A comparison of post‐receptor signal transduction events in Jurkat cells transfected with either IL‐8R1 or IL‐8R2 Chemokine mediated activation of p42/p44 MAP‐kinase (ERK‐2)

Open Access
Publisher Website
Google Scholar
Abstract
The CXC chemokine, IL‐8, is a potent chemoattractant of neutrophils and binds to two distinct receptors, termed IL‐8R1 and IL‐8R2. These receptors share high affinity for IL‐8, however, only IL‐8R1 is specific for IL‐8 whereas IL‐8R2 binds other related chemokines, including GROα with high affinity. Stable Jurkat transfectants were generated expressing either functional IL‐8R1 or IL‐8R2 (J‐IL8R1 and J‐IL812). Both J‐IL8R1 and J‐IL8R2 exhibited high affinity IL‐8 binding (K d 3–5nM) with respective receptor densities of23,000 ± 3,000 and18,500 ± 1,500. Pre‐treatment of both transfectants with 1.0 μg/mlB. pertussis toxin (PTx) resulted in inhibition of IL‐8 mediated intracellular Ca2+ mobilisation and chemotaxis, without altering the receptor's affinity for its ligand. This indicates that both receptors couple to a PTx‐sensitive G‐protein. Further studies showed that IL‐8R1 and IL‐8R2 could mediate time‐dependent phosphorylation of p42/p44 MAP‐kinase. In both transfectants, phosphorylation was maximal at 1–2 min after IL‐8 stimulation and could be inhibited by PTx. Stimulation of J‐IL8R1 and J‐IL8R2 with GROα revealed that this chemokine was a more potent activator of MAP‐kinase in J‐IL8R2, an observation reflected in the high affinity binding of GROα to IL‐8R2. These studies indicate that chemokines are capable of activating protein kinases and with regards to PTx‐sensitivity and MAP‐kinase stimulation, no significant differences between IL‐ 8R1 and IL‐8R2 post‐receptor signalling occur during cell activation by IL‐8.