Release of extracellular membrane particles carrying the stem cell marker prominin-1 (CD133) from neural progenitors and other epithelial cells

Primary sensory neuron addition in the adult rat trigeminal ganglion: evidence for neural crest glio-neuronal precursor maturation

It is debated whether primary sensory neurons of the dorsal root ganglia increase the number in adult animals and, if so, whether the increase is attributable to postnatal neurogenesis or maturation of dormant, postmitotic precursors. Similar studies are lacking in the trigeminal ganglion (TG). Here we demonstrate by stereological methods that the number of neurons in the TG of adult male rats nearly doubles between the third and eighth months of age. The increase is mainly attributable to the addition of small, B-type neurons, with a smaller contribution of large, A-neurons. We looked for possible proliferative or maturation mechanisms that could explain this dramatic postnatal expansion in neuron number, using bromodeoxyuridine (BrdU) labeling, immunocytochemistry for neural precursor cell antigens, retrograde tracing identification of peripherally projecting neurons, and in vitro isolation of precursor cells from adult TG explant cultures. Cell proliferation identified months after an extended BrdU administration was sparse and essentially corresponded to glial cells. No BrdU-labeled cell took up the peripherally injected tracer, and only a negligible number coexpressed BrdU and the pan-neuronal tracer neuron-specific enolase. In contrast, a population of cells not recognizable as mature neurons in the TG and neighboring nerve expressed neuronal precursor antigens, and neural crest glioneuronal precursor cells were successfully isolated from adult TG explants. Our data suggest that a protracted maturation process persists in the TG that can be responsible for the neuronal addition found in the adult rat.

GM1 and GM3 gangliosides highlight distinct lipid microdomains within the apical domain of epithelial cells

The apical domain of epithelial cells is composed of distinct subdomains such as microvilli, primary cilia and a non-protruding region. Using the cholesterol-binding protein prominin-1 as a specific marker of plasma membrane protrusions we have previously proposed the co-existence of different cholesterol-based lipid microdomains (lipid rafts) within the apical domain [Röper, K., Corbeil, D. and Huttner, W.B. (2000), Retention of prominin in microvilli reveals distinct cholesterol-based lipid microdomains in the apical plasma membrane. Nat. Cell Biol. 2, 582-592]. To substantiate the hypothesis that the microvillar plasma membrane subdomains contain a distinct set of lipids compared to the planar portion we have investigated the distribution of prominin-1 and two raft-associated gangliosides GM(1) and GM(3) by fluorescence microscopy. GM(1) was found to co-localize with prominin-1 on microvilli whereas GM(3) was segregated from there suggesting its localization in the planar region. Regarding the primary cilium, overlapping fluorescent signals of GM(1) or GM(3) and prominin-1 were observed. Thus, our data demonstrate that specific ganglioside-enriched rafts are found in different apical subdomains and reveal that two plasma membrane protrusions with different structural bases (actin for the microvillus and tubulin for the cilium) are composed of distinct types of lipid.

Cloning and expression analysis of goldfish (Carassius auratus L.) prominin

The integral membrane protein known as prominin was first identified on the apical surface of mouse neural epithelial cells as well as on the surface of human haematopoietic progenitor cells. This report describes a prominin-like sequence and expression analysis of the prominin in the goldfish. The predicted amino acid sequence for goldfish prominin shares all of the hallmark structural characteristics of the prominin family, however the relatedness assessed using the percent amino acid identity indicated that goldfish prominin cannot be placed into the current mammalian dichotomy of type 1 or 2. The real time PCR analyses indicated that prominin was broadly expressed in different tissues with particularly high levels observed in the kidney and gill of the goldfish. Goldfish prominin was also found to be differentially expressed in subpopulations of in vitro-derived goldfish macrophages, with the highest expression observed in progenitor cells.

Manipulation of proliferation and differentiation of human bone marrow-derived neural stem cells in vitro and in vivo

Recent evidence has demonstrated that neural stem cells (NSC) can be expanded from a variety of sources, including embryos, fetuses, and adult bone marrow and brain tissue. We have previously reported the generation of adult rat bone marrow-derived cellular spheres that are morphologically and phenotypically similar to neurospheres derived from brain NSC. Here we show that adult human bone marrow-derived neural stem cells (HBM-NSC) are capable of generating spheres that are similar to brain neural-derived neurospheres. Additionally, we sought to promote proliferation and differentiation of HBM-NSC through transduction with nonreplicative recombinant adenovirus encoding the cDNA sequence for Gli, rADV-Gli-1; sonic hedgehog, rADV-Shh; or Nurr1, rADV-Nurr1. Immunocytochemistry and RT-PCR analysis showed that HBM-NSC could be efficiently expanded and differentiated in vitro and that HBM-NSC transduced with rADV-Gli-1 or rADV-Shh dramatically increased NSC time-related proliferation; however, Nurr1 had no effect on proliferation. We also transplanted HBM-NSC into chicken embryos to examine their potential function in vivo. We found that transduction of HBM-NSC with rADV-Gli-1 or rADV-Shh and subsequent transplantation into chicken embryos increased HBM-NSC proliferation, whereas rADV-Nurr1 promoted migration and differentiation in vivo. Our findings suggest that HBM-NSC can be efficiently expanded and differentiated in vitro and in vivo by overexpressing Gli-1, Shh or Nurr1.

The expression and functions of glycoconjugates in neural stem cells

The mammalian central nervous system is organized by a variety of cells such as neurons and glial cells. These cells are generated from a common progenitor, the neural stem cell (NSC). NSCs are defined as undifferentiated neural cells that are characterized by their high proliferative potential while retaining the capacity for self-renewal and multipotency. Glycoconjugates carrying carbohydrate antigens, including glycoproteins, glycolipids, and proteoglycans, are primarily localized on the plasma-membrane surface of cells and serve as excellent biomarkers at various stages of cellular differentiation. Moreover, they also play important functional roles in determining cell fate such as self-renewal, proliferation, and differentiation. In the present review, we discuss the expression pattern and possible functions of glycoconjugates and carbohydrate antigens in NSCs, with an emphasis on stage-specific embryonic antigen-1, human natural killer antigen-1, polysialic acid-neural cell-adhesion molecule, prominin-1, gp130, chondroitin sulfate proteoglycans, heparan sulfate proteoglycans, cystatin C, galectin-1, glycolipids, and Notch.

Midbody and primary cilium of neural progenitors release extracellular membrane particles enriched in the stem cell marker prominin-1

Expansion of the neocortex requires symmetric divisions of neuroepithelial cells, the primary progenitor cells of the developing mammalian central nervous system. Symmetrically dividing neuroepithelial cells are known to form a midbody at their apical (rather than lateral) surface. We show that apical midbodies of neuroepithelial cells concentrate prominin-1 (CD133), a somatic stem cell marker and defining constituent of a specific plasma membrane microdomain. Moreover, these apical midbodies are released, as a whole or in part, into the extracellular space, yielding the prominin-1–enriched membrane particles found in the neural tube fluid. The primary cilium of neuroepithelial cells also concentrates prominin-1 and appears to be a second source of the prominin-1–bearing extracellular membrane particles. Our data reveal novel origins of extracellular membrane traffic that enable neural stem and progenitor cells to avoid the asymmetric inheritance of the midbody observed for other cells and, by releasing a stem cell membrane microdomain, to potentially influence the balance of their proliferation versus differentiation.

Isolation of murine hair-inducing cells using the cell surface marker prominin-1/CD133

Hair is a mini-organ in which dermal papilla (DP) cells play important roles in hair follicle morphogenesis and formation via interactions with epithelial cells. DP cells have previously been difficult to analyze because of the lack of a specific surface marker. We have demonstrated that prominin-1/CD133 (CD133) is a useful marker for murine DP cells. DP cells express CD133 during the early anagen stage (active growth phase) not only during hair morphogenesis, but also during the growth phase of hairs after birth. Gene expression and flow cytometric analysis revealed that CD133-positive (+) cells in the skin possess the characteristics of DP cells. The CD133(+) cells isolated from embryonic or adult skin-induced new hair follicles in vivo when they were transplanted into nude mice mixed with embryonic epithelial cells, but CD133-negative (-) cells could not. We propose that the CD133 is a novel surface marker useful for collecting DP cells in the anagen stage and for analyzing the function of DP.

A human colon cancer cell capable of initiating tumour growth in immunodeficient mice

Colon cancer is one of the best-understood neoplasms from a genetic perspective, yet it remains the second most common cause of cancer-related death, indicating that some of its cancer cells are not eradicated by current therapies. What has yet to be established is whether every colon cancer cell possesses the potential to initiate and sustain tumour growth, or whether the tumour is hierarchically organized so that only a subset of cells--cancer stem cells--possess such potential. Here we use renal capsule transplantation in immunodeficient NOD/SCID mice to identify a human colon cancer-initiating cell (CC-IC). Purification experiments established that all CC-ICs were CD133+; the CD133- cells that comprised the majority of the tumour were unable to initiate tumour growth. We calculated by limiting dilution analysis that there was one CC-IC in 5.7 x 10(4) unfractionated tumour cells, whereas there was one CC-IC in 262 CD133+ cells, representing >200-fold enrichment. CC-ICs within the CD133+ population were able to maintain themselves as well as differentiate and re-establish tumour heterogeneity upon serial transplantation. The identification of colon cancer stem cells that are distinct from the bulk tumour cells provides strong support for the hierarchical organization of human colon cancer, and their existence suggests that for therapeutic strategies to be effective, they must target the cancer stem cells.

Prominin-2 is a cholesterol-binding protein associated with apical and basolateral plasmalemmal protrusions in polarized epithelial cells and released into urine

Prominin-2 is a pentaspan membrane glycoprotein structurally related to the cholesterol-binding protein prominin-1, which is expressed in epithelial and non-epithelial cells. Although prominin-1 expression is widespread throughout the organism, the loss of its function solely causes retinal degeneration. The finding that prominin-2 appears to be restricted to epithelial cells, such as those found in kidney tubules, raises the possibility that prominin-2 functionally substitutes prominin-1 in tissues other than the retina and provokes a search for a definition of its morphological and biochemical characteristics. Here, we have investigated, by using MDCK cells as an epithelial cell model, whether prominin-2 shares the biochemical and morphological properties of prominin-1. Interestingly, we have found that, whereas prominin-2 is not restricted to the apical domain like prominin-1 but is distributed in a non-polarized fashion between the apical and basolateral plasma membranes, it retains the main feature of prominin-1, i.e. its selective concentration in plasmalemmal protrusions; prominin-2 is confined to microvilli, cilia and other acetylated tubulin-positive protruding structures. Similar to prominin-1, prominin-2 is partly associated with detergent-resistant membranes in a cholesterol-dependent manner, suggesting its incorporation into membrane microdomains, and binds directly to plasma membrane cholesterol. Finally, prominin-2 is also associated with small membrane particles that are released into the culture media and found in a physiological fluid, i.e. urine. Together, these data show that all the characteristics of prominin-1 are shared by prominin-2, which is in agreement with a possible redundancy in their role as potential organizers of plasma membrane protrusions.

Temporal expression profiling of the uterine luminal epithelium of the pseudo-pregnant mouse suggests receptivity to the fertilized egg is associated with complex transcriptional changes

BACKGROUND

The molecular basis of changes underlying the altered sensitivity of the uterine luminal epithelium (LE) to the embryo over the peri-implantation period is not fully understood.

METHODS

Microarray analysis was performed on purified LE isolated from the pseudo-pregnant mouse uterus at 12-h intervals from pre-receptivity through the implantation window to refractoriness. The aim was to identify genes whose expression changes in the LE during this period.

RESULTS

A total of 447 transcripts were identified whose abundance changed more than 2-fold in the LE but which did not change in the underlying stroma (S) and glands. Six major patterns of changing expression were noted. Of the 447 genes, 140 were expressed in LE at least 15-fold higher than in S and glandular epithelium (GE) (101 of these more than 20-fold). Detailed spatiotemporal expression profiles were derived for several genes previously implicated in implantation (including Edg7, Ptgs1, Pla2g4a and Alox15).

CONCLUSIONS

Functional changes in LE receptivity are characterized by changing constellations of gene expression. Pre-receptivity has a different molecular footprint to refractoriness. Because we have used the pseudo-pregnant mouse model, these changes are driven solely by endocrine signals rather than events downstream of embryo attachment. Some of these genes have been described in previous microarray studies on endometrium, but for the majority, this is the first time they have been implicated in implantation. The 140 genes enriched in the LE greatly expand the list of epithelial markers and provide many novel candidates for further studies to identify genes playing important roles in receptivity and embryo attachment.

Release and trafficking of lipid-linked morphogens

Wnt and Hedgehog family proteins are secreted morphogens that act on surrounding cells to pattern many different tissues in both vertebrates and invertebrates. The discovery that these proteins are covalently linked to lipids has raised the puzzling problem of how they come to be released from cells and move through tissue. A synergistic combination of biochemical, cell biological and genetic approaches over the past several years is beginning to illuminate both the forms in which lipid-linked morphogens are released from cells and the variety of molecular and cell biological mechanisms that control their dispersal.

Potential role of NF-kappaB in adult neural stem cells: the underrated steersman?

Neural stem cells are precursors of neurons and glial cells. During brain development, these cells proliferate, migrate and differentiate into specific lineages. Recently neural stem cells within the adult central nervous system were identified. Informations are now emerging about regulation of stem cell proliferation, migration and differentiation by numerous soluble factors such as chemokines and cytokines. However, the signal transduction mechanisms downstream of these factors are less clear. Here, we review potential evidences for a novel central role of the transcription factor nuclear factor kappa B (NF-kappaB) in these crucial signal transduction processes. NF-kappaB is an inducible transcription factor detected in neurons, glia and neural stem cells. NF-kappaB was discovered by David Baltimore's laboratory as a transcription factor in lymphocytes. NF-kappaB is involved in many biological processes such as inflammation and innate immunity, development, apoptosis and anti-apoptosis. It has been recently shown that members of the NF-kappaB family are widely expressed by neurons, glia and neural stem cells. In the nervous system, NF-kappaB plays a crucial role in neuronal plasticity, learning, memory consolidation, neuroprotection and neurodegeneration. Recent data suggest an important role of NF-kappaB on proliferation, migration and differentiation of neural stem cells. NF-kappaB is composed of three subunits: two DNA-binding and one inhibitory subunit. Activation of NF-kappaB takes place in the cytoplasm and results in degradation of the inhibitory subunit, thus enabling the nuclear import of the DNA-binding subunits. Within the nucleus, several target genes could be activated. In this review, we suggest a model explaining the multiple action of NF-kappaB on neural stem cells. Furthermore, we discuss the potential role of NF-kappaB within the so-called brain cancer stem cells.

Release of extracellular membrane particles carrying the stem cell marker prominin-1 (CD133) from neural progenitors and other epithelial cells

Apical plasma membrane constituents of mammalian neural stem/progenitor cells have recently been implicated in maintaining their stem/progenitor cell state. Here, we report that in the developing embryonic mouse brain, the fluid in the lumen of the neural tube contains membrane particles carrying the stem cell marker prominin-1 (CD133), a pentaspan membrane protein found on membrane protrusions of the apical surface of neuroepithelial cells. Two size classes of prominin-1-containing membrane particles were observed in the ventricular fluid: approximately 600-nm particles, referred to as P2 particles, and 50-80-nm vesicles, referred to as P4 particles. The P2 and P4 particles appeared in the ventricular fluid at the very onset and during the early phase of neurogenesis, respectively. Concomitant with their appearance, the nature of the prominin-1-containing apical plasma membrane protrusions of neuroepithelial cells changed, in that microvilli were lost and large pleiomorphic protuberances appeared. P4 particles were found in various body fluids of adult humans, including saliva, seminal fluid and urine, and were released by the epithelial model cell line Caco-2 upon differentiation. Importantly, P4 particles were distinct from exosomes. Our results demonstrate the widespread occurrence of a novel class of extracellular membrane particles containing proteins characteristic of stem cells, and raise the possibility that the release of the corresponding membrane subdomains from the apical surface of neural progenitors and other epithelial cells may have a role in tissue development and maintenance. Moreover, the presence of prominin-1-containing membrane particles in human body fluids may provide the basis for a protein-based diagnosis of certain diseases.

Symmetric versus asymmetric cell division during neurogenesis in the developing vertebrate central nervous system

The type and number of cell divisions of neuronal progenitors determine the number of neurons generated during the development of the vertebrate central nervous system. Over the past several years, there has been substantial progress in characterizing the various kinds of neuronal progenitors and the types of symmetric and asymmetric divisions they undergo. The understanding of the cell-biological basis of symmetric versus asymmetric progenitor cell division has been consolidated, and the molecular machinery controlling these divisions is beginning to be unravelled. Other recent advances include comparative studies of brain development in rodents and primates, as well as the identification of gene mutations in humans that affect the balance between the various types of cell division of neuronal progenitors.

Cortical development: the art of generating cell diversity

The fascinating question of how the enormous diversity of neuronal and glial cells in the cerebral cortex is generated during development was recently discussed at a meeting on cortical development and stem cells in Greece. What emerged from this meeting is an equally fascinating answer, namely that precursor diversity at rather early stages of development anticipates later cell type diversity.

Incidence of hypothyroidism after 131I therapy for hyperthyroidism. Relation to pretherapy serum levels of T3, T4 and thyroid antibodies

A correlation is reported between serum levels of triiodothyronine (S-T3) and thyroxine (S-T4) before treatment, as well as levels of thyroid antibodies before treatment, and the development of hypothyroidism following 131I therapy in 86 patients with hyperthyroidism. Patients with marked elevation of S-T3 or S-T4 had demonstrable antibodies to thyroid cytoplasmic antigen more often than those with normal or moderately elevated levels, and patients with markedly elevated levels of S-T3 also had a higher incidence of hypothyroidism after treatment. Patients with nodular thyroid glands and with markedly elevated levels of S-T3 required a larger number of 131I doses before no signs of hyperthyroidism persisted in comparison to those with moderately elevated levels.