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Abstract 20669: LRRC10 and Dilated Cardiomyopathy-Associated I195T LRRC10 Mutation Differentially Regulate Cav1.2 L-Type Ca2+ Channels
Leucine-rich repeat containing protein 10 (LRRC10) is a cardiac-specific protein and loss of LRRC10 in LRRC10 mice results in dilated cardiomyopathy (DCM). Here we describe a novel mutation in human LRRC10, I195T, associated with early onset DCM. However, the mechanism by which LRRC10 and mutations...
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Published in: | Circulation (New York, N.Y.) N.Y.), 2016-11, Vol.134 (Suppl_1 Suppl 1), p.A20669-A20669 |
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Main Authors: | , , , , , , , , , |
Format: | Article |
Language: | English |
Online Access: | Get full text |
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Summary: | Leucine-rich repeat containing protein 10 (LRRC10) is a cardiac-specific protein and loss of LRRC10 in LRRC10 mice results in dilated cardiomyopathy (DCM). Here we describe a novel mutation in human LRRC10, I195T, associated with early onset DCM. However, the mechanism by which LRRC10 and mutations in LRRC10 contribute to DCM remains unknown. Because LRRC10 hearts exhibit defective contractility and LRRC10 is localized to the dyad, we tested the hypothesis that LRRC10 interacts with and regulates Cav1.2 channels. We performed whole-cell patch clamp electrophysiology on isolated ventricular myocytes from wild-type (WT) and LRRC10 mice. The L-type Ca currents (ICa,L) was significantly decreased in LRRC10 myocytes (-4.9 ± 0.22 pA/pF, N=10; 7 mice) compared to wild-type (-7.7 ± 0.72 pA/pF, N=5; 4 mice). The voltage dependence of current activation and inactivation, however, were not significantly different between LRRC10 and WT. Western blot experiments using heart lysates from LRRC10 and WT showed no significant difference in the expression of the Cav1.2 L-type Ca channel protein. Co-immunoprecipitation experiments using WT heart lysates revealed an association between LRRC10 and the Cav1.2 channel subunit. To determine whether LRRC10 or I195T mutation modulates Cav1.2 L-type Ca channels, additional whole-cell patch clamp electrophysiology and biochemistry experiments were performed using HEK293 cells transiently transfected with the L-type Ca channel complex (Cav1.2, β2CN2, α2δ subunits) alone or with WT or I195T LRRC10. Electrophysiology studies showed an increase in ICa,L with WT LRRC10 coexpression (-81 ± 5.3 pA/pF, N=12), but a decrease in ICa,Lwith I195T LRRC10 coexpression (-18.2 ± 3.3 pA/pF, N=9) compared to control (-34.1 ± 2.2 pA/pF, N=17) at 0mV. Surface biotinylation experiments using lysates prepared from transiently transfected HEK293 cells revealed that neither the WT nor I195T LRRC10 altered the expression of L-type Ca channels on the plasma membrane. Taken together, these findings identify a role for LRRC10 in the regulation of cardiac L-type Ca channels and that mutations in the LRR motif of LRRC10 can directly impact L-type Ca channel function possibly contributing to the development of DCM. |
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ISSN: | 0009-7322 1524-4539 |