Involvement of SOCS-1, the suppressor of cytokine signaling, in the prevention of prolactin-responsive gene expression in decidual cells.
The cells forming the rat decidua produce PRL and PRL-related proteins and express both the long and short forms of the PRL receptor. Yet, only a defined subpopulation, the mesometrial cells, express the PRL-dependent alpha2-macroglobulin gene. This gene is silenced in vivo in the antimesometrial cells and in the GG-AD cell line, derived from antimesometrial cells. To examine whether the lack of alpha2-macroglobulin expression is due to defective components in the PRL signaling pathway, we compared the relative expression of Janus kinase 2 (Jak2), signal transducer and activator of transcription 5 a and b (Stat5 a and b), suppressor of cytokine signaling-1 (SOCS-1), and the tyrosine phosphatase SHP-2 mRNA in mesometrial and antimesometrial decidua on days 12 and 13 of pseudopregnancy, the time of maximal alpha2-macroglobulin expression. We found no significant differences in the relative expression of either Jak2, Stat5 (a and b), or SHP-2 in the two cell populations. However, we discovered a profound difference in the expression of SOCS-1, an inhibitor of the Jak/Stat pathway. This gene was highly expressed in the antimesometrial cells and in the GG-AD cells, which do not produce alpha2-macroglobulin. Immunoprecipitation experiments with GG-AD cells revealed that although Jak2 and Stat5 coprecipitate in response to PRL stimulation, no phosphorylation of Jak2 and Stat5 could be observed. To examine whether SOCS-1 plays a role in silencing the alpha2-macroglobulin gene, we cultured GG-AD cells in the presence of either a SOCS-1 antisense oligonucleotide or an irrelevant oligonucleotide for 4, 12, and 28 h. Cells were also treated with PRL. Within 4 h of SOCS-1 antisense treatment, alpha2-macroglobulin mRNA expression was initiated. After 28 h, only cells treated with PRL and SOCS-1 antisense oligonucleotide retained the ability to express the alpha2-macroglobulin gene. In summary, results of this study reveal that constitutive expression of SOCS-1 can prevent PRL signaling and that the lack of PRL-induced expression of alpha2-macroglobulin in a defined decidual cell population is largely due to SOCS-1 expression in these cells.
Barkai
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U
Department of Physiology and Biophysics, College of Medicine, University of Illinois, Chicago 60612, USA.
Prigent-Tessier
A
A
Tessier
C
C
Gibori
G B
GB
Gibori
G
G
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D003656:Decidua / Q000378:metabolism*; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011388:Prolactin / Q000494:pharmacology*; D011555:Pseudopregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012097:Repressor Proteins; D015398:Signal Transduction; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D014599:Uterus / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000235:genetics
D002352:Carrier Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D012097:Repressor Proteins; C491589:Socs1 protein, rat; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D000511:alpha-Macroglobulins; D011388:Prolactin