Feeds:
Posts
Comments

Posts Tagged ‘regulation of metabolism’


brown adipocyte protein CIDEA promotes lipid droplet fusion

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

 

 

The brown adipocyte protein CIDEA promotes lipid droplet fusion via a phosphatidic acid-binding

Parker, Nicholas T Ktistakis, Ann M Dixon, Judith Klein-Seetharaman, Susan Henry, Mark Christian Dirk Dormann, Gil-Soo Han, Stephen A Jesch, George M Carman, Valerian Kagan, et al.

eLife 2015;10.7554/eLife.07485     http://dx.doi.org/10.7554/eLife.07485

 

Maintenance of energy homeostasis depends on the highly regulated storage and release of triacylglycerol primarily in adipose tissue and excessive storage is a feature of common metabolic disorders. CIDEA is a lipid droplet (LD)-protein enriched in brown adipocytes promoting the enlargement of LDs which are dynamic, ubiquitous organelles specialized for storing neutral lipids. We demonstrate an essential role in this process for an amphipathic helix in CIDEA, which facilitates embedding in the LD phospholipid monolayer and binds phosphatidic acid (PA). LD pairs are docked by CIDEA trans-complexes through contributions of the N-terminal domain and a C-terminal dimerization region. These complexes, enriched at the LD-LD contact site, interact with the cone-shaped phospholipid PA and likely increase phospholipid barrier permeability, promoting LD fusion by transference of lipids. This physiological process is essential in adipocyte differentiation as well as serving to facilitate the tight coupling of lipolysis and lipogenesis in activated brown fat.

 

Evolutionary pressures for survival in fluctuating environments that expose organisms to times of both feast and famine have selected for the ability to efficiently store and release energy in the form of triacyclglycerol (TAG). However, excessive or defective lipid storage is a key feature of common diseases such as diabetes, atherosclerosis and the metabolic syndrome (1). The organelles that are essential for storing and mobilizing intracellular fat are lipid droplets (LDs) (2). They constitute a unique cellular structure where a core of neutral lipids is stabilized in the hydrophilic cytosol by a phospholipid monolayer embedding LD-proteins. While most mammalian 46 cells present small LDs (<1 Pm) (3), white (unilocular) adipocytes contain a single giant LD occupying most of their cell volume. In contrast, brown (multilocular) adipocytes hold multiple LDs of lesser size, increasing the LD surface/volume ratio which facilitates the rapid consumption of lipids for adaptive thermogenesis (4).

The exploration of new approaches for the treatment of metabolic disorders has been stimulated by the rediscovery of active brown adipose tissue (BAT) in adult humans (5, 6) and by the induction of multilocular brown-like cells in white adipose tissue (WAT) (7). The multilocular morphology of brown adipocytes is a defining characteristic of these cells along with expression of genes such as Ucp1. The acquisition of a unilocular or multilocular phenotype is likely to be controlled by the regulation of LD growth. Two related proteins, CIDEA and CIDEC promote LD enlargement in adipocytes (8-10), with CIDEA being specifically found in BAT. Together with CIDEB, they form the CIDE (cell death-inducing DFF45-like effector) family of LD-proteins, which have emerged as important metabolic regulators (11).

Different mechanisms have been proposed for LD enlargement, including in situ neutral lipid synthesis, lipid uptake and LD-LD coalescence (12-14). The study of CIDE 62 proteins has revealed a critical role in the LD fusion process in which a donor LD progressively transfers its content to an acceptor LD until it is completely absorbed (15). However, the underlying mechanism by which CIDEC and CIDEA facilitate the interchange of triacylglycerol (TAG) molecules between LDs is not understood. In the present study, we have obtained a detailed picture of the different steps driving this LD enlargement process, which involves the stabilization of LD pairs, phospholipid binding, and the permeabilization of the LD monolayer to allow the transference of lipids.

 

CIDEA expression mimics the LD dynamics observed during the differentiation of brown adipocytes

Phases of CIDEA activity: LD targeting, LD-LD docking and LD growth

A cationic amphipathic helix in C-term drives LD targeting

The amphipathic helix is essential for LD enlargement

LD-LD docking is induced by the formation of CIDEA complexes

CIDEC differs from CIDEA in its dependence on the N-term domain

CIDEA interacts with Phosphatidic Acid

PA is required for LD enlargement

 

The Cidea gene is highly expressed in BAT, induced in WAT following cold exposure (46), and is widely used by researchers as a defining marker to discriminate brown or brite adipocytes from white adipocytes (7, 28). As evidence indicated a key role in the LD biology (47) we have characterized the mechanism by which CIDEA promotes LD enlargement, which involves the targeting of LDs, the docking of LD pairs and the transference of lipids between them. The lipid transfer step requires the interaction of CIDEA and PA through a cationic amphipathic helix. Independently of PA-binding, this helix is also responsible for anchoring CIDEA in the LD membrane. Finally, we demonstrate that the docking of LD pairs is driven by the formation of CIDEA complexes involving the N-term domain and a C-term interaction site.

CIDE proteins appeared during vertebrate evolution by the combination of an ancestor N-term domain and a LD-binding C-term domain (35). In spite of this, the full process of LD enlargement can be induced in yeast by the sole exogenous expression of 395 CIDEA, indicating that in contrast to SNARE-triggered vesicle fusion, LD fusion by lipid transference does not require the coordination of multiple specific proteins (48). Whereas vesicle fusion implicates an intricate restructuring of the phospholipid bilayers, LD fusion is a spontaneous process that the cell has to prevent by tightly controlling their phospholipid composition (23). However, although phospholipid-modifying enzymes have been linked with the biogenesis of LDs (49, 50), the implication of phospholipids in physiologic LD fusion processes has not been previously described.

Complete LD fusion by lipid transfer can last several hours, during which the participating LDs remain in contact. Our results indicate that both the N-term domain and a C-term dimerization site (aa 126-155) independently participate in the docking of LD pairs by forming trans interactions (Fig. 7). Certain mutations in the dimerization sites that do not eliminate the interaction result in a decrease on the TAG transference efficiency, reflected on the presence of small LDs docked to enlarged LDs. This suggests that in addition to stabilizing the LD-LD interaction, the correct conformation of the 409 CIDEA complexes is necessary for optimal TAG transfer. Furthermore, the formation of stable LD pairs is not sufficient to trigger LD fusion by lipid transfer. In fact, although LDs can be tightly packed in cultured adipocytes, no TAG transference across neighbour LDs is observed in the absence of CIDE proteins (15), showing that the phospholipid monolayer acts as a barrier impermeable to TAG. Our CG-MD simulations indicate that certain TAG molecules can escape the neutral lipid core of the LD and be integrated within the aliphatic chains of the phospholipid monolayer. This could be a transition state 416 prior to the TAG transference and our data indicates that the docking of the amphipathic helix in the LD membrane could facilitate this process. However, the infiltrated TAGs in LD membranes in the presence of mutant helices, or even in the absence of docking, suggests that this is not enough to complete the TAG transference.

To be transferred to the adjacent LD, the TAGs integrated in the hydrophobic region of the LD membrane should cross the energy barrier defined by the phospholipid polar heads, and the interaction of CIDEA with PA could play a role in this process, as suggested by the disruption of LD enlargement by the mutations preventing PA-binding (K167E/R171E/R175E) and the inhibition of CIDEA after PA depletion. The minor effects observed with more conservative substitutions in the helix, suggests that the presence of positive charges is sufficient to induce TAG transference by attracting anionic phospholipids present in the LD membrane. PA, which requirement is indicated by our PA-depletion experiments, is a cone-shaped anionic phospholipid which could locally destabilize the LD monolayer by favoring a negative membrane curvature incompatible with the spherical LD morphology (51). Interestingly, while the zwitterion PC, the main component of the monolayer, stabilizes the LD structure (23), the negatively charged PA promote their coalescence (29). This is supported by our CD-MD results which resulted in a deformation of the LD shape by the addition of PA. We propose a model in which the C-term amphipathic helix positions itself in the LD monolayer and interacts with PA molecules in its vicinity, which might include trans interactions with PA in the adjacent LD. The interaction with PA disturbs the integrity of the phospholipid barrier at the LD-LD interface, allowing the LD to LD transference of TAG molecules integrated in the LD membrane (Fig. 7). Additional alterations in the LD composition could be facilitating TAG transference, as differentiating adipocytes experience a reduction in saturated fatty acids in the LD phospholipids (52), and in their PC/PE ratio (53) which could increase the permeability of the LD membranes, and we previously observed that a change in the molecular structures of TAG results in an altered migration pattern to the LD surface (32).

During LD fusion by lipid transfer, the pressure gradient experienced by LDs favors TAG flux from small to large LDs (15). However, the implication of PA, a minor component of the LD membrane, could represent a control mechanism, as it is plausible that the cell could actively influence the TAG flux direction by differently regulating the levels of PA in large and small LDs, which could be controlled by the activity of enzymes such as AGPAT3 and LIPIN-1J (13, 30). This is a remarkable possibility, as a switch in the favored TAG flux direction could promote the acquisition of a multilocular phenotype and facilitate the browning of WAT (24). Interestingly, Cidea mRNA is the LD protein- encoding transcript that experiences the greatest increase during the cold-induced process by which multilocular BAT-like cells appear in WAT (24). Furthermore, in BAT, cold exposure instigates a profound increase in CIDEA protein levels that is independent of transcriptional regulation (54). The profound increase in CIDEA is coincident with elevated lipolysis and de novo lipogenesis that occurs in both brown and white adipose tissues after E-adrenergic receptor activation (55). It is likely that CIDEA has a central role in coupling these processes to package newly synthesized TAG in LDs for subsequent lipolysis and fatty acid oxidation. Importantly, BAT displays high levels of glycerol kinase activity (56, 57) that facilitates glycerol recycling rather than release into the blood stream, following induction of lipolysis (58), which occurs in WAT. Hence, the reported elevated glycerol released from cells depleted of CIDEA (28) is likely to be a result of decoupling lipolysis from the ability to efficiently store the products of lipogenesis in LDs and therefore producing a net increase in detected extracellular glycerol. This important role of CIDEA is supported by the marked depletion of TAG in the BAT of Cidea null mice following overnight exposure to 4 °C (28) and our findings that CIDEA-dependent LD enlargement is maintained in a lipase negative yeast strain.

Cidea and the genes that are required to facilitate high rates of lipolysis and lipogenesis are associated with the “browning” of white fat either following cold exposure (46) or in genetic models such as RIP140 knockout WAT (59). The induction of a brown- like phenotype in WAT has potential benefits in the treatment and prevention of metabolic disorders (60). Differences in the activity and regulation of CIDEC and CIDEA could also be responsible for the adoption of unilocular or multilocular phenotypes. In addition to their differential interaction with PLIN1 and 5, we have observed that CIDEC is more resilient to the deletion of the N-term than CIDEA, indicating that it may be less sensitive to regulatory posttranslational modifications of this domain. This robustness of CIDEC activity together with its potentiation by PLIN1, could facilitate the continuity of the LD enlargement in white adipocytes until the unilocular phenotype is achieved. In contrast, in brown adipocytes expressing CIDEA the process would be stopped at the multilocular stage for example due to post-translational modifications that modulate the function or stability of the protein or alteration of the PA levels in LDs.

Read Full Post »


Larry H Bernstein, MD, FCAP, Contributor

https://pharmaceuticalintelligence.com/5-6-2014/larryhbern/ The Discovery_and_Properties_of_Avemar – Fermented_ Wheat_Germ_Extract:_Carcinogenesis_Suppressor

The following discussion will be a review of the current interest in Avemar, a nontoxic, fermentation product of wheat germ extract, garnering interest with respect to alternative and complementary medicinal use.

Extracts from an interview by Sandra Cascio with Mate Hidvegi

Mate’s Transylvania Professor Lajos David was the organizer of the Department of Pharmacy of the University of Szeged in the 1920’s. He was elected as the Dean of the Faculty of Medicine, the first and only pharmacist who reached this high position at the University since. Dr. Hidvegy’s grandfather was a devout Roman catholic, who publicly opposed Nazi persecution of Jews during the Holocaust. One of his colleagues and, perhaps his best friend, was Albert Szent­Gyorgyi, the Nobel laureate who discovered vitaminC. Szent­Gyorgyi moved to the United States after World War II, where he turned to studies of muscle biochemistry. In his later years he turned to cancer research. He  theorized that a revolutionary anticancer drug could be based upon vitamin C combined with methoxy­substituted benzoquinones, the precursors of which can be found in wheat germ. After completion of the PhD, Dr. Hidvegi spent two years with the Wheat Grain Trust in Winnipeg, Canada, before returning to Hungary in 1990.  He decided to followthepathwaythat Szent­Gyorgyi was now engaged intocompletehisgoals.He contacted anoldfriend,GaborFodor, a brilliantchemist, also a collaborator withSzent­Gyorgyiincancerresearch.

He wasinvited by Hermann Esterbauer, the head of the Institute of Biochemistry at the University of Graz, to work in his laboratory. Thanks to the generosity of Professor Esterbauer,  he accomplished much at Graz  together with his student, Dr. Rita Farkas.  It was soon after Szent­-Gyorgyi’s death when, with the help of Dr. Fodor, they prepared the chemicals to make the drug Szent­-Gyorgyi had intended to make, with encouragement from the great quantum­ biochemist, Janos Ladik.  They made wheat germ extracts with the highest free benzoquinone content.This required a  fermentation process to liberate the benzoquinone moieties from the chemical bonds which keep them in natural forms: in glycosides. He recalls the purple colored active molecules in the fermentation liquid. Living cells with their exo­ and endo­enzymes are used to split bonds and make new molecules. This is also true for the manufacturing process of Avemar. This extract contains new molecules which cannot be found elsewhere.

“WhenAvemar was voted by the majority of the more than 50,000 professionals for NutrAward, it became obvious that this product is of biological efficacy  plus safety, and it is based on good science.” It received the financial support needed. From this, he was able to complete the experiments and get the approval for the registration. The time arrived when he really had to give a name to the product which had only had a code name. One late night it just came: Avemar, from the Latin prayer: Ave Maria.

Avemar with widely used chemotherapeutic drugs completely inhibited the development of metastases. Exploring its whole activity profile might even take a lifetime of research. So far he has supervised Avemar research done in Hungary, Israel, the United States, Austria, Italy, Spain, Slovakia, the Czech Republic, Germany,the United Kingdom, Russia, Australia, Korea, Vietnam. It has been a good experience to see the scientific interest it has generated worldwide. In 2009, Dr. Hidvegy received an invitation from the Nobel laureate, James Watson, co­discoverer of DNA’s double helix. It was a great honor. Avemar, he hopes,will be a significant cancer drug.

Mate Hidvegi was born in Budapest, Hungary, in 1955. He studied, then  taughat what is now Budapest University of Technology  and Economics.  After finishing university, he worked in the cereal industry and was co­developer of patented feed advisory system based on near infrared ingredient      data. In Hungary, Hidvegi was one of the pioneers in the development of           technologies for large ­scale production of instantized extracts for  therapeutic use.

 

Carcinogenesis vol.22 no.10 pp.1649–1652, 2001

Wheat germ extract inhibits experimental colon carcino-genesis in F-344 rats

Attila Zalatnai, Karoly Lapis, Bela Szende, Erzsebet Raso, Andros Telekes, Akos Resetar, and Mate Hidvegi

 

It has been demonstrated for the first time that a wheat germ extract prevents colonic cancer in laboratory animals. Four-week-old inbred male F-344 rats were used in the study. Colon carcinogenesis was induced by azoxy-methane (AOM). Ten rats served as untreated controls (group 1). For the treatment of the animals in group 2, AOM was dissolved in physiologic saline and the animals were given three weekly subcutaneous injections at 15 mg/kg body weight (b/w). In two additional groups Avemar (MSC), a fermented wheat germ extract standardized to 2,6-dimethoxy-p-benzoquinone was administered as a tentative chemo-preventive agent. MSC was dissolved in water and was given by gavage at a dose of 3 g/kg b/w once a day. In group 3, animals started to receive MSC 2 weeks prior to the first injection of AOM daily and continuously thereafter until they were killed 32 weeks later. In group 4 only the basal diet and MSC were administered. At the end of the experiment all the rats were exsanguinated under a light ether anesthesia and necropsied. Percentage of animals developing colon tumors and number of tumors per animals: group 1 – 0 and 0; group 2– 83.0 and 2.3; group 3 – 44.8 (P ≤ 0.001) and 1.3 (P ≤ 0.004); group 4 – 0 and 0. All the tumors were histologically neoplastic. The numbers of the aberrant crypt foci (ACF) per area (cm2) in group 2 were 4.85 while in group 3 the ACF numbers were 2.03 only (P ≤ 0.0001).
Table I. Macroscopic findings in the large intestines of F-344 rats treated with MSC or MSC +  AOM
No. of animals     w/tumorw   Average
# tumors
Average
diameter

N

1 Untreated
controls (10)
0/10 0/10
2.  AOM (47) 39/47
(83.0%)
2.3 ­+ 0.21
(range 1–8)
2.35 +
0.25
3.   MSC +
AOM (29)
13/29
(44.8%)
1.3 + 0.17
(range 1–3)
2.21 +
0.12
4.  MSC (9) 0/9 0/9
Fig. 1. Experimental schedule. Colon carcinogenesis was induced by three consecutive s.c. doses of AOM 1 week apart in F-344 rats. Oral administration of MSC was started 2 weeks before the carcinogen treatments. All the animals were killed at the end of the experiment, e.g. on the 32nd week.  (not shown)

 

Summing up, although the chemoprevention of colon cancers (and their pre-neoplastic lesions) has well and long been established and could be achieved by totally different compounds, the mechanisms have still remained to be clarified. This is also true for MSC.

The exact mechanism by which the fermented wheat germ concentration can prevent colon cancer is still partly unknown. MSC did inhibit the AOM-induced ACF and colon neoplasm formation, the multiplicity of the tumors, apparently acting in the initiation phase. Regarding this, we can hypothesize that MSC acts as an immunomodulator.

 

Wheat Germ Extract Decreases Glucose Uptake and RNARibose Formation but Increases Fatty Acid Synthesis in MIAPancreatic Adenocarcinoma Cell

LG Boros, K Lapis, B Szende, R Tömösközi-Farkas, Ádám Balogh, …., and M Hidvégi

UCLA School of Medicine, Harbor-UCLA Research and Education Institute, Torrance, Ca.; First Institute of Pathology and Experimental Cancer Research, Semmelweis  Medical University, Budapest, Hungary; Central Food Research Institute, Budapest, Hungary; Department of Surgery, Albert Szent-Gyorgyi Medical and Pharmaceutical Center, School of General Medicine, University of Szeged, Szeged, Hungary; Department of Biochemistry and Molecular Biology, Institut d’Investigacions Biomediques August Pi i Sunyer, University of Barcelona, Barcelona, Spain; andDepartment of Biochemistryand Food Technology, Technical University of Budapest and Biromedicina Company, Budapest, Hungary

Pancreas 2001; 23 (2), pp. 141–147

Summary: The fermented wheat germ extract with standardized composition has potent tumor inhibitory properties. The fermented wheat germ extract controls tumor propagation. The authors show that this extract induces profound metabolic changes in cultured MIA pancreatic adenocarcinoma cells when the [1,2- 13C2] glucose isotope is used as the single tracer with biologic gas chromatography–mass spectrometry.

MIA cells treated with 0.1, 1, and 10 mg/mL wheat  germ extract showed a dose-dependent decrease in cell glucose consumption, consumption, uptake of isotope into ribosomal RNA (2.4%, 9.4%, and 8.0%), and release of 13CO2 . Conversely, direct glucose oxidation and ribose recycling in the pentose cycle showed a dose-dependent increase of 1.2%, 20.7%, and 93.4%. The newly synthesized fraction of cell palmitate and the 13C enrichment of acetyl units were also increased with all doses of wheat germ extract.

The fermented wheat germ extract controls tumor propagation primarily by regulating glucose carbon redistribution between cell proliferation–related and cell differentiation–related macromolecules. Wheat germ extract treatment is likely associated with the phosphor-ylation and transcriptional regulation of metabolic enzymes that are involved in glucose carbon redistribution between cell the direct oxidative degradation of glucose,proliferation–related structural and functional macromolecules(RNA, DNA) and the direct oxidative degradation and survival of pancreatic adenocarcinoma cells in culture.

Key Words: Pentose cycle—Ribose synthesis—Fermented wheat germ extract—Nonoxidative glucose metabolism—Cell proliferation—Avemar.

 

Fig 1 glu consumption of MIA pancreatic carcinoma cells in response to WGE

Fig 1 glu consumption of MIA pancreatic carcinoma cells in response to WGE

 

 

 

 

 

 

 

 

 

 

 

Figure 1. Glucose consumption of MIA pancreatic adenocarcinoma cells in response to increasing doses of fermented wheat germ extract (Avemar) treatment after 72 hours of culture. Glucose consumption (measured in milligrams) was estimated by the difference in media glucose content between Avemar-treated and control cultures. MIA cell glucose consumption was significantly inhibited in the presence of either 1 mg/mL (*p < 0.05) or 10 mg/mL (**p < 0.01) Avemar (x + SD;  n = 6).

 

fig-3-rna-syn-of-mia-pancreatic-carcinoma-cells-in-response-to-wge.jpg

fig-3-rna-syn-of-mia-pancreatic-carcinoma-cells-in-response-to-wge.jpg

 

 

 

 

 

 

 

 

 

 

 

Figure 3. Ribosomal RNA synthesis of MIA pancreatic adenocarcinoma cells in response to increasing doses of fermented wheat germ extract (Avemar) treatment after 72 hours of culture. Glucose carbon incorporation into ribose isolated from ribosomal RNA is expressed as molar enrichment. The dose-dependent decrease in of rRNA after Avemar treatment indicates that ribosomal RNA synthesis is the primary site significantly affected by all doses of Avemar treatment with a maximum decrease of 29% after 10 mg/mL treatment (x + SD; n = 9; *p < 0.05, **p < 0.01).

changes in metabolic activity indicate that Avemar treatment affects cell metabolism primarily by decreasing glucose uptake and nucleic acid ribose synthesis while increasing glucose oxidation through the oxidative reactions of the pentose cycle and fatty acid  synthesis from glucose carbon. The effect of Avemar treatment on lactate production and TCA cycle anapleurotic flux compared with glucose oxidation is less prominent

 

Fermented wheat germ extract induces apoptosis and downregulation of major histocompatibility complex class I proteins in tumor T and B cell lines

R FAJKA-BOJA, M HIDVÉGI, Y SHOENFELD, G  ION, D DEMYDENKO, R TÖMÖSKÖZI-FARKAS, et al.

INTL J ONCOLOGY 2002; 20: 563-570.

Lymphocyte Signal Transduction Laboratory, Institute of Genetics, and Cytokine Group, Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Szeged; Department of Biochemistry and Food Technology, Budapest University of Technology and Economics, Budapest, Hungary; Department of Medicine ‘B’, Center for Autoimmune Diseases, Sheba Medical Center, Tel-Hashomer, Israel; Central Food Research Institute; National Institute of Oncology; Biromedicina Co., Budapest, Hungary
Abstract. The fermented wheat germ extract (code name:  on cyto-fluorimeter using a monoclonal antibody to the  MSC, trade name: Avemar), with standardized benzoquinone non-polymorphic region of the human MHC class I. MSC  content has been shown to inhibit tumor propagation and stimulated tyrosine phosphorylation of intracellular proteins metastases formation in vivo. The aim of this study was to  understand the molecular and cellular mechanisms of the anti-tumor effect of MSC. Therefore, we have designed in vitro model experiments using T and B tumor lymphocytic cell lines. As a result of the MSC treatment, cell surface MHC class I proteins was downregulated by 70-85% compared to the non-stimulated control.

Prominent apoptosis of and the influx of extracellular Ca2+ resulted in elevation of the amount of the intracellular Ca2+ concentration. 20-40% was detected upon 24 h of MSC treatment of the cell lines. Apoptosis was measured with cytofluorimetry by staining the DNA with propidium iodide and detecting the ‘sub-G ’ cell population.

Tyrosine phosphorylation of intra-cellular proteins and elevation of the intracellular Ca2+ concentration were examined using immunoblotting with anti-phosphotyrosine antibody and cytofluorimetry by means of Ca2+ sensitive fluorescence dyes, Fluo-3AM and FuraRed-AM, respectively. MSC did not induce a similar degree of apoptosis in healthy peripheral blood mononuclear cells.

Inhibition of the cellular tyrosine phosphatase activity or Ca2+ influx resulted in the opposite effect – increasing or diminishing the Avemar induced apoptosis as well as the MHC class I downregulation. The level of the cell surface MHC class I molecules was analysed with indirect immunofluorescence. The benzoquinone component (2,6-dimethoxi-p-benzoquinone) in MSC induced similar apoptosis and downregulation of the MHC class I molecules in the tumor T and B cell lines to that of MSC. These results suggest that MSC acts on lymphoid tumor cells by reducing MHC class I expression and selectively promoting apoptosis of tumor cells on a tyrosine phosphorylation and Ca2+ influx dependent way.  One of the components in MSC, 2,6-dimethoxi-p-benzoquinone was shown to be an important factor in MSC mediated cell response.

 

Abbreviations:MHC, major histocompatibility complex;NK, natural killer;DMBQ, 2,6-dimethoxi-p-benzoquinone; FCS, fetal calf serum;PBMC, peripheral bloodmononuclear cells; TCR, T cell receptor;BCR, B cell receptor; mAb, monoclonal antibody;PMSF,phenylmethyl-sulfonylfluoride;pNPP, para-nitrophenyl-phosphate; PHA,phytohemagglutinineKey words: fermented wheat germ extract, Avemar, MSC, 2+ benzoquinone, tyrosine phosphorylation, intracellular Ca , CD45, tyrosine phosphatase, MHC class I downregulation, apoptosis

 

fig-4-apoptosis-of-t-cell-lines-induced-by-avamer.jpg

fig-4-apoptosis-of-t-cell-lines-induced-by-avamer.jpg

 

 

 

 

 

Figure 4. Apoptosis of tumor T cell lines and healthy lymphocytes upon MSC treatment. Jurkat cells were treated with 1 mg/ml MSC or .3 µg/ml DMBQ and PBMC were treated with 1 mg/ml
MSC for 24 h (A) or Jurkat cells were treated for 12 h (thick line in panel B). Control cells were left unstimulated (black bars in panel A or thin line on panel B). Apoptotic cells were enumerated
with the DNA analysis of the ‘sub-G ’ population (A) or with staining the cells with FITC1 labeled Annexin V
(B). Representative experiments are shown. The difference between the % of apoptosis in the case of treated and non-treated Jurkat cells was significant (MSC, p<0.001, n=14; DMBQ, p<0.05, n=3,
using  paired, two-tailed t-test). No difference was found for PBMC (n=2).

MSC treatment causes prominent apoptosis in lymphoid tumor cells but it does not induce apoptosis of healthy resting mononuclear cells. Moreover, although MSC blocks the proliferation of PBM cells stimulated with PHA, it does not induce apoptosis in PHA stimulated cells (data not shown).

Read Full Post »