Abstract 4370058: Dynamic organization of the centrosome regulates cardiomyocyte division and maturation

Introduction: The centrosome is a key regulator of cell division, structure, and function. While it acts as the microtubule-organizing center (MTOC) in proliferating cells, differentiated cells often repurpose it for tissue-specific roles. In cardiomyocytes (CMs), the loss of proliferative capacity after birth is well established, but how centrosome remodeling contributes to CM division and maturation is not well understood. Hypothesis: We hypothesize that centrosome structural dynamics—specifically, the disassembly and relocalization of pericentriolar material (PCM) components—regulate the balance between CM division and maturation. Aims: This study aims to define centrosome reorganization during CM development, assess PCM remodeling outcomes, and identify upstream regulators of centrosome disassembly. Approach: We utilized developing mouse hearts and human iPSC-derived CMs to track the centrosome throughout differentiation. CRISPR-Cas9 was used to deplete PCM1 and PCNT. Immunofluorescence, live imaging, and functional assays were used to assess centrosome positioning, sarcomere structure, microtubules, and mitochondria. Single-cell transcriptomics profiled gene expression during remodeling and maturation. Results: Upon CM differentiation, centrosomes disassemble in a stepwise manner, with PCM1 relocating to the nuclear envelope before PCNT. This relocalization shifts MTOC activity to the nuclear periphery. Depletion of key PCM components, PCM1 or PCNT, disrupts sarcomere organization, impairs contractility, and alters mitochondrial dynamics. Single-cell transcriptomic analysis revealed that PCM inactivation leads to impaired transcriptional maturation of CMs, reinforcing the importance of centrosome remodeling in coordinating structural and molecular aspects of CM development. These results suggest that PCM1 translocation is essential for establishing a nuclear envelope-centered microtubule scaffold that supports sarcomere organization and promotes cardiomyocyte maturation. Conclusion: Centrosome remodeling, via PCM translocation to the nuclear envelope, regulates the transition from CM division to maturation. PCM1 plays a central role in this process by establishing a perinuclear microtubule network that facilitates sarcomere assembly. Together, these findings highlight the importance of centrosome structural dynamics in suppressing mitotic apparatus formation and enabling cardiomyocyte maturation via a nuclear envelope-anchored cytoskeletal architecture.