• 생명과학회지
• /
• 제19권10호
• /
• pp.1346-1351
• /
• 2009

Neural crest는 신경계의 발생과정에서 생긴 특정화된 외배엽으로서 말초신경계(peripheral nervous system)의 모든 sensory cells과 peripheral cells, unipolar spinal ganglion cell, cranial sensory ganglia, peripheral nerve의 neurolemmal sheath cells, ganglia의 capsule cells, sympathetic ganglia, chromaffin cells, pigment cell 등의 자율신 경계의 대부분의 세포로 분화 한다. 최근pluripotetic neural crest cells의 운명이 이미 제한되어 있으며, 이러한 fate-restricted crest cells이 neural tube에서 emigration된다고 보고된바 있다. 또한 본 연구자는 Wnt와 Wnt의 antagonist가 neural crest cell의 specification이 일어나는 시기에 발현하여, neural crest cell의 segregation과 differentiation에 직접적으로 관여함을 밝혔다. 이를 보다 명확히 규명하기 위해, 본 연구에서는 neural tube에 Wnt-3a expressing cell의 grafting 혹은 dominant negative GSK construct의 electroporation을 통해 Wnt signaling을 modulation 하여 downstream mediator를 조사하였다. Wnt signaling의 stimulation은 neural crest cell의 melanoblast 로의 commitment를 유도하였으며, 이와 더불어 cadherin 7과 slug의 발현을 조절함을 확인하였다.

• Animal Bioscience
• /
• 제36권12호
• /
• pp.1905-1917
• /
• 2023

Objective: Nanog homeobox (NANOG) is a core transcription factor that contributes to pluripotency along with octamer binding transcription factor-4 (OCT4) and sex determining region-Y box-2 (SOX2). It is an epiblast lineage marker in mammalian pre-implantation embryos and exhibits a species-specific expression pattern. Therefore, it is important to understand the lineage of NANOG, the trophectoderm, and the primitive endoderm in the pig embryo. Methods: A loss- and gain-of-function analysis was done to determine the role of NANOG in lineage specification in parthenogenetic porcine blastocysts. We analyzed the relationship between NANOG and pluripotent core transcription factors and other lineage makers. Results: In NANOG-null late blastocysts, OCT4-, SOX2-, and SOX17-positive cells were decreased, whereas GATA binding protein 6 (GATA6)-positive cells were increased. Quantitative real-time polymerase chain reaction revealed that the expression of SOX2 was decreased in NANOG-null blastocysts, whereas that of primitive endoderm makers, except SOX17, was increased. In NANOG-overexpressing blastocysts, caudal type homeobox 2 (CDX2-), SOX17-, and GATA6-positive cells were decreased. The results indicated that the expression of primitive endoderm markers and trophectoderm-related genes was decreased. Conclusion: Taken together, the results demonstrate that NANOG is involved in the epiblast and primitive endoderm differentiation and is essential for maintaining pluripotency within the epiblast.

• IMMUNE NETWORK
• /
• 제23권1호
• /
• pp.5.1-5.28
• /
• 2023

Th cell lineage determination and functional specialization are tightly linked to the activation of lineage-determining transcription factors (TFs) that bind cis-regulatory elements. These lineage-determining TFs act in concert with multiple layers of transcriptional regulators to alter the epigenetic landscape, including DNA methylation, histone modification and threedimensional chromosome architecture, in order to facilitate the specific Th gene expression programs that allow for phenotypic diversification. Accumulating evidence indicates that Th cell differentiation is not as rigid as classically held; rather, extensive phenotypic plasticity is an inherent feature of T cell lineages. Recent studies have begun to uncover the epigenetic programs that mechanistically govern T cell subset specification and immunological memory. Advances in next generation sequencing technologies have allowed global transcriptomic and epigenomic interrogation of CD4+ Th cells that extends previous findings focusing on individual loci. In this review, we provide an overview of recent genome-wide insights into the transcriptional and epigenetic regulation of CD4+ T cell-mediated adaptive immunity and discuss the implications for disease as well as immunotherapies.

• BMB Reports
• /
• 제42권2호
• /
• pp.72-80
• /
• 2009

In mammals, major progress has recently been made with the dissection of early embryonic cell specification, the isolation of stem cells from early embryos, and the production of embryonic-like stem cells from adult cells. These studies have overcome long-standing species barriers for stem cell isolation, have revealed a deeper than expected similarity of embryo cell types across species, and have led to a better understanding of the lineage identities of embryo-derived stem cells, most notably of mouse and human embryonic stem (ES) cells. Thus, it has now become possible to propose a species-overarching classification of embryo stem cells, which are defined here as pre- to early post-implantation conceptus-derived stem cell types that maintain embryonic lineage identities in vitro. The present article gives an overview of these cells and discusses their relationships with each other and the conceptus. Consequently, it is debated whether further embryo stem cell types await isolation, and the study of the earliest extraembryonically committed stem cells is identified as a promising new research field.

• Molecules and Cells
• /
• 제43권2호
• /
• pp.114-120
• /
• 2020

Drosophila hematopoiesis is comparable to mammalian differentiation of myeloid lineages, and therefore, has been a useful model organism in illustrating the molecular and genetic basis for hematopoiesis. Multiple novel regulators and signals have been uncovered using the tools of Drosophila genetics. A Runt domain protein, lozenge, is one of the first players recognized and closely studied in the hematopoietic lineage specification. Here, we explore the role of lozenge in determination of prohemocytes into a special class of hemocyte, namely the crystal cell, and discuss molecules and signals controlling the lozenge function and its implication in immunity and stress response. Given the highly conserved nature of Runt domain in both invertebrates and vertebrates, studies in Drosophila will enlighten our perspectives on Runx-mediated development and pathologies.

• Animal cells and systems
• /
• 제6권1호
• /
• pp.69-74
• /
• 2002

Recent evidence has suggested that trunk neural crest cell generally assumed to have equivalent differentiation potentials, demonstrate differentiation bias along the anterior/posterior axis. In amphibian and fish, neural crest cells give rise to three chromatophore types, melanophores, xantho-phores, and iridophores. Each pigment cell type has distinct characteristics but there is speculation about the cellular plasticity that exists among them. Neural crest cells migrate along specific routes, ventromedially and dorsolaterally. Neural crest cells that travel dorsolaterally are the first cells to begin migration in the axolotl and are the major contributors to the visible pigment pattern. Many factors and mechanisms that are responsible for guiding migratory neural crest cells along potential pathways or determining their fate remain unknown. A single lineage of the crest, which becomes restricted to one of the three pigment cell types, gives us the opportunity to examine the existence of neural crest stem cell populations and cellular plasticity. Study presented here showed results from recent in vitro studies designed to identify parameters influencing differentiation events of individual neural crest-derived pigment cell lineages. Melanophore production from neural crest explants originating from different levels along the anterior/posterior axis of wild type-axolotl embryos were compared and demonstrate that the differentiation of melanophores is enhanced in subpopulation of neural crest treated with forskolin. Forskolin (an adenylate cyclase activator) increases intracellular CAMP concentration and eventually activates the protein kinase-A signaling pathway. Melanophore number, melanin content, and tyrosinase activity in explants taken from the anterior-most region of the crest increased significantly in response to forskolin treatment. This study suggests implications of region specific influences and developmental regulation in the development of pigment pattern.

• Biomolecules & Therapeutics
• /
• 제22권5호
• /
• pp.371-383
• /
• 2014

The nematode Caenorhabditis elegans (C. elegans) offers a unique opportunity for biological and basic medical researches due to its genetic tractability and well-defined developmental lineage. It also provides an exceptional model for genetic, molecular, and cellular analysis of human disease-related genes. Recently, C. elegans has been used as an ideal model for the identification and functional analysis of drugs (or small-molecules) in vivo. In this review, we describe conserved oncogenic signaling pathways (Wnt, Notch, and Ras) and their potential roles in the development of cancer stem cells. During C. elegans germline development, these signaling pathways regulate multiple cellular processes such as germline stem cell niche specification, germline stem cell maintenance, and germ cell fate specification. Therefore, the aberrant regulations of these signaling pathways can cause either loss of germline stem cells or overproliferation of a specific cell type, resulting in sterility. This sterility phenotype allows us to identify drugs that can modulate the oncogenic signaling pathways directly or indirectly through a high-throughput screening. Current in vivo or in vitro screening methods are largely focused on the specific core signaling components. However, this phenotype-based screening will identify drugs that possibly target upstream or downstream of core signaling pathways as well as exclude toxic effects. Although phenotype-based drug screening is ideal, the identification of drug targets is a major challenge. We here introduce a new technique, called Drug Affinity Responsive Target Stability (DARTS). This innovative method is able to identify the target of the identified drug. Importantly, signaling pathways and their regulators in C. elegans are highly conserved in most vertebrates, including humans. Therefore, C. elegans will provide a great opportunity to identify therapeutic drugs and their targets, as well as to understand mechanisms underlying the formation of cancer.

• Molecules and Cells
• /
• 제43권12호
• /
• pp.1011-1022
• /
• 2020

Cell type specification is a delicate biological event in which every step is under tight regulation. From a molecular point of view, cell fate commitment begins with chromatin alteration, which kickstarts lineage-determining factors to initiate a series of genes required for cell specification. Several important neuronal differentiation factors have been identified from ectopic over-expression studies. However, there is scarce information on which DNA regions are modified during induced pluripotent stem cell (iPSC) to neuronal progenitor cell (NPC) differentiation, the cis regulatory factors that attach to these accessible regions, or the genes that are initially expressed. In this study, we identified the DNA accessible regions of iPSCs and NPCs via the Assay for Transposase-Accessible Chromatin sequencing (ATAC-seq). We identified which chromatin regions were modified after neuronal differentiation and found that the enhancer regions had more active histone modification changes than the promoters. Through motif enrichment analysis, we found that NEUROD1 controls iPSC differentiation to NPC by binding to the accessible regions of enhancers in cooperation with other factors such as the Hox proteins. Finally, by using Hi-C data, we categorized the genes that directly interacted with the enhancers under the control of NEUROD1 during iPSC to NPC differentiation.

• Asian-Australasian Journal of Animal Sciences
• /
• 제22권10호
• /
• pp.1447-1460
• /
• 2009

Myogenic satellite cells have been isolated and identified by several recently elucidated molecular markers. Furthermore, knowledge about the precise function of these markers has provided insight into the early and terminal events of satellite cells during proliferation, differentiation, transdifferentiation, specification and activation. Recently, quiescent myogenic satellite cells have been associated with possession of Pax 3 and 7 that represent pluripotent stem cells capable of differentiating into other lineages. However, the mechanism by which myogenic satellite cells attain pluripotent potential remain elusive. Later, transdifferentiating ability of these cells to another lineage in the absence or presence of certain growth factor/ or agents has revolutionized the scope of these pluripotent myogenic satellite cells for manipulation of animal production (in terms of quality and quantity of muscle protein) and health (in terms of repair of skeletal muscle, cartilage or bone).

• Animal cells and systems
• /
• 제13권2호
• /
• pp.235-245
• /
• 2009

Embryonic stem (ES) cells have a capability to generate all types of cells. However, the mechanism by which ES cells differentiate into specific cell is still unclear. Using microarray technology, the differentiation process in mouse embryonic stem cells was characterized by temporal gene expression changes of mouse ES cells during differentiation in a monolayer culture. A large number of genes were differentially regulated from 1 day to 14 days, and less number of genes were differentially expressed from 14 days to 28 days. The number of up-regulated genes was linearly increased throughout the 28 days of in vitro differentiation, while the number of down-regulated genes reached the plateau from 14 days to 28 days. Most differentially expressed genes were functionally classified into transcriptional regulation, development, extra cellular matrix (ECM),cytoskeleton organization, cytokines, receptors, RNA processing, DNA replication, chromatin assembly, proliferation and apoptosis related genes. While genes encoding ECM proteins were up-regulated, most of the genes related to proliferation, chromatin assembly, DNA replication, RNA processing, and cytoskeleton organization were down-regulated at 14 days. Genes known to be associated with embryo development or transcriptional regulation were differentially expressed mostly after 14 days of differentiation. These results indicate that the altered expression of ECM genes constitute an early event during the spontaneous differentiation, followed by the inhibition of proliferation and lineage specification. Our study might identify useful time-points for applying selective treatments for directed differentiation of mouse ES cells.