Biology subjects

Grana Castro, O.

Publications and source records attributed to Grana Castro, O..

3 recordsLinked to original sources

bioRxiv2020

miR-203 imposes an intrinsic barrier during cellular reprogramming by targeting NFATC2

Cellular reprogramming from somatic to pluripotent cells is the basis for multiple applications aimed to replace damaged tissues in regenerative medicine. However, this process is limited by intrinsic barriers that are induced in response to reprogramming factors. In this manuscript we report that miR-203, a microRNA with multiple functions in differentiation and tumor suppression, acts as an endogenous barrier to reprogramming. Genetic ablation of miR-203 results in enhanced reprogramming whereas its expression prevents the formation of pluripotent cells both in vitro and in vivo. Mechanistically, this effect correlates with the direct repression of NFATC2, a transcription factor involved in the early phases of reprogramming. Inhibition of NFATC2 mimics miR-203 effects whereas NFATC2 overexpression rescues inducible cell pluripotency in miR-203-overexpressing cultures. These data suggest that miR-203 repression may favor the efficiency of reprogramming in a variety of cellular models.

cell biology↗

bioRxiv2020

Lack of adaptation to centriolar defects leads to p53-independent microcephaly in the absence of Cep135

Autosomal Recessive Primary Microcephaly (MCPH) is a rare disease associated to proteins involved in centrosomal and spindle dynamics including Cep135 (MCPH8). Although Cep135 has been associated to centriolar assembly, the mechanisms associated to the pathogenesis underlying MCPH8 mutations are unclear. By using a series of CRISPR/Cas9-edited murine Cep135 alleles, we report here that lack of Cep135 results in perinatal lethality accompanied by significant microcephaly in a dosis-dependent manner. Cep135 deficiency, but not that of other centrosomal microcephaly proteins such as Aspm or Cdk5rap2, induces centrosome duplication defects, and perturbed centriole structure and dynamics. Whereas other cell types are able to quickly adapt to these defects, neural progenitors display a prolonged response leading to chromosomal instability and cell death in later developmental stages. Genetic ablation of Trp53 in these mutant embryos prevents apoptotic cell death but does not rescue the microcephaly induced by Cep135 loss. These results suggest that microcephaly can arise from the lack of adaptation to centriole defects in neural progenitors of the developing neocortex in a p53-independent manner.

cell biology↗

bioRxiv2019

A novel microRNA-based strategy to expand the differentiation potency of stem cells

Full differentiation potential along with self-renewal capacity is a major property of pluripotent stem cells (PSCs). However, the differentiation capacity frequently decreases during expansion of PSCs in vitro. We show here that transient exposure to a single microRNA, expressed at early stages during normal development, improves the differentiation capacity of already-established murine and human PSCs. Short exposure to miR-203 in PSCs (miPSCs) results in expanded differentiation potency as well as improved efficiency in stringent assays such as tetraploid complementation and human-mouse interspecies chimerism. Mechanistically, these effects are mediated by direct repression of de novo DNA methyltransferases Dnmt3a and Dnmt3b, leading to transient and reversible erasing of DNA methylation. As a proof of concept, miR-203 improves differentiation and maturation of PSCs into cardiomyocytes in vitro as well as cardiac regeneration in vivo, after cardiac injury. These data support the use of transient exposure to miR-203 as a general and single method to reset the epigenetic memory in PSCs, and improve their use in regenerative medicine.

cell biology↗