Abstract Body: Background: The centrosome regulates cell division, architecture, and function during development and homeostasis. In proliferating cells, the centrosome organizes mitotic spindles to ensure accurate division, whereas in differentiated cells it adopts noncanonical, tissue-specific functions. Mammalian cardiomyocytes (CMs) lose their dividing capacity as the heart progresses from fetal development to postnatal maturation. However, the role of centrosome dynamics in CM maturation remains poorly understood.
Aim: To define how centrosome remodeling links microtubule organization to CM maturation.
Methods and Results: Using developing mouse hearts and human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs), we investigated centrosome remodeling through imaging, functional assays, and single-cell RNA sequencing. Following differentiation, the centrosome disassembles, with its pericentriolar matrix (PCM) components translocating stepwise to the nuclear envelope. While the centrosome functions as the primary microtubule-organizing center (MTOC) in proliferating CMs, microtubule nucleation shifts to the nuclear envelope, establishing perinuclear non-centrosomal MTOCs in maturing CMs. Depletion of PCM1, a key PCM component, disrupts this process, leading to reduced perinuclear microtubules, impaired nuclear envelope-anchored MTOC formation. Functionally, PCM1 deficiency compromises sarcomere organization, contractility, and mitochondrial dynamics, ultimately impairing structural maturation of CMs.
Single-cell RNA sequencing of PCM1-knockout maturing CMs reveals downregulation of genes involved in muscle contraction, calcium handling, and microtubule-based transport, alongside enrichment of mitochondrial and translational pathways. SCENIC analysis further demonstrates that WT CMs maintain developmental, mechanosensitive, and nuclear receptor-driven transcriptional networks, whereas PCM1-deficient CMs shift toward an HBP1-associated restrictive state with reduced transcriptional plasticity and downregulation of genes associated with cardiomyocyte maturation.
Consistently, microtubule disruption by nocodazole reduces sarcomere assembly and induces mitochondrial fragmentation, resulting in defective maturation and partially recapitulating PCM1-deficient phenotypes.
Conclusions: These findings identify centrosome remodeling as a key mechanism coordinating microtubule organization with structural and mitochondrial maturation to drive cardiomyocyte maturation.