Brito, G. | bioRxiv Science

bioRxiv2024

Myogenic dedifferentiation involves a p53-dependent reorganization of PLK4 localization during centrosome regeneration

Multinucleated skeletal muscle cells are stably withdrawn from the cell cycle in most vertebrates. Muscle dedifferentiation is however naturally occurring during limb regeneration in newts and can be artificially induced in mammalian myotubes. Dedifferentiation involves fragmentation of myofibers and myotubes into mononucleate cells which subsequently reenter the cell cycle, and give rise to proliferative progeny. Here we addressed the dynamics of centrosomes, which are key organelles for cell proliferation during myogenic differentiation and dedifferentiation. We show that, in contrast to their mammalian counterparts, newt muscle cells retain centrosomes during differentiation and demonstrate that regeneration of centrosomes in dedifferentiated mouse muscle cells depends on inhibition of the tumor suppressor p53. We also find that regulation of the subcellular localization of Polo-Like Kinase 4 rather than its expression level is a hallmark of myogenic differentiation and dedifferentiation, identifying a novel cellular process underlying the plasticity of the differentiated state.

developmental biology↗

bioRxiv2020

BRET sensors unravel that Plasmodium falciparum serpentine receptor 12 (PfSR12) increases surface expression of mammalian GPCRs in HEK293 cells

Considered a significant public health issue, the growing resistance to conventional antimalarials necessitates the identification of new targets for drug development. Given that G protein-coupled receptors (GPCRs) are readily druggable targets, we explored the cellular role and potential structure of a GPCR-like protein identified in the P. falciparum genome, serpentine receptor 12 (SR12). Alphafold structure analysis, coupled with molecular dynamics simulations of SR12, revealed structural similarities to the Golgi dynamics domain (GOLD)-seven-transmembrane helix protein family (GOST proteins). This family of proteins, which includes TMEM87A and the orphan GPCRs GPR180, GPR107, and GPR108, is involved in subcellular trafficking. Consistent with such a trafficking role, SR12 is mainly present in the secretory pathway when expressed in mammalian cells. Co-expression of SR12 with GPCRs PAR1 and M3R led to increased plasma membrane targeting of these receptors. SR12 expression in HEK293 cells conferred Gq-dependent calcium signaling in response to the protease activated receptor 1 (PAR1) agonist thrombin. This response was completely abrogated in cells genetically devoid of PARs (PAR KO cells), consistent with its functions as a chaperone-like protein, promoting receptor trafficking to the plasma membrane. Taken together, the data show that the Plasmodium falciparum SR12 promotes GPCR trafficking when expressed in mammalian cells. Although the physiological consequences of such activity remain to be determined, the finding revealed the presence of a GOST protein in the parasite genome.

cell biology↗