Dclk1 facilitates intestinal tumor growth via enhancing pluripotency and epithelial mesenchymal transition

Doublecortin-like kinase 1 (Dclk1) is overexpressed in many cancers including colorectal cancer (CRC) and it specifically marks intestinal tumor stem cells. However, the role of Dclk1 in intestinal tumorigenesis in Apc mutant conditions is still poorly understood. We demonstrate that Dclk1 expression and Dclk1+ cells are significantly increased in the intestinal epithelium of elderly Apc^Min/+ mice compared to young Apc^Min/+ mice and wild type mice. Intestinal epithelial cells of Apc^Min/+ mice demonstrate increased pluripotency, self-renewing ability, and EMT. Furthermore, miRNAs are dysregulated, expression of onco-miRNAs are significantly increased with decreased tumor suppressor miRNAs. In support of these findings, knockdown of Dclk1 in elderly Apc^Min/+ mice attenuates intestinal adenomas and adenocarcinoma by decreasing pluripotency, EMT and onco-miRNAs indicating that Dclk1 overexpression facilitates intestinal tumorigenesis. Knocking down Dclk1 weakens Dclk1-dependent intestinal processes for tumorigenesis. This study demonstrates that Dclk1 is critically involved in facilitating intestinal tumorigenesis by enhancing pluripotency and EMT factors in Apc mutant intestinal tumors and it also provides a potential therapeutic target for the treatment of colorectal cancer.     

Spred1, a negative regulator of Ras�CMAPK�CERK, is enriched in CNS germinal zones, dampens NSC proliferation, and maintains ventricular zone structure

Neural stem cells (NSCs) have great potential for self-renewal, which must be tightly regulated to generate appropriate cell numbers during development and to prevent tumor formation. The Ras–MAPK–ERK pathway affects mitogen-stimulated proliferation, and negative regulators are likely to be important for keeping self-renewal in check. Sprouty-related protein with an EVH1 domain (Spred1) is a recently discovered negative Ras–MAPK–ERK regulator linked to a neurofibromatosis 1 (NF-1)-like human syndrome; however, its role in CNS development has not been explored. We show that Spred1 is highly enriched in CNS germinal zones during neurogenesis. Spred1 knockdown increases NSC self-renewal and progenitor proliferation cell-autonomously, and overexpression causes premature differentiation. Surprisingly, Spred1 knockdown in vivo in the embryonic mouse forebrain frequently resulted in periventricular heterotopia, developmental abnormalities often associated with mutations in genes in the vesicular trafficking pathway that cause disruption of germinal zones and impair cell migration. In cortical progenitor cells, Spred1 localizes within distinct vesicles, indicating a potential role in transport. Spred1 knockdown gradually leads to disruption of the apical ventricular zone and loss of radial glia alignment. This impairs late neuronal migration, resulting in the formation of periventricular masses. Thus, Spred1 is critical for normal cortical development, as it modulates progenitor self-renewal/proliferation and helps maintain the integrity and organization of germinal zones.     

The nuclear receptor tailless is required for neurogenesis in the adult subventricular zone

The tailless (Tlx) gene encodes an orphan nuclear receptor that is expressed by neural stem/progenitor cells in the adult brain of the subventricular zone (SVZ) and the dentate gyrus (DG). The function of Tlx in neural stem cells of the adult SVZ remains largely unknown. We show here that in the SVZ of the adult brain Tlx is exclusively expressed in astrocyte-like B cells. An inducible mutation of the Tlx gene in the adult brain leads to complete loss of SVZ neurogenesis. Furthermore, analysis indicates that Tlx is required for the transition from radial glial cells to astrocyte-like neural stem cells. These findings demonstrate the crucial role of Tlx in the generation and maintenance of NSCs in the adult SVZ in vivo.     

对不同性质乳腺组织中乳腺干细胞比例的测定

目的:了解乳腺干细胞在不同性质的乳腺组织中的含量。方法:取得手术后不同性质的乳腺组织,用胶原酶消化法制备成单细胞悬液后,采用流式细胞技术测定乳腺细胞的CD44和CD24表达情况。结果:从正常、乳腺疾病到乳腺癌组织,CD44 CD24-/low乳腺细胞的比例上升;当乳腺癌细胞生长加速时,CD44 CD24 乳腺细胞比例明显增加。结论:乳腺干细胞的含量可以反映乳腺组织的性质,而CD44 CD24 乳腺细胞可能是祖细胞,并且其含量可以反映乳腺组织的生长情况。     

The embryonic node behaves as an instructive stem cell niche for axial elongation

In warm-blooded vertebrate embryos (mammals and birds), the axial tissues of the body form from a growth zone at the tail end, Hensen’s node, which generates neural, mesodermal, and endodermal structures along the midline. While most cells only pass through this region, the node has been suggested to contain a small population of resident stem cells. However, it is unknown whether the rest of the node constitutes an instructive niche that specifies this self-renewal behavior. Here, we use heterotopic transplantation of groups and single cells and show that cells not destined to enter the node can become resident and self-renew. Long-term resident cells are restricted to the posterior part of the node and single-cell RNA-sequencing reveals that the majority of these resident cells preferentially express G2/M phase cell-cycle–related genes. These results provide strong evidence that the node functions as a niche to maintain self-renewal of axial progenitors.

In higher vertebrate embryos the body axis forms in head-to-tail direction from a growth zone at the tail end, which is present from gastrula stages through to the end of axis elongation, several days later. Hensen’s node is part of this growth zone. Rather than defining a distinct cell population arising very early in development, the node represents a dynamic region at the tip of the primitive streak, which appears as a morphological “node” from HH4 (1) in chick. The initial cells that make up this region are derived from two distinct cell populations, which meet at the tip of the elongating primitive streak (HH3 to 3+ in chick) (2–4). These are then joined by cells from the epiblast lateral to the anterior streak and node (5) (at stages HH3+ to HH4) and from the primitive streak immediately caudal to the node during regression (from stage HH5) (6, 7). Although ingression of cells from adjacent epiblast along most of the length of the streak continues later into development (6), this ceases at the level of the node by HH4+ (5, 8, 9). After stage 5, the node begins to regress caudally (7), while cells exit the node to lay down the midline of the developing head–tail axis, contributing to axial (notochord) and paraxial (medial somite) mesoderm, definitive endoderm, and neural midline (floorplate) tissues (Fig. 1 A–C) (5, 10–12).Open in a separate windowFig. 1.The node confers resident behavior. (A–C) Node replacement using a GFP donor showing normal node axial fates. (D and E) Epiblast lateral to the HH3+/4 node ingresses into it and gives rise to the axis and to regressing node as resident cells. (F and G) Anterior epiblast not normally fated to enter the node behaves as lateral epiblast when forced to do so. (H and I) Anterior epiblast normally gives rise to head structures. (J and K) Lateral epiblast no longer gives rise to node-derived axial structures when prevented from entering the node. (L) Quantifying tissue contribution of lateral (D, green) versus anterior (F, blue) epiblast grafts to the host. E, endoderm; F, floorplate; MS, medial-somite; N, notochord; RC, resident cell. Transverse dashed lines show levels of accompanying sections. The field of view of the wholemount images (C, E, G, I, K) is approximately 2 mm x 5 mm.Therefore, most cells pass transiently though the node, temporarily gaining a node-like gene-expression signature, which they lose upon leaving the node (5). However, transplantation of cell groups and fate-mapping experiments in chick (10, 13–15) and mouse (16–20) during early development have suggested that the node may also contain a few resident self-renewing cells that persist within the node during axial elongation, while other cells leave (Fig. 1C, “RC”). In particular, labeling of single cells in the node has provided a few examples of cells that contribute to midline structures and appear to self-renew because one or more cells remain at the site of labeling after some progeny have left (10, 17, 21, 22). At a cell-population level, grafts of groups of cells transplanted repeatedly between older and younger tailbud regions can contribute to midline structures over two or more hosts, while again some cells remain in the tailbud (14, 19). These findings have led to the idea that some cells in the node (most likely a very small subset) may have the ability to self-renew, perhaps indefinitely, thus displaying stem cell behavior.Are the self-renewing cells a special population that arose in earlier development, or might the node act as an environment (niche) (23–25) that captures a subset of the cells that enter it and instructs them to become resident and acquire self-renewal behavior and act as stem cells (26–28)? To demonstrate self-renewal and to test whether the node is an instructive stem cell niche, it is critical to test whether an individual cell can acquire this behavior when introduced to the node environment; this has not yet been attempted. Here we address this question using transplantation of groups of cells and of single cells in vivo and single-cell RNA sequencing (scRNA-seq). We find that the tip of the primitive streak is able to impart notochord and somite identity to most or all cells that enter it, while capturing a small subset to become resident and acquire self-renewal behavior. Cells from epiblast that would never have entered the node region during normal development are able to read these cues. We also define the developmental stage at which epiblast cells lose competence to respond to node signals. Long-term resident cells are preferentially located in the posterior part of the node, and display enriched expression of G2/M cell cycle markers.     

Probability of progenitor renewal (PPR) and production of clonogenic progeny (CFU-GM) by primitive adherent progenitor cells in adult human bone marrow and umbilical cord blood

Summary. Human haemopoietic tissues contain primitive plastic-adherent progenitor cells (PΔ cells) that can be detected by measurement of their granulocyte-macrophage colony-forming cell (CFU-GM) progeny. Limiting dilution analysis and Poisson statistics are necessary for determining the frequency of PΔ cells because each of them produces several CFU-GM. Limiting dilution also permits measurement of the abilities of individual PΔ progenitors to produce CFU-GM. Here we report that the frequencies of PΔ progenitors in cord blood and adult marrow are similar (5.6 and 7.8/10⁵ mononuclear cells respectively) and individual cord blood PΔ progenitors produce fewer CFU-GM than adult PΔ progenitors. To test the possibility that the lower production of differentiated progeny by cord blood cells was the result of a higher rate of self-renewal, we devised a two-stage limiting dilution assay relying on the relative production of CFU-GM after two consecutive weeks of incubation. The probability of progenitor renewal (PPR) was derived from the number of wells (progenitors) that produced CFU-GM on both occasions compared with the number that produced CFU-GM on the first occasion only. The total number of CFU-GM produced on the second occasion compared with the number produced on the first occasion provided an index of the overall change in the size of the PΔ cell population. The data indicate that PΔ cells in cord blood have a higher PPR (0.59) than those in adult marrow (036). Also, the relative numbers of CFU-GM produced in the second and first weeks were greater for cord blood (1.2) than for adult marrow (0.36). Therefore PΔ cells in cord blood have a greater capacity for self-maintenance and possibly for expansion than PΔ cells in adult marrow.     

Plasticity of male germline stem cells and their applications in reproductive and regenerative medicine

Spermatogonial stem cells (SSCs), also known as male germline stem cells, are a small subpopulation of type A spermatogonia with the potential of self-renewal to maintain stem cell pool and differentiation into spermatids in mammalian testis. SSCs are previously regarded as the unipotent stem cells since they can only give rise to sperm within the seminiferous tubules. However, this concept has recently been challenged because numerous studies have demonstrated that SSCs cultured with growth factors can acquire pluripotency to become embryonic stem-like cells. The in vivo and in vitro studies from peers and us have clearly revealed that SSCs can directly transdifferentiate into morphologic, phenotypic, and functional cells of other lineages. Direct conversion to the cells of other tissues has important significance for regenerative medicine. SSCs from azoospermia patients could be induced to differentiate into spermatids with fertilization and developmental potentials. As such, SSCs could have significant applications in both reproductive and regenerative medicine due to their unique and great potentials. In this review, we address the important plasticity of SSCs, with focuses on their self-renewal, differentiation, dedifferentiation, transdifferentiation, and translational medicine studies.     

多发性骨髓瘤干细胞的来源及分化

背景：多发性骨髓瘤干细胞可能源于正常干细胞的积累突变和通过基因突变重新获得自我更新能力的祖细胞或已经完全分化的成熟细胞,其特异标志物正处于研究阶段。目的：概述多发性骨髓瘤干细胞的来源、生物学特性以及研究进展。方法：应用计算机检索1998年1月至2012年5月万方数据库相关文章,检索词＂多发性骨髓瘤干细胞＂,并限定文章语言种类为中文。同时计算机检索1998年1月至2012年5月PubMed数据库相关文章,检索词＂stem cells,multiple myeloma,tumors＂,并限定文章语言种类为English。共检索到文献251篇,最终纳入符合标准的文献31篇。结果与结论：多发性骨髓瘤干细胞可能来源于记忆B细胞,具有自我更新和分化潜能,CD19和CD20是目前应用得最多的多发性骨髓瘤干细胞表面标记物,多发性骨髓瘤干细胞的研究对阐明多发性骨髓瘤发生机制、生物学行为及临床治疗、预后判断都具有重要意义。