RT Journal Article
SR Electronic
T1 Impaired Inactivation Gate Stabilization Predicts Increased Persistent Current for an Epilepsy-Associated <em>SCN1A</em> Mutation
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 10958
OP 10966
DO 10.1523/JNEUROSCI.3378-06.2006
VO 26
IS 43
A1 Kahlig, Kristopher M.
A1 Misra, Sunita N.
A1 George, Alfred L.
YR 2006
UL http://www.jneurosci.org/content/26/43/10958.abstract
AB Mutations in SCN1A (encoding the neuronal voltage-gated sodium channel α1 subunit, NaV1.1, or SCN1A) are associated with genetic epilepsy syndromes including generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy of infancy. Here, we present the formulation and use of a computational model for SCN1A to elucidate molecular mechanisms underlying the increased persistent sodium current exhibited by the GEFS+ mutant R1648H. Our model accurately reproduces all experimentally measured SCN1A whole-cell biophysical properties including biphasic whole-cell current decay, channel activation, and entry into and recovery from fast and slow inactivation. The model predicts that SCN1A open-state inactivation results from a two-step process that can be conceptualized as initial gate closure, followed by recruitment of a mechanism (“latch”) to stabilize the inactivated state. Selective impairment of the second latching step results in an increase in whole-cell persistent current similar to that observed for the GEFS+ mutant R1648H. These results provide a deeper level of understanding of mutant SCN1A dysfunction in an inherited epilepsy syndrome, which will enable more precise computational studies of abnormal neuronal activity in epilepsy and may help guide new targeted therapeutic strategies.