| First Author | Gillet L | Year | 2015 |
| Journal | Heart Rhythm | Volume | 12 |
| Issue | 1 | Pages | 181-92 |
| PubMed ID | 25447080 | Mgi Jnum | J:237676 |
| Mgi Id | MGI:5816439 | Doi | 10.1016/j.hrthm.2014.09.057 |
| Citation | Gillet L, et al. (2015) Cardiac-specific ablation of synapse-associated protein SAP97 in mice decreases potassium currents but not sodium current. Heart Rhythm 12(1):181-92 |
| abstractText | BACKGROUND: Membrane-associated guanylate kinase (MAGUK) proteins are important determinants of ion channel organization in the plasma membrane. In the heart, the MAGUK protein SAP97, encoded by the DLG1 gene, interacts with several ion channels via their PDZ domain-binding motif and regulates their function and localization. OBJECTIVE: The purpose of this study was to assess in vivo the role of SAP97 in the heart by generating a genetically modified mouse model in which SAP97 is suppressed exclusively in cardiomyocytes. METHODS: SAP97(fl/fl) mice were generated by inserting loxP sequences flanking exons 1-3 of the SAP97 gene. SAP97(fl/fl) mice were crossed with alphaMHC-Cre mice to generate alphaMHC-Cre/SAP97(fl/fl) mice, thus resulting in a cardiomyocyte-specific deletion of SAP97. Quantitative reverse transcriptase-polymerase chain reaction, western blots, and immunostaining were performed to measure mRNA and protein expression levels, and ion channel localization. The patch-clamp technique was used to record ion currents and action potentials. Echocardiography and surface ECGs were performed on anesthetized mice. RESULTS: Action potential duration was greatly prolonged in alphaMHC-Cre/SAP97(fl/fl) cardiomyocytes compared to SAP97(fl/fl) controls, but maximal upstroke velocity was unchanged. This was consistent with the decreases observed in IK1, Ito, and IKur potassium currents and the absence of effect on the sodium current INa. Surface ECG revealed an increased corrected QT interval in alphaMHC-Cre/SAP97(fl/fl) mice. CONCLUSION: These data suggest that ablation of SAP97 in the mouse heart mainly alters potassium channel function. Based on the important role of SAP97 in regulating the QT interval, DLG1 may be a susceptibility gene to be investigated in patients with congenital long QT syndrome. |
