TY - JOUR
T1 - Involvement of protein kinase C in Rickettsia rickettsii-induced transcriptional activation of the host endothelial cell
AU - Sahni, Sanjeev K.
AU - Turpin, Loel C.
AU - Brown, Tracy L.
AU - Sporn, Lee Ann
PY - 1999/12
Y1 - 1999/12
N2 - Our laboratory has reported on a biphasic pattern of nuclear factor κB (NF-κB) activation in cultured human umbilical vein endothelial cells during infection with Rickettsia rickettsii, an obligate, intracellular bacterium, and the etiologic agent of Rocky Mountain spotted fever. Transcriptional activation of the tissue factor (TF) gene during this infection has been shown to involve NF-κB. To further understand the signal transduction events underlying these phenomena, we studied the role of protein kinase C (PKC), a ubiquitous family of phospholipid-dependent enzymes implicated in the regulation of a variety of cell signaling pathways. Two inhibitors of PKC, namely, bisindolylmaleimide I hydrochloride (BM-1) and calphostin C, which exhibit different inhibitory properties towards various isozymes of PKC, were used. Infection of cells with R. rickettsii in the presence of BM-1 (50 nM) did not significantly affect NF-κB, whereas calphostin C (2.5 μM) complete]y blocked the early phase of NF-κB activation. The late, sustained phase also was not affected by treatment with BM-1. Downregulation of phorbol ester-sensitive PKCs by long-term treatment with phorbol 12-myristate 13- acetate (PMA) did not inhibit NF-κB activation. Likewise, this downregulation had no effect on induction of TF activity. The activity of TF was, however, sensitive to BM-1 and calphostin C, whereas expression of TF mRNA was inhibited only by calphostin C. Overall, these results suggest the lack of involvement of classical PKC pathways in R. rickettsii-induced NF-δB activation but the possible involvement of a non-PMA-responsive PKC isoform in the posttranscriptional control of TF expression.
AB - Our laboratory has reported on a biphasic pattern of nuclear factor κB (NF-κB) activation in cultured human umbilical vein endothelial cells during infection with Rickettsia rickettsii, an obligate, intracellular bacterium, and the etiologic agent of Rocky Mountain spotted fever. Transcriptional activation of the tissue factor (TF) gene during this infection has been shown to involve NF-κB. To further understand the signal transduction events underlying these phenomena, we studied the role of protein kinase C (PKC), a ubiquitous family of phospholipid-dependent enzymes implicated in the regulation of a variety of cell signaling pathways. Two inhibitors of PKC, namely, bisindolylmaleimide I hydrochloride (BM-1) and calphostin C, which exhibit different inhibitory properties towards various isozymes of PKC, were used. Infection of cells with R. rickettsii in the presence of BM-1 (50 nM) did not significantly affect NF-κB, whereas calphostin C (2.5 μM) complete]y blocked the early phase of NF-κB activation. The late, sustained phase also was not affected by treatment with BM-1. Downregulation of phorbol ester-sensitive PKCs by long-term treatment with phorbol 12-myristate 13- acetate (PMA) did not inhibit NF-κB activation. Likewise, this downregulation had no effect on induction of TF activity. The activity of TF was, however, sensitive to BM-1 and calphostin C, whereas expression of TF mRNA was inhibited only by calphostin C. Overall, these results suggest the lack of involvement of classical PKC pathways in R. rickettsii-induced NF-δB activation but the possible involvement of a non-PMA-responsive PKC isoform in the posttranscriptional control of TF expression.
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M3 - Article
C2 - 10569758
AN - SCOPUS:0032723011
SN - 0019-9567
VL - 67
SP - 6418
EP - 6423
JO - Infection and immunity
JF - Infection and immunity
IS - 12
ER -