Distribution of leukotriene B4 receptors in human hematopoietic cells

Leukotriene B4 (LTB4), a product of arachidonic acid metabolism, plays an important role in inflammatory responses. We have cloned from human erythroleukemia cells, a G protein-coupled receptor, designated P2Y(7), which was later identified as the receptor for LTB4 (B-LTR). We have investigated the distribution of LTB4 receptors in various hematopoietic cells. Northern blotting and reverse transcription-coupled polymerase chain reaction (RT-PCR) analyses using radiolabeled LTB4 receptor cDNA as a probe indicated the presence of LTB4 receptor mRNA in peripheral blood leukocytes but not in platelets. Flow cytometry analysis of peripheral blood cells using specific LTB4 receptor antibodies revealed that monocytes, granulocytes, and lymphocytes, but not platelets, express LTB4 receptors. RT-PCR-Southern hybridization analysis revealed that peripheral blood leukocytes and human umbilical vein endothelial cells express the LTB4 receptor. Of the hematopoietic cell lines tested, promonocytic U937 cells, promyelocytic HL-60 cells, K562 cells, and human erythroleukemia cells express the LTB4 receptor. These results suggest a physiological role for the LTB4 receptor in the stimulation of monocytes, neutrophils, and endothelial cells.

Stromal cell-derived factor-1 and macrophage-derived chemokine: 2 chemokines that activate platelets

Platelets play roles in both thrombosis and inflammation, and chemokines that are released at sites of inflammation could potentially activate platelets. Among the chemokine receptors expressed on platelets, the CXCR4 is the receptor for chemokine stromal cell-derived factor-1 (SDF-1), and the CCR4 is the receptor for macrophage-derived chemokine (MDC). Of the chemokines tested, SDF-1 and MDC were the only 2 that activated platelets. Both are weak agonists, but they enhanced response to low-dose adenosine 5'-diphosphate (ADP), epinephrine, or serotonin. When SDF-1 and MDC were added together, full and brisk platelet aggregation occurred. Platelet activation by these 2 chemokines appears to involve distinct pathways: SDF-1 inhibited an increase in cyclic adenosine monophosphate (cAMP) following prostaglandin (PG) I(2), while MDC had no effect. In contrast, MDC, but not SDF-1, lead to Ca(++) mobilization by platelets. Further, second-wave aggregation induced by MDC in platelet-rich plasma was inhibited by aspirin, ADP scavenger creatine phosphate/creative phosphokinase (CP/CPK), and ARL-66096, an antagonist of the ADP P2T(AC) receptor involved in adenylyl cyclase inhibition. But the aggregation was not affected by A3P5PS, an inhibitor of the ADP P2Y receptor. SDF-1-induced aggregation was inhibited by aspirin, but it was only slightly affected by CP/CPK, ARL-66096, or A3P5PS. Finally, the presence of chemokines in platelets was determined. Reverse transcriptase-polymerase chain reaction studies with platelet RNA did not detect the presence of SDF-1 or MDC. In summary, SDF-1 and MDC are platelet agonists that activate distinct intracellular pathways. Their importance in the development of thrombosis at sites of inflammation needs to be further evaluated.

[The dynamic measurements of human body's unbalance]

A through study of the postural stability of 40 subjects has been conducted with a stabilometer and the computer system. The subjects stand on the testing platform for 10 seconds and meanwhile the sum of frequency spectrum is being analyzed. The most men subjects maintain a little sway well within timits during the trials. The testing conditions include open eyes, close eyes, 10 degrees, 20 degrees, 30 degrees of platform inclination, transverse vision tracking, longitudinal vision tracking and vectorial vision tracking, All testing results show that there are unbalance differences between different age groups under different conditions.

Surgical treatment of spondylolisthesis with SOCON instrumentation

OBJECTIVE

To observe the clinical outcomes of using a new instrumentation SOCON system in the treatment of degenerative spondylolisthesis.

METHODS

Retrospective clinical and roentgenograph review of 21 patients who suffered from degenerative spondylolisthesis with spinal stenosis treated by decompression, posterolateral intertransverse arthrodesis, and with transpedicle instrumentation of SOCON system.

RESULTS

Nineteen of 21 patients were completely recovery from their preoperative symptoms, 17 of 18 cases with grade one slippage reduced to normal spine alignment, 2 cases of grade two slippage fully reduced, and one case of grade two spondylolisthesis got 70% reduction. Post-operative satisfactory rate was 90.5%. Pain relief was 90.5%. Neither infection nor neurologic complication occurred in this series.

CONCLUSION

Our short time follow-up and limited cases showed satisfactory preliminary result of surgical treatment of spondylolisthesis with SOCON instrumentation.

The P2Y1 receptor mediates ADP-induced p38 kinase-activating factor generation in human platelets

U46619, a thromboxane A2 mimetic, but not ADP, caused activation of p38 mitogen activated protein (MAP) kinase in aspirin-treated platelets. In nonaspirinated human platelets ADP activated p38 MAP kinase in both a time-and concentration-dependent manner, suggesting that ADP-induced p38 MAP kinase activation requires generation of thromboxane A2. However, neither a thromboxane A2/prostaglandin H2 receptor antagonist SQ29548 and a thromboxane synthase inhibitor, furegrelate, either alone or together, nor indomethacin blocked ADP-induced p38 kinase activation in nonaspirinated platelets. Other cycloxygenase products, PGE2, PGD2, and PGF2alpha, failed to activate p38 kinase in aspirin-treated platelets. Hence, ADP must be generating an agonist, other than thromboxane A2, via an aspirin-sensitive pathway, which is capable of activating p38 kinase. AR-C66096, a P2TAC (platelet ADP receptor coupled to inhibition of adenylate cyclase) antagonist, did not inhibit ADP-induced p38 MAP kinase activation. The P2X receptor selective agonist, alpha, beta-methylene ATP, failed to activate p38 MAP kinase. On the other hand, the P2Y1 receptor selective antagonist, adenosine-2'-phosphate-5'-phosphate inhibited ADP-induced p38 kinase activation in a concentration-dependent manner, indicating that the P2Y1 receptor alone mediates ADP-induced generation of the p38 kinase-activating factor. These results demonstrate that ADP causes the generation of a factor in human platelets, which can activate p38 kinase, and that this response is mediated by the P2Y1 receptor. Neither the P2TAC receptor nor the P2X1 receptor has any significant role in this response.

[Effects of mifepristone on estrogen and progestin receptors in human uterine leiomyoma]

OBJECTIVES

To study the effects of mifepristone on estrogen receptors (ER) and progestin receptors (PR) in human uterine leiomyoma and myometrium.

METHODS

20 patients with uterine leiomyoma who had surgical indication received 25 mg of mifepristone daily for 90 days beginning on the first day of menstrual cycle. Ultrasound examination, serum hormonal parameters, liver and renal function, electrolyte, complete blood count were monitored prior to and at the end of treatment. Hysterectomy or myomectomy was performed just when the treatment finished. Leiomyomata and myometrial tissue were obtained for immunohistochemical ER and PR analyses using monoclonal antibody. Control group included 20 patients who had matched age, weight, size and position of leiomyoma, and operated in the follicular phase of the cycle.

RESULTS

After 90 days of mifepristone treatment, the leiomyoma volume decreased by (37.3 +/- 19.0)% and the uterine volume decreased (27.4 +/- 21.9)%. Hormonal parameters were within the levels of follicular phase. ER and PR positive rate in leiomyoma but not in myometrium of study group were significantly less than those of control group (P < 0.001). The positive rate of ER and PR of control group and PR of study group in leiomyoma were significantly higher than those in myometrial tissue of both groups (P < 0.05). ER of study group in leiomyoma was similar to myometrial tissue (P > 0.05).

CONCLUSIONS

Mifepristone is a safe and effective drug for treating uterine leiomyoma. It can significantly decrease ER and PR in leiomyoma but not in myometrial tissue.

[Clinical and experimental study on Yinhua mixture aerosol in treating infantile viral pneumonia]

OBJECTIVE

To explore the therapeutic effect of using Yinhua mixture aerosol in treating infantile viral pneumonia and its mechanism.

METHODS

Comparing sixty-nine infantile viral pneumonia patients using Yinhua mixture aerosol with 33 infantile viral pneumonia patients using gentamycin, pharmacodynamical animal experiments of anti-tussis and anti-asthma were also observed.

RESULTS

The markedly effective rate of Yinhua mixture aerosol and gentamycin aerosol were 58.0% and 27.3% respectively, while the total effective rate of these two drugs was 95.7% and 69.7% respectively. Experimental study revealed that Yinhua mixture was effective in antifebrile, anti-asthma and expectorative effect, which was better than that of gentamycin (P < 0.05).

CONCLUSION

Yinhua mixture aerosol is effective in antifebrile, anti-asthma, and expectorative effect.

Opposite translational control of GLUT1 and GLUT4 glucose transporter mRNAs in response to insulin. Role of mammalian target of rapamycin, protein kinase b, and phosphatidylinositol 3-kinase in GLUT1 mRNA translation

Prolonged exposure of 3T3-L1 adipocytes to insulin increases GLUT1 protein content while diminishing GLUT4. These changes arise in part from changes in mRNA transcription. Here we examined whether there are also specific effects of insulin on GLUT1 and GLUT4 mRNA translation. Insulin enhanced association of GLUT1 mRNA with polyribosomes and decreased association with monosomes, suggesting increased translation. Conversely, insulin arrested the majority of GLUT4 transcripts in monosomes. Insulin inactivates the translational suppressor eukaryotic initiation factor 4E-binding protein-1 (4E-BP1) through the mammalian target of rapamycin (mTOR). Hence, we examined the effect of rapamycin on GLUT1 mRNA translation and protein expression. Rapamycin abrogated the insulin-mediated increase in GLUT1 protein synthesis through partial inhibition of GLUT1 mRNA translation and partial inhibition of the rise in GLUT1 mRNA. 4E-BP1 inhibited GLUT1 mRNA translation in vitro. Because phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB), in concert with mTOR, inactivate 4E-BP1, we explored their role in GLUT1 protein expression. Cotransfection of cytomegalovirus promoter-driven, hemagglutinin epitope-tagged GLUT1 with dominant inhibitory mutants of PI3K or PKB inhibited the insulin-elicited increase in hemagglutinin-tagged GLUT1 protein. These results unravel the opposite effects of insulin on GLUT1 and GLUT4 mRNA translation. Increased GLUT1 mRNA translation appears to occur via the PI3K/PKB/mTOR/4E-BP1 cascade.

Self-Assembled Monolayer and Multilayer of Trichlorogermane Hexyl Propylate and Formation of GeO(2)/SiO(2) Interface

Monolayer and multilayer films of trichlorogermane hexyl propylate (Ge6) were formed by the self-assembly method on hydroxylated silicon substrates. The results showed that this kind of trichlorogermane had virtually the same self-assembly behavior as trichlorosilanes. Ellipsometry proved that the self-assembled monolayers and multilayers (SAMs) of Ge6 exhibited a tilted orientation to the substrate surface. The multilayer film of Ge6 on silicon substrate was obtained by reducing the monolayer SAMs to alcohol hydroxylated surface with LiAlH(4) and repeating the self-assembly process. The self-assembled multilayer film was calcined in air at 500 degrees C to form a thin layer of GeO(2) on SiO(2)/Si substrate surface. The XPS measurement detected the formation of GeO(2) layer. Copyright 1999 Academic Press.

Molecular mechanism of thromboxane A(2)-induced platelet aggregation. Essential role for p2t(ac) and alpha(2a) receptors

Thromboxane A(2) is a positive feedback lipid mediator produced following platelet activation. The G(q)-coupled thromboxane A(2) receptor subtype, TPalpha, and G(i)-coupled TPbeta subtype have been shown in human platelets. ADP-induced platelet aggregation requires concomitant signaling from two P2 receptor subtypes, P2Y1 and P2T(AC), coupled to G(q) and G(i), respectively. We investigated whether the stable thromboxane A(2) mimetic, (15S)-hydroxy-9, 11-epoxymethanoprosta-5Z,13E-dienoic acid (U46619), also causes platelet aggregation by concomitant signaling through G(q) and G(i), through co-activation of TPalpha and TPbeta receptor subtypes. Here we report that secretion blockade with Ro 31-8220, a protein kinase C inhibitor, completely inhibited U46619-induced, but not ADP- or thrombin-induced, platelet aggregation. Ro 31-8220 had no effect on U46619-induced intracellular calcium mobilization or platelet shape change. Furthermore, U46619-induced intracellular calcium mobilization and shape change were unaffected by A3P5P, a P2Y1 receptor-selective antagonist, and/or cyproheptadine, a 5-hydroxytryptamine subtype 2A receptor antagonist. Either Ro 31-8220 or AR-C66096, a P2T(AC) receptor selective antagonist, abolished U46619-induced inhibition of adenylyl cyclase. In addition, AR-C66096 drastically inhibited U46619-mediated platelet aggregation, which was further inhibited by yohimbine, an alpha(2A)-adrenergic receptor antagonist. Furthermore, inhibition of U46619-induced platelet aggregation by Ro 31-8220 was relieved by activation of the G(i) pathway by selective activation of either the P2T(AC) receptor or the alpha(2A)-adrenergic receptor. We conclude that whereas thromboxane A(2) causes intracellular calcium mobilization and shape change independently, thromboxane A(2)-induced inhibition of adenylyl cyclase and platelet aggregation depends exclusively upon secretion of other agonists that stimulate G(i)-coupled receptors.

Role of intracellular signaling events in ADP-induced platelet aggregation

Human platelets express two distinct G protein-coupled ADP receptors, one coupled to phospholipase C through Gq, P2Y1, and the other to inhibition of adenylyl cyclase through Gi, P2TAC. We have recently shown that concomitant intracellular signaling from both the P2TAC and P2Y1 receptors is essential for ADP-induced platelet aggregation. Previous studies have tested whether ADP causes a decrease in the basal cAMP level and this reduction promotes platelet aggregation, but did not study the effect of decreased cAMP levels when the Gq pathway is selectively activated. Since we are now aware that platelet aggregation requires activation of two receptors, we investigated whether the function of P2TAC receptor activation, leading to inhibition of platelet adenylyl cyclase, could be replaced by direct inhibition of adenylyl cyclase, when Gq pathway is also activated, a possibility that has not been addressed to date. In the present study, we supplemented the P2Y1 mediated Gq signaling pathway with inhibition of the platelet adenylyl cyclase by using SQ22536 or dideoxyadenosine, or by selective activation of the alpha2A adrenoceptors with epinephrine. Although SQ22536, dideoxyadenosine, and epinephrine reduced the cAMP levels, only epinephrine could mimic the P2TAC receptor mediated signaling events, suggesting that reduction in basal cAMP levels does not directly contribute to ADP-induced platelet activation. Adenosine-5'-phosphate-3'-phosphosulfate, a P2Y1 receptor antagonist, completely blocked ADP-induced inositol 1,4,5-trisphosphate and inositol 1,3.4-trisphosphate formation suggesting that P2TAC-mediated activation of Gi (or other G proteins) does not activate phospholipase C. These results suggest that a signaling event downstream from Gi, independent of the inhibition of platelet adenylyl cyclase, contributes to alphaIIb beta3 activation.

Alternative splicing creates sex-specific transcripts and truncated forms of the furin protease in the parasite Dirofilaria immitis

Many extracellular proteins are activated by specific cleavage with an endoprotease. In nematodes, several proteins are cleaved after RX(K/R)R, the recognition site for the subtilisin-like proprotein convertases, furin and blisterase. To characterize furin in the parasitic nematode Dirofilaria immitis, we determined the sequence of the difur gene and its multiple transcripts. The gene spans 11 kb; encodes 16 exons and has a complex pattern of alternative splicing which generates at least 16 distinct mRNAs. The major transcript is a 4.4 kb mRNA which codes for a protein of 834 aa with an unusually long prodomain of 254 aa. Sex-specific splice variants of difur were observed by RT-PCR. The three female-specific and five male-specific transcripts are the first reported examples of sex-specific splicing in parasitic nematodes. This suggests that nematodes have sex-specific factors which regulate RNA splicing. Other splice variants are predicted to alter the phosphorylation and localization of the protease. Alternative splicing after the prodomain encodes a truncated protein that may be an inhibitor and/or substrate of Difurin.

[Re-assessment of the inframammary crease ligament]

OBJECTIVE

An anatomical study was carried out to examine the existence of the inframammary crease ligament.

METHODS

18 breasts of preserved female cadavers were dissected and dyed for the fascia.

RESULTS

The so-called inframammary crease ligament described by other authors does not exist.

CONCLUSION

The reinforced Cooper's ligament supports the inframammary fold in position.

Maintenance of sinus rhythm with oral d,l-sotalol therapy in patients with symptomatic atrial fibrillation and/or atrial flutter. d,l-Sotalol Atrial Fibrillation/Flutter Study Group

Currently d,l-sotalol is widely used to prevent recurrence of atrial fibrillation and/or atrial flutter, although a randomized dose-response study has not previously been conducted to guide therapy for this indication. This study summarizes findings of a double-blind, placebo-controlled, multicenter, randomized trial evaluating the efficacy, safety, and dose-response relation of 3 fixed doses of d,l-sotalol (80, 120, and 160 mg twice daily) for the maintenance of sinus rhythm in 253 patients with atrial fibrillation and/or atrial flutter. All patients were in sinus rhythm at randomization. Treatment (69 patients on placebo, 59 on 80 mg, 63 on 120 mg, and 62 on 160 mg given twice daily) was continued for 12 months or until documented recurrence of symptomatic atrial fibrillation and/or flutter. Transtelephonic electrocardiographic monitoring was used to detect symptomatic recurrences. Demographic characteristics were not different in the 4 groups. Structural heart disease was present in 57% of patients. Patients with a history of heart failure were excluded. The time from randomization to symptomatic arrhythmia recurrence was significantly longer in the 2 higher d,l-sotalol dose groups than in the placebo group. The median times to recurrence were 27, 106, 229, and 175 days for the placebo, 80, 120, and 160 mg groups, respectively. There were no deaths or cases of torsade de pointes, sustained ventricular tachycardia, or ventricular fibrillation reported. Thus, d,l-sotalol appeared to be both safe and effective in maintaining sinus rhythm in patients with symptomatic atrial fibrillation and/or flutter. Further, the 120-mg twice daily dose appeared to provide the most favorable benefit and/or risk.

Analysis of the role of glutamine 190 in the catalytic mechanism of murine leukemia virus reverse transcriptase

To determine the catalytic role of Gln(190), a member of the highly conserved LPQG motif in Moloney murine leukemia virus reverse transcriptase, we carried out site-directed mutagenesis of this residue to generate Q190N and Q190A. Both mutant proteins exhibited a significant loss in their polymerase and pyrophosphorolysis activities with a more pronounced effect noted with the Gln --> Asn substitution. The catalytic efficiencies of the mutants exhibited a 40-70-fold reduction with poly(rC) and poly(dC) templates in the presence of Mg(2+) and a 10-20-fold reduction with poly(rA) template in the presence of Mn(2+). Interestingly, the K(m) for NTP exhibited only a moderate 3-10-fold increase irrespective of the template-primer and the metal ion. Photoaffinity labeling of both the mutant and the WT enzymes exhibited an identical affinity for RNA.DNA and DNA.DNA template-primers. However, unlike the WT enzyme, the mutant enzymes exhibited a significantly reduced ability to catalyze the nucleotidyltransferase reaction on the covalently immobilized template-primer. An examination of the rate constants for the first and the second nucleotide for the mutant enzymes indicated dissimilar rates, indicating that Gln(190) may be involved in a rate-limiting, conformational change step both before and after the phosphodiester bond formation. Furthermore, the processivity of DNA synthesis by the mutant enzymes was decreased severely, which may result from the lower catalytic efficiency as well as translocation defect.

New buccinator myomucosal island flap: anatomic study and clinical application

The authors studied the vascular anatomy of the buccinator muscle by dissecting fresh cadavers. The anatomy of the buccal branches of the facial artery consistently confirmed the existence of a posterior buccal branch, a few inferior buccal branches, and anterior buccal branches to the posterior, inferior, and anterior portions of the buccinator. The buccal artery and posterior buccal branch anastomose to each other and ramify over the muscle. Several veins originate from the lateral aspect of the muscle, converge into the buccal venous plexus, and drain into the facial vein (from two to four tributaries) or into the pterygoid plexus and the internal maxillary vein (from the buccal vein). These vessels and nerves enter the posterior half of the buccinator posterolaterally. The facial artery and vein are located at variable distances from each other around the oral commissure and the nasal base. Two patterns of buccinator musculomucosal island flaps supplied by these buccal arterial branches are proposed in this article. The buccal musculomucosal neurovascular island flap (posteriorly based), supplied by the buccal artery, its posterior buccal branch, and the long buccal nerve, can be passed through a tunnel under the pterygomandibular ligament for closure of mucosal defects in the palate, pharyngeal sites, the alveolus, and the floor of the mouth. The buccal musculomucosal reversed-flow arterial island flap (superiorly based), supplied by the distal portion of the facial artery through the anterior buccal branches, can be used to close mucosal defects in the anterior hard palate, alveolus, maxillary antrum, nasal floor and septum, lip, and orbit. The authors have used the flaps in 12 patients. There has been no flap necrosis, and results have been satisfactory, both aesthetically and functionally.

[Experimental study of immunization of mice with hepatitis C virus genetic vaccine constructs]

OBJECTIVE

To inquire into the immune responses to expression protein in mice immunized with genetic vaccine of hepatitis C virus (HCV) and lay a foundation for HCV genetic vaccine development in future.

METHODS

The gene fragments coding C and most E regions of HCV-II type were inserted into pCD-SRalpha(1) of eukaryotic expression vector and formed genetic vaccine constructs of pCD-HCV(1) and then was injected into the quadriceps muscles of Balb/c mice. The serum anti-HCV level of mice was tested by ELISA and peripheral blood mononuclear cell (PBMC) proliferative responses to HCV antigens were detected by (3)H-TdR incorporation method (cpm).

RESULTS

The serum antibody level reached to 0.71 +/- 0.08 - 0.77 +/- 0.06 (A value, the same below) after genetic vaccine pCD-HCV(1) (100 microg/mouse) were inoculated into the mice (n = 12) three or four times while blank vector pCD-SRalpha(1) could not induce the mice (n = 8) to generate antibody response in same way. After the antibody levels in mice (n = 8) immunized by pCD-HCV(1) had ascended to peak value (0.71), there was no trend of descending during the following 18 weeks of detection (0.68 +/- 0.06 - 0.75 +/- 0.07). Specific fragment of HCV cDNA identified by polymerase chain reaction (PCR) from DNA extracted from the muscles of the mice after pCD-HCV(1) had been inoculated three months. PBMC proliferative responses to HCV synthetic peptides CP(9) and gene recombinant antigens C, E(1) in the mice immunized with pCD-HCV(1) were detected and its stimulation indexes (SI) were 4.07 +/- 1.58, 3.88 +/- 0.70 and 3.69 +/- 1.13 respectively and there was a significant difference (P < 0.001) as compared with that of PBMC in mice immunized with pCD-SRalpha(1).

CONCLUSION

These investigations demonstrated that genetic vaccine constructs made of HCV structural region can induce Balb/c mice to generate antibody and PBMC proliferative responses to HCV antigens via DNA immunization.

Protein kinase B/Akt participates in GLUT4 translocation by insulin in L6 myoblasts

L6 myoblasts stably transfected with a GLUT4 cDNA harboring an exofacial myc epitope tag (L6-GLUT4myc myoblasts) were used to study the role of protein kinase B alpha (PKBalpha)/Akt1 in the insulin-induced translocation of GLUT4 to the cell surface. Surface GLUT4myc was detected by immunofluorescent labeling of the myc epitope in nonpermeabilized cells. Insulin induced a marked translocation of GLUT4myc to the plasma membrane within 20 min. This was prevented by transient transfection of a dominant inhibitory construct of phosphatidylinositol (PI) 3-kinase (Deltap85alpha). Transiently transfected cells were identified by cotransfection of green fluorescent protein. A constitutively active PKBalpha, created by fusion of a viral Gag protein at its N terminus (GagPKB), increased the cell surface density of GLUT4myc compared to that of neighboring nontransfected cells. A kinase-inactive, phosphorylation-deficient PKBalpha/Akt1 construct with the mutations K179A (substitution of alanine for the lysine at position 179), T308A, and S473A (AAA-PKB) behaved as a dominant-negative inhibitor of insulin-dependent activation of cotransfected wild-type hemagglutinin (HA)-tagged PKB. Furthermore, AAA-PKB markedly inhibited the insulin-induced phosphorylation of cotransfected BAD, demonstrating inhibition of the endogenous PKB/Akt. Under the same conditions, AAA-PKB almost entirely blocked the insulin-dependent increase in surface GLUT4myc. PKBalpha with alanine substitutions T308A and S473A (AA-PKB) or K179A (A-PKB) alone was a less potent inhibitor of insulin-dependent activation of wild-type HA-PKB or GLUT4myc translocation than was AAA-PKB. Cotransfection of AAA-PKB with a fourfold DNA excess of HA-PKB rescued insulin-stimulated GLUT4myc translocation. AAA-PKB did not prevent actin bundling (membrane ruffling), though this response was PI 3-kinase dependent. Therefore, it is unlikely that AAA-PKB acted by inhibiting PI 3-kinase signaling. These results outline an important role for PKBalpha/Akt1 in the stimulation of glucose transport by insulin in muscle cells in culture.