Cystatin B Associates with Signal Transducer and Activator of Transcription 1 in Monocyte-Derived and Placental Macrophages

• Published in: Placenta (Eastbourne) Vol. 30; no. 5; pp. 464 - 467
• Main Authors: Luciano-Montalvo, C, Meléndez, L.M
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2009; Elsevier
• Subjects: Biological and medical sciences; Cystatin B; Cystatin B - physiology; Embryology: invertebrates and vertebrates. Teratology; Female; Fundamental and applied biological sciences. Psychology; HIV Infections - metabolism; HIV-1; Humans; Internal Medicine; Macrophages - physiology; Macrophages - virology; Monocyte-derived macrophages; Obstetrics and Gynecology; Phosphorylation - drug effects; Placenta - cytology; Placental macrophages; Pregnancy; STAT-1; STAT1 Transcription Factor - metabolism; Tyrosine - metabolism; HIV-1; STAT-1; Placental macrophages; Cystatin B; Monocyte-derived macrophages; Transducer; Cystatin; Vertebrata; Mammalia; Placenta; Monocyte; Transcription; Fetal membrane; Activator; Macrophage
• ISSN: 0143-4004; 1532-3102
• DOI: 10.1016/j.placenta.2009.03.003

Abstract Cystatin (CSTB, also known as stefin B), a cysteine protease inhibitor, recently was found to be down-regulated in the proteome of uninfected and HIV-1-infected placental macrophages (PMs) and associated with restricted HIV-1 replication in PM but not in monocyte-derived macrophages (MDMs). We investigated CSTB interactions with signal transducer and activator of transcription 1 (STAT-1) by immunoprecipitation studies because this molecule is known to activate HIV-1 replication. Since both CSTB and STAT-1 are related to HIV-1 replication, we hypothesized that these proteins could be interacting. We applied immunoprecipitation assays to determine STAT-1–CSTB interaction in uninfected and HIV-1-infected PM as compared with MDM. We found that CSTB associates with STAT-1 in PM and MDM. Further analyses indicated that the levels of STAT-1 tyrosine phosphorylation were higher in PM than MDM. High levels of tyrosine phosphorylation previously have been associated with HIV-1 inhibitory activity. This is the first report to demonstrate that cystatin B interacts with STAT-1 and that the levels of STAT-1 tyrosine phosphorylation (but not serine phosphorylation) between uninfected and HIV-infected PM and MDM are differentially regulated.