Biology subjects

Hernandez-Martinez, R.

Publications and source records attributed to Hernandez-Martinez, R..

3 recordsLinked to original sources

bioRxiv2025

Cell Cycle Arrest of a "Zippering" Epithelial Cell Cluster Shapes the Face and is Disrupted in Craniofacial Disorders

Facial features identify individuals, but the mechanisms shaping the human face remain elusive. Orofacial clefting (OFC), the most common craniofacial abnormality, results from failed fusion of the facial prominences that is in part caused by persistence of the cephalic epithelium. Here we uncover the identity, behaviors, and molecular blueprints of a novel craniofacial epithelial population, the Zippering Lambda (ZL), which mediates prominence fusion and is characterized by cell cycle arrest in mouse and human embryos. Remarkably, cell cycle is unleashed in the ZL of Pbx1/2 and p63 mutant mice with OFC. Intersection of ZL-enriched genes with human OFC whole-genome sequencing datasets identifies ZFHX3 variants in affected individuals and cephalic epithelial Zfhx3 deletion causes murine OFC. ZFHX3 and PBX1 genetically interact and synergistically regulate cell cycle inhibitor genes within a complex in embryonic faces. Collectively, we deconstruct new mechanisms that pattern the face, connecting cell cycle arrest to developmental tissue fusion.

developmental biology↗

bioRxiv2024

Axin1 and Axin2 regulate the WNT-signaling landscape to promote distinct mesoderm programs

How distinct mesodermal lineages - extraembryonic, lateral, intermediate, paraxial and axial - are specified from pluripotent epiblast during gastrulation is a longstanding open question. By investigating AXIN, a negative regulator of the WNT/{beta}-catenin pathway, we have uncovered new roles for WNT signaling in the determination of mesodermal fates. We undertook complementary approaches to dissect the role of WNT signaling that augmented a detailed analysis of Axin1;Axin2 mutant mouse embryos, including single-cell and single-embryo transcriptomics, with in vitro pluripotent Epiblast-Like Cell differentiation assays. This strategy allowed us to reveal two layers of regulation. First, WNT initiates differentiation of primitive streak cells into mesoderm progenitors, and thereafter, WNT amplifies and cooperates with BMP/pSMAD1/5/9 or NODAL/pSMAD2/3 to propel differentiating mesoderm progenitors into either posterior streak derivatives or anterior streak derivatives, respectively. We propose that Axin1 and Axin2 prevent aberrant differentiation of pluripotent epiblast cells into mesoderm by spatially and temporally regulating WNT signaling levels.

developmental biology↗

bioRxiv2023

Macrophages allocate before apoptosis initiation and produce reactive oxygen species during interdigital phagocytosis

During programmed cell death (PCD), it is commonly accepted that macrophages are recruited by apoptotic cells to complete cell degradation. Interdigital cell death, a classical model of PCD, contributes to digit individualization in limbs of mammals and other vertebrates. Here we show that macrophages are present in interdigits before significant cell death occurs and remain after apoptosis inhibition. The typical interdigital phagocytic activity was not observed after a partial depletion of macrophages and was markedly reduced by engulfment/phagosome maturation inhibition, as detected by its association with high lysosomal activity. {beta}-galactosidase activity in this region was also coupled with phagocytosis, against its relationship with cellular senescence. Interdigital phagocytosis correlated with high levels of reactive oxygen species (ROS), common in embryo regions carrying abundant cell death, suggesting that macrophages are the major source of ROS. ROS generation was dependent on NADPH oxidases and blood vessel integrity, but not directly associated with lysosomal activity. Therefore, macrophages prepattern regions where abundant cell death is going to occur, and high lysosomal activity and the generation of ROS by an oxidative burst-like phenomenon are activities of phagocytosis. Summary statementRecruitment of macrophages to the interdigital regions is not linked to apoptosis initiation and they phagocytize by a mechanism involving high lysosomal activity and an oxidative burst-like phenomenon.

developmental biology↗