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Extraction of Peptidoglycan from L. paracasei subp. Paracasei X12 and Its Preliminary Mechanisms of Inducing Immunogenic Cell Death in HT-29 Cells.

Tian PJ, Li BL, Shan YJ, Zhang JN, Chen JY, Yu M, Zhang LW - Int J Mol Sci (2015)

Bottom Line: X12-PG could induce the production of apoptotic bodies observed by transmission electron microscopy (TEM).X12-PG could significantly induced the translocation of calreticulin (CRT) and the release of high mobility group box 1 protein (HMGB1), the two notable hallmarks of immunogenic cell death (ICD), with the endoplastic reticulum (ER) damaged and subsequently intracellular [Ca(2+)] elevated.Our findings implied that X12-PG could induce the ICD of HT-29 cells through targeting at the ER.

View Article: PubMed Central - PubMed

Affiliation: School of Food Science and Engineering, Harbin Institute of Technology, No. 73 Huanghe Road, Harbin 150000, China. tianpei0202@gmail.com.

ABSTRACT
L. paracasei subp. paracasei X12 was previously isolated from a Chinese traditional fermented cheese with anticancer activities and probiotic potential. Herein, the integral peptidoglycan (X12-PG) was extracted by a modified trichloroacetic acid (TCA) method. X12-PG contained the four representative amino acids Asp, Glu, Ala and Lys, and displayed the similar lysozyme sensitivity, UV-visible scanning spectrum and molecular weight as the peptidoglycan standard. X12-PG could induce the production of apoptotic bodies observed by transmission electron microscopy (TEM). X12-PG could significantly induced the translocation of calreticulin (CRT) and the release of high mobility group box 1 protein (HMGB1), the two notable hallmarks of immunogenic cell death (ICD), with the endoplastic reticulum (ER) damaged and subsequently intracellular [Ca(2+)] elevated. Our findings implied that X12-PG could induce the ICD of HT-29 cells through targeting at the ER. The present results may enlighten the prospect of probiotics in the prevention of colon cancer.

No MeSH data available.


Related in: MedlinePlus

Properties of immunogenic cell death (ICD) induced by X12-PG in HT-29 cells. As a result of endoplasmic reticulum stress (stimulated by X12-PG), cancer cells expose CRT on their plasma membrane at a pre-apoptotic stage. This facilitates the recruitment of dendritic cells (DCs) into the tumor bed, the engulfment of tumor antigens by DCs (stimulated by CRT), and optimal antigen presentation to T cells (stimulated by HMGB1). CRT served as an “eat-me” signal, and CRT exposure may be regulated by cytosolic [Ca2+].
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ijms-16-20033-f008: Properties of immunogenic cell death (ICD) induced by X12-PG in HT-29 cells. As a result of endoplasmic reticulum stress (stimulated by X12-PG), cancer cells expose CRT on their plasma membrane at a pre-apoptotic stage. This facilitates the recruitment of dendritic cells (DCs) into the tumor bed, the engulfment of tumor antigens by DCs (stimulated by CRT), and optimal antigen presentation to T cells (stimulated by HMGB1). CRT served as an “eat-me” signal, and CRT exposure may be regulated by cytosolic [Ca2+].

Mentions: CRT exposure on the membrane serves as an engulfment signal in pre-apoptotic cells for specific interaction with dendritic cells (DCs), which could engulf, process, and present antigen from dying tumor cells to T-lymphocytes. The activated immune defensing system will eventually kill the tumor cells. Obeid et al. reported that CRT was exposed on the surface of cells undergoing ICD, but was lacking in those cells with non-immunogenic cell death [24]. Conversely, anti-neoplastic agents that fail to induce CRT exposure are intrinsically incapable of provoking ICD [41]. All these studies identify CRT as a major checkpoint of ICD. CRT is an abundant chaperone that is normally secluded in the ER lumen; it is able to translocate to the plasma membrane under a series of ER stress responses through a complex pathway, including paracrine signals and transduction cascade activations. CRT is also a high capacity Ca2+-binding protein of intracellular Ca2+ stores and CRT translocation breaks ER-regulation of Ca2+ homeostasis [42]. Moreover, this disturbance may synergistically aggravate CRT translocation. As described in a previous study, after cells were transfected with a Reticulon-1C (an evolutionary conserved protein to decrease the [Ca2+] in the ER) overexpression plasmid, the ER could no longer mediate CRT exposure in response to anthracyclin treatment [43]. In addition, cells undergoing ICD release the nuclear protein HMGB1 as their membranes become permeabilized during secondary necrosis [29]. HMGB1 can interact with several receptors expressed on the surface of DCs including the toll-like receptor 4 (TLR4) [26,28]. Combing the previous studies and our experimental results, we speculate that the ER structure damages induced by X12-PG treatment, directly results in the reduction of endoplasmic reticulum [Ca2+] levels and elevation of intracellular [Ca2+]. Subsequently, Ca2+ served as a translocation signal and triggered CRT exposure onto the cell surface (Figure 8). To our knowledge, no detailed molecular mechanisms of how CRT translocated to the cell membrane has been clearly clarified, and it is a problem that requires further investigation.


Extraction of Peptidoglycan from L. paracasei subp. Paracasei X12 and Its Preliminary Mechanisms of Inducing Immunogenic Cell Death in HT-29 Cells.

Tian PJ, Li BL, Shan YJ, Zhang JN, Chen JY, Yu M, Zhang LW - Int J Mol Sci (2015)

Properties of immunogenic cell death (ICD) induced by X12-PG in HT-29 cells. As a result of endoplasmic reticulum stress (stimulated by X12-PG), cancer cells expose CRT on their plasma membrane at a pre-apoptotic stage. This facilitates the recruitment of dendritic cells (DCs) into the tumor bed, the engulfment of tumor antigens by DCs (stimulated by CRT), and optimal antigen presentation to T cells (stimulated by HMGB1). CRT served as an “eat-me” signal, and CRT exposure may be regulated by cytosolic [Ca2+].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581339&req=5

ijms-16-20033-f008: Properties of immunogenic cell death (ICD) induced by X12-PG in HT-29 cells. As a result of endoplasmic reticulum stress (stimulated by X12-PG), cancer cells expose CRT on their plasma membrane at a pre-apoptotic stage. This facilitates the recruitment of dendritic cells (DCs) into the tumor bed, the engulfment of tumor antigens by DCs (stimulated by CRT), and optimal antigen presentation to T cells (stimulated by HMGB1). CRT served as an “eat-me” signal, and CRT exposure may be regulated by cytosolic [Ca2+].
Mentions: CRT exposure on the membrane serves as an engulfment signal in pre-apoptotic cells for specific interaction with dendritic cells (DCs), which could engulf, process, and present antigen from dying tumor cells to T-lymphocytes. The activated immune defensing system will eventually kill the tumor cells. Obeid et al. reported that CRT was exposed on the surface of cells undergoing ICD, but was lacking in those cells with non-immunogenic cell death [24]. Conversely, anti-neoplastic agents that fail to induce CRT exposure are intrinsically incapable of provoking ICD [41]. All these studies identify CRT as a major checkpoint of ICD. CRT is an abundant chaperone that is normally secluded in the ER lumen; it is able to translocate to the plasma membrane under a series of ER stress responses through a complex pathway, including paracrine signals and transduction cascade activations. CRT is also a high capacity Ca2+-binding protein of intracellular Ca2+ stores and CRT translocation breaks ER-regulation of Ca2+ homeostasis [42]. Moreover, this disturbance may synergistically aggravate CRT translocation. As described in a previous study, after cells were transfected with a Reticulon-1C (an evolutionary conserved protein to decrease the [Ca2+] in the ER) overexpression plasmid, the ER could no longer mediate CRT exposure in response to anthracyclin treatment [43]. In addition, cells undergoing ICD release the nuclear protein HMGB1 as their membranes become permeabilized during secondary necrosis [29]. HMGB1 can interact with several receptors expressed on the surface of DCs including the toll-like receptor 4 (TLR4) [26,28]. Combing the previous studies and our experimental results, we speculate that the ER structure damages induced by X12-PG treatment, directly results in the reduction of endoplasmic reticulum [Ca2+] levels and elevation of intracellular [Ca2+]. Subsequently, Ca2+ served as a translocation signal and triggered CRT exposure onto the cell surface (Figure 8). To our knowledge, no detailed molecular mechanisms of how CRT translocated to the cell membrane has been clearly clarified, and it is a problem that requires further investigation.

Bottom Line: X12-PG could induce the production of apoptotic bodies observed by transmission electron microscopy (TEM).X12-PG could significantly induced the translocation of calreticulin (CRT) and the release of high mobility group box 1 protein (HMGB1), the two notable hallmarks of immunogenic cell death (ICD), with the endoplastic reticulum (ER) damaged and subsequently intracellular [Ca(2+)] elevated.Our findings implied that X12-PG could induce the ICD of HT-29 cells through targeting at the ER.

View Article: PubMed Central - PubMed

Affiliation: School of Food Science and Engineering, Harbin Institute of Technology, No. 73 Huanghe Road, Harbin 150000, China. tianpei0202@gmail.com.

ABSTRACT
L. paracasei subp. paracasei X12 was previously isolated from a Chinese traditional fermented cheese with anticancer activities and probiotic potential. Herein, the integral peptidoglycan (X12-PG) was extracted by a modified trichloroacetic acid (TCA) method. X12-PG contained the four representative amino acids Asp, Glu, Ala and Lys, and displayed the similar lysozyme sensitivity, UV-visible scanning spectrum and molecular weight as the peptidoglycan standard. X12-PG could induce the production of apoptotic bodies observed by transmission electron microscopy (TEM). X12-PG could significantly induced the translocation of calreticulin (CRT) and the release of high mobility group box 1 protein (HMGB1), the two notable hallmarks of immunogenic cell death (ICD), with the endoplastic reticulum (ER) damaged and subsequently intracellular [Ca(2+)] elevated. Our findings implied that X12-PG could induce the ICD of HT-29 cells through targeting at the ER. The present results may enlighten the prospect of probiotics in the prevention of colon cancer.

No MeSH data available.


Related in: MedlinePlus