Large-Scale Production of Wholly Cellular Bioinks via the Optimization of Human Induced Pluripotent Stem Cell Aggregate Culture in Automated Bioreactors.

Combining the sustainable culture of billions of human cells and the bioprinting of wholly cellular bioinks offers a pathway toward organ-scale tissue engineering. Traditional 2D culture methods are not inherently scalable due to cost, space, and handling constraints. Here, the suspension culture of human induced pluripotent stem cell-derived aggregates (hAs) is optimized using an automated 250 mL stirred tank bioreactor system.

ROR and RYK extracellular region structures suggest that receptor tyrosine kinases have distinct WNT-recognition modes.

WNTs play key roles in development and disease, signaling through Frizzled (FZD) seven-pass transmembrane receptors and numerous co-receptors including ROR and RYK family receptor tyrosine kinases (RTKs). We describe crystal structures and WNT-binding characteristics of extracellular regions from the Drosophila ROR and RYK orthologs Nrk (neurospecific receptor tyrosine kinase) and Derailed-2 (Drl-2), which bind WNTs though a FZD-related cysteine-rich domain (CRD) and WNT-inhibitory factor (WIF) domain respectively. Our crystal structures suggest that neither Nrk nor Drl-2 can accommodate the acyl chain typically attached to WNTs.

Coordinated changes in the expression of Wnt pathway genes following human and rat peripheral nerve injury.

A human neuroma-in continuity (NIC), formed following a peripheral nerve lesion, impedes functional recovery. The molecular mechanisms that underlie the formation of a NIC are poorly understood. Here we show that the expression of multiple genes of the Wnt family, including Wnt5a, is changed in NIC tissue from patients that underwent reconstructive surgery.

Axonal chemokine-like Orion induces astrocyte infiltration and engulfment during mushroom body neuronal remodeling.

The remodeling of neurons is a conserved fundamental mechanism underlying nervous system maturation and function. Astrocytes can clear neuronal debris and they have an active role in neuronal remodeling. Developmental axon pruning of Drosophila memory center neurons occurs via a degenerative process mediated by infiltrating astrocytes.

Htt is a repressor of Abl activity required for APP-induced axonal growth.

Huntington's disease is a progressive autosomal dominant neurodegenerative disorder caused by the expansion of a polyglutamine tract at the N-terminus of a large cytoplasmic protein. The Drosophila huntingtin (htt) gene is widely expressed during all developmental stages from embryos to adults. However, Drosophila htt mutant individuals are viable with no obvious developmental defects.

Interplay between axonal Wnt5-Vang and dendritic Wnt5-Drl/Ryk signaling controls glomerular patterning in the Drosophila antennal lobe.

Despite the importance of dendritic targeting in neural circuit assembly, the mechanisms by which it is controlled still remain incompletely understood. We previously showed that in the developing Drosophila antennal lobe, the Wnt5 protein forms a gradient that directs the ~45˚ rotation of a cluster of projection neuron (PN) dendrites, including the adjacent DA1 and VA1d dendrites. We report here that the Van Gogh (Vang) transmembrane planar cell polarity (PCP) protein is required for the rotation of the DA1/VA1d dendritic pair.

Dystrobrevin is required postsynaptically for homeostatic potentiation at the Drosophila NMJ.

Evolutionarily conserved homeostatic systems have been shown to modulate synaptic efficiency at the neuromuscular junctions of organisms. While advances have been made in identifying molecules that function presynaptically during homeostasis, limited information is currently available on how postsynaptic alterations affect presynaptic function. We previously identified a role for postsynaptic Dystrophin in the maintenance of evoked neurotransmitter release.

Dystrophin is required for normal synaptic gain in the Drosophila olfactory circuit.

The Drosophila olfactory system provides an excellent model to elucidate the neural circuits that control behaviors elicited by environmental stimuli. Despite significant progress in defining olfactory circuit components and their connectivity, little is known about the mechanisms that transfer the information from the primary antennal olfactory receptor neurons to the higher order brain centers. Here, we show that the Dystrophin Dp186 isoform is required in the olfactory system circuit for olfactory functions.

Muscular Dystrophy Model.

Muscular dystrophy (MD) is a group of muscle weakness disease involving in inherited genetic conditions. MD is caused by mutations or alteration in the genes responsible for the structure and functioning of muscles. There are many different types of MD which have a wide range from mild symptoms to severe disability.

Retrovirus-like Gag Protein Arc1 Binds RNA and Traffics across Synaptic Boutons.

Arc/Arg3.1 is required for synaptic plasticity and cognition, and mutations in this gene are linked to autism and schizophrenia. Arc bears a domain resembling retroviral/retrotransposon Gag-like proteins, which multimerize into a capsid that packages viral RNA.

The non-canonical Wnt receptor Ryk regulates hematopoietic stem cell repopulation in part by controlling proliferation and apoptosis.

The development of blood and immune cells requires strict control by various signaling pathways in order to regulate self-renewal, differentiation and apoptosis in stem and progenitor cells. Recent evidence indicates critical roles for the canonical and non-canonical Wnt pathways in hematopoiesis. The non-canonical Wnt pathway is important for establishment of cell polarity and cell migration and regulates apoptosis in the thymus.

This bud's for you: mechanisms of cellular nucleocytoplasmic trafficking via nuclear envelope budding.

The nuclear envelope (NE) physically separates the cytoplasmic and nuclear compartments. While this barrier provides advantages, it also presents a challenge for the nuclear export of large ribonucleoprotein (RNP) complexes. Decades-old dogma holds that all such border-crossing is via the nuclear pore complex (NPC).

Synaptic Orb2A Bridges Memory Acquisition and Late Memory Consolidation in Drosophila.

To adapt to an ever-changing environment, animals consolidate some, but not all, learning experiences to long-term memory. In mammals, long-term memory consolidation often involves neural pathway reactivation hours after memory acquisition. It is not known whether this delayed-reactivation schema is common across the animal kingdom or how information is stored during the delay period.

Guidance of Drosophila Mushroom Body Axons Depends upon DRL-Wnt Receptor Cleavage in the Brain Dorsomedial Lineage Precursors.

In vivo axon pathfinding mechanisms in the neuron-dense brain remain relatively poorly characterized. We study the Drosophila mushroom body (MB) axons, whose α and β branches connect to different brain areas. We show that the Ryk family WNT5 receptor, DRL (derailed), which is expressed in the dorsomedial lineages, brain structure precursors adjacent to the MBs, is required for MB α branch axon guidance.

Wnt5 and drl/ryk gradients pattern the Drosophila olfactory dendritic map.

During development, dendrites migrate to their correct locations in response to environmental cues. The mechanisms of dendritic guidance are poorly understood. Recent work has shown that the Drosophila olfactory map is initially formed by the spatial segregation of the projection neuron (PN) dendrites in the developing antennal lobe (AL).

Wnt signaling through the Ror receptor in the nervous system.

The receptor tyrosine kinase-like orphan receptor (Ror) proteins are conserved tyrosine kinase receptors that play roles in a variety of cellular processes that pattern tissues and organs during vertebrate and invertebrate development. Ror signaling is required for skeleton and neuronal development and modulates cell migration, cell polarity, and convergent extension. Ror has also been implicated in two human skeletal disorders, brachydactyly type B and Robinow syndrome.

Homodimerization of the Wnt receptor DERAILED recruits the Src family kinase SRC64B.

Ryk pseudokinase receptors act as important transducers of Wnt signals, particularly in the nervous system. Little is known, however, of their interactions at the cell surface. Here, we show that a Drosophila Ryk family member, DERAILED (DRL), forms cell surface homodimers and can also heterodimerize with the two other fly Ryks, DERAILED-2 and DOUGHNUT ON 2.

mRNA cycles through hypoxia-induced stress granules in live Drosophila embryonic muscles.

In some myopathies, hypoxia can be the result of pathologic effects like muscle necrosis and abnormal blood flow. At the molecular level, the consequence of hypoxic conditions is not yet fully understood. Under stress conditions, many housekeeping gene mRNAs are translationally silenced, while translation of other mRNAs increases.

WNT5 interacts with the Ryk receptors doughnut and derailed to mediate muscle attachment site selection in Drosophila melanogaster.

In recent years a number of the genes that regulate muscle formation and maintenance in higher organisms have been identified. Studies employing invertebrate and vertebrate model organisms have revealed that many of the genes required for early mesoderm specification are highly conserved throughout evolution. Less is known about the molecules that mediate the steps subsequent to myogenesis, e.

The RhoGAP crossveinless-c interacts with Dystrophin and is required for synaptic homeostasis at the Drosophila neuromuscular junction.

Duchenne muscular dystrophy is caused by mutations in the Dystrophin gene and is characterized by muscle degeneration and the occurrence of mental deficits in a significant number of patients. Although Dystrophin and its closely related ortholog Utrophin are present at a variety of synapses, little is known about their roles in the nervous system. Previously, we reported that absence of postsynaptic Dystrophin from the Drosophila neuromuscular junction (NMJ) disrupts synaptic homeostasis, resulting in increased stimulus-evoked neurotransmitter release.

Ryks: new partners for Wnts in the developing and regenerating nervous system.

Conserved Ryk transmembrane proteins, tyrosine kinase-related Wnt receptors, are important during neurogenesis, axon guidance and synaptogenesis. Here, we review the increasingly complex biology of the Wnt/Ryk pathway, emphasizing the mechanisms by which Ryks transduce or sometimes block the Wnt signal. Recent studies reveal that Wnts signal through Ryk via multiple mechanisms, including nuclear translocation of their intracellular domains and pathways employing Src Family Kinases and members of the canonical Wnt pathway.

The roles of the dystrophin-associated glycoprotein complex at the synapse.

Duchenne muscular dystrophy is caused by mutations in the dystrophin gene and is characterized by progressive muscle wasting. A number of Duchenne patients also present with mental retardation. The dystrophin protein is part of the highly conserved dystrophin-associated glycoprotein complex (DGC) which accumulates at the neuromuscular junction (NMJ) and at a variety of synapses in the peripheral and central nervous systems.

In vivo monitoring of mRNA movement in Drosophila body wall muscle cells reveals the presence of myofiber domains.

Background: In skeletal muscle each muscle cell, commonly called myofiber, is actually a large syncytium containing numerous nuclei. Experiments in fixed myofibers show that mRNAs remain localized around the nuclei in which they are produced.

Methodology/principal Findings: In this study we generated transgenic flies that allowed us to investigate the movement of mRNAs in body wall myofibers of living Drosophila embryos.

Src family kinases are required for WNT5 signaling through the Derailed/RYK receptor in the Drosophila embryonic central nervous system.

Members of the RYK/Derailed family have recently been shown to regulate axon guidance in both Drosophila and mammals by acting as Wnt receptors. Little is known about how the kinase activity-deficient RYKs transduce Wnt signals. Here, we show that the non-receptor Src family tyrosine kinases, SRC64B and SRC42A, are involved in WNT5-mediated signaling through Derailed in the Drosophila embryonic central nervous system.

The dystrophin Dp186 isoform regulates neurotransmitter release at a central synapse in Drosophila.

The Dystrophin protein is encoded by a gene that, when mutated in humans, can cause Duchenne muscular dystrophy, a disease characterized by progressive muscle wasting. A number of Duchenne patients also exhibit poorly understood mental retardation, likely associated with loss of a brain-specific isoform. Furthermore, although Dystrophin isoforms and the related Utrophin protein have long been known to localize at synapses, their functions remain essentially unknown.