Regeneration of Cytologically Stable Plants Through Dedifferentiation, Redifferentiation, and Artificial Seeds in Spathoglottis plicata Blume.(Orchidaceae)

Spathoglottis plicata Blume. is a horticulturally important vulnerable ground orchid with beautiful flowers blooming round the year. Highfrequency protocorm-like body(PLB) formation was established via callus culture from vegetative tissues of in vitro germinated seedlings of S.plicata. Media containing MS salts and Gamborg's B5 vitamins supplemented with 1.0 mg·L^(-1) 2,4-dichlorophenoxyacetic acid(2,4-D), 3.0 mg·L^(-1) α-naphthaleneacetic acid(NAA), 1.0 mg·L^(-1) kinetin(KIN), and 10%(v/v) ‘Aloe vera gel'(Av G) were effective in fragile calli induction. A maximum of(22.3 ± 0.52) PLBs were induced from about 250 mg callus within 45–55 days in the presence of 2.0 mg·L^(-1) NAA and 3.0 mg·L^(-1) 6-benzylaminopurine(BAP). Briefly, 3.0% sodium alginate was found to be most suitable for the formation of an appropriate shape and good germination rates(86.7%)of artificial seeds. Out of three different temperatures(4, 15, and 24 °C), the best result was achieved at 4 °C with 66.7% germinability even after90 days of storage. Plantlets were acclimatized with 86.6% survival rate and 76.3% of these plants produced flowers within 12–15 months of field transfer. Chromosomal studies revealed cytological stability of all regenerants containing 2 n = 40 chromosomes as in the parental plants.The present protocol can be applied reliably for the purposes of large-scale commercial propagation and short-term conservation of this orchid.

Mechanism of Ascorbic Acid-induced Reversion Against Malignant Phenotype in Human Gastric Cancer Cells

Objective To find out the mechanisms of redifferentiation and reversion of malignant human gastric cancer cells induced by ascorbic acid. Methods Human gastric cancer cells grown in the laboratory were used. The Trypan blue dye exclusion method was used to determine the cell doubling time. The electrophoresis rate and colonogenic potential were the indices used to measure the rate of redifferentiation. The content of malondialdehyde （MDA） was measured using the thiobarbituric acid （TBA） method. The activities of superoxide dismutase （SOD）, catalase （CAT） and the content of H2O2 were evaluated by spectrophotography. Results Six mmol/L ascorbic acid was used as a positive control. Human gastric cancer cells were treated with 75 μm hydrogen peroxide, which alleviated many of the malignant characteristics. For example, the cell surface charge obviously decreased and the electrophoresis rate dropped from 2.21 to 1.10 pm·s^-1·cm^-1 The colonogenic potential, a measure of cell differentiation, decreased 90.2%. After treatment with ascorbic acid, there was a concentration- and time-dependent increase in hydrogen peroxide （H2O2） and the activity of superoxide dismutase （SOD）. However, the activity of catalase （CAT） resulted in a concentration- and time-dependent decrease. SOD and 3-amino- 1,2,4-triazole （AT） exhibited some effects, but there were statistically significant differences between the SOD and AT group and the H2O2 group, Conclusions Ascurbic acid induces growth inhibition and redifferentiation of human gastric cancer cells through the production of hydrogen peroxide.

Cell Fate Switch during In Vitro Plant Organogenesis

Plant mature cells have the capability to reverse their state of differentiation and produce new organs under cultured conditions. Two phases, dedifferenUation and redifferentiation, are commonly characterized during in vitro organogenesis. In these processes, cells undergo fate switch several times regulated by both extrinsic and intrinsic factors, which are associated with reentry to the cell cycle, the balance between euchromatin and heterochromatin, reprogramming of gene expression, and so forth. This short article reviews the advances in the mechanism of organ regeneration from plant somatic cells in molecular, genomic and epigenetic aspects, aiming to provide important information on the mechanism underlying cell fate switch during in vitro plant organogenesis.

Transcriptional control of pancreaticβ-cell identity and plasticity during the pathogenesis of type 2 diabetes

Type 2 diabetes(T2D)is caused by insulin resistance and insufficient insulin secretion.Evidence has increasingly indicated that pancreaticβ-cell dysfunction is the primary determinant of T2D disease progression and remission.High plasticity is an important feature of pancreaticβ-cells.During T2D development,pancreaticβ-cells undergo dynamic adaptation.Althoughβ-cell death/apoptosis in later-stage T2D is the major cause ofβ-cell dysfunction,recent studies have revealed thatβ-cell dedifferentiation and reprogramming,which play critical roles inβ-cell functional regulation in the early and middle T2D progression stages,are characterized by(i)a loss of matureβ-cell-enriched genes;(ii)dedifferentiation to a progenitor-like state;and(iii)transdifferentiation into other cell types.The roles of transcription factors(TFs)in the establishment and maintenance ofβ-cell identity during pancreatic development have been extensively studied.Here,we summarize the roles and underlying mechanisms of TFs in the maintenance ofβ-cell identity under physiological and type 2 diabetic conditions.Several feasible approaches for restoring islet functions are also discussed.A better understanding of the transcriptional control ofβ-cell identity and plasticity will pave the way for developing more effective strategies,such asβ-cell regeneration therapy,to treat T2D and associated metabolic disorders.

Capsaicin restores sodium iodine symportermediated radioiodine uptake through bypassing canonical TSH–TSHR pathway in anaplastic thyroid carcinoma cells

Anaplastic thyroid cancer(ATC)is a rare but highly lethal disease.ATCs are resistant to standard therapies and are extremely difficult to manage.The stepwise cell dedifferentiation results in the impairment of the iodine-metabolizing machinery and the infeasibility of radioiodine treatment in ATC.Hence,reinducing iodine-metabolizing gene expression to restore radioiodine avidity is considered as a promising strategy to fight against ATC.In the present study,capsaicin(CAP),a natural potent transient receptor potential vanilloid type 1(TRPV1)agonist,was discovered to reinduce ATC cell differentiation and to increase the expression of thyroid transcription factors(TTFs including TTF-1,TTF-2,and PAX8)and iodine-metabolizing proteins,including thyroidstimulating hormone receptor(TSHR),thyroid peroxidase,and sodium iodine symporter(NIS),in two ATC cell lines,8505C and FRO.Strikingly,CAP treatment promoted NIS glycosylation and its membrane trafficking,resulting in a significant enhancement of radioiodine uptake of ATC cells in vitro.Mechanistically,CAP-activated TRPV1 channel and subsequently triggered Ca2þinflux,cyclic adenosine monophosphate(cAMP)generation,and cAMP-responsive element-binding protein(CREB)signal activation.Next,CREB recognized and bound to the promoter of SLC5A5 to facilitate its transcription.Moreover,the TRPV1 antagonist CPZ,the calcium chelator BAPTA,and the PKA inhibitor H-89 effectively alleviated the redifferentiation exerted by CAP,demonstrating that CAP might improve radioiodine avidity through the activation of the TRPV1–Ca2þ/cAMP/PKA/CREB signaling pathway.In addition,our study indicated that CAP might trigger a novel cascade to redifferentiate ATC cells and provide unprecedented opportunities for radioiodine therapy in ATC,bypassing canonical TSH–TSHR pathway.