Biomaterial Database

Induction of rat liver parenchymal cell apoptosis by hepatic myofibroblasts via transforming growth factor beta. 1996

A M Gressner, and B Polzar, and B Lahme, and H G Mannherz

Department of Clinical Chemistry and Central Laboratory, Philipps University, Marburg, Germany.

The induction of apoptosis of rat liver parenchymal cells (PC) by transforming growth factor beta (TGF-beta)-expressing transforming fat-storing cells (FSC), i.e., myofibroblasts (MFB), was studied under culture conditions and compared with the apoptotic effect of human recombinant TGF-beta1. MFB were obtained by subculture of FSC. The TGF-beta concentration in the conditioned medium of myofibroblast (MFBcM) determined with the Mink cell proliferation inhibition assay was <0.25 ng/mL/24 in the native medium, but 1.9 ng/mL24 h after transient acidification. MFBcM added in various dilutions and for different times to PC monolayers induced progressive cell detachment from the plastic support and increase of lactate dehydrogenase (LDH) activity in the medium. The reduction of mitochondrial dehydrogenase activity in PC (XTT or WST-1 test) was an early sign of MFBcM-induced functional impairment of PC. Short term exposure of PC with MFBcM for 3 hours was sufficient to induce the deleterious effects on PC, but neither native (nonactivated) MFBcM nor conditioned medium of untransformed FSC (FSCcM), in which TGF-beta was not detectable, were able to impair function and viability of PC. Activated MFBcM increased strongly (up to 21-fold) the concentration of oligonucleosomal DNA fragments both in the adherent and detached fraction of PC. Internucleosomal DNA fragments (DNA ladder) were demonstrated by electrophoresis of extracted DNA on agarose gels and by in situ end-labeling of DNA breaks (TUNEL reaction) only in MFBcM-exposed PC. MFBcM-treated PC exhibited intense fluorescence after staining with DNA-binding dye Hoechst 33342 and an increased number of cells with fragmented nuclei. All these criteria point to MFBcM-generated apoptosis of cultured PC, which were found to be very similar to those induced by human recombinant TGF-beta1. The exclusive role of active TGF-beta in MFBcM as mediator of the apoptotic effects of MFB was proven by preincubation of the conditioned medium with human recombinant latency-associated peptide, which reversed completely MFBcM induced reduction of the XTT-test and the MFBcM-generated increase of oligonucleosomal DNA fragments. Partial reversibility was reached by preincubation of the medium with recombinant soluble type II TGF-beta receptor. The data let us conclude that transformed FSC, i.e., MFB in damaged liver, could participate in the mechanisms of PC apoptosis by paracrine loops involving TGF-beta.

UI	MeSH Term	Description	Entries
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008297	Male		Males
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D003470	Culture Media	Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.	Media, Culture
D004249	DNA Damage	Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.	DNA Injury,DNA Lesion,DNA Lesions,Genotoxic Stress,Stress, Genotoxic,Injury, DNA,DNA Injuries
D005347	Fibroblasts	Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.	Fibroblast
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D016212	Transforming Growth Factor beta	A factor synthesized in a wide variety of tissues. It acts synergistically with TGF-alpha in inducing phenotypic transformation and can also act as a negative autocrine growth factor. TGF-beta has a potential role in embryonal development, cellular differentiation, hormone secretion, and immune function. TGF-beta is found mostly as homodimer forms of separate gene products TGF-beta1, TGF-beta2 or TGF-beta3. Heterodimers composed of TGF-beta1 and 2 (TGF-beta1.2) or of TGF-beta2 and 3 (TGF-beta2.3) have been isolated. The TGF-beta proteins are synthesized as precursor proteins.	Bone-Derived Transforming Growth Factor,Platelet Transforming Growth Factor,TGF-beta,Milk Growth Factor,TGFbeta,Bone Derived Transforming Growth Factor,Factor, Milk Growth,Growth Factor, Milk
D017209	Apoptosis	A regulated cell death mechanism characterized by distinctive morphologic changes in the nucleus and cytoplasm, including the endonucleolytic cleavage of genomic DNA, at regularly spaced, internucleosomal sites, i.e., DNA FRAGMENTATION. It is genetically programmed and serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.	Apoptosis, Extrinsic Pathway,Apoptosis, Intrinsic Pathway,Caspase-Dependent Apoptosis,Classic Apoptosis,Classical Apoptosis,Programmed Cell Death,Programmed Cell Death, Type I,Apoptoses, Extrinsic Pathway,Apoptoses, Intrinsic Pathway,Apoptosis, Caspase-Dependent,Apoptosis, Classic,Apoptosis, Classical,Caspase Dependent Apoptosis,Cell Death, Programmed,Classic Apoptoses,Extrinsic Pathway Apoptoses,Extrinsic Pathway Apoptosis,Intrinsic Pathway Apoptoses,Intrinsic Pathway Apoptosis