
Sox9 is a critical transcription factor that marks long-lived limbal stem cells and is required for the proper regulation of asymmetric cell fate decisions, which is essential to maintain corneal epithelial homeostasis.


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Adult tissues with high cellular turnover require a balance between stem cell renewal and differentiation, yet the mechanisms underlying this equilibrium are unclear. The cornea exhibits a polarized lateral flow of progenitors from the peripheral stem cell niche to the center; attributed to differences in cellular fate. To identify genes that are critical for regulating the asymmetric fates of limbal stem cells and their transient amplified progeny in the central cornea, we utilized an in vivo cell cycle reporter to isolate proliferating basal cells across the anterior ocular surface epithelium and performed single-cell transcriptional analysis. This strategy greatly increased the resolution and revealed distinct basal cell identities with unique expression profiles of structural genes and transcription factors. We focused on Sox9; a transcription factor implicated in stem cell regulation across various organs. Sox9 was found to be differentially expressed between limbal stem cells and their progeny in the central corneal. Lineage tracing analysis confirmed that Sox9 marks long-lived limbal stem cells and conditional deletion led to abnormal differentiation and squamous metaplasia in the central cornea. These data suggest a requirement for Sox9 for the switch to asymmetric fate and commitment toward differentiation, as transient cells exit the limbal niche. By inhibiting terminal differentiation of corneal progenitors and forcing them into perpetual symmetric divisions, we replicated the Sox9 loss-of-function phenotype. Our findings reveal an essential role for Sox9 for the spatial regulation of asymmetric fate in the corneal epithelium that is required to sustain tissue homeostasis.

### Competing Interest Statement

The authors have declared no competing interest.

Sox9 marks limbal stem cells and is required for asymmetric cell fate switch in the corneal epithelium

identification-of-the-transcription-factor-sox9-as-a-key-regulator-of-limbal-stem-cell-fate-and-corneal-epithelial-homeostasis


Identification of the Transcription Factor Sox9 as a Key Regulator of Limbal Stem Cell Fate and Corneal Epithelial Homeostasis


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성체 장 조직에서 Lgr5 양성 줄기세포와 독립적인 별도의 발달 계열이 장 상피 재생에 관여한다.


Collagenase/dispase treatment of intestinal tissue from adult mice generates cells growing in matrigel as immortal cystic spheroids in addition to differentiated organoids. Contrary to classical EDTA-derived organoids, these spheroids display poor intestinal differentiation and are independent of Rspondin/Noggin/EGF for growth. Their transcriptome resembles strikingly that of fetal intestinal spheroids, with downregulation of crypt base columnar cell (CBC) markers (Lgr5, Ascl2, Smoc2, Olfm4). In addition, they display upregulation of inflammatory and mesenchymal genetic programs, together with robust expression of YAP target genes. Lineage tracing, cell-sorting and single cell RNA sequencing experiments demonstrate that adult spheroid-generating cells belong to a hitherto undescribed developmental lineage, independent of Lgr5+ve CBCs, and are involved in regeneration of the epithelium following CBC ablation.

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### Competing Interest Statement

The authors have declared no competing interest.

 [1]: pending:yes

An Lgr5-independent developmental lineage is involved in mouse intestinal regeneration

성체-장-조직에서-lgr5-독립적인-발달-계열이-장-재생에-관여한다


성체 장 조직에서 Lgr5 독립적인 발달 계열이 장 재생에 관여한다



A distinct lineage of quiescent intestinal stem cells, independent of the Lgr5-positive crypt base columnar cells, contributes to epithelial regeneration following injury.


identification-of-a-novel-lgr5-independent-intestinal-lineage-involved-in-epithelial-regeneration


Identification of a Novel Lgr5-Independent Intestinal Lineage Involved in Epithelial Regeneration



TERT의 역전사 활성과 무관하게 TERT 불활성화가 줄기세포 경쟁을 저해하며, TERT와 MYC 사이의 유전적 연결고리가 있음을 보여준다.


Studies in mice show that telomerase reverse transcriptase (TERT) has a role in enhancing stem cell competition that is independent of its reverse transcriptase activity, and&nbsp;promotes chromatin accessibility and activity of the MYC oncogene.

Clonal inactivation of TERT impairs stem cell competition - Nature

tert-불활성화가-줄기세포-경쟁을-저해한다


TERT 불활성화가 줄기세포 경쟁을 저해한다



TERT の不活性化は、精子幹細胞の競争力を低下させ、幹細胞分化を促進し、クロマチンの開放性を全ゲノムにわたって減少させる。この TERT の役割は、逆転写酵素活性や正規のテロメラーゼ複合体とは独立している。


マウスの精子幹細胞における-tert-の不活性化が幹細胞競争を損なうことを示す


マウスの精子幹細胞における TERT の不活性化が幹細胞競争を損なうことを示す



ヒト多能性幹細胞からの造血前駆細胞産生を促進するためには、RUNX1T1とIGFBP2の発現誘導が重要である。


A major challenge in the stem cell biology field is the ability to produce fully functional cells from induced pluripotent stem cells (iPSCs) that are a valuable resource for cell therapy, drug screening and disease modelling. Here we developed a novel inducible CRISPR-mediated activation strategy (iCRISPRa) to drive the expression of multiple endogenous transcription factors important for in vitro cell fate and differentiation of iPSCs to haematopoietic progenitor cells and used this to identify a key paracrine role for IGFBP2 in the development of hematopoietic progenitors. We first identified nine candidate transcription factors that we predicted to be involved in blood cell emergence during development, then generated novel gRNAs directed to the transcriptional start site of these transcription factors that could also be detected during scRNAseq. iCRISPRa activation of these endogenous transcription factors resulted in a significant expansion of arterial-fated endothelial cells expressing high levels of IGFBP2 and showed that IGFBP2 remodels the metabolic activity during in vitro endothelial to hematopoietic transition. As well as providing fundamental new insights into the mechanisms of haematopoietic cell fate and differentiation, the broader applicability of iCRISPRa provides a valuable tool for studying dynamic processes controlling developmental events as well as for recapitulating abnormal phenotypes characterised by ectopic activation of specific endogenous gene expression in a wide range of systems.

### Competing Interest Statement

The authors have declared no competing interest.

A novel human pluripotent stem cell-based gene activation system identifies IGFBP2 as a mediator in the production of hematopoietic progenitors in vitro

ヒト多能性幹細胞を基盤とした新規遺伝子活性化システムによりigfbp2がin-vitroでの造血前駆細胞産生の仲介因子であることが明らかになった


ヒト多能性幹細胞を基盤とした新規遺伝子活性化システムによりIGFBP2がin vitroでの造血前駆細胞産生の仲介因子であることが明らかになった



Activation of nine endogenous transcription factors, including RUNX1T1, in human pluripotent stem cells leads to an expansion of arterial endothelial cells and increased production of functional hematopoietic progenitors, mediated in part by the paracrine factor IGFBP2.


activation-of-endogenous-transcription-factors-expands-arterial-endothelial-cells-and-enhances-hematopoietic-progenitor-production-from-human-pluripotent-stem-cells


Activation of Endogenous Transcription Factors Expands Arterial Endothelial Cells and Enhances Hematopoietic Progenitor Production from Human Pluripotent Stem Cells



The degree of pigmentation in in vitro cultured human iPSC-derived retinal pigment epithelium (iPSC-RPE) cells does not correlate strongly with their gene expression profiles or functional characteristics.


Retinal pigment epithelium (RPE) cells show heterogeneous level of pigmentation when cultured in vitro . To know whether their color in appearance is correlated with the function of the RPE, we analyzed the color intensities of human-induced pluripotent stem cell-derived RPE cells (iPSC-RPE) together with the gene expression profile at the single cell level. For this purpose, we utilized our recent invention, Automated Live imaging and cell Picking System (ALPS), which enabled photographing each cell before RNA-sequencing analysis to profile the gene expression of each cell. While our iPSC-RPE were categorized in 4 clusters by gene expression, the color intensity of iPSC-RPE did not project any specific gene expression profiles. We reasoned this by less correlation between the actual color and the gene expressions that directly define the level of pigmentation, from which we hypothesized the color of RPE cells may be a temporal condition not strongly indicating the functional characteristics of the RPE.

### Competing Interest Statement

The authors have declared no competing interest.

Pigmentation level of human iPSC-derived retinal pigment epithelium cell does not indicate a specific gene expression profile

in-vitro-pigmentation-of-human-ipsc-derived-retinal-pigment-epithelium-cells-does-not-reflect-their-functional-characteristics


In vitro Pigmentation of Human iPSC-Derived Retinal Pigment Epithelium Cells Does Not Reflect Their Functional Characteristics
