MBNL1 regulates programmed postnatal switching between regenerative and differentiated cardiac states.

Bailey, L. R. J.; Bugg, D.; Reichardt, I. M.; Ortac, C. D.; Gunaje, J.; Johnson, R.; MacCoss, M. J.; Sakamoto, T.; Kelly, D. P.; Regnier, M.; Davis, J. M.

doi:10.1101/2023.03.16.532974

bioRxiv · 10.1101/2023.03.16.532974

MBNL1 regulates programmed postnatal switching between regenerative and differentiated cardiac states.

Bailey, L. R. J.·Bugg, D.·Reichardt, I. M.·Ortac, C. D.·Gunaje, J.·Johnson, R.·MacCoss, M. J.·Sakamoto, T.·Kelly, D. P.·Regnier, M.·Davis, J. M.

View original source ↗Export metadata ↓

Abstract

Discovering determinants of cardiomyocyte maturity and the maintenance of differentiated states is critical to both understanding development and potentially reawakening endogenous regenerative programs in adult mammalian hearts as a therapeutic strategy. Here, the RNA binding protein Muscleblind-like 1 (MBNL1) was identified as a critical regulator of cardiomyocyte differentiated states and their regenerative potential through transcriptome-wide control of RNA stability. Targeted MBNL1 overexpression early in development prematurely transitioned cardiomyocytes to hypertrophic growth, hypoplasia, and dysfunction, whereas loss of MBNL1 function increased cardiomyocyte cell cycle entry and proliferation through altered cell cycle inhibitor transcript stability. Moreover, MBNL1-dependent stabilization of the estrogen-related receptor signaling axis was essential for maintaining cardiomyocyte maturity. In accordance with these data, modulating MBNL1 dose tuned the temporal window of cardiac regeneration, where enhanced MBNL1 activity arrested myocyte proliferation, and MBNL1 deletion promoted regenerative states with prolonged myocyte proliferation. Collectively these data suggest MBNL1 acts as a transcriptome-wide switch between regenerative and mature myocyte states postnatally and throughout adulthood.

Source connections

Published article ↗

Explore related subjects

cell biology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Bailey, L. R. J., Bugg, D., Reichardt, I. M., Ortac, C. D., Gunaje, J., Johnson, R., MacCoss, M. J., Sakamoto, T., Kelly, D. P., Regnier, M., Davis, J. M.. 2023-03-16. MBNL1 regulates programmed postnatal switching between regenerative and differentiated cardiac states.. https://doi.org/10.1101/2023.03.16.532974

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

High-content screening identifies FDA-approved activators of mitophagy

Mitochondrial diseases are highly heterogeneous disorders caused by defects in oxidative phosphorylation, for which only limited therapeutic options are available. The elimination of dysfunctional mitochondria via mitophagy activation is an attractive strategy to treat several mitochondrial diseases, irrespective of the underlying genetic defect. To identify pharmacological activators of this pathway, we performed a high-content screening of 1,971 FDA-approved compounds using cellular reporters of TFEB nuclear translocation and mitophagy. This screening identified 294 compounds that promoted TFEB translocation, nine of which increased the number of mitolysosomes without compromising cell viability or damaging mitochondria. Among the selected compounds, Meptazinol and Ponatinib emerged as the top-ranked mitophagy inducers in fibroblasts from patients with complex I and IV deficiency, respectively, and were prioritised for further characterisation. However, they did not rescue the bioenergetic defect, suggesting that the stimulation of mitophagy per se is not sufficient to ameliorate the OXPHOS defect in mitochondrial diseases. Overall, our findings establish a scalable platform for the identification of pharmacological activators of TFEB and identify candidate compounds for therapeutic modulation of mitophagy.

cell biology↗

bioRxiv2026

A LOV-domain photoreceptor mediates phototaxis in brown algae

Phototaxis enables motile cells to navigate light environments and plays a critical role in survival and reproduction across diverse eukaryotic lineages. This ability has evolved independently through distinct photoreceptor systems. Yet, the molecular mechanisms underlying phototaxis remain poorly understood in many major eukaryotic lineages, including stramenopiles. Here, combining functional genetics, cell biology and evolutionary analyses, we identify Helmchrome (HELM), a LOV-domain protein required for phototaxis in the brown alga Ectocarpus. HELM localizes to the posterior flagellum and is responsible for the characteristic flavin-associated fluorescence of brown algal gametes. Loss of HELM abolishes phototactic accumulation and directional orientation without affecting basal motility or fertilization, demonstrating its specific requirement for light-directed movement. Phylogenetic analyses reveal that HELM-like proteins are distributed across diverse stramenopile lineages and that their domain architecture evolved through repeated duplication of an ancestral RGS-LOV module. Our findings identify HELM as a key component of the light-sensing machinery in brown algae, provide a molecular explanation for the long-standing observation of flagellar flavin fluorescence, and reveal a distinct phototaxis system that expands the known diversity of eukaryotic light-sensing mechanisms.

cell biology↗

bioRxiv2026

A distinct chondrogenic progenitor population from human umbilical cord derived mesenchymal stromal cells for osteoarthritis therapy

Stem cell-based cartilage regeneration remains constrained by functional heterogeneity and phenotypic drift in conventional cell sources, compromising durable structural repair. Human umbilical cord-derived mesenchymal stromal cells (UC-MSCs) represent an accessible, off-the-shelf cell source; however, their broad clinical utility is hampered by cellular heterogeneity, leaving the key chondrogenic subpopulation responsible for cartilage repair unresolved. By integrating single-cell transcriptomics with functional assays, we identified and prospectively isolated a distinct, highly expandable subpopulation of skeletal stem cell-like progenitors (U-CPCs) from the human umbilical cord, establishing an extra-skeletal cell source uniquely primed for joint restoration. Single-cell transcriptomics reveal their inherent regulatory landscape, uncovering a distinct transcriptional state uniquely primed for chondrogenesis. In comparison with conventional stem cells and other tissue-derived SSC-like populations (from umbilical cord, bone marrow, adipose tissue, and dental pulp), U-CPCs exhibit a markedly enhanced chondrogenic capacity. In both a mouse cartilage injury model and a rat osteoarthritis model, the administration of U-CPCs effectively mitigates joint degeneration and drives the restoration of a structurally sound, hyaline-like matrix. Mechanistically, U-CPCs secrete extracellular vesicles enriched with microRNA Let-7a-5p, which specifically modulates DUSP7/MAPK/ERK signaling in recipient chondrocytes, thereby restoring extracellular matrix homeostasis and promoting cartilage repair. By characterizing these specialized extra-skeletal progenitors and elucidating both their intrinsic chondrogenic priming and paracrine regulation of host tissue, this study establishes U-CPCs as a robust, lineage-restricted cellular source for osteoarthritis therapy.

cell biology↗