Modulation of mammalian cardiomyocyte cytokinesis by extracellular matrix proteins
Presented by: Chi-Chung Wu
Presentation time:
Cardiomyocyte polyploidy (multinucleation and/or polyploid nucleus) is observed in many mammalian species and has been shown to limit the regenerative potential of the heart. Shortly after birth, rodent cardiomyocytes become binucleated due to cytokinesis defects, and they exit the cell cycle. Cardiomyocyte binucleation is correlated with extensive changes in the cellular and structural composition of the postnatal heart, including the number of cardiac fibroblasts (cFbs) and the composition of extracellular matrix (ECM).
To investigate how these changes modulate cardiomyocyte cytokinesis, we used primary postnatal cardiomyocyte cultures as a model. Combining various co-culture and cell-derived ECM approaches, our previous work showed that 1) postnatal cFbs promote cardiomyocyte binucleation via ECM modulation, and 2) postnatal, but not embryonic, cFb-derived ECM provides a non-permissive environment for cardiomyocyte cytokinesis. Quantitative proteomic analysis and functional assessment further identified multiple ECM proteins that promote or inhibit cardiomyocyte cytokinesis.
One of the identified targets, SLIT2, plays crucial roles in axon guidance and embryonic heart development, but has not been implicated in postnatal heart growth. We found that Slit2, Slit3, and their receptor Robo1 are expressed in a subset of cardiomyocytes in the early postnatal heart, and that their expression is enriched in the mononuclear population at P7. Functionally, knockdown of Slit2 or Slit3 significantly inhibited cardiomyocyte cytokinesis in vitro while injection of SLIT2 recombinant protein was sufficient to promote cardiomyocyte cytokinesis in postnatal mice. Through mass spec analysis, we found that treating primary cardiomyocytes with SLIT2 recombinant protein induced the levels of LIS1 and TBC1D15, which have been shown to be critical for furrow ingression and successful cytokinesis.
Altogether, we found that SLIT factors are required for cardiomyocyte cytokinesis, which further support a key role for the cardiac ECM in heart development and regeneration.
To investigate how these changes modulate cardiomyocyte cytokinesis, we used primary postnatal cardiomyocyte cultures as a model. Combining various co-culture and cell-derived ECM approaches, our previous work showed that 1) postnatal cFbs promote cardiomyocyte binucleation via ECM modulation, and 2) postnatal, but not embryonic, cFb-derived ECM provides a non-permissive environment for cardiomyocyte cytokinesis. Quantitative proteomic analysis and functional assessment further identified multiple ECM proteins that promote or inhibit cardiomyocyte cytokinesis.
One of the identified targets, SLIT2, plays crucial roles in axon guidance and embryonic heart development, but has not been implicated in postnatal heart growth. We found that Slit2, Slit3, and their receptor Robo1 are expressed in a subset of cardiomyocytes in the early postnatal heart, and that their expression is enriched in the mononuclear population at P7. Functionally, knockdown of Slit2 or Slit3 significantly inhibited cardiomyocyte cytokinesis in vitro while injection of SLIT2 recombinant protein was sufficient to promote cardiomyocyte cytokinesis in postnatal mice. Through mass spec analysis, we found that treating primary cardiomyocytes with SLIT2 recombinant protein induced the levels of LIS1 and TBC1D15, which have been shown to be critical for furrow ingression and successful cytokinesis.
Altogether, we found that SLIT factors are required for cardiomyocyte cytokinesis, which further support a key role for the cardiac ECM in heart development and regeneration.