Project description:Macrophages play integral roles in maintaining homeostasis and function in their tissues of residence. In the skin, prenatally seeded and highly specialized macrophages physically interact with sensory nerves and contribute to their regeneration after injury. However, mechanisms underlying the development and maintenance of this paradigmatic, potentially lifelong commitment of macrophages to nociceptors remain largely elusive. Here, we found that infiltrating myeloid progenitor cells approached the sprouting axons of sensory nerves and gradually adopted a nerve-associated macrophage-like profile. This change in identity was steered and maintained by the immediate microenvironment, in particular TGF-β, which was produced by neurons and locally activated by the physical interaction with nerves and integrin-mediated cleavage. Following injury, TGF-β driven specification of macrophages essentially supported nerve regeneration. Overall, we identified TGF-β as a central mediator governing local imprinting and long-term specialization of macrophages in the skin, providing insights into the bidirectional communication between macrophages and sensory nerves.
Project description:Macrophages play integral roles in maintaining homeostasis and function in their tissues of residence. In the skin, prenatally seeded and highly specialized macrophages physically interact with sensory nerves and contribute to their regeneration after injury. However, mechanisms underlying the development and maintenance of this paradigmatic, potentially lifelong commitment of macrophages to nociceptors remain largely elusive. Here, we found that infiltrating myeloid progenitor cells approached the sprouting axons of sensory nerves and gradually adopted a nerve-associated macrophage-like profile. This change in identity was steered and maintained by the immediate microenvironment, in particular TGF-β, which was produced by neurons and locally activated by the physical interaction with nerves and integrin-mediated cleavage. Following injury, TGF-β driven specification of macrophages essentially supported nerve regeneration. Overall, we identified TGF-β as a central mediator governing local imprinting and long-term specialization of macrophages in the skin, providing insights into the bidirectional communication between macrophages and sensory nerves.
Project description:The distinct blend of molecular and cellular features that define neuronal subtype identity are central to shaping how individual subtypes impact animal behavior. The diversity of the mammalian nervous system is vast — the retina alone contains over 100 neuronal subtypes. Yet, the genetic processes giving rise to this stunning structural and functional diversity remain poorly understood. Here, we uncover a graded expression pattern of the transcription factor Brn3b that tunes and maintains multiple, subtype-defining transcriptional and morphophysiological features of the melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs). Disruption of this Brn3b gradient causes the transcriptional and morphophysiological identity of ipRGC subtypes to begin to converge, leading to dysfunction in multiple ipRGC-dependent behaviors. These findings show that a single transcription factor gradient can tune a diverse array of features to shape neuronal identity and circuit function to drive behavior.
Project description:Pluripotency is the ability to give rise to all cell types of the body and is first observed in a mass of disorganised cells of the embryo. Upon implantation, pluripotent cells form a columnar epithelium and undergo lumenogenesis. At gastrulation, a portion of the pluripotent epiblast will undergo epithelial to mesenchymal transition (EMT), forming the primitive streak (PS). It still remains unclear what molecular mechanism supports the epithelial identity of the pluripotent epiblast before gastrulation. Here we developed an optimised, chemically defined 3D model of human pluripotent epiblast formation in which conventional pluripotent stem cells (PSCs) self-organise into a columnar epithelium with a lumen in 48 hours. From 72 hours we observed spontaneous symmetry breaking and specification of PS-like cells, as confirmed by single-cell RNA sequencing. We found that Insulin and FGF signalling are both required for the proliferation and survival of the pluripotent epiblast model. Conversely, TGF-beta signalling maintains epithelial identity. Epithelial identity appears uncoupled from the expression of canonical pluripotency markers OCT4, NANOG and PRDM14, but under the control of ZNF398. Once the pluripotent epithelium is established, TGF-beta inhibition is inconsequential, and stimulation with Activin A leads to highly efficient PS induction. We conclude that TGF-beta dynamically orchestrates epithelial identity of human pluripotent cells.
Project description:Pluripotency is the ability to give rise to all cell types of the body and is first observed in a mass of disorganised cells of the embryo. Upon implantation, pluripotent cells form a columnar epithelium and undergo lumenogenesis. At gastrulation, a portion of the pluripotent epiblast will undergo epithelial to mesenchymal transition (EMT), forming the primitive streak (PS). It still remains unclear what molecular mechanism supports the epithelial identity of the pluripotent epiblast before gastrulation. Here we developed an optimised, chemically defined 3D model of human pluripotent epiblast formation in which conventional pluripotent stem cells (PSCs) self-organise into a columnar epithelium with a lumen in 48 hours. From 72 hours we observed spontaneous symmetry breaking and specification of PS-like cells, as confirmed by single-cell RNA sequencing. We found that Insulin and FGF signalling are both required for the proliferation and survival of the pluripotent epiblast model. Conversely, TGF-beta signalling maintains epithelial identity. Epithelial identity appears uncoupled from the expression of canonical pluripotency markers OCT4, NANOG and PRDM14, but under the control of ZNF398. Once the pluripotent epithelium is established, TGF-beta inhibition is inconsequential, and stimulation with Activin A leads to highly efficient PS induction. We conclude that TGF-beta dynamically orchestrates epithelial identity of human pluripotent cells.
Project description:Pluripotency is the ability to give rise to all cell types of the body and is first observed in a mass of disorganised cells of the embryo. Upon implantation, pluripotent cells form a columnar epithelium and undergo lumenogenesis. At gastrulation, a portion of the pluripotent epiblast will undergo epithelial to mesenchymal transition (EMT), forming the primitive streak (PS). It still remains unclear what molecular mechanism supports the epithelial identity of the pluripotent epiblast before gastrulation. Here we developed an optimised, chemically defined 3D model of human pluripotent epiblast formation in which conventional pluripotent stem cells (PSCs) self-organise into a columnar epithelium with a lumen in 48 hours. From 72 hours we observed spontaneous symmetry breaking and specification of PS-like cells, as confirmed by single-cell RNA sequencing. We found that Insulin and FGF signalling are both required for the proliferation and survival of the pluripotent epiblast model. Conversely, TGF-beta signalling maintains epithelial identity. Epithelial identity appears uncoupled from the expression of canonical pluripotency markers OCT4, NANOG and PRDM14, but under the control of ZNF398. Once the pluripotent epithelium is established, TGF-beta inhibition is inconsequential, and stimulation with Activin A leads to highly efficient PS induction. We conclude that TGF-beta dynamically orchestrates epithelial identity of human pluripotent cells.