2 - In contrast to chemical transmission, few proteins have been shown associated with gap junction-mediated electrical synapses. Mixed (electrical and glutamatergic) synaptic terminals on the teleost Mauthner cell known as "Club endings" constitute because of their unusual large size and presence of connexin 35 (Cx35), an ortholog of the widespread mammalian Cx36, a valuable model for the study of electrical transmission. Remarkably, both components of their mixed synaptic response undergo activity-dependent potentiation. Changes in electrical transmission result from interactions with colocalized glutamatergic synapses, the activity of which leads to the activation of Ca2+/calmodulin-dependent kinase II (CaMKII), required for the induction of changes in both forms of transmission. However, the distribution of this kinase and potential localization to electrical synapses remains undetermined. Taking advantage of the unparalleled experimental accessibility of Club endings, we explored the presence and intraterminal distribution of CaMKII within these terminals. Here we show that (1) unlike other proteins, both CaMKII labeling and distribution were highly variable between contiguous contacts, and (2) CaMKII was not restricted to the periphery of the terminals, in which glutamatergic synapses are located, but also was present at the center in which gap junctions predominate. Accordingly, double immunolabeling indicated that Cx35 and CaMKII were colocalized, and biochemical analysis showed that these proteins associate. Because CaMKII characteristically undergoes activitydependent translocation, the observed variability of labeling likely reflects physiological differences between electrical synapses of contiguous Club endings, which remarkably coexist with differing degrees of conductance. Together, our results indicate that CaMKII should be considered a component of electrical synapses, although its association is nonobligatory and likely driven by activity. Copyright
AB - In contrast to chemical transmission, few proteins have been shown associated with gap junction-mediated electrical synapses. Mixed (electrical and glutamatergic) synaptic terminals on the teleost Mauthner cell known as "Club endings" constitute because of their unusual large size and presence of connexin 35 (Cx35), an ortholog of the widespread mammalian Cx36, a valuable model for the study of electrical transmission. Remarkably, both components of their mixed synaptic response undergo activity-dependent potentiation. Changes in electrical transmission result from interactions with colocalized glutamatergic synapses, the activity of which leads to the activation of Ca2+/calmodulin-dependent kinase II (CaMKII), required for the induction of changes in both forms of transmission. However, the distribution of this kinase and potential localization to electrical synapses remains undetermined. Taking advantage of the unparalleled experimental accessibility of Club endings, we explored the presence and intraterminal distribution of CaMKII within these terminals. Here we show that (1) unlike other proteins, both CaMKII labeling and distribution were highly variable between contiguous contacts, and (2) CaMKII was not restricted to the periphery of the terminals, in which glutamatergic synapses are located, but also was present at the center in which gap junctions predominate. Accordingly, double immunolabeling indicated that Cx35 and CaMKII were colocalized, and biochemical analysis showed that these proteins associate. Because CaMKII characteristically undergoes activitydependent translocation, the observed variability of labeling likely reflects physiological differences between electrical synapses of contiguous Club endings, which remarkably coexist with differing degrees of conductance. Together, our results indicate that CaMKII should be considered a component of electrical synapses, although its association is nonobligatory and likely driven by activity. Copyright
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U2 - 10.1523/JNEUROSCI.4466-09.2010
DO - 10.1523/JNEUROSCI.4466-09.2010
M3 - Article
C2 - 20631177
AN - SCOPUS:77954724789
SN - 0270-6474
VL - 30
SP - 9488
EP - 9499
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 28
ER -