Dorsal Cells Research Articles

Pax3 Hypomorphs Reveal Hidden Pax7 Functional Genetic Compensation in Utero

Pax3 and Pax7 transcription factors are paralogs within the Pax gene family that that are expressed in early embryos in partially overlapping expression domains and have distinct functions. Significantly, mammalian development is largely unaffected by Pax7 systemic deletion but systemic Pax3 deletion results in defects in neural tube closure, neural crest emigration, cardiac outflow tract septation, muscle hypoplasia and in utero lethality by E14. However, we previously demonstrated that Pax3 hypomorphs expressing only 20% functional Pax3 protein levels exhibit normal neural tube and heart development, but myogenesis is selectively impaired. To determine why only some Pax3-expressing cell lineages are affected and to further titrate Pax3 threshold levels required for neural tube and heart development, we generated hypomorphs containing both a hypomorphic and a null Pax3 allele. This resulted in mutants only expressing 10% functional Pax3 protein with exacerbated neural tube, neural crest and muscle defects, but still a normal heart. To examine why the cardiac neural crest appears resistant to very low Pax3 levels, we examined its paralog Pax7. Significantly, Pax7 expression is both ectopically expressed in Pax3-expressing dorsal neural tube cells and is also upregulated in the Pax3-expressing lineages. To test whether this compensatory Pax7 expression is functional, we deleted Pax7 both systemically and lineage-specifically in hypomorphs expressing only 10% Pax3. Removal of one Pax7 allele resulted in partial outflow tract defects, and complete loss of Pax7 resulted in full penetrance outflow tract defects and in utero lethality. Moreover, combinatorial loss of Pax3 and Pax7 resulted in severe craniofacial defects and a total block of neural crest cell emigration from the neural tube. Pax7Cre lineage mapping revealed ectopic labeling of Pax3-derived neural crest tissues and within the outflow tract of the heart, experimentally confirming the observation of ectopic activation of Pax7 in 10% Pax3 hypomorphs. Finally, genetic cell ablation of Pax7Cre-marked cells is sufficient to cause outflow tract defects in hypomorphs expressing only 10% Pax3, confirming that ectopic and induced Pax7 can play an overlapping functional genetic compensational role in both cardiac neural crest lineage and during craniofacial development, which is normally masked by the dominant role of Pax3.

Grpr expression defines a population of superficial dorsal horn vertical cells that have a role in both itch and pain.

Neurons in the superficial dorsal horn that express the gastrin-releasing peptide receptor (GRPR) are strongly implicated in spinal itch pathways. However, a recent study reported that many of these correspond to vertical cells, a population of interneurons that are believed to transmit nociceptive information. In this study, we have used a GRPR CreERT2 mouse line to identify and target cells that possess Grpr mRNA. We find that the GRPR cells are highly concentrated in lamina I and the outer part of lamina II, that they are all glutamatergic, and that they account for ∼15% of the excitatory neurons in the superficial dorsal horn. We had previously identified 6 neurochemically distinct excitatory interneuron populations in this region based on neuropeptide expression and the GRPR cells are largely separate from these, although they show some overlap with cells that express substance P. Anatomical analysis revealed that the GRPR neurons are indeed vertical cells, and that their axons target each other, as well as arborising in regions that contain projection neurons: lamina I, the lateral spinal nucleus, and the lateral part of lamina V. Surprisingly, given the proposed role of GRPR cells in itch, we found that most of the cells received monosynaptic input from Trpv1-expressing (nociceptive) afferents, that the majority responded to noxious and pruritic stimuli, and that chemogenetically activating them resulted in pain-related and itch-related behaviours. Together, these findings suggest that the GRPR cells are involved in spinal cord circuits that underlie both pain and itch.

LM22B-10 promotes corneal nerve regeneration through in vitro 3D co-culture model and in vivo corneal injury model

Corneal nerve wounding often causes abnormalities in the cornea and even blindness in severe cases. In this study, we construct a dorsal root ganglion-corneal stromal cell (DRG-CSC, DS) co-culture 3D model to explore the mechanism of corneal nerve regeneration. Firstly, this model consists of DRG collagen grafts sandwiched by orthogonally stacked and orderly arranged CSC-laden plastic compressed collagen. Nerve bundles extend into the entire corneal stroma within 14 days, and they also have orthogonal patterns. This nerve prevents CSCs from apoptosis in the serum withdrawal medium. The conditioned medium (CM) for CSCs in collagen scaffolds contains NT-3, IL-6, and other factors. Among them, NT-3 notably promotes the activation of ERK-CREB in the DRG, leading to the growth of nerve bundles, and IL-6 induces the upregulation of anti-apoptotic genes. Then, LM22B-10, an activator of the NT-3 receptor TrkB/TrkC, can also activate ERK-CREB to enhance nerve growth. After administering LM22B-10 eye drops to regular and diabetic mice with corneal wounding, LM22B-10 significantly improves the healing speed of the corneal epithelium, corneal sensitivity, and corneal nerve density. Overall, the DS co-culture model provides a promising platform and tools for the exploration of corneal physiological and pathological mechanisms, as well as the verification of drug effects in vitro. Meanwhile, we confirm that LM22B-10, as a non-peptide small molecule, has future potential in nerve wound repair. Statement of significanceThe cornea accounts for most of the refractive power of the eye. Corneal nerves play an important role in maintaining corneal homeostasis. Once the corneal nerves are damaged, the corneal epithelium and stroma develop lesions. However, the mechanism of the interaction between corneal nerves and corneal cells is still not fully understood. Here, we construct a corneal stroma-nerve co-culture in vitro model and reveal that NT-3 expressed by stromal cells promotes nerve growth by activating the ERK-CREB pathway in nerves. LM22B-10, an activator of NT-3 receptors, can also induce nerve growth in vitro. Moreover, it is used as eye drops to enhance corneal epithelial wound healing, corneal nerve sensitivity and density of nerve plexus in corneal nerve wounding model in vivo.

Molecular and functional heterogeneity in dorsal and ventral oligodendrocyte progenitor cells of the mouse forebrain in response to DNA damage

In the developing mouse forebrain, temporally distinct waves of oligodendrocyte progenitor cells (OPCs) arise from different germinal zones and eventually populate either dorsal or ventral regions, where they present as transcriptionally and functionally equivalent cells. Despite that, developmental heterogeneity influences adult OPC responses upon demyelination. Here we show that accumulation of DNA damage due to ablation of citron-kinase or cisplatin treatment cell-autonomously disrupts OPC fate, resulting in cell death and senescence in the dorsal and ventral subsets, respectively. Such alternative fates are associated with distinct developmental origins of OPCs, and with a different activation of NRF2-mediated anti-oxidant responses. These data indicate that, upon injury, dorsal and ventral OPC subsets show functional and molecular diversity that can make them differentially vulnerable to pathological conditions associated with DNA damage.

Visual Stimulation Induces Distinct Forms of Sensitization of On-Off Direction-Selective Ganglion Cell Responses in the Dorsal and Ventral Retina.

Experience-dependent modulation of neuronal responses is a key attribute in sensory processing. In the mammalian retina, the On-Off direction-selective ganglion cell (DSGC) is well known for its robust direction selectivity. However, how the On-Off DSGC light responsiveness dynamically adjusts to the changing visual environment is underexplored. Here, we report that On-Off DSGCs tuned to posterior motion direction [i.e. posterior DSGCs (pDSGCs)] in mice of both sexes can be transiently sensitized by prior stimuli. Notably, distinct sensitization patterns are found in dorsal and ventral pDSGCs. Although responses of both dorsal and ventral pDSGCs to dark stimuli (Off responses) are sensitized, only dorsal cells show the sensitization of responses to bright stimuli (On responses). Visual stimulation to the dorsal retina potentiates a sustained excitatory input from Off bipolar cells, leading to tonic depolarization of pDSGCs. Such tonic depolarization propagates from the Off to the On dendritic arbor of the pDSGC to sensitize its On response. We also identified a previously overlooked feature of DSGC dendritic architecture that can support dendritic integration between On and Off dendritic layers bypassing the soma. By contrast, ventral pDSGCs lack a sensitized tonic depolarization and thus do not exhibit sensitization of their On responses. Our results highlight a topographic difference in Off bipolar cell inputs underlying divergent sensitization patterns of dorsal and ventral pDSGCs. Moreover, substantial crossovers between dendritic layers of On-Off DSGCs suggest an interactive dendritic algorithm for processing On and Off signals before they reach the soma.SIGNIFICANCE STATEMENT Visual neuronal responses are dynamically influenced by the prior visual experience. This form of plasticity reflects the efficient coding of the naturalistic environment by the visual system. We found that a class of retinal output neurons, On-Off direction-selective ganglion cells, transiently increase their responsiveness after visual stimulation. Cells located in dorsal and ventral retinas exhibit distinct sensitization patterns because of different adaptive properties of Off bipolar cell signaling. A previously overlooked dendritic morphologic feature of the On-Off direction-selective ganglion cell is implicated in the cross talk between On and Off pathways during sensitization. Together, these findings uncover a topographic difference in the adaptive encoding of upper and lower visual fields and the underlying neural mechanism in the dorsal and ventral retinas.

Identification of a coproporphyrinogen-III oxidase gene and its correlation with nacre color in Hyriopsis cumingii.

Pearl color is an important factor influencing pearl value, and is affected by the nacre color of the shell in Hyriopsis cumingii. Coproporphyrinogen-III oxidase (CPOX) is a key enzyme in porphyrin synthesis, and porphyrins are involved in color formation in different organisms, including in the nacre color of mussels. In this study, a CPOX gene (HcCPOX) was identified from H. cumingii, and its amino acid sequence was found to contain a coprogen-oxidase domain. HcCPOX mRNA was expressed widely in the tissues of white and purple mussels, and the highest expression was found in the gill, followed by the fringe mantle. The expression of HcCPOX in all tissues of purple mussels (except in the middle mantle) was higher than that of white mussels. Strong hybridization signals for HcCPOX were observed in the dorsal epithelial cells of the outer fold of the mantle. The activity of CPOX in the gill, fringe mantle, and foot of purple mussels was significantly higher than that in white mussels. Moreover, the expression of HcCPOX and CPOX activity were decreased in RNA interference experiments. The findings indicate that HcCPOX might contributes to nacre color formation in H. cumingii by being involved in porphyrin synthesis.

Pinus koraiensis needle or cone extracts alleviate atopic dermatitis symptoms by regulating immunity and suppressing inflammation in HaCaT cells and Nc/Nga mice.

Pinus koraiensis needles (PKN) and cones (PKC) have been shown to protect against inflammation and pathogenic bacteria. We investigated the efficacies and action mechanisms of topical applications of 1,3-butylene glycol (BG) extracts and oral administration of their water extracts on atopic dermatitis (AD) symptoms. After exposing HaCaT cells and Nc/Nga mice dorsal skins to 2,4-dinitrochlorobenzene (DNCB) to induce atopic dermatitis models, they were topically applied BG (AD-control), 30% PKNX, or 30% PKCX to the skin lesions and fed water extracts (0.5%) in high-fat diets for 5weeks. Normal-control mice had no DNCB exposure. Serum immunoglobulin E (IgE), IL-4, and TNF-α levels and gene expressions of TNF-α, IL-4, IL-6, and IFN-γ in the dorsal skin and HaCaT cells were measured. The AD-control mice elevated TNF-α and IL-6 mRNA levels in HaCaT cells. Both extracts attenuated clinical AD symptoms in AD-induced Nc/Nga mice: PKNX improved hemorrhage, erythema, and lichenification of dorsal skin better than PKCX while both similarly alleviated erythema, edema, excoriation, and itching behavior. PKCX reduced IgE contents and increased filaggrin mRNA expression better than PKNX, but PKNX reduced lipid peroxides and mRNA levels of TNF-α and IL-4 in the dorsal skin. In the histological analysis of the dorsal skin, the administration of both extracts significantly decreased mast cell numbers, immune cell infiltration, gaps between the epidermis and dermis, and abnormal cell and nucleus shapes. In conclusion, both PKCX and PKNX treatment alleviated the DNCB-induced clinical symptoms of AD by alleviating immune-related symptoms and inflammation in partially different pathways. Therefore, PKNX and PKCX may be effective for AD therapy. PRACTICAL APPLICATIONS: Atopic dermatitis (AD) is related to an overly activated immune response, and it has steadily increased last 3 decades. However, no optimal sustainable treatments are available. Pinus koraiensis needles and cones extracts have been used for anti-inflammatory and antimicrobial treatment. The present study demonstrated that their intake and topical administration onto the AD lesion alleviated clinical AD symptoms associated with reduced proinflammatory cytokines, mast cell numbers, and immune cell infiltrates to maintain dermal structure with maintaining filaggrin expression in AD-induced HaCaT cells and Nc/Nga mice. These results suggested that Pinus koraiensis needles and cones extracts can be developed and applied as beneficial alternative therapies for AD.

LXR agonist improves peripheral neuropathy and modifies PNS immune cells in aged mice

BackgroundPeripheral neuropathy is a common and progressive disorder in the elderly that interferes with daily activities. It is of importance to find efficient treatments to treat or delay this age-related neurodegeneration. Silencing macrophages by reducing foamy macrophages showed significant improvement of age-related degenerative changes in peripheral nerves of aged mice. We previously demonstrated that activation of the cholesterol sensor Liver X receptor (LXR) with the potent agonist, GW3965, alleviates pain in a diet-induced obesity model. We sought to test whether LXR activation may improve neuropathy in aged mice.Methods21-month-old mice were treated with GW3965 (25 mg/Kg body weight) for 3 months while testing for mechanical allodynia and thermal hyperalgesia. At termination, flow cytometry was used to profile dorsal root ganglia and sciatic nerve cells. Immune cells were sorted and analyzed for cholesterol and gene expression. Nerve fibers of the skin from the paws were analyzed. Some human sural nerves were also evaluated. Comparisons were made using either t test or one-way ANOVA.ResultsTreatment with GW3965 prevented the development of mechanical hypersensitivity and thermal hyperalgesia over time in aged mice. We also observed change in polarization and cholesterol content of sciatic nerve macrophages accompanied by a significant increase in nerve fibers of the skin.ConclusionsThese results suggest that activation of the LXR may delay the PNS aging by modifying nerve-immune cell lipid content. Our study provides new potential targets to treat or delay neuropathy during aging.

Tetrabromobisphenol A perturbs cell fate decisions via BMP signaling in the early embryonic development of zebrafish

Tetrabromobisphenol A (TBBPA) readily accumulates in the egg yolk of aquatic oviparous animals and is transferred to their embryos. Early embryogenesis is vital for organ formation and subsequent development. The developmental toxicity of TBBPA in aquatic animals has been extensively reported. However, few studies have assessed the toxic effects of TBBPA in the early embryonic development. In this work, we found that TBBPA perturbed cell fate decisions along the dorsal-ventral (DV) axis during gastrulation, further disrupting early organogenesis in the entire embryo. TBBPA exposure increased the number of embryonic cells that acquired a ventral cell fate, which formed epidermis, blood and heart tissues. In return, the number of embryonic cells that acquired a dorsal cell fate was greatly decreased, causing the TBBPA-exposed embryos to develop a small brain and small eyes. We revealed that TBBPA elevated the activity gradient of bone morphogenetic protein (BMP) signaling which is responsible for cell fate specification along the DV axis, with up-regulation of BMP ligands (bmp4, bmp7a) and target genes (szl) and promotion signal transduction through phosphorylation of Smad1/5. As the function of BMP signaling in embryogenesis is highly conserved among many vertebrates, these findings highlight the ecological and health risks of TBBPA.

Divergent Ca2+/calmodulin feedback regulation of CaV1 and CaV2 voltage-gated calcium channels evolved in the common ancestor of Placozoa and Bilateria

CaV1 and CaV2 voltage-gated calcium channels evolved from an ancestral CaV1/2 channel via gene duplication somewhere near the stem animal lineage. The divergence of these channel types led to distinguishing functional properties that are conserved among vertebrates and bilaterian invertebrates and contribute to their unique cellular roles. One key difference pertains to their regulation by calmodulin (CaM), wherein bilaterian CaV1 channels are uniquely subject to pronounced, buffer-resistant Ca2+/CaM-dependent inactivation, permitting negative feedback regulation of calcium influx in response to local cytoplasmic Ca2+ rises. Early diverging, nonbilaterian invertebrates also possess CaV1 and CaV2 channels, but it is unclear whether they share these conserved functional features. The most divergent animals to possess both CaV1 and CaV2 channels are placozoans such as Trichoplax adhaerens, which separated from other animals over 600 million years ago shortly after their emergence. Hence, placozoans can provide important insights into the early evolution of CaV1 and CaV2 channels. Here, we build upon previous characterization of Trichoplax CaV channels by determining the cellular expression and ion-conducting properties of the CaV1 channel orthologue, TCaV1. We show that TCaV1 is expressed in neuroendocrine-like gland cells and contractile dorsal epithelial cells. In vitro, this channel conducts dihydropyridine-insensitive, high-voltage–activated Ca2+ currents with kinetics resembling those of rat CaV1.2 but with left-shifted voltage sensitivity for activation and inactivation. Interestingly, TCaV1, but not TCaV2, exhibits buffer-resistant Ca2+/CaM-dependent inactivation, indicating that this functional divergence evolved prior to the emergence of bilaterian animals and may have contributed to their unique adaptation for cytoplasmic Ca2+ signaling within various cellular contexts.

Neuromeric Distribution of Nicotinamide Adenine Dinucleotide Phosphate-Diaphorase Activity in the Adult Lamprey Brain.

This study reports for the first time the distribution and morphological characterization of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d; a reliable marker of nitric oxide synthase activity) positive elements in the central nervous system of the adult river lamprey (Lampetra fluviatilis) on the framework of the neuromeric model and compares their cytoarchitectonic organization with that of gnathostomes. Both NADPH-d exhibiting cells and fibers were observed in all major divisions of the lamprey brain as well as in the spinal cord. In the secondary prosencephalon, NADPH-d positive cells were observed in the mitral cell layer of the olfactory bulb, evaginated pallium, amygdala, dorsal striatum, septum, lateral preoptic nucleus, caudal paraventricular area, posterior entopeduncular nucleus, nucleus of the stria medullaris, hypothalamic periventricular organ and mamillary region sensu lato. In the lamprey diencephalon, NADPH-d labeled cells were observed in several nuclei of the prethalamus, epithalamus, pretectum, and the basal plate. Especially remarkable was the staining observed in the right habenula and several pretectal nuclei. NADPH-d positive cells were also observed in the following mesencephalic areas: optic tectum (two populations), torus semicircularis, nucleus M5 of Schöber, and a ventral tegmental periventricular nucleus. Five different cell populations were observed in the isthmic region, whereas the large sensory dorsal cells, some cells located in the interpeduncular nucleus, the motor nuclei of most cranial nerves, the solitary tract nucleus, some cells of the reticular nuclei, and small cerebrospinal fluid-contacting (CSF-c) cells were the most evident stained cells of the rhombencephalon proper. Finally, several NADPH-d positive cells were observed in the rostral part of the spinal cord, including the large sensory dorsal cells, numerous CSF-c cells, and some dorsal and lateral interneurons. NADPH-d positive fibers were observed in the olfactory pathways (primary olfactory fibers and stria medullaris), the fasciculus retroflexus, and the dorsal column tract. Our results on the distribution of NADPH-d positive elements in the brain of the adult lamprey L. fluviatilis are significantly different from those previously reported in larval lampreys and demonstrated that these animals possess a complex nitrergic system readily comparable to those of other vertebrates, although important specific differences also exist.

Nodal Enhances Perineural Invasion in Pancreatic Cancer by Promoting Tumor-Nerve Convergence.

Perineural invasion (PNI) is a typical feature of pancreatic ductal adenocarcinoma (PDAC), which occurs in most cases. The embryonic protein Nodal plays a critical role in embryonic neural development and is overexpressed in human pancreatic cancer. In this study, we explored the contribution of Nodal to pancreatic cancer PNI and progression. We evaluated the function of Nodal in PNI by coculturing rat dorsal root ganglia and pancreatic cancer cells in vitro and performing cellular and molecular biology assays. The results illustrate that Nodal upregulates NGF (nerve growth factor), BDNF (brain-derived neurotrophic factor), and GDNF (glial cell line-derived neurotrophic factor) expression in pancreatic cancer cells and promotes cancer cell migration/invasion. Furthermore, in the in vitro 3D PNI model, Nodal enhances nerve outgrowth to pancreatic cancer cell colonies. Our study indicates that Nodal participates in tumor invasion by mediating neural and tumor cell signaling interactions, and inhibiting the expression of Nodal represents a potential strategy for targeting PNI in pancreatic cancer therapy.

Galangin Reverses H2O2-Induced Dermal Fibroblast Senescence via SIRT1-PGC-1α/Nrf2 Signaling.

UV radiation and H2O2 are the primary factors that cause skin aging. Both trigger oxidative stress and cellular aging. It has been reported that deacetylase silent information regulator 1 (SIRT1), a longevity gene, enhances activation of NF-E2-related factor-2 (Nrf2), as well as its downstream key antioxidant gene hemeoxygenase-1 (HO-1), to protect cells against oxidative damage by deacetylating the transcription coactivator PPARγ coactivator-1α (PGC-1α). Galangin, a flavonoid, possesses anti-oxidative and anti-inflammatory potential. In the present study, we applied Ultraviolet B/H2O2-induced human dermal fibroblast damage as an in vitro model and UVB-induced photoaging of C57BL/6J nude mice as an in vivo model to investigate the underlying dermo-protective mechanisms of galangin. Our results indicated that galangin treatment attenuates H2O2/UVB-induced cell viability reduction, dermal aging, and SIRT1/PGC-1α/Nrf2 signaling activation. Furthermore, galangin treatment enhanced Nrf2 activation and nuclear accumulation, in addition to inhibiting Nrf2 degradation. Interestingly, upregulation of antioxidant response element luciferase activity following galangin treatment indicated the transcriptional activation of Nrf2. However, knockdown of SIRT1, PGC-1α, or Nrf2 by siRNA reversed the antioxidant and anti-aging effects of galangin. In vivo evidence further showed that galangin treatment, at doses of 12 and 24 mg/kg on the dorsal skin cells of nude mice resulted in considerably reduced UVB-induced epidermal hyperplasia and skin senescence, and promoted SIRT1/PGC-1α/Nrf2 signaling. Furthermore, enhanced nuclear localization of Nrf2 was observed in galangin-treated mice following UVB irradiation. In conclusion, our data indicated that galangin exerts anti-photoaging and antioxidant effects by promoting SIRT1/PGC-1α/Nrf2 signaling. Therefore, galangin is a potentially promising agent for cosmetic skin care products against UV-induced skin aging.

Hymenostylium chapadense M.J.Cano & J.A.Jiménez (Pottiaceae), a new species from Brazil and its phylogenetic position based on molecular data

ABSTRACT Introduction In the context of a taxonomic revision of the tribe Pleuroweisieae in South America, we studied a specimen of Hymenostylium that did not match any previously known species of this genus in America. Here we present our arguments for recognising this moss as a new species. Methods The morphology of the potential new species was compared with that of the species of Hymenostylium presently recognised. A phylogenetic analysis based on the nuclear ITS and plastid rps4 regions was performed to investigate relationships between the new species and closely related taxa. Key results and conclusions Based on morphological and molecular data, we describe this new species from Brazil, Hymenostylium chapadense M.J.Cano & J.A.Jiménez. The species is strikingly distinguished by a stem with central strand and hyalodermis, oblong-ligulate to oblong-elliptical leaves that are when dry slightly crisped in the upper part and usually constricted just above the base and recurved on one side in the lower third, with uni- to bistratose margins, obtuse apex, costa wide and ending below the apex or percurrent with ventral and dorsal surface cells of the costa differentiated as an epidermis, and middle laminal cells usually with a simple, coarse, central papilla. Our molecular study placed H. chapadense as sister to H. hildebrandtii (Müll.Hal.) R.H.Zander. Possible confusion with the latter species and other closely related taxa is discussed. A key to the South American species of Hymenostylium is provided.

The Lamellipodin homologue MIG-10 is not essential for dorsal intercalation in the embryonic epidermis of the C. elegans embryo.

Dorsal intercalation of the embryonic epidermis in the Caenorhabditis elegans embryo is a promising system for genetic analysis of convergent extension, a conserved process in animal embryos. We sought to identify functionally important actin regulators in dorsal epidermal cells. A promising candidate is MIG-10, the single MIG-10/RIAM/Lamellipodin (MRL) family member in C. elegans. We endogenously tagged all mig-10 isoforms with mNeonGreen and analyzed mig-10 mutants using 4-dimensional microscopy. MIG-10::mNG is expressed prominently in muscle progenitors but is not detectable in the dorsal epidermis. mig-10(ct41) homozygotes complete dorsal intercalation in a manner indistinguishable from wildtype, indicating MIG-10 is not essential during dorsal intercalation.

Reprogramming of Adult Human Dermal Fibroblasts to Induced Dorsal Forebrain Precursor Cells Maintains Aging Signatures

Reprogramming of Adult Human Dermal Fibroblasts to Induced Dorsal Forebrain Precursor Cells Maintains Aging Signatures

Force measurements of Myosin II waves at the yolk surface during Drosophila dorsal closure

The mechanical properties and the forces involved during tissue morphogenesis have been the focus of much research in the last years. Absolute values of forces during tissue closure events have not yet been measured. This is also true for a common force-producing mechanism involving Myosin II waves that results in pulsed cell surface contractions. Our patented magnetic tweezer, CAARMA, integrated into a spinning disk confocal microscope, provides a powerful explorative tool for quantitatively measuring forces during tissue morphogenesis. Here, we used this tool to quantify the in vivo force production of Myosin II waves that we observed at the dorsal surface of the yolk cell in stage 13 Drosophila melanogaster embryos. In addition to providing for the first time to our knowledge quantitative values on an active Myosin-driven force, we elucidated the dynamics of the Myosin II waves by measuring their periodicity in both absence and presence of external perturbations, and we characterized the mechanical properties of the dorsal yolk cell surface.

The T-box gene optomotor-blind organizes proximodistal leg patterning in the beetle Tribolium castaneum by repressing dorsal Dpp pathway activity

Leg axis formation in Drosophila is organized by Wingless (Wg) and Decapentaplegic (Dpp) that control a number of downstream factors to pattern the dorsoventral (DV) and proximodistal (PD) axis. The T-box genes are important downstream factors mainly involved in dorsoventral leg axis formation. The ventral side is specified by H15 and midline, whereas optomotor-blind (omb) and Dorsocross (Doc1) are factors to specify dorsal cell fates. We show here that omb also organizes PD leg axis patterning in the beetle Tribolium castaneum. In the legs, Tc-omb is expressed along the dorsal side and represses ventral factors like wg and H15. Intriguingly, removing Tc-omb function leads to the activation of the Dpp pathway along the dorsal side of the legs, thus mimicking normal dpp expression in Drosophila. Dpp activity along the dorsal side leads to altered expression of proximal-distal patterning genes such as Distal-less (Dll) and dachshund (dac). Our results indicate a cell-autonomous activation of Dll and repression of dac by dpp. These findings are compatible with the cross-regulatory “cascade model“ of proximal-distal leg imaginal disc patterning of Drosophila.

Synaptic targets of photoreceptors specialized to detect color and skylight polarization in Drosophila.

Color and polarization provide complementary information about the world and are detected by specialized photoreceptors. However, the downstream neural circuits that process these distinct modalities are incompletely understood in any animal. Using electron microscopy, we have systematically reconstructed the synaptic targets of the photoreceptors specialized to detect color and skylight polarization in Drosophila, and we have used light microscopy to confirm many of our findings. We identified known and novel downstream targets that are selective for different wavelengths or polarized light, and followed their projections to other areas in the optic lobes and the central brain. Our results revealed many synapses along the photoreceptor axons between brain regions, new pathways in the optic lobes, and spatially segregated projections to central brain regions. Strikingly, photoreceptors in the polarization-sensitive dorsal rim area target fewer cell types, and lack strong connections to the lobula, a neuropil involved in color processing. Our reconstruction identifies shared wiring and modality-specific specializations for color and polarization vision, and provides a comprehensive view of the first steps of the pathways processing color and polarized light inputs.

Antiallodynic action of phosphodiesterase inhibitors in a mouse model of peripheral nerve injury

Neuropathic pain arises as a consequence of a lesion or disease affecting the somatosensory nervous system. It is accompanied by neuronal and non-neuronal alterations, including alterations in intracellular second messenger pathways. Cellular levels of 3′,5′-cyclic adenosine monophosphate (cAMP) and 3′,5′-cyclic guanosine monophosphate (cGMP) are regulated by phosphodiesterase (PDE) enzymes. Here, we studied the impact of PDE inhibitors (PDEi) in a mouse model of peripheral nerve injury induced by placing a cuff around the main branch of the sciatic nerve. Mechanical hypersensitivity, evaluated using von Frey filaments, was relieved by sustained treatment with the non-selective PDEi theophylline and ibudilast (AV-411), with PDE4i rolipram, etazolate and YM-976, and with PDE5i sildenafil, zaprinast and MY-5445, but not by treatments with PDE1i vinpocetine, PDE2i EHNA or PDE3i milrinone. Using pharmacological and knock-out approaches, we show a preferential implication of delta opioid receptors in the action of the PDE4i rolipram and of both mu and delta opioid receptors in the action of the PDE5i sildenafil. Calcium imaging highlighted a preferential action of rolipram on dorsal root ganglia non-neuronal cells, through PDE4B and PDE4D inhibition. Rolipram had anti-neuroimmune action, as shown by its impact on levels of the pro-inflammatory cytokine tumor necrosis factor-α (TNFα) in the dorsal root ganglia of mice with peripheral nerve injury, as well as in human peripheral blood mononuclear cells (PBMCs) stimulated with lipopolysaccharides. This study suggests that PDEs, especially PDE4 and 5, may be targets of interest in the treatment of neuropathic pain.This article is part of the Special Issue on ‘Advances in mechanisms and therapeutic targets relevant to pain’.