Amphiphysin (BIN1) negatively regulates dynamin 2 for normal muscle maturation
Belinda S. Cowling, … , Aurélien Roux, Jocelyn Laporte
Belinda S. Cowling, … , Aurélien Roux, Jocelyn Laporte
Published December 1, 2017; First published November 13, 2017
Citation Information: J Clin Invest. 2017;127(12):4477-4487. https://doi.org/10.1172/JCI90542.
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Categories: Research Article Muscle biology

Amphiphysin (BIN1) negatively regulates dynamin 2 for normal muscle maturation

Abstract

Regulation of skeletal muscle development and organization is a complex process that is not fully understood. Here, we focused on amphiphysin 2 (BIN1, also known as bridging integrator-1) and dynamin 2 (DNM2), two ubiquitous proteins implicated in membrane remodeling and mutated in centronuclear myopathies (CNMs). We generated Bin1–/– Dnm2+/– mice to decipher the physiological interplay between BIN1 and DNM2. While Bin1–/– mice die perinatally from a skeletal muscle defect, Bin1–/– Dnm2+/– mice survived at least 18 months, and had normal muscle force and intracellular organization of muscle fibers, supporting BIN1 as a negative regulator of DNM2. We next characterized muscle-specific isoforms of BIN1 and DNM2. While BIN1 colocalized with and partially inhibited DNM2 activity during muscle maturation, BIN1 had no effect on the isoform of DNM2 found in adult muscle. Together, these results indicate that BIN1 and DNM2 regulate muscle development and organization, function through a common pathway, and define BIN1 as a negative regulator of DNM2 in vitro and in vivo during muscle maturation. Our data suggest that DNM2 modulation has potential as a therapeutic approach for patients with CNM and BIN1 defects. As BIN1 is implicated in cancers, arrhythmia, and late-onset Alzheimer disease, these findings may trigger research directions and therapeutic development for these common diseases.

Authors

Belinda S. Cowling, Ivana Prokic, Hichem Tasfaout, Aymen Rabai, Frédéric Humbert, Bruno Rinaldi, Anne-Sophie Nicot, Christine Kretz, Sylvie Friant, Aurélien Roux, Jocelyn Laporte

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Figure 1

Dnm2 downregulation rescues the neonatal lethality of Bin1–/– mice.

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Dnm2 downregulation rescues the neonatal lethality of Bin1–/– mice. (A) ...
(A) Targeted disruption of mouse Bin1 gene. Exon 20 (blue) and surrounding intronic region (orange). (B) Overview of lifespan and time points used to analyze Bin1–/– Dnm2+/– mice. (C) Mice whole-body weight, and representative photo of mice at 12 months of age. Note that all genotyped Bin1–/– Dnm2+/– mice survived beyond 12 months of age. (D) Immunoblot analysis of DNM2 and BIN1 protein expression from muscle lysates. (E) Relative level of DNM2 protein expression was determined by densitometry of DNM2 signal standardized to GAPDH. n = 4 mice/genotype. (F) Hanging test where 10-week-old mice were required to hang from a cage lid for up to 60 seconds. (G) Four-paw grip test. (H) Rotarod test performed under acceleration mode (4–40 rpm in 5 minutes). n = 3 trials/mouse/day, 6-month-old mice. (I) Specific muscle force (sPo) of the tibialis anterior (TA) muscle (mN force/mg TA muscle). (J) Fatigue of the TA muscle, measured as the time taken to reach 50% of the maximum muscle force (seconds). All graphs depict the mean ± SEM. Statistical analysis was performed using an unpaired 2-tailed Student’s t test for all graphs except H, where a 2-way ANOVA followed by Dunn’s multiple comparison test was used. *P < 0.05, **P < 0.01. n = minimum 5 mice per group for C, F–J.