A fully defined and scalable 3D culture system for human pluripotent stem cell expansion and differentiation
Yuguo Lei and David V. Schaffer
Human pluripotent stem cells can be cultured in vitro and differentiated into presumably all cell types of the human body, and they therefore represent highly promising cell sources for biomedical applications such as cell therapies, tissue engineering, and drug discovery. These applications (pp. E5039–E5048) require large numbers of high-quality cells, and we report an efficient, defined, scalable, and good manufacturing practice-compatible 3D system for the production of human pluripotent stem cells and their progeny. The ease of use and flexible scalability of this system makes it suitable for numerous applications from the laboratory toward the clinic.
Role of Loc1p in assembly and reorganization of nuclear ASH1 messenger ribonucleoprotein particles in yeast
Annika Niedner, Marisa Müller, Balaji T. Moorthy, Ralf-Peter Jansen, and Dierk Niessing
Cytoplasmic mRNA localization is preceded by the formation of nuclear pre-mRNPs. To date the requirement of the nuclear mRNP assembly is not well understood. We used ASH1 mRNA localization from budding yeast to understand the mechanisms of nuclear priming for cytoplasmic mRNA transport. We found (pp. E5049–E5058) that the nuclear factor Loc1p is required to stably and specifically tether the bona fide ASH1 RNA-binding protein She2p to RNA in the nucleus, offering an explanation for the requirement of Loc1p for ASH1 mRNA localization. Because Loc1p is not part of the cytoplasmic ASH1 mRNP, it must be removed before mRNA transport. We show that the cytoplasmic transport factor She3p displaces Loc1p from the ASH1 mRNP, allowing for the maturation of the localizing ASH1 mRNP.
Pivotal role of NOD2 in inflammatory processes affecting atherosclerosis and periodontal bone loss
Huaiping Yuan, Sami Zelka, Marina Burkatovskaya, Rohit Gupte, Susan E. Leeman, and Salomon Amar
Apolipoprotein E−/− (ApoE−/−) mice deficient in nucleotide binding oligomerization domain-containing protein 2 (NOD2) and subjected to an oral gavage of Porphyromonas gingivalis developed elevated serum inflammatory cytokines, cholesterol, alveolar bone loss, and atherosclerosis (pp. E5059–E5068). Stimulation of NOD2 by Muramyl DiPeptide (MDP) in ApoE−/− mice reduced P. gingivalis-induced inflammatory cytokines, cholesterol, alveolar bone loss, and atherosclerosis by reducing the expression of inhibitor of NF-κB kinase-β, NF-κB, JNK mRNA, and TNF-α protein levels. A reduction in body weight gain was observed in ApoE−/− mice fed a high-fat diet (HFD) and injected with MDP compared to ApoE−/− mice fed a HFD but saline injected. MDP activation of NOD2 should be considered in the treatment of inflammatory processes affecting atherosclerosis, bone loss, and possibly, weight gain.
Osmosensory signaling in Mycobacterium tuberculosis mediated by a eukaryotic-like Ser/Thr protein kinase
Stavroula K. Hatzios, Christina E. Baer, Tige R. Rustad, M. Sloan Siegrist, Jennifer M. Pang, Corrie Ortega, Tom Alber, Christoph Grundner, David R. Sherman, and Carolyn R. Bertozzi
Osmotic stress is one of many environmental hazards encountered by bacteria during the course of infection, but our understanding of how bacteria perceive and respond to changes in extracellular osmolarity is still incomplete. We show (pp. E5069–E5077) that Mycobacterium tuberculosis, the pathogen that causes tuberculosis in humans, responds, in part, through an osmosensory pathway regulated by the Ser/Thr protein kinase (STPK) PknD. Our work demonstrates that increasing extracellular osmolarity induces expression of a PknD substrate that regulates bacterial transcription, cell wall remodeling, and virulence factor production. Because STPKs are prevalent in bacteria, these proteins may play a broad role in bacterial osmosensing.
A theory for how sensorimotor skills are learned and retained in noisy and nonstationary neural circuits
Robert Ajemian, Alessandro D’Ausilio, Helene Moorman, and Emilio Bizzi
The synaptic trace theory of memory posits that the brain retains information through learning-induced changes in synaptic connections. Once consolidated, a memory is embodied through its fixed trace. For the case of motor memories, e.g., learning how to ride a bicycle, we propose a slight variation on this theme. Because there are so many different ways for the motor system to accomplish the same task goal, motor memories are defined not by fixed patterns of synaptic connections, but rather by nonstationary patterns that fluctuate coherently while still generating the same fixed input–output mapping. This mechanism (pp. E5078–E5087) provides a noisy sensorimotor system with enough flexibility so that motor learning can occur rapidly with respect to new memories without overwriting older memories.
Pepducin targeting the C-X-C chemokine receptor type 4 acts as a biased agonist favoring activation of the inhibitory G protein
Julie Quoyer, Jay M. Janz, Jiansong Luo, Yong Ren, Sylvain Armando, Viktoria Lukashova, Jeffrey L. Benovic, Kenneth E. Carlson, Stephen W. Hunt III, and Michel Bouvier
Pepducins are a class of biologics that allosterically control G protein-coupled receptor (GPCR) activity, but very little is known about their mode of action. Here (pp. E5088–E5097), we report that ATI-2341, a pepducin targeting the C-X-C chemokine receptor type 4 (CXCR4), functions as a biased ligand, favoring Gαi activation over Gα13. Moreover, contrary to the natural CXCR4 agonist, stromal cell-derived factor-1α, ATI-2341 does not promote β-arrestin recruitment. In addition to revealing the selective signaling underlying ATI-2341 effects on hematopoietic cell mobilization, the study shows that pepducins are powerful tools offering perspectives for studying GPCR functional selectivity that could impact the development of drugs with fewer side effects.