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Articles 1 - 11 of 11

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Actin Filaments Target The Oligomeric Maturation Of The Dynamin Gtpase Drp1 To Mitochondrial Fission Sites, Wei-Ke Ji, Anna L. Hatch, Ronald A. Merrill, Stefan Strack, Henry N. Higgs Nov 2015

Actin Filaments Target The Oligomeric Maturation Of The Dynamin Gtpase Drp1 To Mitochondrial Fission Sites, Wei-Ke Ji, Anna L. Hatch, Ronald A. Merrill, Stefan Strack, Henry N. Higgs

Open Dartmouth: Faculty Open Access Scholarship

While the dynamin GTPase Drp1 plays a critical role during mitochondrial fission, mechanisms controlling its recruitment to fission sites are unclear. A current assumption is that cytosolic Drp1 is recruited directly to fission sites immediately prior to fission. Using live-cell microscopy, we find evidence for a different model, progressive maturation of Drp1 oligomers on mitochondria through incorporation of smaller mitochondrially-bound Drp1 units. Maturation of a stable Drp1 oligomer does not forcibly lead to fission. Drp1 oligomers also translocate directionally along mitochondria. Ionomycin, a calcium ionophore, causes rapid mitochondrial accumulation of actin filaments followed by Drp1 accumulation at the fission site ...


Gaip Interacting Protein C-Terminus Regulates Autophagy And Exosome Biogenesis Of Pancreatic Cancer Through Metabolic Pathways, Santanu Bhattacharya, Krishnendu Pal, Anil K. Sharma, Shamit K. Dutta, Julie S. Lau, Irene K. Yan, Enfeng Wang, Ahmed Elkhanany, Khalid M. Alkharfy, Arunik Sanyal, Tushar C. Patel, Suresh T. Chari, Mark R. Spaller, Debabrata Mukhopadhyay Dec 2014

Gaip Interacting Protein C-Terminus Regulates Autophagy And Exosome Biogenesis Of Pancreatic Cancer Through Metabolic Pathways, Santanu Bhattacharya, Krishnendu Pal, Anil K. Sharma, Shamit K. Dutta, Julie S. Lau, Irene K. Yan, Enfeng Wang, Ahmed Elkhanany, Khalid M. Alkharfy, Arunik Sanyal, Tushar C. Patel, Suresh T. Chari, Mark R. Spaller, Debabrata Mukhopadhyay

Open Dartmouth: Faculty Open Access Scholarship

GAIP interacting protein C terminus (GIPC) is known to play an important role in a variety of physiological and disease states. In the present study, we have identified a novel role for GIPC as a master regulator of autophagy and the exocytotic pathways in cancer. We show that depletion of GIPC-induced autophagy in pancreatic cancer cells, as evident from the upregulation of the autophagy marker LC3II. We further report that GIPC regulates cellular trafficking pathways by modulating the secretion, biogenesis, and molecular composition of exosomes. We also identified the involvement of GIPC on metabolic stress pathways regulating autophagy and microvesicular ...


Killerflip: A Novel Lytic Peptide Specifically Inducing Cancer Cell Death, B Pennarun, G. Gaidos, O Bucur, A Tinari Oct 2013

Killerflip: A Novel Lytic Peptide Specifically Inducing Cancer Cell Death, B Pennarun, G. Gaidos, O Bucur, A Tinari

Open Dartmouth: Faculty Open Access Scholarship

One of the objectives in the development of effective cancer therapy is induction of tumor-selective cell death. Toward this end, we have identified a small peptide that, when introduced into cells via a TAT cell-delivery system, shows a remarkably potent cytoxicity in a variety of cancer cell lines and inhibits tumor growth in vivo, whereas sparing normal cells and tissues. This fusion peptide was named killer FLIP as its sequence was derived from the C-terminal domain of c-FLIP, an anti-apoptotic protein. Using structure activity analysis, we determined the minimal bioactive core of killerFLIP, namely killerFLIP-E. Structural analysis of cells using ...


Live-Cell Monitoring Of Periodic Gene Expression In Synchronous Human Cells Identifies Forkhead Genes Involved In Cell Cycle Control, Gavin D. Grant, Joshua Gamsby, Viktor Martyanov, Lionel Brooks, Lacy K. George, J. Matthew Mahoney, Jennifer J. Loros, Jay C. Dunlap, Michael L. Whitfield Jun 2012

Live-Cell Monitoring Of Periodic Gene Expression In Synchronous Human Cells Identifies Forkhead Genes Involved In Cell Cycle Control, Gavin D. Grant, Joshua Gamsby, Viktor Martyanov, Lionel Brooks, Lacy K. George, J. Matthew Mahoney, Jennifer J. Loros, Jay C. Dunlap, Michael L. Whitfield

Open Dartmouth: Faculty Open Access Scholarship

We developed a system to monitor periodic luciferase activity from cell cycle-regulated promoters in synchronous cells. Reporters were driven by a minimal human E2F1 promoter with peak expression in G1/S or a basal promoter with six Forkhead DNA-binding sites with peak expression at G2/M. After cell cycle synchronization, luciferase activity was measured in live cells at 10-min intervals across three to four synchronous cell cycles, allowing unprecedented resolution of cell cycle-regulated gene expression. We used this assay to screen Forkhead transcription factors for control of periodic gene expression. We confirmed a role for FOXM1 and identified two novel ...


Cdk1 And Plk1 Mediate A Clasp2 Phospho-Switch That Stabilizes Kinetochore–Microtubule Attachments, Ana R. R. Maia, Zaira Garcia, Lilian Kabeche, Marin Barisic Jan 2012

Cdk1 And Plk1 Mediate A Clasp2 Phospho-Switch That Stabilizes Kinetochore–Microtubule Attachments, Ana R. R. Maia, Zaira Garcia, Lilian Kabeche, Marin Barisic

Open Dartmouth: Faculty Open Access Scholarship

Accurate chromosome segregation during mitosis relies on a dynamic kinetochore (KT)-microtubule (MT) interface that switches from a labile to a stable condition in response to correct MT attachments. This transition is essential to satisfy the spindle-assembly checkpoint (SAC) and couple MT-generated force with chromosome movements, but the underlying regulatory mechanism remains unclear. In this study, we show that during mitosis the MT- and KT-associated protein CLASP2 is progressively and distinctively phosphorylated by Cdk1 and Plk1 kinases, concomitant with the establishment of KT-MT attachments. CLASP2 S1234 was phosphorylated by Cdk1, which primed CLASP2 for association with Plk1. Plk1 recruitment to ...


Serum- And Glucocorticoid-Induced Kinase 3 In Recycling Endosomes Mediates Acute Activation Of Na+/H+ Exchanger Nhe3 By Glucocorticoids, Peijian He, Sei-Jung Lee, Songbai Lin, Ursula Seidler, Florian Lang, Geza Fejes-Toth, Aniko Naray-Fejes-Toth, C. Chris Yun Aug 2011

Serum- And Glucocorticoid-Induced Kinase 3 In Recycling Endosomes Mediates Acute Activation Of Na+/H+ Exchanger Nhe3 By Glucocorticoids, Peijian He, Sei-Jung Lee, Songbai Lin, Ursula Seidler, Florian Lang, Geza Fejes-Toth, Aniko Naray-Fejes-Toth, C. Chris Yun

Open Dartmouth: Faculty Open Access Scholarship

Na(+)/H(+) exchanger 3 (NHE3) is the major Na(+) transporter in the intestine. Serum- and glucocorticoid-induced kinase (SGK) 1 interacts with NHE regulatory factor 2 (NHERF2) and mediates activation of NHE3 by dexamethasone (Dex) in cultured epithelial cells. In this study, we compared short-term regulation of NHE3 by Dex in SGK1-null and NHERF2-null mice. In comparison to wild-type mice, loss of SGK1 or NHERF2 significantly attenuated regulation of NHE3 by Dex but did not completely obliterate the effect. We show that transfection of SGK2 or SGK3 in PS120 cells resulted in robust activation of NHE3 by Dex. However, unlike SGK1 ...


Examining The Link Between Chromosomal Instability And Aneuploidy In Human Cells, Sarah L. Thompson, Duane A. Compton Jan 2008

Examining The Link Between Chromosomal Instability And Aneuploidy In Human Cells, Sarah L. Thompson, Duane A. Compton

Open Dartmouth: Faculty Open Access Scholarship

Solid tumors can be highly aneuploid and many display high rates of chromosome missegregation in a phenomenon called chromosomal instability (CIN). In principle, aneuploidy is the consequence of CIN, but the relationship between CIN and aneuploidy has not been clearly defined. In this study, we use live cell imaging and clonal cell analyses to evaluate the fidelity of chromosome segregation in chromosomally stable and unstable human cells. We show that improper microtubule–chromosome attachment (merotely) is a cause of chromosome missegregation in unstable cells and that increasing chromosome missegregation rates by elevating merotely during consecutive mitoses generates CIN in otherwise ...


Arsenite Regulates Cystic Fibrosis Transmem­Brane Conductance Regulator And P-Glycoprotein: Evidence Of Pathway Independence, Rangan Maitra, Joshua Hamilton Jan 2005

Arsenite Regulates Cystic Fibrosis Transmem­Brane Conductance Regulator And P-Glycoprotein: Evidence Of Pathway Independence, Rangan Maitra, Joshua Hamilton

Open Dartmouth: Faculty Open Access Scholarship

In the past, people have argued for and against the theory of reciprocal regulation of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and P-glycoprotein (Pgp). Data have indicated that this may occur in vitro during drug-induced selection of cells, and in vivo during development. Much of this debate has been caused by a severe lack of mechanistic details involved in such regulation. Our past data indicate that certain Pgp modulators can affect CFTR expression and function. The goal of this study was to investigate the effects of trivalent arsenic (arsenite), a known transcriptional activator of Pgp, on CFTR expression. In ...


The Kini Kinesin Kif2a Is Required For Bipolar Spindle Assembly Through A Functional Relationship With Mcak, Neil J. Ganem, Duane A. Compton Aug 2004

The Kini Kinesin Kif2a Is Required For Bipolar Spindle Assembly Through A Functional Relationship With Mcak, Neil J. Ganem, Duane A. Compton

Open Dartmouth: Faculty Open Access Scholarship

Although the microtubule-depolymerizing KinI motor Kif2a is abundantly expressed in neuronal cells, we now show it localizes to centrosomes and spindle poles during mitosis in cultured cells. RNAi-induced knockdown of Kif2a expression inhibited cell cycle progression because cells assembled monopolar spindles. Bipolar spindle assembly was restored in cells lacking Kif2a by treatments that altered microtubule assembly (nocodazole), eliminated kinetochore–microtubule attachment (loss of Nuf2), or stabilized microtubule plus ends at kinetochores (loss of MCAK). Thus, two KinI motors, MCAK and Kif2a, play distinct roles in mitosis, and MCAK activity at kinetochores must be balanced by Kif2a activity at poles for ...


Pv1 Is A Key Structural Component For The Formation Of The Stomatal And Fenestral Diaphragms, Radu V. Stan, Eugene Tkachenko, Ingrid R. Niesman May 2004

Pv1 Is A Key Structural Component For The Formation Of The Stomatal And Fenestral Diaphragms, Radu V. Stan, Eugene Tkachenko, Ingrid R. Niesman

Open Dartmouth: Faculty Open Access Scholarship

PV1 is an endothelial-specific integral membrane glycoprotein associated with the stomatal diaphragms of caveolae, transendothelial channels, and vesiculo-vacuolar organelles and the diaphragms of endothelial fenestrae. Multiple PV1 homodimers are found within each stomatal and fenestral diaphragm. We investigated the function of PV1 within these diaphragms and their regulation and found that treatment of endothelial cells in culture with phorbol myristate acetate (PMA) led to upregulation of PV1. This correlated with de novo formation of stomatal diaphragms of caveolae and transendothelial channels as well as fenestrae upon PMA treatment. The newly formed diaphragms could be labeled with anti-PV1 antibodies. The upregulation ...


Differential Regulation Of Collagenase Gene Expression By Retinoic Acid Receptors--Alpha, Beta And Gamma, Luying Pan, Stephen H. Chamberlain, David T. Auble, Constance E. Brinckerhoff Jun 1992

Differential Regulation Of Collagenase Gene Expression By Retinoic Acid Receptors--Alpha, Beta And Gamma, Luying Pan, Stephen H. Chamberlain, David T. Auble, Constance E. Brinckerhoff

Open Dartmouth: Faculty Open Access Scholarship

The mechanisms involved in retinoic acid (RA)-mediated regulation of the collagenase gene in a rabbit synovial fibroblast cell line (HIG82) were investigated. When HIG82 cells are cotransfected with expression vectors containing cDNAs for retinoic acid receptor (RAR) α1, β2, or γ1 and collagenase promoter-driven CAT reporter constructs, only RAR-γ1 represses basal CAT expression upon RA treatment, while RAR-α1, β2, and γ1 all suppress phorbol-induced CAT expression. Thus, transcriptional regulation of collagenase by RA is mediated by RARs in an RAR-type specific manner. Using mutatlonal and deletional analysis, we find that interaction between elements within 182 bp collagenase promoter plays ...