1,720,970 research outputs found
Characterization of hsp genes in planarian stem cells
No full textPlanarians are a model system known for regenerative potential, body plasticity and continuous turnover of all differentiated cell types. These characteristics are based on the presence of pluripotent stem cells, called neoblasts. Damage or reduction in the number of neoblasts deeply affects planarian regeneration and survival. Heat shock proteins (HSPs) are known to perform essential cytoprotective functions in all organisms. To investigate the potential role of hsp-related genes on the dynamics of planarian stem cells, representative hsp-related genes were identified and characterized in normal conditions and after different stress stimuli. Our work revealed that two different hsp genes (Djhsp60 and Djmot) are constitutively expressed in neoblasts, suggesting that their products play important roles in cytoprotection of these cells. RNAi-based functional studies provide evidence of an involvement of Djhsp60 and Djmot in the adaptive response of planarian stem cells to stress and indicate that expression of these genes is critical for planarian survival
Aiming to understand the mechanisms underlying the different responses to berberine among different cell lines
Full text linkBerberine, a bioactive natural isoquinoline alkaloid, is known
to generate a variety of pharmacological effects in different cell
types. Because of its ability to arrest the cell cycle and cause
apoptosis in several malignant cell lines, berberine has received
attention as a potential anticancer agent. To investigate the
mechanisms underlying the different responses to berberine, we
started to analyze its dose-dependent and time-dependent intracellular
localization in two human tumor cell lines: MIA PaCa-
2 (from pancreatic carcinoma), U343 (from glioblastoma).
Human dermal fibroblasts (HDF) were used as a non-tumor
control. Berberine presents natural green fluorescence, which
allows identification of the intracellular site of accumulation in
living cells. We found that the alkaloid may accumulate in different
cell compartments, with a dynamic dose-dependent and
time-dependent pattern of localization. The results revealed different
localization of berberine in cytoplasm and mitochondria
and/or nuclei in cancer cells with respect to non-tumor cells.
Moreover, berberine treatments reduced cell viability in a cell
line-specific manner. To further investigate the effects of berberine,
the expression profile of genes involved at different levels in
fundamental biological processes, was analyzed. As tumor suppressor
genes are often methylated in the process of carcinogenesis,
we evaluated DNMT1 and DNMT3B coding for maintenance
and de novo methyltransferases, respectively.
Additionally, MGMT, a geneencoding O6-methylguanine-DNA
methyltransferase, and recognized to play a crucial role in the
defense against chemotherapy alkylating agents, was analyzed.
As literature data demonstrate that berberine may induce apoptosis
in cancer cells but not in normal cells and this observation
is valuable for development of new anti-cancer therapies, we
also compared the variation in the gene expression level of cysteine-
aspartic acid protease 3 (CASP3) and the activity of this
enzyme in MIA PaCa-2, U343 and HDF cell lines. On the whole
the results indicate that berberine differentially affects the behaviour of MIA PaCa-2, U343, and non-tumor HDF cells
A mortalin-like gene is crucial for planarian stem cell viability
No full textSUMMARY - In adult organisms, stem cells are crucial to homeostasis and regeneration of damaged tissues. In planarians, adult stem cells (neoblasts) are endowed with an extraordinary replicative potential that guarantees unlimited replacement of all differentiated cell types and extraordinary regenerative ability. The molecular mechanisms by which neoblasts combine long-term stability and constant proliferative activity, overcoming the impact of time, remain by far unknown. Here we investigate the role of Djmot, a planarian orthologue that encodes a peculiar member of the HSP70 family, named Mortalin, on the dynamics of stem cells of Dugesia japonica. Planarian stem cells and progenitors constitutively express Djmot. Transient Djmot expression in differentiated tissues is only observed after X-ray irradiation. DjmotRNA interference causes inability to regenerate and death of the animals, as a result of permanent growth arrest of stem cells. These results provide the first evidence that an hsp-related gene is essential for neoblast viability and suggest the possibility that high levels of Djmot serve to keep a p53-like protein signaling under control, thus allowing neoblasts to escape cell death programs. Further studies are needed to unravel the molecular pathways involved in these processes
Berberine exposure triggers developmental effects on planarian regeneration
No full textThe mechanisms of action underlying the pharmacological properties of the natural alkaloid berberine still
need investigation. Planarian regeneration is instrumental in deciphering developmental responses
following drug exposure. Here we report the effects of berberine on regeneration in the planarian Dugesia
japonica. Our findings demonstrate that this compound perturbs the regenerative pattern. By real-time
PCR screening for the effects of berberine exposure on gene expression, we identified alterations in the
transcriptional profile of genes representative of different tissues, as well as of genes involved in extracellular
matrix (ECM) remodeling. Although berberine does not influence cell proliferation/apoptosis, our
experiments prove that this compound causes abnormal regeneration of the planarian visual system.
Potential berberine-induced cytotoxic effects were noticed in the intestine. Although we were unable to
detect abnormalities in other structures, our findings, sustained by RNAi-based investigations, support the
possibility that berberine effects are critically linked to anomalous ECM remodeling in treated planarians
A cellular and molecular study of the effects of chelidonine and berberine alkaloids on planarian regeneration
No full textIn vivo effects of natural compounds present in Chelidonium majus on stem cells using a simple animal model
No full textPlanarians are a well-known model for regeneration and provide an excellent system to study the
behavior of stem cells in vivo. Despite the potential attractiveness of planarians these organisms
have not been used yet in large-scale chemical screenings to see the effects of compounds on
different key aspects of regeneration as, for instance, stem cell proliferation and differentiation.
Our work focuses on the analysis of the effects produced by the main alkaloids (chelidonine,
berberine, sanguinarine, chelerytrine, protopine and coptisine) present in Chelidonium majus
(Papaveraceae), an herb showing interesting therapeutical properties. We demonstrate that
chelidonine produces a significant anti-proliferative effect on planarian stem cells, supporting the
possibility that this alkaloid acts on cell cycle progression by inhibition of tubulin polymerization.
Berberine treatment perturbs the regenerative pattern. Although berberine does not influence
cell proliferation/apoptosis, this compound causes abnormal regeneration of the planarian
visual system. Our findings, sustained by RNAi-based investigations, support the possibility that
berberine effects are critically linked to anomalous extracellular matrix remodeling. Abnormal
head regeneration has also been observed following sanguinarine treatment. Preliminary results
provide evidence that sanguinarine induces apoptosis through a caspase-dependent mechanism,
but does not influence cell proliferation. The study presented here might become a good test to
determine the potentiality of planarians as a model to analyze drug effects. At the same time,
such screenings and experiments could help to better understand the process of planarian
regeneration itself by providing novel information about how proliferation, differentiation and/or
morphogenesis and patterning are regulated during this amazing process
Effects of natural compounds present in Chelidonium majus on stem cells and embryo development
No full textDespite their potential attractiveness as model for regeneration, planarians have not been used yet in large-scale chemical screenings to test the effects of compounds on different key aspects of regeneration, such as stem cell proliferation and differentiation. Our work focuses on the analysis of the effects produced by the main alkaloids (chelidonine, berberine, sanguinarine) present in Chelidonium majus, an herb with therapeutical properties. The data obtained so far indicate that chelidonine generates anti-proliferative effects on planarian stem cells, possibly due to inhibition of tubulin polymerization, berberine induces a perturbation of the regenerative pattern and sanguinarine produces abnormal head regeneration. In particular, we find that berberine causes abnormal regeneration of the visual system, without affecting cell proliferation/apoptosis, while sanguinarine induces apoptosis through a caspase dependent mechanism. These results clearly indicate the potentiality of planarians as a model to analyze drug effects. We are currently exploiting the well-established zebrafish model to assess and compare the effects of the same compounds during vertebrate embryo development
La planaria come sistema modello per valutare in vivo il ruolo dei geni codificanti metalloproteasi di matrice durante l’omeostasi e la rigenerazione
No full textA planarian kuzbanian-like gene is a key regulator during regeneration of the nervous system
No full textKuzbanian is a crucial member of the ADAM family of metalloproteinases. Kuzbanian-mediated
cleavage of Notch represents in fact one of the fundamental steps leading to activation of the
Notch pathway during early neurogenesis. This enzyme also plays important roles in later stages
of neural development, modulating axon guidance and extension. Planarians are a model system
well known for regenerative potential. These characteristics depend on a population of adult stem
cells that guarantees replacement of all differentiated cell types, including nerve cells. Here we
report the functional characterization of a planarian Kuzbanian-like gene (Smed-kuzbanian3).
Smed-kuzbanian3 is expressed in the mesenchyme and in the central nervous system (CNS) and
is overexpressed during regeneration of this structure. Functional ablation of Smed-kuzbanian3
by RNAi causes abnormal CNS regeneration. Anomalous eye morphogenesis, including atypical
axonal projections of the optic chiasm, is observed. The architecture of the regenerating cephalic
ganglia also appears unusual, with an aberrant number and distribution of nerve cells. We
speculate that Smed-Kuzbanian3, similarly to that observed in other organisms, plays different
roles during CNS regeneration. To test whether Smed-kuzbanian3 plays a conserved role during
neurogenesis we plan to use Xenopus laevis embryos as a model system. Gain of function
experiments will allow us to demonstrate the involvement of Smed-kuzbanian3 in modulating
early Notch-mediated lateral inhibition mechanisms and the guidance of axonal extensions at
later developmental stages
The regenerative biology of the planarian model for evaluating the effects of isoquinoline alkaloids: a case study with berberine
No full text- …
