Resolving titin’s lifecycle and the spatial organization of protein turnover in mouse cardiomyocytes

Franziska Rudolph, Judith Hüttemeister, Katharina da Silva Lopes, René Jüttner, Lily Yu, Nora Bergmann, Dhana Friedrich, Stephan Preibisch, Eva Wagner, Stephan E. Lehnart, Carol C. Gregorio, Michael Gotthardt

Research output: Contribution to journalArticle

Abstract

Cardiac protein homeostasis, sarcomere assembly, and integration of titin as the sarcomeric backbone are tightly regulated to facilitate adaptation and repair. Very little is known on how the >3-MDa titin protein is synthesized, moved, inserted into sarcomeres, detached, and degraded. Here, we generated a bifluorescently labeled knockin mouse to simultaneously visualize both ends of the molecule and follow titin’s life cycle in vivo. We find titin mRNA, protein synthesis and degradation compartmentalized toward the Z-disk in adult, but not embryonic cardiomyocytes. Originating at the Z-disk, titin contributes to a soluble protein pool (>15% of total titin) before it is integrated into the sarcomere lattice. Titin integration, disintegration, and reintegration are stochastic and do not proceed sequentially from Z-disk to M-band, as suggested previously. Exchange between soluble and integrated titin depends on titin protein composition and differs between individual cardiomyocytes. Thus, titin dynamics facilitate embryonic vs. adult sarcomere remodeling with implications for cardiac development and disease.

Original languageEnglish (US)
Pages (from-to)25126-25136
Number of pages11
JournalProceedings of the National Academy of Sciences of the United States of America
Volume116
Issue number50
DOIs
StatePublished - Dec 10 2019

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Keywords

  • Live imaging
  • Proteostasis
  • Sarcomere
  • STED microscopy
  • Titin

ASJC Scopus subject areas

  • General

Cite this

Rudolph, F., Hüttemeister, J., da Silva Lopes, K., Jüttner, R., Yu, L., Bergmann, N., Friedrich, D., Preibisch, S., Wagner, E., Lehnart, S. E., Gregorio, C. C., & Gotthardt, M. (2019). Resolving titin’s lifecycle and the spatial organization of protein turnover in mouse cardiomyocytes. Proceedings of the National Academy of Sciences of the United States of America, 116(50), 25126-25136. https://doi.org/10.1073/pnas.1904385116