Cell Biology Commons^™

Early Innate Immunity Determines Outcome Of Mycobacterium Tuberculosis Pulmonary Infection In Rabbits, Selvakumar Subbian, Nirmalya Bandyopadhyay, Liana Tsenova, Paul O'Brien, Viraj Khetani, Nicole L. Kushner, Blas Peixoto, Patricia Soteropoulos, Joel S. Bader, Petros C. Karakousis, Dorothy Fallows, Gilla Kaplan

Publications and Research

Background: Pulmonary infection of humans by Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), results in active disease in 5-10% of individuals, while asymptomatic latent Mtb infection (LTBI) is established in the remainder. The host immune responses that determine this differential outcome following Mtb infection are not fully understood. Using a rabbit model of pulmonary TB, we have shown that infection with the Mtb clinical isolate HN878 (a hyper-virulent W-Beijing lineage strain) leads to progressive cavitary disease similar to what is seen in humans with active TB. In contrast, infection with Mtb CDC1551 (a hyper-immunogenic clinical isolate) is efficiently …

A Myosin-Va Tail Fragment Sequesters Dynein Light Chains Leading To Apoptosis In Melanoma Cells, Tc Izidoro-Toledo, Ac Borges, Dd Araujo, Dps Leitao Mazzi, Fo Nascimento Junior, Jf Sousa, Cp Alves, Apb Paiva, Dm Trindade, Ev Patussi, Pablo M. Peixoto, Kw Kinnally, Em Espreafico

Publications and Research

Previous studies proposed that myosin-Va regulates apoptosis by sequestering pro-apoptotic Bmf to the actin cytoskeleton through dynein light chain-2 (DLC2). Adhesion loss or other cytoskeletal perturbations would unleash Bmf, allowing it to bind and inhibit pro-survival Bcl2 proteins. Here, we demonstrated that over expression of a myosin-Va medial tail fragment (MVaf) harboring the binding site for DLC2 dramatically decreased melanoma cell viability. Morphological and molecular changes, including surface blebbing, mitochondrial outer membrane permeabilization, cytochrome-c and Smac release, as well as caspase-9/-3 activation and DNA fragmentation indicated that melanoma cells died of apoptosis. Immobilized MVaf interacted directly with DLCs, but complexed …

Differential Transcriptional Regulation Of Meis1 By Gfi1b And Its Co-Factors Lsd1 And Corest, Asif H. Chowdhury, Johnny R. Ramroop, Ghanshyam Upadhyay, Ananya Sengupta, Anna Andrzejczyk, Shireen Saleque

Publications and Research

Gfi1b (growth factor independence 1b) is a zinc finger transcription factor essential for development of the erythroid and megakaryocytic lineages. To elucidate the mechanism underlying Gfi1b function, potential downstream transcriptional targets were identified by chromatin immunoprecipitation and expression profiling approaches. The combination of these approaches revealed the oncogene meis1, which encodes a homeobox protein, as a direct and prominent target of Gfi1b. Examination of the meis1 promoter sequence revealed multiple Gfi1/1b consensus binding motifs. Distinct regions of the promoter were occupied by Gfi1b and its cofactors LSD1 and CoREST/Rcor1, in erythroid cells but not in the closely related megakaryocyte lineage. …

Identification Of An Archaeal Presenilin-Like Intramembrane Protease, Celia Torres-Arancivia, Carolyn M. Ross, Jose Chavez, Zahra Assur, Georgia Dolios, Filippo Mancia, Iban Ubarretxena-Belandia

Publications and Research

Background: The GXGD-type diaspartyl intramembrane protease, presenilin, constitutes the catalytic core of the c-secretase multi-protein complex responsible for activating critical signaling cascades during development and for the production of b-amyloid peptides (Ab) implicated in Alzheimer’s disease. The only other known GXGD-type diaspartyl intramembrane proteases are the eukaryotic signal peptide peptidases (SPPs). The presence of presenilin-like enzymes outside eukaryots has not been demonstrated. Here we report the existence of presenilin-like GXGD-type diaspartyl intramembrane proteases in archaea.

Methodology and Principal Findings: We have employed in vitro activity assays to show that MCMJR1, a polytopic membrane protein from the archaeon Methanoculleus marisnigri JR1, …

Yeast Cell Adhesion Molecules Have Functional Amyloid-Forming Sequences, Caleen B. Ramsook, Cho Tan, Melissa C. Garcia, Raymond Fung, Gregory Soybelman, Ryan Henry, Anna Litewka, Shanique O’Meally, Henry N. Otoo, Roy A. Khalaf, Anne M. Dranginis, Nand K. Gaur, Stephen A. Klotz, Jason M. Rauceo, Chong K. Jue, Peter N. Lipke

Publications and Research

The occurrence of highly conserved amyloid-forming sequences in Candida albicans Als proteins (H. N. Otoo et al., Eukaryot. Cell 7:776–782, 2008) led us to search for similar sequences in other adhesins from C. albicans and Saccharomyces cerevisiae. The beta-aggregation predictor TANGO found highly beta-aggregation-prone sequences in almost all yeast adhesins. These sequences had an unusual amino acid composition: 77% of their residues were beta-aggregation aliphatic amino acids Ile, Thr, and Val, which is more than 4-fold greater than their prevalence in the S. cerevisiae proteome. High beta-aggregation potential peptides from S. cerevisiae Flo1p and C. albicans Eap1p rapidly formed insoluble …

Structure And Function Of Glycosylated Tandem Repeats From Candida Albicans Als Adhesins, Aaron T. Frank, Caleen B. Ramsook, Henry N. Otoo, Cho Tan, Gregory Soybelman, Jason M. Rauceo, Nand K. Gaur, Stephen A. Klotz, Peter N. Lipke

Publications and Research

Tandem repeat (TR) regions are common in yeast adhesins, but their structures are unknown, and their activities are poorly understood. TR regions in Candida albicans Als proteins are conserved glycosylated 36-residue sequences with cell-cell aggregation activity (J. M. Rauceo, R. De Armond, H. Otoo, P. C. Kahn, S. A. Klotz, N. K. Gaur, and P. N. Lipke, Eukaryot. Cell 5:1664–1673, 2006). Ab initio modeling with either Rosetta or LINUS generated consistent structures of three-stranded antiparallel beta-sheet domains, whereas randomly shuffled sequences with the same composition generated various structures with consistently higher energies. O- and N-glycosylation patterns showed that each TR …

Pivotal Role Of The A2a-Adrenoceptor In Producing Inflammation And Organ Injury In A Rat Model Of Sepsis, Michael Miksa, Padmalaya Des, Mian Zhou, Rongqian Wu, Weifeng Dong, Youxin Ji, Sanna M. Goyert, Thanjavur S. Ravikumar, Ping Wang

Publications and Research

Background: Norepinephrine (NE) modulates the responsiveness of macrophages to proinflammatory stimuli through the activation of adrenergic receptors (ARs). Being part of the stress response, early increases of NE in sepsis sustain adverse systemic inflammatory responses. The intestine is an important source of NE release in the early stage of cecal ligation and puncture (CLP)-induced sepsis in rats, which then stimulates TNF-a production in Kupffer cells (KCs) through the activation of the a2-AR. It is important to know which of the three a2-AR subtypes (i.e., a2A, a2B or a2C) is responsible for the upregulation of TNF-a production. The aim of this …

Naloxone's Pentapeptide Binding Site On Filamin A Blocks Mu Opioid Receptor–Gs Coupling And Creb Activation Of Acute Morphine, Hoau-Yan Wang, Lindsay H. Burns

Publications and Research

Chronic morphine causes the mu opioid receptor (MOR) to switch its coupling from Gi/o to Gs, resulting in excitatory signaling via both Gαs and its Gβγ dimer. Ultra-low-dose naloxone (NLX) prevents this switch and attenuates opioid tolerance and dependence. This protective effect is mediated via a high-affinity interaction of NLX to a pentapeptide region in c-terminal filamin A (FLNA), a scaffolding protein interacting with MOR. In organotypic striatal slice cultures, we now show that acute morphine induces a dose-dependent Go-to-Gs coupling switch at 5 and 15 min that resolves by 1 hr. The acute Gs coupling induced by 100 µM …