Getting started: altering promoter choice as a mechanism for cell type differentiation.

Decision letter: Single-cell RNA sequencing of the Strongylocentrotus purpuratus larva reveals the blueprint of major cell types and nervous system of a non-chordate deuterostome

Chapter nine - Transcriptional Switches Direct Plant Organ Formation and Patterning

Cell-type phylogenetics and the origin of endometrial stromal cells.

Stem cells are seen as a possible solution for organ and tissue regeneration and for the treatment or even cure of various diseases. There are basically two types of stem cells: embryonic and adult stem cells. Embryonic stem cells are derived from embryos and exhibit an extensive multiplication and differentiation potential. On the other hand, adult stem cells, which are found in bone marrow and other tissues, have a lower multiplication and differentiation capacity but are more easily isolated and applied. In adult stem cell therapies using bone marrow or umbilical cord blood transplantation, the differentiation of a certain cell type is induced and its multiplication is stimulated, followed by the implantation of these cells into damaged tissues. Examples of the application of stem cells include the treatment of autoimmune diseases such as type 1 diabetes mellitus and heart diseases. Stem cells open up new prospects for the treatment of a series of diseases. In this respect, basic knowledge of the mechanisms of growth and differentiation of these cells is of the utmost importance to optimize therapeutic results. In this review, we discuss the mechanisms of stem cell differentiation and describe the clinical results reported in the literature, mainly by Brazilian research groups.

Onecut1 and Onecut2 transcription factors operate downstream of Pax6 to regulate horizontal cell development

Zebrafish have been and continue to be an important model organism for studies of fundamental biology and biomedicine, including reproductive development and the cell intrinsic and extrinsic mechanisms regulating early gonocyte differentiation. Wild zebrafish strains determine sex using a ZW genetic system wherein the maternally inherited sex chromosome determines the embryo’s sex. Like other species, including humans, regulation of conserved autosomal genes is crucial for gonocyte and sexual differentiation. How these conserved factors are regulated by the diverse mechanisms found throughout the animal kingdom is an active area of investigation. Domesticated zebrafish strains lack the ZW sex determination system found in wild strains and undergo gonocyte and sexual differentiation through a process exclusively governed by autosomal genes and nongenetic influences like environmental factors. Through mutational analysis, molecular genetics, and RNA sequencing, our understanding of the complexity of oocyte and spermatocyte differentiation has become clearer. In this review, we explore the most recent studies of the conserved and divergent mechanisms of gonocyte differentiation between wild and domesticated zebrafish as well as possible adaptations related to their domestication. Further, the contributions of individual genes and their molecular genetic hierarchy in regulating gonocyte differentiation are discussed and related to other species where relevant. We also address the recent characterization of a novel oocyte-progenitor and its potential implications in gonad differentiation. Finally, the role of gonocyte-extrinsic mechanisms, specifically communication between differentiating gonocytes and surrounding somatic gonad cells and the influence of resident and infiltrating immune cells, is discussed.

Vascular plants (Tracheophytes) have adapted to a variety of environments ranging from arid deserts to tropical rainforests, and now comprise >250,000 species. While they differ widely in appearance and growth habit, all of them share a similar specialized tissue system (vascular tissue) for transporting water and nutrients throughout the organism. Plant vascular systems connect all plant organs from the shoot to the root, and are comprised of two main tissue types, xylem and phloem. In this review we examine the current state of knowledge concerning the process of vascular tissue formation, and highlight important mechanisms underlying key steps in vascular cell type specification, xylem and phloem tissue patterning, and, finally, the differentiation and maturation of specific xylem cell types.

Human embryonic stem cells are proliferating, self-renewing cells that have the great potential of differentiating into diverse cell types in vivo and in vitro. Investigations on human embryonic stem cells have allowed us to probe critical early stages of development, including the mechanisms of pluripotency, lineage specification, the formation and differentiation of specific cell and tissue types, and the underlying molecular and genetic mechanisms. In addition to the three main tissue lineages, embryonic stem cells can also give rise to the germ cell lineage, which produces the male or female gametes. With the difficulties of studying early human germ cell development in vivo, stem cells can provide a unique model and window into human germ cell differentiation. Further, as infertility is quite common in humans, most often due to defects in sperm and egg quantity or quality, embryonic stem cells and the recently discovered induced pluripotent stem cells might one day provide clinical applications for the treatment of infertility and reproductive disorders. Thus, stem cells have the great potential to revolutionize regenerative and reproductive medicine and numerous cutting-edge investigations and techniques are underway. This chapter summarizes our current understanding of the earliest events of human germ cell formation and gamete differentiation both in vivo and in vitro and the genetic requirements of this process as resolved from both human and animal studies. We also review the current literature on the formation of germ cells from embryonic stem cells and, finally, discuss needed future improvements and clinical implications of this work.KeywordsGerm cellsGametesSpermOocytesDeleted in AZoospermiaHuman embryonic stem cellsInduced pluripotent stem cells

Molecular Analysis of Gene Expression in the Developing Pontocerebellar Projection System

Ion channels in stem cells and their roles in stem cell biology and vascular diseases

Alternative splicing of the LIM-homeodomain transcription factor Isl1 in the mouse retina.

Epidermal basal cells invaginate into the dermis to form sweat ducts, which then grow downwards further to form secretory coils during the ontogenesis of eccrine sweat glands, but the time course of differentiation of different cell types in 3D-reconstructed eccrine sweat glands remain unclear. In this study, secretory cell-specific marker K7, clear secretory cell-specific marker CA II, dark secretory cell-specific marker GCDFP-15, myoepithelial cell-specific marker α-SMA, inner duct cell-specific marker S100P and outer duct cell-specific marker S100A2 were detected by immunofluorescence staining. The results showed that S100P and S100A2 were first detected at 2 weeks post implantation, K7 and α-SMA at 3 weeks, and GCDFP-15 and CA II at 4 weeks. The differentiation of ducts preceded secretory coils in 3D-reconstructed eccrine sweat glands. After 8 weeks post implantation, the distribution of these markers in 3D-reconstructed eccrine sweat glands was similar to that in native ones, and the percentage of the 3D-reconstructed glands expressing these markers maintained steady. We conclude that although the 3D-reconstructed and native eccrine sweat glands originated from different cells, the differentiation of different cell types in 3D-reconstructed eccrine sweat glands parallels the sequence observed during embryonic development.

The bHLH gene Hes1 regulates differentiation of multiple cell types.

Inhibitor of DNA binding (Id) proteins bind to and inhibit the function of basic helix-loop-helix (bHLH) transcription factors including those that regulate pancreatic development. Moreover, bone morphogenetic proteins (BMPs) regulate the expression of Ids. We hypothesized that BMP4 and Id proteins play a role in the expansion and differentiation of epithelial progenitor cells. We demonstrate that BMP4 induces the expression of Id2 along with the expansion of AR42J pancreatic epithelial cells. Furthermore, neutralization of BMP4 significantly reduced duct epithelial cell expansion in a mouse model of islet regeneration. BMP4 stimulation promotes Id2 binding to the bHLH transcription factor NeuroD, which is required for the differentiation of pancreatic islet cells. Therefore, our results indicate that BMP4 stimulation blocks the differentiation of endocrine progenitor cells and instead promotes their expansion thereby revealing a novel paradigm of signaling explaining the balance between expansion and differentiation of pancreatic duct epithelial progenitors. Understanding the mechanisms of BMP and Id function elucidates a key step during pancreas embryogenesis, which is important knowledge for expanding pancreatic progenitors in vitro.

Determinants of the Drosophila Odorant Receptor Pattern