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1.
An earlier theory of cell differentiation and morphogenesis (Wassermann, 1972, 1973, 1978) is combined with the genetic control
model of Davidson and Britten (e.g. 1979). The resulting new theory suggests how, bysystematic process algorithms, specifically enumerated combinations of batteries of structural genes can become switched on in particularly enumerated
cells, via battery-specific enumerable regulator genes. The systematization is idealized. Up to a certain stage of development
in each mitotically arising cell a unique cell-specific combination of structural genes called ‘marker genes’ is active. Marker
genes are assumed to code for cell-specifying marker proteins (CSMPs) which permit cells carrying related markers to recognize
each other, thus permitting specific cell sorting.Batteries of marker genes could ensure great developmental precision and can safeguard—via redundancies of CSMP types—against accidental
loss or detrimental mutational modification of CSMPs or marker genes, respectively. This paper is much concerned with cell
lineage in relation to ‘microdifferentiation’, where ‘microdifferentiation’ of a cell refers to a cell's active marker genes
and its syntheses of CSMPs. A drastic distinction is made between ‘microdifferentiation’ and ‘gross’ differentiation of a
cell, where the same ‘gross’ differentiation may be shared by a large number of cells that could each be uniquely ‘microdifferentiated’.
Typical ‘gross’ differentiation could manifest itself in tissue specificity, whereas, up to certain stages of development,
all cells of the same gross differentiation type (say tissue specificity) could each be uniquely ‘microdifferentiated’. The
theory also assumes that at certain stages of the developmental process some (or in some organisms all) of the previously
uniquely specified cells could give rise to small (or occasionally large) clones of equispecified cells, some of which might
form clusters that represent complete ‘morphogenetic fields’ Tentative implementation mechanisms are proposed which suggest
how the theory could operate in molecular biological terms. In particular, CSMPs could endow cell surface membranes with a
highly specific protein network, and an associated equally specific cell surface coat. It is suggested how these highly specified
cell surface coats and other systems could provide an ‘extracellular guidance network’ which could help to direct cells to
attain energetically optimal locations relative to each other based on the matching of their surface specificities. In numerous
experimental situations, where normally present optimal matching of cells is excluded, ‘alternative matching’ based on experiment-specific
suboptimal matching could explain many data, notably in experimental development neurobiology (Wassermann, 1978). 相似文献
2.
Emily Hays Jaime Schmidt Nalini Chandar 《In vitro cellular & developmental biology. Animal》2009,45(7):361-370
Selective knockdown of phosphatase and tensin homolog (PTEN) has been recently shown to increase life long accumulation of
bone and its ability to increase osteoblast lifespan. In order to determine how loss of PTEN function affects osteoblast differentiation,
we created cell lines with stable knockdown of PTEN expression using short hairpin RNA vectors and characterized several clones.
The effect of deregulated PTEN in osteoblasts was studied in relationship to cell proliferation and differentiation. Downregulation
of PTEN initially affected the cell’s attachment and spreading on plastic but cells recovered after a brief period of time.
When cell proliferation was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, we noticed
a small but significant increase in growth rates with PTEN reduction. The size of individual cells appeared larger when compared
to control cells. Differentiation properties of these osteoblasts were increased as evidenced by higher expression of several
of the bone markers tested (alkaline phosphatase, osteocalcin, osterix, bone morphogenetic protein 2, Cbfa1, osteoprotegerin,
and receptor activator of NF-kappaB ligand) and their mineralization capacity in culture. As stabilization of beta-catenin
is known to be responsible for growth deregulation with PTEN loss in other cell types, we investigated the activation of the
canonical Wnt pathway in our cell lines. Immunofluorescence staining, protein expression in subcellular fractions for beta-catenin,
and assays for activation of the canonical Wnt/beta-catenin signaling were studied in the PTEN downregulated cells. There
was an overall decrease in β-catenin expression in cells with PTEN knockdown. The distribution of β-catenin was more diffuse
within the cell in the PTEN-reduced clones when compared to controls where they were mostly present in cell borders. Signaling
through the canonical pathway was also reduced in the PTEN knockdown cells when compared to control. The results of this study
suggest that while decreased PTEN augments cell proliferation and positively affects differentiation, there is a decrease
in β-catenin levels and activity in osteoblasts. Therefore, at least in osteoblasts, β-catenin is not responsible for mediating
the activation of osteoblast differentiation with reduction in PTEN function. 相似文献
3.
Yuan RT Young S Liang J Schmid MC Mielgo A Stupack DG 《Apoptosis : an international journal on programmed cell death》2012,17(3):229-235
Caspase-8 can trigger cell death following prodomain-mediated recruitment to the ‘death-inducing signaling complex.’ The prodomain
consists of two death effector domain (DED) motifs that undergo homotypic interactions within the cell. Aside from mediating
recruitment of procaspase-8, the prodomains have also been implicated in regulating cell survival, proliferation, death, senescence,
differentiation, and substrate attachment. Here, we perform the initial characterization of a novel isoform of caspase-8,
designated caspase-8 isoform 6 (Casp-8.6), which encodes both prodomain DEDs followed by a unique C-terminal tail. Casp-8.6
is detected in cells of the hematopoietic compartment as well as several other tissues. When Casp-8.6 expression is reconstituted
in caspase-8-deficient cells, Casp-8.6 does not significantly impact cellular proliferation, contrasting with our previous
results using a domain-defined ‘DED-only’ construct that lacks the C-terminal tail. Like the DED-only construct, Casp-8.6
also robustly forms ‘death effector’ filaments, but in contrast to the DED construct, it does not exhibit a dependence upon
intact microtubules to scaffold filament formation. Both types of death effector filaments promote apoptosis when expressed
in the presence of full length caspase-8 (isoform 1). Together, the results implicate Casp-8.6 as a new physiological modulator
of apoptosis. 相似文献
4.
In Craterostigmus tasmanianus, first results of the cellular organization of anal organs within the ’ano-genital’ capsule are presented. Each valve of the
’ano-genital’ capsule bears four pore fields ventrally, each of them consisting of several pore openings of the anal organs.
The pores lead into a cuticle-lined pore channel, the base of which is surrounded by a single-layered epithelium that is composed
of three different cell types. The main epithelium consists of radially arranged transport-active cells surrounded by exocrine
cells, and the cells of the pore channel. The cells of the transporting epithelium show deep invaginations of the apical and
basal cell surfaces and plasmalemma-mitochondrial complexes. These cells are covered by a specialized cuticle with a prominent
subcuticle. Exocrine glands secrete a mucous layer on the cuticle of the main epithelium. The type of anal organ present in
Craterostigmus tasmanianus shows similarities to coxal and anal organs found in other Pleurostigmophora in the chilopods. The possible function of the
anal organs in uptaking water vapour is discussed. It is appropriate to call the organs within the ’ano-genital’ capsule of
Craterostigmus tasmanianus ”anal organs”, as components of the genital segments are not involved.
Accepted: 17 November 1996 相似文献
5.
Summary Isolation and maintenance of porcine embryonic stem (pES) cells have been hindered by the inability to inhibit differentiation
of the porcine inner cell mass (pICM) in vitro. Culture conditions currently in use have been developed from mouse ES cell culture and are not effective for maintaining
the pICM. Optimizing culture conditions for the pICM is essential. We have developed a grading system to detect changes in
the differentiation status of in vitro cultured pICM. Porcine ICMs (Day 7) were isolated by immunosurgery and cultured for 4 d in either Dulbecco’s modified Eagle’s
medium (DMEM)-based medium (D medium) or DMEM/Ham’s F-10 (1:1)-based medium (D/H medium) with or without human Leukemia Inhibitory
Factor (hLIF, 1000 iu/ml). Colonies were photographed daily for morphological analysis. pICMs were categorized into one of
two types based on their morphological profile: type A, nonepithelial or type B, epithelial-like. Eight investigators evaluated
pICM differentiation using standardized differentiation profiles. Each pICM series was graded on a scale of 1 (fully undifferentiated)
to 5 (fully differentiated) for each time point. Differentiation was verified by alkaline phosphatase activity, cytokeratin
staining, and scanning electron microscopy. Neither hLIF nor culture medium delayed differentiation of pICMs (P=0.08 and P=0.25, respectively). The grading system employed was an effective tool for detecting treatment effects on differentiation
of the developing pICM. These results demonstrate that hLIF cannot significantly inhibit differentiation of the pICM, and
is unlikely to assist in porcine ES cell isolation. Future experiments utilizing homologous cytokines may prove more beneficial. 相似文献
6.
Embryonic stem cells, totipotent cells of the early mouse embryo, were established as permanent cell lines of undifferentiated
cells. ES cells provide an important cellular system in developmental biology for the manipulation of preselected genes in
mice by using the gene targeting technology. Embryonic stem cells, when cultivated as embryo-like aggregates, so-called ‘embryoid
bodies’, are able to differentiate in vitro into derivatives of all three primary germ layers, the endoderm, ectoderm and
mesoderm. We established differentiation protocols for the in vitro development of undifferentiated embryonic stem cells into
differentiated cardiomyocytes, skeletal muscle, neuronal, epithelial and vascular smooth muscle cells. During differentiation,
tissue-specific genes, proteins, ion channels, receptors and action potentials were expressed in a developmentally controlled
pattern. This pattern closely recapitulates the developmental pattern during embryogenesis in the living organism. In vitro,
the controlled developmental pattern was found to be influenced by differentiation and growth factor molecules or by xenobiotics.
Furthermore, the differentiation system has been used for genetic analyses by ‘gain of function’ and ‘loss of function’ approaches
in vitro.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Differentiation of embryonic stem cell (ESC)-derived embryoid bodies (EBs) is a heterogeneous process. ESCs can differentiate
in vitro into different cell types including beating cardiomyocytes. The main aim of the present study was to develop an improved
preparation method for scanning electron microscopic study of ESC-derived cardiac bundles and to investigate the fine structural
characteristics of mouse ESCs-derived cardiomyocytes using electron microscopy. The mouse ESCs differentiation was induced
by EBs’ development through hanging drop, suspension and plating stages. Cardiomyocytes appeared in the EBs’ outgrowth as
beating clusters that grew in size and formed thick branching bundles gradually. Cardiac bundles showed cross striation even
when they were observed under an inverted microscope. They showed a positive immunostaining for cardiac troponin I and α-actinin.
Transmission and scanning electron microscopy (TEM & SEM) were used to study the structural characteristics of ESC-derived
cardiomyocytes. Three weeks after plating, differentiated EBs showed a superficial layer of compact fibrous ECM that made
detailed observation of cardiac bundles impossible. We tried several preparation methods to remove unwanted cells and fibers,
and finally we revealed the branching bundles of cardiomyocytes. In TEM study, most cardiomyocytes showed parallel arrays
of myofibrils with a mature sarcomeric organization marked by H-bands, M-lines and numerous T-tubules. Cardiomyocytes were
connected to each other by intercalated discs composed of numerous gap junctions and fascia adherences. 相似文献
8.
Human mesenchymal stem cells (hMSCs) are able to self-replicate and differentiate into a variety of cell types including osteoblasts,
chondrocytes, adipocytes, endothelial cells, and muscle cells. It was reported that fibroblast growth factor-2 (FGF-2) increased
the growth rate and multidifferentiation potentials of hMSCs. In this study, we investigated the genes involved in the promotion
of osteogenic and chondrogenic differentiation potentials of hMSCs in the presence of FGF-2. hMSCs were maintained in the
medium with FGF-2. hMSCs were harvested for the study of osteogenic or chondrogenic differentiation potential after 15 days’
culture. To investigate osteogenic differentiation, the protein levels of alkaline phosphatase (ALP) and the mRNA expression
levels of osteocalcin were measured after the induction of osteogenic differentiation. Moreover, the investigation for chondrogenic
differentiation was performed by measuring the mRNA expression levels of type II and type X collagens after the induction
of chondrogenic differentiation. The expression levels of ALP, type II collagen, and type X collagen of hMSCs cultured with
FGF-2 were significantly higher than control. These results suggested that FGF-2 increased osteogenic and chondrogenic differentiation
potentials of hMSCs. Furthermore, microarray analysis was performed after 15 days’ culture in the medium with FGF-2. We found
that the overall insulin-like growth factor-I (IGF-I) and transforming growth factor-β (TGF-β) signaling pathways were inactivated
by FGF-2. These results suggested that the inactivation of IGF-I and TGF-β signaling promotes osteogenic and chondrogenic
differentiation potential of hMSCs in the presence of FGF-2. 相似文献
9.
Loeb MJ Martin PA Narang N Hakim RS Goto S Takeda M 《In vitro cellular & developmental biology. Animal》2001,37(6):348-352
Summary Differentiated cells in the insect midgut depend on stem cells for renewal. We have immunologically identified Integrin β1, a promotor of cell-cell adhesion that also induces signals mediating proliferation, differentiation, and apoptosis on the
surfaces of culturedHeliothis virescens midgut cells; clusters of immunostained integrin β1-like material, indicative of activated integrin, were detected on aggregating midgut columnar cells. Growth factor-like peptides
(midgut differentiation factors 1 and 2 [MDF1 and MDF2]), isolated from conditioned medium containingManduca sexta midgut cells, may be representative of endogenous midgut signaling molecules. Exposing the cultured midgut cells toBacillus thuringiensis (Bt) toxin caused large numbers of mature differentiated cells to die, but the massive cell death simultaneously induced
a 150–200% increase in the numbers of midgut stem and differentiating cells. However, after the toxin was washed out, the
proportions of cell types returned to near-control levels within 2 d, indicating endogenous control of cell-population dynamics.
MDF1 was detected immunologically in larger numbers of Bt-treated columnar cells than controls, confirming its role in inducing
the differentiation of rapidly produced stem cells. However, other insect midgut factors regulating increased proliferation,
differentiation, as well as inhibition of proliferation and adjustment of the ratio of cell types, remain to be discovered.
Products mentioned in this article are not endorsed by the U.S. Department of Agriculture. 相似文献
10.
Bakhshalizadeh S Esmaeili F Houshmand F Shirzad H Saedi M 《In vitro cellular & developmental biology. Animal》2011,47(8):550-557
Selegiline, the irreversible inhibitor of monoamine oxidase B (MAO-B), is currently used to treat Parkinson’s disease. However,
the mechanism of action of selegiline is complex and cannot be explained solely by its MAO-B inhibitory action. It stimulates
gene expression, as well as expression of a number of mRNAs or proteins in nerve and glial cells. Direct neuroprotective and
anti-apoptotic actions of selegiline have previously been observed in vitro. Previous studies showed that selegiline can induce
neuronal phenotype in cultured bone marrow stem cells and embryonic stem cells. Embryonal carcinoma (EC) cells are developmentaly
pluripotene cells which can be differentiated into all cell types under the appropriate conditions. The present study was
carried out to examine the effects of selegiline on undifferentiated P19 EC cells. The results showed that selegiline treatment
had a dramatic effect on neuronal morphology. It induced the differentiation of EC cells into neuron-like cells in a concentration-dependent
manner. The peak response was in a dose of selegiline significantly lower than required for MAO-B inhibition. The differentiated
cells were immunoreactive for neuron-specific proteins, synaptophysin, and β-III tubulin. Stem cell therapy has been considered
as an ideal option for the treatment of neurodegenerative diseases. Generation of neurons from stem cells could serve as a
source for potential cell therapy. This study suggests the potential use of combined selegiline and stem cell therapy to improve
deficits in neurodegenerative diseases. 相似文献
11.
Matrix and TGF-β-related gene expression during human dental pulp stem cell (DPSC) mineralization 总被引:2,自引:0,他引:2
Liu J Jin T Chang S Ritchie HH Smith AJ Clarkson BH 《In vitro cellular & developmental biology. Animal》2007,43(3-4):120-128
We have recently reported the induction of dental pulp stem cells (DPSCs) into dentin-secreting odontoblast-like cells after
stimulation by isolated dentin matrix components, thus mimicking the nature of tissue regeneration seen after tooth disease
and injury. After confluency, the cells were further cultured for 21 d in the 10% fetal bovine serum (FBS) Dulbecco’s modified
Eagle’s medium (DMEM) (control), and in this medium, with the addition of dentin extract (DE) and the mineralization supplement
(MS) of ascorbic acid and β-glycerophosphate (treatment). To identify genes associated with this process, specimens were analyzed
with a HG-U133A human gene chip and Arrayassist software. A total of 425 genes, among them 21 matrix and eight TGF-β-related
genes, were either up- or downregulated in the experimental group in which the cells showed odontoblast-like differentiation
and mineralization. Expression of selected genes was further confirmed by real-time polymerase chain reaction (PCR) analysis.
Of the extracellular matrix (ECM)-related genes, two types of collagen genes were upregulated and seven others downregulated.
Other ECM-related genes, for example fibulin-1, tenascin C, and particularly thrombospondin 1, were upregulated, and fibulin-2
was downregulated. Most noticeably, the matrix metalloproteinase 1 was induced by the treatment. In the TGF-β superfamily,
upregulation of the type II receptor, endoglin, and growth/differentiation factor 5 was coordinated with the downregulation
of activin A, TGF-β2, and TGF-β1 itself. This study identifies the matrix and TGF-β-related gene profiles during the DPSC
cell mineralization in which several genes are reported for the first time to be associated with this process, thus greatly
expanding our molecular knowledge of the induced disease repair process. 相似文献
12.
Cytokine effect on ex vivo expansion of haemopoietic stem cells from different human sources 总被引:3,自引:0,他引:3
Sandro Eridani Umberto Mazza Paolo Massaro Maria Luisa La Targia Anna Teresa Maiolo Andrea Mosca 《Biotherapy》1998,11(4):291-296
Human pluripotential stem cells (PSC) are currently the target for transplantation attempts and genetic manipulation. We have
therefore investigated the frequency and the expansion potential of PSC’s in different types of blood samples. CD 34+ cells were thus obtained from human bone marrow (BM), as well as from peripheral blood (PB) and cord blood (CB) samples.
After immuno-magnetic separation the highest yields of CD 34+ cells were from BM (1.08–2.25%) and CB (0.42–1.32%) while PB samples gave much lower values. Suspension cultures of PSC’s
from the three sources were then set up, in the presence of combinations of haemopoietic growth factors. A remarkable amplification
of the nucleated cell pool was observed reaching a maximum between 10 and 15 days of culture; earliest and maximum expansion
(up to 220-fold) was achieved when Erythropoietin (Epo) was added to the culture medium, but this resulted in reduction of
colony-forming cells and differentiation into erythroid progenitors. Clonogenic tests for BFU-E’s derived colonies showed
a peak value at 5 days of liquid culture. Further studies are advisable to establish the best cytokine combination for a valuableex vivo expansion, coupled with preservation of stem cell properties. 相似文献
13.
F. Bertolero M. E. Kaighn R. F. Camalier U. Saffiotti 《In vitro cellular & developmental biology. Plant》1986,22(7):423-428
Summary Mouse epidermal keratinocytes (MK cells) were grown as replicating subcultures at clonal density, in a serum-free, low calcium
basal medium supplemented with seven different growth factors (Bertolero et al., Exp. Cell. Res. 155:64–80, 1984). This serum-free
system was used to investigate the activity of cells. bovine serum (FBS) and of serum-derived factors on the growth and differentiation
of MK cells. Unfractionated, whole FBS inhibited growth and induced terminal differentiation of normal MK cells. The growth
inhibitory activity was considerably reduced by passing whole FBS over a resin (Chelex) to remove Ca2+ and other di- and trivalent cations. It is not known whether this treatment removed other factors.
Addition of individual serum components either stimulated or inhibited cell-growth and differentiation. Fetuin, a major α-globulin
of FBS, and high density lipoprotein strongly inhibited the colony forming efficiency (CFE) of MK cells, whereas bovine serum
albumin increased the CFE 4.5-fold and stimulated the growth rate as well. The addition of impure commercial preparations
of platelet-derived growth factor inhibited the CFE and induced the morphological features of squamous terminally-differentiating
keratinocytes.
As reported in other systems, transforming growth factor beta (TGF-β) inhibited the growth of secondary keratinocytes in a
dose-dependent manner. Thus, at least three factors present in FBS inhibited growth whereas others were stimulatory. These
observations explain the difficulties in obtaining replicating subcultures of mouse keratinocytes in serum-supplemented media
and emphasize the importance of a serum-free system for studies on growth control and carcinogenesis in keratinocytes.
Editor’s Statement This report contributes significantly to our knowledge of keratinocyte cell biology in two ways. First,
a serum-free medium has been developed that can now be used by many investigators to define growth versus differentiation
factors for these cells. This is important since several impure or relatively crude preparations of factors are known to influence
these cells. Second, the finding that TGF-Beta is an inhibitor of keratinocyte growth opens new avenues to investigate the
biochemical events leading to differentiation. David A. Sirbasku 相似文献
14.
Pontes B Viana NB Campanati L Farina M Neto VM Nussenzveig HM 《European biophysics journal : EBJ》2008,37(2):121-129
We investigate properties of a reported new mechanism for cell–cell interactions, tunneling nanotubes (TNT’s). TNT’s mediate
actin-based transfer of vesicles and organelles and they allow signal transmission between cells. The effects of lateral pulling
with polystyrene beads trapped by optical tweezers on TNT’s linking separate U-87 MG human glioblastoma cells in culture are
described. This cell line was chosen for handling ease and possible pathology implications of TNT persistence in communication
between cancerous cells. Observed nanotubes are shown to have the characteristic features of TNT’s. We find that pulling induces
two different types of TNT bifurcations. In one of them, termed V-Y bifurcation, the TNT is first distorted into a V-shaped
form, following which a new branch emerges from the apex. In the other one, termed I-D bifurcation, the pulled TNT is bent
into a curved arc of increasingly broader span. Curves showing the variation of pulling force with displacement are obtained.
Results yield information on TNT structure and elastic properties.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
Growth factor regulation of proliferation in primary cultures of small intestinal epithelium 总被引:1,自引:0,他引:1
C. Booth G. S. Evans C. S. Potten 《In vitro cellular & developmental biology. Animal》1995,31(3):234-243
Summary Although the intestinal epithelium is one of the most rapidly renewing tissues, little is known about the major growth factors
that control the rate of cell replacement and migration. Recently, a primary culture model has been described for the developing
rat small intestinal epithelium, which permits epithelial growth while maintaining interactions with associated stromal cells,
thereby possessing several contextual advantages over established cell lines (Evans et al., 1992). We have used this model
to begin to determine the factors that may be involved in controlling intestinal epithelial cell proliferation. Under the
conditions examined, no single growth factor promoted exclusive proliferation of epithelial cells; stromal cell proliferation
was also apparent. The most potent stimulators of epithelial proliferation were insulin and insulin-like growth factor 1 (IGF-1).
These factors also appeared to inhibit migration of the epithelial cells. 5–10 ng/ml EGF, 5–20 ng/ml TGFα, and 10–20 ng/ml
PDGF also slightly increased epithelial cell numbers. Cell proliferation was inhibited by 0.1 ng/ml TGFβ-1. In Dulbecco’s
modified Eagle’s medium (DMEM) containing 0.25 IU/ml insulin, glucose levels of 2–3 g/liter permitted epithelial growth with
limited expansion of the stromal cell population. Higher levels of glucose further stimulated the nonepithelial cell types.
Transferrin was also a potent stimulator of both cell types. 相似文献
16.
A method for the isolation and serial propagation of keratinocytes,endothelial cells,and fibroblasts from a single punch biopsy of human skin 总被引:5,自引:0,他引:5
Summary When multiple types of cells from normal and diseased human skin are required, techniques to isolate cells from small skin
biopsies would facilitate experimental studies. The purpose of this investigation was to develop a method for the isolation
and propagation of three major cell types (keratinocytes, microvascular endothelial cells, and fibroblasts) from a 4-mm punch
biopsy of human skin.
To isolate and propagate keratinocytes from a punch biopsy, the epidermis was separated from the dermis by treatment with
dispase. Keratinocytes were dissociated from the epidermis by trypsin and plated on a collagen-coated tissue culture petri
dish. A combination of two commercial media (Serum-Free Medium and Medium 154) provided optimal growth conditions.
To isolate and propagate microvascular endothelial cells from the dermis, cells were released following dispase incubation
and plated on a gelatin-coated tissue culture dish. Supplementation of a standard growth medium with a medium conditioned
by mouse 3T3 cells was required for the establishment and growth of these cells. Epithelioid endothelial cells were separated
from spindle-shaped endothelial cells and from dendritic cells by selective attachment toUlex europeus agglutinin I-coated paramagnetic beads.
To establish fibroblasts, dermal explants depleted of keratinocytes and endothelial cells were attached to plastic by centrifugation,
and fibroblasts were obtained by explant culture and grown in Dulbecco’s modified Eagle’s medium (DMEM) containing fetal bovine
serum (FBS).
Using these isolation methods and growth conditions, two confluent T-75 flasks of keratinocytes, one confluent T-25 flask
of purified endothelial cells, and one confluent T-25 flask of fibroblasts could be routinely obtained from a 4-mm punch biopsy
of human skin. This method should prove useful in studies of human skin where three cell types must be grown in sufficient
quantities for molecular and biochemical analysis. 相似文献
17.
18.
An isologous diversification theory for cell differentiation is proposed, based on simulations of interacting cells with biochemical
networks and the cell division process following consumption of some chemicals. According to the simulations of the interaction-based
dynamical systems model, the following scenario of the cell differentiation is proposed. (1) Up to some threshold number,
divisions bring about almost identical cells with synchronized biochemical oscillations. (2) As the number is increased, the
oscillations lose synchrony, leading to groups of cells with different phases of oscilaations. (3) Amplitudes of oscillation
and averaged chemical compositions start to differ by groups of cells. The differentiated behavior of states is transmitted
to daughter cells. (4) Recursivity is formed so that the daughter cells keep the identical chemical character. This “memory”
is made possible through the transfer of initial conditions. (5) Successive differentiation proceeds.
The mechanism of tumor cell formation, origin of stem cells, anomalous differentiation by transplantations, apoptosis and
other features of cell differentiation process are also discussed, with some novel predictions. 相似文献
19.
John F. Fullard Abhijit Kale Nicholas E. Baker 《Apoptosis : an international journal on programmed cell death》2009,14(8):1029-1037
Apoptotic corpses can be engulfed and cleared by many other cell types in addition to ‘professional’ phagocytes such as macrophage.
Studies of several organisms have contributed to the understanding of apoptotic corpse engulfment. Two partially redundant
engulfment pathways have been characterized that act even in non-professional phagocytes to promote corpse engulfment. This
review summarizes some recent progress in signaling by these pathways, including the exposure of eat-me-signals on apoptotic
cells, and insights from Drosophila on the roles of the bridging receptor Six Microns Under, the non-receptor tyrosine kinase Shark, and store-operated calcium
release in the Draper/Ced-1 pathway of corpse recognition and internalization. The mechanism of apoptotic phagosome maturation
is outlined, and possible connections between corpse engulfment and proliferation, cell competition, and immunity are discussed. 相似文献
20.
Bieberich E 《Neurochemical research》2012,37(6):1208-1229
Lipids are often considered membrane components whose function is to embed proteins into cell membranes. In the last two decades,
studies on brain lipids have unequivocally demonstrated that many lipids have critical cell signaling functions; they are
called “bioactive lipids”. Pioneering work in Dr. Robert Ledeen’s laboratory has shown that two bioactive brain sphingolipids,
sphingomyelin and the ganglioside GM1 are major signaling lipids in the nuclear envelope. In addition to derivatives of the
sphingolipid ceramide, the bioactive lipids discussed here belong to the classes of terpenoids and steroids, eicosanoids,
and lysophospholipids. These lipids act mainly through two mechanisms: (1) direct interaction between the bioactive lipid
and a specific protein binding partner such as a lipid receptor, protein kinase or phosphatase, ion exchanger, or other cell
signaling protein; and (2) formation of lipid microdomains or rafts that regulate the activity of a group of raft-associated
cell signaling proteins. In recent years, a third mechanism has emerged, which invokes lipid second messengers as a regulator
for the energy and redox balance of differentiating neural stem cells (NSCs). Interestingly, developmental niches such as
the stem cell niche for adult NSC differentiation may also be metabolic compartments that respond to a distinct combination
of bioactive lipids. The biological function of these lipids as regulators of NSC differentiation will be reviewed and their
application in stem cell therapy discussed. 相似文献