Transforming growth factor-beta1 induces apoptosis of rat microglia without relation to bcl-2 oncoprotein expression.
Transforming growth factor-beta (TGF-beta) plays a role as an immunosuppressive cytokine within the central nervous system (CNS). The CNS cells targeted by action of TGF-beta1 have not been defined. In this study, we tested the effect of TGF-beta1 on microglia, astrocytes and oligodendrocytes from newborn rats. TGF-beta1 selectively induced apoptosis of microglia, and not of astrocytes or oligodendrocytes. To study the apoptotic mechanism, bcl-2 oncoprotein expression in microglia, astrocytes and oligodendrocytes was measured. Bcl-2 was mainly expressed in microglia, indicating that microglial bcl-2 does not prevent TGF-beta1-mediated microglial apoptosis. The relative protein expression of bcl-2 in microglia was not related to frequency of microglial apoptosis. Thus, TGF-beta1-induced microglial apoptosis was regulated by a bcl-2-independent mechanism. Expression of cytokine (IL-1beta, IL-6, IL-12, IFN-gamma and TNF-alpha) mRNA on microglia was not influenced by treatment with TGF-beta1.
Xiao
B G
BG
Division of Neurology, Karolinska Institute, Huddinge University Hospital, Sweden.
Bai
X F
XF
Zhang
G X
GX
Link
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D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects*; D001253:Astrocytes / Q000166:cytology / Q000502:physiology; D001921:Brain / Q000166:cytology / Q000502:physiology*; D016207:Cytokines / Q000096:biosynthesis*; D053938:DNA Fragmentation; D006801:Humans; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009836:Oligodendroglia / Q000166:cytology / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011917:Rats, Inbred Lew; D011994:Recombinant Proteins / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D016207:Cytokines; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta