Calreticulin reveals a critical Ca2+ checkpoint in cardiac myofibrillogenesis

Jian Li, Michel Pucéat, Carmen M Terzic, Annabelle Mery, Kimitoshi Nakamura, Marek Michalak, Karl Heinz Krause, Marisa E. Jaconi

Research output: Contribution to journalArticle

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Abstract

Calreticulin (crt) is an ubiquitously expressed and multifunctional Ca2+-binding protein that regulates diverse vital cell functions, including Ca2+ storage in the ER and protein folding. Calreticulin deficiency in mice is lethal in utero due to defects in heart development and function. Herein, we used crt-/- embryonic stem (ES) cells differentiated in vitro into cardiac cells to investigate the molecular mechanisms underlying heart failure of knockout embryos. After 8 d of differentiation, beating areas were prominent in ES-derived wild-type (wt) embryoid bodies (EBs), but not in ES-derived crt-/- EBs, despite normal expression levels of cardiac transcription factors. Crt-/- EBs exhibited a severe decrease in expression and a lack of phosphorylation of ventricular myosin light chain 2 (MLC2v), resulting in an impaired organization of myofibrils. Crt-/- phenotype could be recreated in wt cells by chelating extracellular or cytoplasmic Ca2+ with EGTA or BAPTA, or by inhibiting Ca2+/calmodulin-dependent kinases (CaMKs). An imposed ionomycin-triggered cystolicfree Ca2+ concentration ([Ca2+]c) elevation restored the expression, phosphorylation, and insertion of MLC2v into sarcomeric structures and in turn the myofibrillogenesis. The transcription factor myocyte enhancer factor C2 failed to accumulate into nuclei of crt-/- cardiac cells in the absence of ionomycin-triggered [Ca2+]c increase. We conclude that the absence of calreticulin interferes with myofibril formation. Most importantly, calreticulin deficiency revealed the importance of a Ca2+-dependent checkpoint critical for early events during cardiac myofibrillogenesis.

Original languageEnglish (US)
Pages (from-to)103-113
Number of pages11
JournalJournal of Cell Biology
Volume158
Issue number1
DOIs
StatePublished - Jul 8 2002

Fingerprint

Calreticulin
Muscle Development
Embryoid Bodies
Ionomycin
Myofibrils
Transcription Factors
Phosphorylation
Ventricular Myosins
Calcium-Calmodulin-Dependent Protein Kinases
Egtazic Acid
Protein Folding
Embryonic Stem Cells
Muscle Cells
Carrier Proteins
Embryonic Structures
Heart Failure
Phenotype

Keywords

  • Ca
  • Calreticulin
  • Cardiac myofibrillogenesis
  • Embryonic stem cells
  • MEF2C

ASJC Scopus subject areas

  • Cell Biology

Cite this

Li, J., Pucéat, M., Terzic, C. M., Mery, A., Nakamura, K., Michalak, M., ... Jaconi, M. E. (2002). Calreticulin reveals a critical Ca2+ checkpoint in cardiac myofibrillogenesis. Journal of Cell Biology, 158(1), 103-113. https://doi.org/10.1083/jcb.200204092

Calreticulin reveals a critical Ca2+ checkpoint in cardiac myofibrillogenesis. / Li, Jian; Pucéat, Michel; Terzic, Carmen M; Mery, Annabelle; Nakamura, Kimitoshi; Michalak, Marek; Krause, Karl Heinz; Jaconi, Marisa E.

In: Journal of Cell Biology, Vol. 158, No. 1, 08.07.2002, p. 103-113.

Research output: Contribution to journalArticle

Li, J, Pucéat, M, Terzic, CM, Mery, A, Nakamura, K, Michalak, M, Krause, KH & Jaconi, ME 2002, 'Calreticulin reveals a critical Ca2+ checkpoint in cardiac myofibrillogenesis', Journal of Cell Biology, vol. 158, no. 1, pp. 103-113. https://doi.org/10.1083/jcb.200204092
Li, Jian ; Pucéat, Michel ; Terzic, Carmen M ; Mery, Annabelle ; Nakamura, Kimitoshi ; Michalak, Marek ; Krause, Karl Heinz ; Jaconi, Marisa E. / Calreticulin reveals a critical Ca2+ checkpoint in cardiac myofibrillogenesis. In: Journal of Cell Biology. 2002 ; Vol. 158, No. 1. pp. 103-113.
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