The increase in MMP 9 level induced by albumin treat ment was merely significantly suppressed by DPI. Taken to gether, these data suggest that ROS produced by NADPH oxidase Inhibitors,Modulators,Libraries in astrocytes probably mediate the pro duction of MMP 9 by albumin in astrocytes. Neither of these inhibitors induced a change in the level of MMP 2 produced by astrocytes. Albumin induced increase in p38 mitogen activated protein kinase and Jun kinase is downstream from activation of NADPH oxidase Next, we investigated whether the activation of MAPKs by albumin was dependent on the production of ROS. Inhibition of NADPH oxidase with DPI sup pressed the increase in the levels of phospho p38 MAPK induced by albumin treatment. Treatment of the astrocytes with DPI induced an increase in the level of phospho ERK measured in the astrocytes at the high est concentration.
DPI suppressed the in crease in the levels of phospho JNK induced by albumin treatment. Albumin induced increase in matrix metalloproteinase 9 does not involve the transforming growth factor B receptor pathway The TGF B receptor has been previously shown to act as a receptor for albumin on astrocytes. We previ Inhibitors,Modulators,Libraries ously showed that the effect of albumin on astrocyte ac tivation partially involves the TGF B receptor pathway, including activation of the canonical Smad signaling pathway. Accordingly, we next investigated whether the effects of albumin on MMP 9 production also involved the TGF B receptor pathway. Inhib ition of the TGF B receptor I with SB431542 did not affect the increase in MMP 9 induced by albumin.
Similarly, inhibition of the Smad pathway with SIS3 did not suppress the increase in MMP 9 produced by the albumin treated astrocytes. Consistent with these data, treatment of astrocytes with TGF B1 did not alter the level of MMP Inhibitors,Modulators,Libraries 9 in astro cytes. These Inhibitors,Modulators,Libraries data suggest that the increase in MMP 9 induced by albumin in astrocytes occurs inde pendently of the TGF B receptor and the Smad pathway. Albumin induces an increase in tissue inhibitor of metalloproteinase 1 production independent of mitogen activated protein kinase pathways Treatment of Inhibitors,Modulators,Libraries astrocytes with albumin also induced the production of endogenous inhibitor of MMP 9, TIMP 1. The time course of expression of TIMP 1 after exposure to albumin was similar to activation of MMP 9, with the maximum level reached at 24 hours.
The level of TIMP 1 also increased over time in the control group but was significantly lower than the albumin exposed group. The increase in TIMP 1 was Ganetespib mw not suppressed by inhibition of the p38 MAPK, ERK or JNK pathways. Furthermore, inhib ition of TGF B receptor I or the Smad path way did not suppress the increase in TIMP 1 induced by exposure to albumin. Finally, inhibition of ROS generation by treatment with SOD and CAT did not suppress the increase in TIMP 1, and in hibition of NADPH oxidase by DPI only partially suppressed TIMP 1 increase at the highest con centration used.