Integrin alpha3beta1 (CD 49c/29) is a cellular receptor for Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) entry into the target cells

Human herpesvirus-8 (HHV-8) is implicated in the pathogenesis of Kaposi's sarcoma. HHV-8 envelope glycoprotein B possesses the RGD motif known to interact with integrin molecules, and HHV-8 infectivity was inhibited by RGD peptides, antibodies against RGD-dependent alpha3 and beta1 integrins, and by soluble alpha3beta1 integrin. Expression of human alpha3 integrin increased the infectivity of virus for Chinese hamster ovary cells. Anti-gB antibodies immunoprecipitated the virus-alpha3 and -beta1 complexes, and virus binding studies suggest a role for alpha3beta1 in HHV-8 entry. Further, HHV-8 infection induced the integrin-mediated activation of focal adhesion kinase (FAK). These findings implicate a role for alpha3beta1 integrin and the associated signaling pathways in HHV-8 entry into the target cells.     

Lipid rafts of primary endothelial cells are essential for Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8-induced phosphatidylinositol 3-kinase and RhoA-GTPases critical for microtubule dynamics and nuclear delivery of viral DNA but dispensable for binding and entry

Early during de novo infection of human microvascular dermal endothelial (HMVEC-d) cells, Kaposi's sarcoma-associated herpesvirus (KSHV) (human herpesvirus 8 [HHV-8]) induces the host cell's preexisting FAK, Src, phosphatidylinositol 3-kinase (PI3-K), Rho-GTPases, Diaphanous-2 (Dia-2), Ezrin, protein kinase C-zeta, extracellular signal-regulated kinase 1/2 (ERK1/2), and NF-kappaB signal pathways that are critical for virus entry, nuclear delivery of viral DNA, and initiation of viral gene expression. Since several of these signal molecules are known to be associated with lipid raft (LR) domains, we investigated the role of LR during KSHV infection of HMVEC-d cells. Pretreatment of cells with LR-disrupting agents methyl beta-cyclo dextrin (MbetaCD) or nystatin significantly inhibited the expression of viral latent (ORF73) and lytic (ORF50) genes. LR disruption did not affect KSHV binding but increased viral DNA internalization. In contrast, association of internalized viral capsids with microtubules (MTs) and the quantity of infected nucleus-associated viral DNA were significantly reduced. Disorganized and disrupted MTs and thick rounded plasma membranes were observed in MbetaCD-treated cells. LR disruption did not affect KSHV-induced FAK and ERK1/2 phosphorylation; in contrast, it increased the phosphorylation of Src, significantly reduced the KSHV-induced PI3-K and RhoA-GTPase and NF-kappaB activation, and reduced the colocalizations of PI3-K and RhoA-GTPase with LRs. Biochemical characterization demonstrated the association of activated PI3-K with LR fractions which was inhibited by MbetaCD treatment. RhoA-GTPase activation was inhibited by PI3-K inhibitors, demonstrating that PI3-K is upstream to RhoA-GTPase. In addition, colocalization of Dia-2, a RhoA-GTPase activated molecule involved in MT activation, with LR was reduced. KSHV-RhoA-GTPase mediated acetylation and aggregation of MTs were also reduced. Taken together, these studies suggest that LRs of endothelial cells play critical roles in KSHV infection and gene expression, probably due to their roles in modulating KSHV-induced PI3-K, RhoA-GTPase, and Dia-2 molecules essential for postbinding and entry stages of infection such as modulation of microtubular dynamics, movement of virus in the cytoplasm, and nuclear delivery of viral DNA.     

Cathepsin-mediated Necrosis Controls the Adaptive Immune Response by Th2 (T helper type 2)-associated Adjuvants

Immunologic adjuvants are critical components of vaccines, but it remains unclear how prototypical adjuvants enhance the adaptive immune response. Recent studies have shown that necrotic cells could trigger an immune response. Although most adjuvants have been shown to be cytotoxic, this activity has traditionally been considered a side effect. We set out to test the role of adjuvant-mediated cell death in immunity and found that alum, the most commonly used adjuvant worldwide, triggers a novel form of cell death in myeloid leukocytes characterized by cathepsin-dependent lysosome-disruption. We demonstrated that direct lysosome-permeabilization with a soluble peptide, Leu-Leu-OMe, mimics the alum-like form of necrotic cell death in terms of cathepsin dependence and cell-type specificity. Using a combination of a haploid genetic screen and cathepsin-deficient cells, we identified specific cathepsins that control lysosome-mediated necrosis. We identified cathepsin C as critical for Leu-Leu-OMe-induced cell death, whereas cathepsins B and S were required for alum-mediated necrosis. Consistent with a role of necrotic cell death in adjuvant effects, Leu-Leu-OMe replicated an alum-like immune response in vivo, characterized by dendritic cell activation, granulocyte recruitment, and production of Th2-associated antibodies. Strikingly, cathepsin C deficiency not only blocked Leu-Leu-OMe-mediated necrosis but also impaired Leu-Leu-OMe-enhanced immunity. Together our findings suggest that necrotic cell death is a powerful mediator of a Th2-associated immune response.     

Clamping,bending, and twisting inter-domain motions in the misfold-recognizing portion of UDP-glucose: Glycoprotein glucosyltransferase

1. Download : Download high-res image (119KB)
2. Download : Download full-size image

     

Comparison of left anterior descending coronary artery hemodynamics before and after angioplasty

Coronary artery disease (CAD) is characterized by the progression of atherosclerosis, a complex pathological process involving the initiation, deposition, development, and breakdown of the plaque. The blood flow mechanics in arteries play a critical role in the targeted locations and progression of atherosclerotic plaque. In coronary arteries with motion during the cardiac contraction and relaxation, the hemodynamic flow field is substantially different from the other arterial sites with predilection of atherosclerosis. In this study, our efforts focused on the effects of arterial motion and local geometry on the hemodynamics of a left anterior descending (LAD) coronary artery before and after clinical intervention to treat the disease. Three-dimensional (3D) arterial segments were reconstructed at 10 phases of the cardiac cycle for both pre- and postintervention based on the fusion of intravascular ultrasound (IVUS) and biplane angiographic images. An arbitrary Lagrangian-Eulerian formulation was used for the computational fluid dynamic analysis. The measured arterial translation was observed to be larger during systole after intervention and more out-of-plane motion was observed before intervention, indicating substantial alterations in the cardiac contraction after angioplasty. The time averaged axial wall shear stress ranged from -0.2 to 9.5 Pa before intervention compared to -0.02 to 3.53 Pa after intervention. Substantial oscillatory shear stress was present in the preintervention flow dynamics compared to that in the postintervention case.     

Micropropagation in Peanut (Arachis hypogaea L.)

Multiple shoots in Arachis hypogaea L. could be induced from the de-embryonated cotyledons (DC), embryo-axes (EA) and mature whole seeds (MWS) in MS medium supplemented with different levels of benzylaminopurine (BAP). DC was the most suitable explant with 57.9 % induction and more than 40 shoots per explant in 31.6 % of cases. Though EA and MWS had high percent induction at or above 30 mg dm^–3 BAP, only 10 – 14 shoots per explant were observed. In DC, multiple shoots were confined to the proximal end and in EA they originated from the axillary bud region. Histological studies on DC confirmed the origin of shoots from the region of attachment with the embryo. Shoots could be rooted in MS medium containing 2 g dm^–3 charcoal and 200 mg dm^–3 casein hydrolysate. Sixty percent of the rooted plantlets could be established in the field.