Phospholipase C-␥ (PLC␥) is the isozyme of PLC phosphorylated by multiple tyrosine kinases including epidermal growth factor, platelet-derived growth factor, nerve growth factor receptors, and nonreceptor tyrosine kinases. In this paper, we present evidence for the association of the insulin receptor (IR) with PLC␥. Precipitation of the IR with glutathione S-transferase fusion proteins derived from PLC␥ and coimmunoprecipitation of the IR and PLC␥ were observed in 3T3-L1 adipocytes. To determine the functional significance of the interaction of PLC␥ and the IR, we used a specific inhibitor of PLC, U73122, or microinjection of SH2 domain glutathione S-transferase fusion proteins derived from PLC␥ to block insulin-stimulated GLUT4 translocation. We demonstrate inhibition of 2-deoxyglucose uptake in isolated primary rat adipocytes and 3T3-L1 adipocytes pretreated with U73122. Antilipolytic effect of insulin in 3T3-L1 adipocytes is unaffected by U73122. U73122 selectively inhibits mitogen-activated protein kinase, leaving the Akt and p70 S6 kinase pathways unperturbed. We conclude that PLC␥ is an active participant in metabolic and perhaps mitogenic signaling by the insulin receptor in 3T3-L1 adipocytes. The insulin receptor (IR)1 is a hetero-tetramer consisting of two ␣-subunits that are entirely extracellular and two ␤-subunits that span the plasma membrane and contain intrinsic tyrosine kinase activity (1, 2). One of the major metabolic effects of insulin in fat and skeletal muscle is the stimulation of glucose uptake (3). This occurs through the translocation of glucose transporters (GLUT4) from intracellular vesicles to the plasma membrane (4). Neither the molecular mechanism by which GLUT4 vesicles fuse with the plasma membrane nor the signaling proteins downstream of the IR leading to the stimulation of glucose transport have been clearly elucidated. An involvement of IRS-1 is indicated by both in vitro studies where primary rat adipocytes were transfected with an antisense ribozyme directed against rat IRS-1 (5) and in vivo studies where insulin-mediated glucose transport was attenuated in mice with targeted disruption of the IRS-1 gene (6). The ability of IRS-1 knock-out mice to transport glucose in response to insulin implies alternative mechanisms of glucose transport activation by insulin. PI 3-kinase has been demonstrated to be required for the insulin effect on glucose transport (7-10).Protein kinase C has been studied extensively as a mediator of insulin-stimulated glucose transport (11). The insulinomimetic effect of phorbol esters on glucose uptake implicates DAG as a potentiator of glucose uptake. Phorbol ester down-regulation reportedly inhibits insulin-stimulated glucose uptake in mouse soleus (12), rat heart (13), and rat adipocytes (14 -16). In 3T3-L1 adipocytes, however, insulin-stimulated glucose uptake has been reported to be refractory to down-regulation by phorbol esters (17,18). There are a number of ways that DAG can be generated in the cell in response to cell-surface receptors. An imme...

Endothehal cell activation 1s Important m the pathogenesls of preeclampsla, however, the nature of the actlvatlon IS unknown We investigated 22 patients with preeclampsla, 29 normotensive pregnancies, and 18 nonpregnant women to test the hypothesis that serum from preeclamptlc patients induces expresslon of mtercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-l (VCAM-1) and stimulates mtracellular free calcium concentrations [Ca"], m cultured endothehal cells We then asked whether the correspondmg mtegrm adhesive counter receptors lymphocyte function-associated antigen-1 (CDlla/CD18), macrophage-1 antigen (CDllb/CD18), p150,95 (CD1 1 c/CD18), and very late actlvatlon antigen-4 (CD49/CD29) are Increased m patients with preeclampsla In the pregnant women, the measurements were conducted both before and after delivery Integrm expression was measured by fluorescent antibody cell sorting analysis using monoclonal antibodies ICAMand VCAM-1 were analyzed on endothehal cells by enzymelinked lmmunosorbent assay [Ca2+], was measured with fura 2 Serum from preeclamptlc patients increased endothehal cell ICAM-expresslon but not VCAM-1 expresslon Preeclamptlc I ntact endothehal cells have antiadhesive and antlcoagulant properties, regulate vascular permeability, and modulate the effect of vasoconstrlctor agomsts on the vessel wall 1 Several lmes of evidence support the hypothesis that dysfunction of the vascular endothelmm is important m the pathogenesis of preeclampsla 2-4 The vascular response to vasoconstrictors in preeclamptic women 1s greatly enhanced, the tendency for coagulation is increased,5-* the capillaries are more permeable,6*9-11 and the plasma concentrations of endothelm and fibronectm are elevated I*-** Glomerular capillary endothehal cells show charactenstlc signs of endothehal cell dysfunction.22 Indirect evidence suggests that endothelial cell leukocyte adhesion 1s also altered m preeclampsla, however, neither expression of endothehal cell adhesion molecules nor the leukocyte counterreceptor mtegrins have been investigatedEndothehal cell leukocyte adhesion IS medlated by four classes of adhesion molecules, the selectms, carbohydrate-contammg selectm hgands, mtegrms, and immunoglobulm-like (Ig-like) molecules.23 The mteractlon between mtegrms on the surface of leukocytes and Ig-hke molecules on endothelium 1s necessary for stable adhe- The four integrins that appear most important in leukocyte-endothelial adhesion are three p2 mtegnns, each with a different (Y subunit, and one pl mtegrin. The @l mtegrin is the VLA-4 mtegrin, also termed a4pl according to the integrin nomenclature, or CD49/CD29 according to the CD nomenclature. The three p2 mtegrms share the p2 chain (CD18) and are named LFA-1, also termed (uLp1 or CD1 la/CD18; MAC-l, also termed aMP2 or CD1 lb/CD18; and the glycoprotein p150,95, also termed (~Xp2 or CDllc/CD18.Evidence exists for an as yet umdentlfied circulatmg factor which 1s released from the hypoxlc placenta into the maternal clrculatlon m preeclampsla. This...

AECA are frequently present in patients with Takayasu arteritis. They may play a role in the pathogenesis. Furthermore, they may be useful as an additional diagnostic tool.