STAT3/NFkappaB interplay in the regulation of alpha2-macroglobulin gene expression during rat liver development and the acute phase response.
The synthesis of alpha-2-macroglobulin (alpha(2)M) is low in adult rat liver and elevated in fetal liver. During the acute-phase (AP) response it becomes significantly increased in both adult and fetal liver. In this work, the cross talk of STAT3 and NF-kappaB transcription factors during alpha(2)M gene expression was analysed. Using immunoblotting, their cellular compartmentalization was examined by comparing the cytoplasmic levels of STAT3 and NF-kappaB with their active equivalents, the 86 and 91 kDa isoforms and p65-subunit, respectively, in the nuclear extract and nuclear matrix. Different partitioning dynamics of the transcription factors were observed. At the level of protein-DNA interactions, studied by alpha(2)M promoter affinity chromatography, it was established that different ratios of promoter-binding STAT3 isoforms participated in elevated hepatic transcription in the basal state fetus and the AP-adult, but only the 91 kDa isoform in the AP-fetus. Unchanged levels of DNA-bound p65 in the control and AP-fetus suggest that it participated in constitutive transcription. The promoter-binding of p65 observed in the AP-adult suggests that it was involved in transcriptional stimulation of alpha(2)M expression. The selective enrichment of the AP-adult nuclear matrix with promoter-binding STAT3 disclosed the importance of this association in the induction of transcription. Protein-protein interactions were examined by co-immunoprecipitation. Interactions between the 86 kDa STAT3 isoform and p65 that were observed in the control and AP-fetus and of both the 86 and 91 kDa STAT3 isoforms with p65 in the AP-adult, suggest that protein-protein interactions were functionally connected to increased transcription. We concluded that alpha(2)M gene expression is driven by developmental- and AP-related mechanisms that rely on STAT3/NF-kappaB interplay.
Uskoković
Aleksandra
A
Department of Molecular Biology, Institute for Biological Research, Belgrade, Serbia.
Dinić
Svetlana
S
Mihailović
Mirjana
M
Grigorov
Ilijana
I
Ivanović-Matić
Svetlana
S
Bogojević
Desanka
D
Grdović
Nevena
N
Arambasić
Jelena
J
Vidaković
Melita
M
Martinović
Vesna
V
Petrović
Miodrag
M
Poznanović
Goran
G
D000210:Acute-Phase Reaction; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D008099:Liver / Q000254:growth & development / Q000378:metabolism; D008297:Male; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000378:metabolism*; D000511:alpha-Macroglobulins / Q000235:genetics / Q000378:metabolism*
D020033:Protein Isoforms; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D051996:Transcription Factor RelA; D000511:alpha-Macroglobulins