The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Jaebong Jang - One of the best experts on this subject based on the ideXlab platform.
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total synthesis of deguelin via an iterative pyran Ring Formation strategy
ChemInform, 2015Co-Authors: Hongchan An, Dongjo Chang, Jaebong JangAbstract:Enantioselective synthesis of (-)-deguelin is accomplished via an iterative pyran-Ring Formation approach.
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total synthesis of deguelin via an iterative pyran Ring Formation strategy
Chemical Communications, 2015Co-Authors: Hongchan An, Dongjo Chang, Jaebong JangAbstract:Enantioselective synthesis of (−)-deguelin was accomplished via an iterative pyran-Ring Formation approach. The key features involve the anionic addition of a chromene unit to aryloxy alkyl aldehyde for the double cyclization precursor and iterative pyran Ring Formation by Pd-catalyzed O-arylation and C-arylation, respectively.
Hongchan An - One of the best experts on this subject based on the ideXlab platform.
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total synthesis of deguelin via an iterative pyran Ring Formation strategy
ChemInform, 2015Co-Authors: Hongchan An, Dongjo Chang, Jaebong JangAbstract:Enantioselective synthesis of (-)-deguelin is accomplished via an iterative pyran-Ring Formation approach.
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total synthesis of deguelin via an iterative pyran Ring Formation strategy
Chemical Communications, 2015Co-Authors: Hongchan An, Dongjo Chang, Jaebong JangAbstract:Enantioselective synthesis of (−)-deguelin was accomplished via an iterative pyran-Ring Formation approach. The key features involve the anionic addition of a chromene unit to aryloxy alkyl aldehyde for the double cyclization precursor and iterative pyran Ring Formation by Pd-catalyzed O-arylation and C-arylation, respectively.
Meenakshi A. Chellaiah - One of the best experts on this subject based on the ideXlab platform.
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Regulation of Sealing Ring Formation by L-plastin and Cortactin in Osteoclasts
Journal of Biological Chemistry, 2010Co-Authors: Tao Ma, Kavitha Sadashivaiah, Meenakshi A. ChellaiahAbstract:The aim of this study is to identify the exact mechanism(s) by which cytoskeletal structures are modulated duRing bone resorption. In this study, we have shown the possible role of different actin-binding and signaling proteins in the regulation of sealing Ring Formation. Our analyses have demonstrated a significant increase in cortactin and a corresponding decrease in L-plastin protein levels in osteoclasts subjected to bone resorption for 18 h in the presence of RANKL, M-CSF, and native bone particles. Time-dependent changes in the localization of L-plastin (in actin aggregates) and cortactin (in the sealing Ring) suggest that these proteins may be involved in the initial and maturation phases of sealing Ring Formation, respectively. siRNA to cortactin inhibits this maturation process but not the Formation of actin aggregates. Osteoclasts treated as above but with TNF-α demonstrated very similar effects as observed with RANKL. Osteoclasts treated with a neutralizing antibody to TNF-α displayed podosome-like structures in the entire subsurface and at the periphery of osteoclast. It is possible that TNF-α and RANKL-mediated signaling may play a role in the early phase of sealing Ring configuration (i.e. either in the disassembly of podosomes or Formation of actin aggregates). Furthermore, osteoclasts treated with alendronate or αv reduced the Formation of the sealing Ring but not actin aggregates. The present study demonstrates a novel mechanistic link between L-plastin and cortactin in sealing Ring Formation. These results suggest that actin aggregates formed by L-plastin independent of integrin signaling function as a core in assembling signaling molecules (integrin αvβ3, Src, cortactin, etc.) involved in the maturation process.
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Dramatic inhibition of osteoclast sealing Ring Formation and bone resorption in vitro by a WASP-peptide containing pTyr294 amino acid
Journal of Molecular Signaling, 2008Co-Authors: Tao Ma, Venkatesababa Samanna, Meenakshi A. ChellaiahAbstract:W iskott A ldrich S yndrome p rotein (WASP) has a unique regulatory role in sealing Ring Formation and bone resorption in osteoclasts. Here, using the TAT-transduction method, we show the possible role of WASP domain(s) in sealing Ring Formation and bone resorption. Transduction of TAT-fused full-length WASP peptide induced Arp2/3 complex Formation, F-actin content, sealing Ring Formation and bone resorption. Transduction of WASP peptides containing basic, verpolin-central, pTyr294, and proline-rich regions inhibited the processes listed above at various levels. The ability to resorb bone by WASP peptides containing basic, verpolin-central, and proline-rich regions was reduced and the resorbed area matched the size of the sealing Ring. However, osteoclasts transduced with WASP peptide containing pTyr294aa demonstrated the following: a) a considerable decrease in the interaction and phosphorylation of c-Src with endogenous WASP; b) total loss of sealing Ring-like structures; c) Formation of actin-rich patches at the peripheral edge that contains filopodia-like projections; d) reduced capacity for bone resorption in vitro. These findings suggest that modulation of phosphorylation state of pTyr294aa assists in integrating multiple signaling molecule and pathways that partake in the assembly of sealing Ring.
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Regulation of actin Ring Formation by rho GTPases in osteoclasts.
Journal of Biological Chemistry, 2005Co-Authors: Meenakshi A. ChellaiahAbstract:Abstract Actin Ring Formation is a prerequisite for osteoclast bone resorption. Although gelsolin null osteoclasts failed to exhibit podosomes, actin Ring was observed in these osteoclasts. Wiscott-Aldrich syndrome protein (WASP) was observed in the actin Ring of gelsolin null osteoclast. Osteoclasts stimulated with osteopontin simulated the effects of Rho and Cdc42 in phosphatidylinositol 4,5-bisphosphate (PIP2) association with WASP as well as Formation of podosomes, peripheral microfilopodia-like structures, and actin Ring. To explore the potential functions of Rho and Cdc42, TAT-mediated delivery of Rho proteins into osteoclasts was performed. Although Rho and Cdc42 are required for actin Ring Formation, transduction of either one of the proteins alone is insufficient for this process. Addition of osteopontin to osteoclasts transduced with Cdc42Val12 or transduction of osteoclasts with both RhoVal14 and Cdc42Val12 augments the Formation of WASP-Arp2/3 complex and actin Ring. Neomycin, an antibiotic, blocked the effects of osteopontin or TAT-RhoVal14 on PIP2 interaction with WASP. WASP distribution was found to be cytosolic in these osteoclasts. Depletion of WASP by short interfeRing RNA-mediated gene silencing blocked actin polymerization as well as actin Ring Formation in osteoclasts. These results suggest that Rho-mediated PIP2 interaction with WASP may contribute to the activation and membrane targeting of WASP. Subsequent interaction of Cdc42 and Arp2/3 with WASP may enhance cortical actin polymerization in the process of actin Ring Formation in osteoclasts.
Dongjo Chang - One of the best experts on this subject based on the ideXlab platform.
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total synthesis of deguelin via an iterative pyran Ring Formation strategy
ChemInform, 2015Co-Authors: Hongchan An, Dongjo Chang, Jaebong JangAbstract:Enantioselective synthesis of (-)-deguelin is accomplished via an iterative pyran-Ring Formation approach.
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total synthesis of deguelin via an iterative pyran Ring Formation strategy
Chemical Communications, 2015Co-Authors: Hongchan An, Dongjo Chang, Jaebong JangAbstract:Enantioselective synthesis of (−)-deguelin was accomplished via an iterative pyran-Ring Formation approach. The key features involve the anionic addition of a chromene unit to aryloxy alkyl aldehyde for the double cyclization precursor and iterative pyran Ring Formation by Pd-catalyzed O-arylation and C-arylation, respectively.
Alan D Grossman - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of a negative regulator of ftsz Ring Formation in bacillus subtilis
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Petra Anne Levin, Iren Kurtser, Alan D GrossmanAbstract:DuRing the bacterial cell cycle, the tubulin-like cell-division protein FtsZ polymerizes into a Ring structure that establishes the location of the nascent division site. We have identified a regulator of FtsZ Ring Formation in Bacillus subtilis. This protein, EzrA, modulates the frequency and position of FtsZ Ring Formation. The loss of ezrA resulted in cells with multiple FtsZ Rings located at polar as well as medial sites. Moreover, the critical concentration of FtsZ required for Ring Formation was lower in ezrA null mutants than in wild-type cells. EzrA was associated with the cell membrane and also colocalized with FtsZ to the nascent septal site. We propose that EzrA interacts either with FtsZ or with one of its binding partners to promote depolymerization.
