Effect of A618T and S619L dynamin-2 mutants in bovine chromaffin cells

LUCAS BAYONÉS; MARÍA JOSÉ GUERRA; XIMENA BAEZ MATUS ; FERNANDO D. MARENGO; ANA MARÍA CÁRDENAS

Chicago

Congreso; Neuroscience 2019; 2019

Society for Neuroscience

Effect of A618T and S619L dynamin-2 mutants in bovine chromaffin cells Lucas Bayonés, María José Guerra, Ximena Baéz-Matus, Fernando D. Marengo and Ana María CárdenasMutations in dynamin-2 (Dyn2) protein can cause rare diseases such as neuropathies and myopathies. In this work we studied two different mutations in Dyn2 (A618T and S619L) which exhibit gain-of-function and cause a severe neonatal phenotype. Our results obtained from amperometric recordings in chromaffin cells showed that in comparison with wild-type (WT) Dyn2 transfected cells, the mutants A618T or S619L decreased significantly the amount of exocytotic events (WT: 16.3±2.5, n= 77; A618T: 7.2±1.8, n= 61; S619L: 7.4±1.4, n=62) obtained during 2 min after stimulation with the nicotinic agonist DMPP (50 µM, 10 s). Consistently with these results, we also observed a reduction of the exocytosis measured by cell capacitance in both mutants respect to WT Dyn2. Analyses of amperometric spike parameters that provide information on the properties of the individual exocytotic events, such as spike amplitude, quantal size, time to peak and half-time, showed no statistical difference between the Dyn2 mutations A618T and S619L and WT Dyn2. However, analyses of durations of ?foot signals?, a small current that precedes the amperometric spike and reflects the flux of transmitters through the fusion pore, indicate that the both Dyn2 mutants significantly reduced foot durations (τwt: 13.9±0.2ms, n=43; τA618T: 10.9±0.3ms, n=24; τS619L: 10.9±0.2ms, n=29; p