The Experts below are selected from a list of 1326 Experts worldwide ranked by ideXlab platform

Deepa Subramanyam - One of the best experts on this subject based on the ideXlab platform.

  • Pluripotency of embryonic stem cells lacking clathrin-mediated endocytosis cannot be rescued by restoring cellular stiffness
    The Journal of biological chemistry, 2020
    Co-Authors: Ridim D Mote, Jyoti Yadav, Surya Bansi Singh, Mahak Tiwari, Shinde Laxmikant, Shivprasad Patil, Deepa Subramanyam
    Abstract:

    Mouse embryonic stem cells (mESCs) display unique mechanical properties, including low cellular stiffness in contrast to differentiated cells, which are stiffer. We have previously shown that mESCs lacking the clathrin heavy chain (CLTC), an essential component for clathrin-mediated endocytosis (CME), display a loss of pluripotency and an enhanced expression of differentiation markers. However, it is not known whether physical properties such as cellular stiffness also change upon loss of CLTC, similar to what is seen in differentiated cells, and if so, how these altered properties specifically impact pluripotency. Using atomic force microscopy (AFM), we demonstrate that mESCs lacking CLTC display higher Young's modulus, indicative of greater cellular stiffness, compared with WT mESCs. The increase in stiffness was accompanied by the presence of actin stress fibers and accumulation of the inactive, phosphorylated, actin-binding protein cofilin. Treatment of CLTC knockdown mESCs with actin polymerization inhibitors resulted in a decrease in the Young's modulus to values similar to those obtained with WT mESCs. However, a rescue in the expression profile of pluripotency factors was not obtained. Additionally, whereas WT mouse embryonic fibroblasts could be reprogrammed to a state of pluripotency, this was inhibited in the absence of CLTC. This indicates that the presence of active CME is essential for the pluripotency of embryonic stem cells. Additionally, whereas physical properties may serve as a simple readout of the cellular state, they may not always faithfully recapitulate the underlying molecular fate.

  • Loss of clathrin heavy chain enhances actin-dependent stiffness of mouse embryonic stem cells
    2020
    Co-Authors: Ridim D Mote, Jyoti Yadav, Surya Bansi Singh, Mahak Tiwari, Shivprasad Patil Vitthal Patil, Deepa Subramanyam
    Abstract:

    Mouse embryonic stem cells (mESCs) display unique mechanical properties, including low cell stiffness, and specific responses to features of the underlying substratum. Using atomic force microscopy (AFM), we demonstrate that mESCs lacking the clathrin heavy chain (CLTC), display higher Young9s modulus, indicative of greater cellular stiffness, in comparison to WT mESCs. We have previously shown that mESCs lacking CLTC display a loss of pluripotency, and an initiation of differentiation. The increased stiffness observed in these cells was accompanied by the presence of actin stress fibres and accumulation of the inactive, phosphorylated, actin binding protein, Cofilin. Treatment of CLTC knockdown mESCs with actin polymerization inhibitors resulted in a decrease in the Young9s modulus, to values similar to those obtained with WT mESCs. However, the expression profile of pluripotency factors was not rescued. This indicates that a restoration of mechanical properties, through modulation of the actin cytoskeleton, may not always be accompanied by a change in the expression of critical transcription factors that regulate the state of a stem cell, and that this may be dependent on the presence of active endocytosis in a cell.

  • Clathrin-Mediated Endocytosis Regulates a Balance between Opposing Signals to Maintain the Pluripotent State of Embryonic Stem Cells
    Elsevier, 2019
    Co-Authors: Yadavalli V. Narayana, Ridim D Mote, Chetan Gadgil, Raghav Rajan, Deepa Subramanyam
    Abstract:

    Summary: Endocytosis is implicated in the maintenance of embryonic stem cell (ESC) pluripotency, although its exact role and the identity of molecular players remain poorly understood. Here, we show that the clathrin heavy chain (CLTC), involved in clathrin-mediated endocytosis (CME), is vital for maintaining mouse ESC (mESC) pluripotency. Knockdown of CLTC resulted in a loss of pluripotency accompanied by reduced E-cadherin (E-CAD) levels and increased levels of transforming growth factor β (TGF-β) and extracellular signal-regulated kinase (ERK) signaling. We demonstrate that both E-CAD and TGF-β receptor type 1 (TGF-βR1) are internalized through CME in mESCs. While E-CAD is recycled, TGF-βR1 is targeted for lysosomal degradation thus maintaining inverse levels of these molecules. Finally, we show that E-CAD interacts with ERK, and that the decreased pluripotency upon CME loss can be rescued by inhibiting TGF-βR, MEK, and GSK3β, or overexpressing E-CAD. Our results demonstrate that CME is critical for balancing signaling outputs to regulate ESC pluripotency, and possibly cell fate choices in early development. : Subramanyam and colleagues demonstrate that clathrin-mediated endocytosis (CME) is necessary to maintain ESC pluripotency by regulating the trafficking of E-CAD and TGF-βR1. Loss of CME results in a loss of pluripotency characterized by decreased E-CAD and enhanced TGF-βR1 and MEK signaling. Expression of pluripotency markers in ESCs lacking CLTC can be restored by inhibiting TGF-βR1 or MEK or by overexpressing E-CAD. Keywords: embryonic stem cells, pluripotency, trafficking, E-cadherin, clathrin, recycling, TGF-β, epithelia

Errol L. Lloyd - One of the best experts on this subject based on the ideXlab platform.

  • Communications in Computing - The Impact of Clustering in Distributed Topology Control.
    2006
    Co-Authors: Liang Zhao, Errol L. Lloyd
    Abstract:

    Topology control is the problem of assigning power levels to the nodes of an ad hoc network so as to maintain a specified network topology while minimizing energy consumption (either minimizing the maximum power used by any node or minimizing the total (i.e. average) power used by the nodes). In [18], a hybrid framework for distributed topology control based on clustering was proposed. That framework, called CLTC, specifies algorithms for both 1-connected and 2-connected topologies, and works with any clustering algorithm. CLTC utilizes centralized topology control within each cluster, but is otherwise fully distributed, hence the characterization of the method as hybrid. This paper studies the effect of six representative clustering methods on the quality of the topology control solutions provided by CLTC. The results establish that the most important factors in determining the performance of CLTC are the average cluster size and the closeness of nodes in clusters. This leads to a tradeoff between the energy consumption, the complexity of cluster formation, and the scope to which the operations of CLTC are fully distributed. The paper also shows that, in general, there is a considerable increase in power usage (in the vicinity of 150%) by requiring a 2-connected network versus a 1-connected network.

  • CLTC: a cluster-based topology control for ad hoc networks
    IEEE Transactions on Mobile Computing, 2004
    Co-Authors: Chien-chung Shen, C. Srisathapornphat, Rui Liu, Zhuochuan Huang, Chaiporn Jaikaeo, Errol L. Lloyd
    Abstract:

    The topology of an ad hoc network has a significant impact on its performance in that a dense topology may induce high interference and low capacity, while a sparse topology is vulnerable to link failure and network partitioning. Topology control aims to maintain a topology that optimizes network performance while minimizing energy consumption. Existing topology control algorithms utilize either a purely centralized or a purely distributed approach. A centralized approach, although able to achieve strong connectivity (k-connectivity for k /spl ges/ 2), suffers from scalability problems. In contrast, a distributed approach, although scalable, lacks strong connectivity guarantees. We propose a hybrid topology control framework, cluster-based topology control (CLTC) that achieves both scalability and strong connectivity. By varying the algorithms utilized in each of the three phases of the framework, a variety of optimization objectives and topological properties can be achieved. In this paper, we present the CLTC framework; describe topology control algorithms based on CLTC and prove that k-connectivity is achieved using those algorithms; analyze the message complexity of an implementation of CLTC, namely, CLTC-A, and present simulation studies that evaluate the effectiveness of CLTC-A for a range of networks.

Theresa A. M. Noble - One of the best experts on this subject based on the ideXlab platform.

  • SIGUCCS - Computing labs and technology classroom (CLTC) initiative: a model for distributed support
    Proceedings of the 31st annual ACM SIGUCCS conference on User services - SIGUCCS '03, 2003
    Co-Authors: Lynda S. Laroche, Julianne M. Miranda, Angie Smock, Theresa A. M. Noble
    Abstract:

    DePauw University is a small, liberal arts institution with 2200 undergraduate residential students and 222 faculty members, located in Greencastle, Indiana. The challenges of supporting a campus with multiple and diverse facilities are further amplified by limited staff support resources. One of the strategies for addressing these challenges led to the formation of the Computing Labs and Technology Classrooms (CLTC) initiative. The CLTC recognizes and draws on the strengths of support specialists with a wide variety of professional training and experience, who regularly collaborate in the support and management of campus-wide labs and technology classrooms.The veritable explosion of new technologies presents its own fiscal challenges. As with many other institutions, our financial ability to hire enough staff with the requisite skills to fulfill the ever-increasing support requests is very limited. In an effort to address these concerns, a committee was formed of individuals active in supporting technology in their respective disciplines.The committee includes faculty members, technical and administrative support specialists, instructional technologist, a graphic artist and the director of Instructional Media Services. Their individual support perspectives combine to provide a broad understanding that enriches and increases each committee member's ability to provide support at all levels. In addition to the focus on support, the CLTC initiative has also provided a forum for collaborative work on budgets, policy and planning.In this paper, four committee members describe the CLTC initiative and the distributed support model developed at DePauw University, along with its impact on labs, technology classrooms and the broader campus community.

  • computing labs and technology classroom CLTC initiative a model for distributed support
    SIGUCCS: User Services Conference, 2003
    Co-Authors: Lynda S. Laroche, Julianne M. Miranda, Angie Smock, Theresa A. M. Noble
    Abstract:

    DePauw University is a small, liberal arts institution with 2200 undergraduate residential students and 222 faculty members, located in Greencastle, Indiana. The challenges of supporting a campus with multiple and diverse facilities are further amplified by limited staff support resources. One of the strategies for addressing these challenges led to the formation of the Computing Labs and Technology Classrooms (CLTC) initiative. The CLTC recognizes and draws on the strengths of support specialists with a wide variety of professional training and experience, who regularly collaborate in the support and management of campus-wide labs and technology classrooms.The veritable explosion of new technologies presents its own fiscal challenges. As with many other institutions, our financial ability to hire enough staff with the requisite skills to fulfill the ever-increasing support requests is very limited. In an effort to address these concerns, a committee was formed of individuals active in supporting technology in their respective disciplines.The committee includes faculty members, technical and administrative support specialists, instructional technologist, a graphic artist and the director of Instructional Media Services. Their individual support perspectives combine to provide a broad understanding that enriches and increases each committee member's ability to provide support at all levels. In addition to the focus on support, the CLTC initiative has also provided a forum for collaborative work on budgets, policy and planning.In this paper, four committee members describe the CLTC initiative and the distributed support model developed at DePauw University, along with its impact on labs, technology classrooms and the broader campus community.

Ridim D Mote - One of the best experts on this subject based on the ideXlab platform.

  • Pluripotency of embryonic stem cells lacking clathrin-mediated endocytosis cannot be rescued by restoring cellular stiffness
    The Journal of biological chemistry, 2020
    Co-Authors: Ridim D Mote, Jyoti Yadav, Surya Bansi Singh, Mahak Tiwari, Shinde Laxmikant, Shivprasad Patil, Deepa Subramanyam
    Abstract:

    Mouse embryonic stem cells (mESCs) display unique mechanical properties, including low cellular stiffness in contrast to differentiated cells, which are stiffer. We have previously shown that mESCs lacking the clathrin heavy chain (CLTC), an essential component for clathrin-mediated endocytosis (CME), display a loss of pluripotency and an enhanced expression of differentiation markers. However, it is not known whether physical properties such as cellular stiffness also change upon loss of CLTC, similar to what is seen in differentiated cells, and if so, how these altered properties specifically impact pluripotency. Using atomic force microscopy (AFM), we demonstrate that mESCs lacking CLTC display higher Young's modulus, indicative of greater cellular stiffness, compared with WT mESCs. The increase in stiffness was accompanied by the presence of actin stress fibers and accumulation of the inactive, phosphorylated, actin-binding protein cofilin. Treatment of CLTC knockdown mESCs with actin polymerization inhibitors resulted in a decrease in the Young's modulus to values similar to those obtained with WT mESCs. However, a rescue in the expression profile of pluripotency factors was not obtained. Additionally, whereas WT mouse embryonic fibroblasts could be reprogrammed to a state of pluripotency, this was inhibited in the absence of CLTC. This indicates that the presence of active CME is essential for the pluripotency of embryonic stem cells. Additionally, whereas physical properties may serve as a simple readout of the cellular state, they may not always faithfully recapitulate the underlying molecular fate.

  • Loss of clathrin heavy chain enhances actin-dependent stiffness of mouse embryonic stem cells
    2020
    Co-Authors: Ridim D Mote, Jyoti Yadav, Surya Bansi Singh, Mahak Tiwari, Shivprasad Patil Vitthal Patil, Deepa Subramanyam
    Abstract:

    Mouse embryonic stem cells (mESCs) display unique mechanical properties, including low cell stiffness, and specific responses to features of the underlying substratum. Using atomic force microscopy (AFM), we demonstrate that mESCs lacking the clathrin heavy chain (CLTC), display higher Young9s modulus, indicative of greater cellular stiffness, in comparison to WT mESCs. We have previously shown that mESCs lacking CLTC display a loss of pluripotency, and an initiation of differentiation. The increased stiffness observed in these cells was accompanied by the presence of actin stress fibres and accumulation of the inactive, phosphorylated, actin binding protein, Cofilin. Treatment of CLTC knockdown mESCs with actin polymerization inhibitors resulted in a decrease in the Young9s modulus, to values similar to those obtained with WT mESCs. However, the expression profile of pluripotency factors was not rescued. This indicates that a restoration of mechanical properties, through modulation of the actin cytoskeleton, may not always be accompanied by a change in the expression of critical transcription factors that regulate the state of a stem cell, and that this may be dependent on the presence of active endocytosis in a cell.

  • Clathrin-Mediated Endocytosis Regulates a Balance between Opposing Signals to Maintain the Pluripotent State of Embryonic Stem Cells
    Elsevier, 2019
    Co-Authors: Yadavalli V. Narayana, Ridim D Mote, Chetan Gadgil, Raghav Rajan, Deepa Subramanyam
    Abstract:

    Summary: Endocytosis is implicated in the maintenance of embryonic stem cell (ESC) pluripotency, although its exact role and the identity of molecular players remain poorly understood. Here, we show that the clathrin heavy chain (CLTC), involved in clathrin-mediated endocytosis (CME), is vital for maintaining mouse ESC (mESC) pluripotency. Knockdown of CLTC resulted in a loss of pluripotency accompanied by reduced E-cadherin (E-CAD) levels and increased levels of transforming growth factor β (TGF-β) and extracellular signal-regulated kinase (ERK) signaling. We demonstrate that both E-CAD and TGF-β receptor type 1 (TGF-βR1) are internalized through CME in mESCs. While E-CAD is recycled, TGF-βR1 is targeted for lysosomal degradation thus maintaining inverse levels of these molecules. Finally, we show that E-CAD interacts with ERK, and that the decreased pluripotency upon CME loss can be rescued by inhibiting TGF-βR, MEK, and GSK3β, or overexpressing E-CAD. Our results demonstrate that CME is critical for balancing signaling outputs to regulate ESC pluripotency, and possibly cell fate choices in early development. : Subramanyam and colleagues demonstrate that clathrin-mediated endocytosis (CME) is necessary to maintain ESC pluripotency by regulating the trafficking of E-CAD and TGF-βR1. Loss of CME results in a loss of pluripotency characterized by decreased E-CAD and enhanced TGF-βR1 and MEK signaling. Expression of pluripotency markers in ESCs lacking CLTC can be restored by inhibiting TGF-βR1 or MEK or by overexpressing E-CAD. Keywords: embryonic stem cells, pluripotency, trafficking, E-cadherin, clathrin, recycling, TGF-β, epithelia

Zhiqi Lin - One of the best experts on this subject based on the ideXlab platform.

  • Fuel consumption and emission performance from light-duty conventional/hybrid-electric vehicles over different cycles and real driving tests
    Fuel, 2020
    Co-Authors: Yachao Wang, Chunxiao Hao, Lijun Hao, Jianwei Tan, Xin Wang, Pengyu Zhang, Yuan Wang, Tian Weidong, Zhiqi Lin
    Abstract:

    Abstract Many studies have found that WLTC (The Worldwide harmonized Light vehicles Test Cycles) doesn’t accord well to real driving in different regions and it’s necessary to develop local test cycles. China announced its local test cycle in 2019: CLTC (China light-duty vehicle test cycle). To evaluate vehicle emission under different cycles, one conventional gasoline vehicle and its hybrid counterpart were tested on the chassis dynamometer following CLTC, WLTC, and RDE (Real Driving Emission). The fuel consumption between WLTC and RDE is at the same level. While for the conventional, CLTC fuel consumption is 8.41% higher than WLTC and for the hybrid, it’s 20.23% lower than WLTC. To get better vehicle fuel efficiency, vehicle application scenarios must be considered. Frequent re-start and longer warm-up time of the hybrid leads to high CO emission than the conventional. High engine speed could result in instantaneous CO spikes and with these spikes, 25% of the total CO could be emitted in less than 10 s. For the conventional, NOx emitted during engine warm-up occupied 85.39%, 87.02%, 43.06%, 31.98%, and 55.43% of the total NOx respectively for CLTC, WLTC and three RDE tests. NOx emitted from the hybrid is less than 10% of the conventional due to lower engine load and less fuel enrichment. Hybrid particle emission is under good control with the equipment of the gasoline particle filter, but the regeneration might increase thin particle exposure to the public. For most pollutants, CLTC doesn't close the gap between laboratory tests and real driving.