CXCL8/CXCR2 signaling mediates bone marrow fibrosis and is a therapeutic target in myelofibrosis.

Proinflammatory signaling is a hallmark feature of human cancer, including in myeloproliferative neoplasms (MPNs), most notably myelofibrosis (MF). Dysregulated inflammatory signaling contributes to fibrotic progression in MF; however, the individual cytokine mediators elicited by malignant MPN cells to promote collagen-producing fibrosis and disease evolution are yet to be fully elucidated. Previously, we identified a critical role for combined constitutive JAK/STAT and aberrant NF-κB proinflammatory signaling in MF development. Using single-cell transcriptional and cytokine-secretion studies of primary cells from patients with MF and the human MPLW515L (hMPLW515L) murine model of MF, we extend our previous work and delineate the role of CXCL8/CXCR2 signaling in MF pathogenesis and bone marrow fibrosis progression. Hematopoietic stem/progenitor cells from patients with MF are enriched for a CXCL8/CXCR2 gene signature and display enhanced proliferation and fitness in response to an exogenous CXCL8 ligand in vitro. Genetic deletion of Cxcr2 in the hMPLW515L-adoptive transfer model abrogates fibrosis and extends overall survival, and pharmacologic inhibition of the CXCR1/2 pathway improves hematologic parameters, attenuates bone marrow fibrosis, and synergizes with JAK inhibitor therapy. Our mechanistic insights provide a rationale for therapeutic targeting of the CXCL8/CXCR2 pathway among patients with MF.

JNK signaling is required for proper tangential migration and laminar allocation of cortical interneurons.

The precise migration of cortical interneurons is essential for the formation and function of cortical circuits, and disruptions to this key developmental process are implicated in the etiology of complex neurodevelopmental disorders, including schizophrenia, autism and epilepsy. We have recently identified the Jun N-terminal kinase (JNK) pathway as an important mediator of cortical interneuron migration in mice, regulating the proper timing of interneuron arrival into the cortical rudiment. In the current study, we demonstrate a vital role for JNK signaling at later stages of corticogenesis, when interneurons transition from tangential to radial modes of migration. Pharmacological inhibition of JNK signaling in ex vivo slice cultures caused cortical interneurons to rapidly depart from migratory streams and prematurely enter the cortical plate. Similarly, genetic loss of JNK function led to precocious stream departure ex vivo, and stream disruption, morphological changes and abnormal allocation of cortical interneurons in vivo These data suggest that JNK signaling facilitates the tangential migration and laminar deposition of cortical interneurons, and further implicates the JNK pathway as an important regulator of cortical development.

Early construction of the thalamocortical axon pathway requires c-Jun N-terminal kinase signaling within the ventral forebrain.

BACKGROUND: Thalamocortical connectivity is essential for normal brain function. This important pathway is established during development, when thalamic axons extend a long distance through the forebrain before reaching the cerebral cortex. In this study, we identify a novel role for the c-Jun N-terminal kinase (JNK) signaling pathway in guiding thalamocortical axons through intermediate target territories. RESULTS: Complete genetic removal of JNK signaling from the Distal-less 5/6 (Dlx5/6) domain in mice prevents thalamocortical axons from crossing the diencephalon-telencephalon boundary (DTB) and the internal capsule fails to form. Ventral telencephalic cells critical for thalamocortical axon extensions including corridor and guidepost neurons are also disrupted. In addition, corticothalamic, striatonigral, and nigrostriatal axons fail to cross the DTB. Analyses of different JNK mutants demonstrate that thalamocortical axon pathfinding has a non-autonomous requirement for JNK signaling. CONCLUSIONS: We conclude that JNK signaling within the Dlx5/6 territory enables the construction of major axonal pathways in the developing forebrain. Further exploration of this intermediate axon guidance territory is needed to uncover mechanisms of axonal pathfinding during normal brain development and to elucidate how this vital process may be compromised in neurodevelopmental disorders.

Mutations in ARL2BP, a protein required for ciliary microtubule structure, cause syndromic male infertility in humans and mice.

Cilia are evolutionarily conserved hair-like structures with a wide spectrum of key biological roles, and their dysfunction has been linked to a growing class of genetic disorders, known collectively as ciliopathies. Many strides have been made towards deciphering the molecular causes for these diseases, which have in turn expanded the understanding of cilia and their functional roles. One recently-identified ciliary gene is ARL2BP, encoding the ADP-Ribosylation Factor Like 2 Binding Protein. In this study, we have identified multiple ciliopathy phenotypes associated with mutations in ARL2BP in human patients and in a mouse knockout model. Our research demonstrates that spermiogenesis is impaired, resulting in abnormally shaped heads, shortened and mis-assembled sperm tails, as well as in loss of axonemal doublets. Additional phenotypes in the mouse included enlarged ventricles of the brain and situs inversus. Mouse embryonic fibroblasts derived from knockout animals revealed delayed depolymerization of primary cilia. Our results suggest that ARL2BP is required for the structural maintenance of cilia as well as of the sperm flagellum, and that its deficiency leads to syndromic ciliopathy.

Functional and resting-state characterizations of a periventricular heterotopic nodule associated with epileptogenic activity.

The object of this study was to extensively characterize a region of periventricular nodular heterotopia (PVNH) in an epilepsy patient to reveal its possible neurocognitive functional role(s). The authors used 3-T MRI approaches to exhaustively characterize a single, right hemisphere heterotopion in a high-functioning adult male with medically responsive epilepsy, which had manifested during late adolescence. The heterotopion proved to be spectroscopically consistent with a cortical-like composition and was interconnected with nearby ipsilateral cortical fundi, as revealed by fiber tractography (diffusion-weighted imaging) and resting-state functional connectivity MRI (rsfMRI). Moreover, the region of PVNH demonstrated two novel characterizations for a heterotopion. First, functional MRI (fMRI), as distinct from rsfMRI, showed that the heterotopion was significantly modulated while the patient watched animated video scenes of biological motion (i.e., cartoons). Second, rsfMRI, which demonstrated correlated brain activity during a task-negative state, uniquely showed directionality within an interconnected network, receiving positive path effects from patent cortical and cerebellar foci while outputting only negative path effects to specific brain foci.These findings are addressed in the context of the impact on noninvasive presurgical brain mapping strategies for adult and pediatric patient workups, as well as the impact of this study on an understanding of the functional cortical architecture underlying cognition from a neurodiversity and evolutionary perspective.

Near- and far-field investigation of dark and bright higher order resonances in square loop elements at mid-infrared wavelengths.

Three different size gold square loop structures were fabricated as arrays on ZnS over a ground plane and designed to have absorptive fundamental, second order, and third order resonances at a wavelength of 10.6 µm and 60° off-normal. The angular dependent far-field spectral absorptivity was investigated over the mid-infrared for each size loop array. It was found that the second order modes were dark at normal incidence, but became excited at off-normal incidence, which is consistent with previous work for similar geometry structures. Furthermore, near-field measurements and simulations at a wavelength of 10.6 µm and 60° off-normal showed that the second order mode (quadrupolar) of the medium size loop yielded a near-field response similar in magnitude to the fundamental mode (dipolar) of the small size loop, which can be important for sensing related applications where both strong near-field enhancement and more uniform or less localized field is beneficial.

Cortical interneurons require Jnk1 to enter and navigate the developing cerebral cortex.

Proper assembly of cortical circuitry relies on the correct migration of cortical interneurons from their place of birth in the ganglionic eminences to their place of terminal differentiation in the cerebral cortex. Although molecular mechanisms mediating cortical interneuron migration have been well studied, intracellular signals directing their migration are largely unknown. Here we illustrate a novel and essential role for c-Jun N-terminal kinase (JNK) signaling in guiding the pioneering population of cortical interneurons into the mouse cerebral cortex. Migrating cortical interneurons express Jnk proteins at the entrance to the cortical rudiment and have enriched expression of Jnk1 relative to noninterneuronal cortical cells. Pharmacological blockade of JNK signaling in ex vivo slice cultures resulted in dose-dependent and highly specific disruption of interneuron migration into the nascent cortex. Time-lapse imaging revealed that JNK-inhibited cortical interneurons advanced slowly and assumed aberrant migratory trajectories while traversing the cortical entry zone. In vivo analyses of JNK-deficient embryos supported our ex vivo pharmacological data. Deficits in interneuron migration were observed in Jnk1 but not Jnk2 single nulls, and those migratory deficits were further exacerbated when homozygous loss of Jnk1 was combined with heterozygous reduction of Jnk2. Finally, genetic ablation of Jnk1 and Jnk2 from cortical interneurons significantly perturbed migration in vivo, but not in vitro, suggesting JNK activity functions to direct their guidance rather than enhance their motility. These data suggest JNK signaling, predominantly mediated by interneuron expressed Jnk1, is required for guiding migration of cortical interneurons into and within the developing cerebral cortex.

PTEN loss in circulating tumour cells correlates with PTEN loss in fresh tumour tissue from castration-resistant prostate cancer patients.

BACKGROUND: PTEN gene loss occurs frequently in castration-resistant prostate cancer (CRPC) and may drive progression through activation of the PI3K/AKT pathway. Here, we developed a novel CTC-based assay to determine PTEN status and examined the correlation between PTEN status in CTCs and matched tumour tissue samples. METHODS: PTEN gene status in CTCs was evaluated on an enrichment-free platform (Epic Sciences) by fluorescence in situ hybridisation (FISH). PTEN status in archival and fresh tumour tissue was evaluated by FISH and immunohistochemistry. RESULTS: Peripheral blood was collected from 76 patients. Matched archival and fresh cancer tissue was available for 48 patients. PTEN gene status detected in CTCs was concordant with PTEN status in matched fresh tissues and archival tissue in 32 of 38 patients (84%) and 24 of 39 patients (62%), respectively. CTC counts were prognostic (continuous, P=0.001). PTEN loss in CTCs associated with worse survival in univariate analysis (HR 2.05; 95% CI 1.17-3.62; P=0.01) and with high lactate dehydrogenase (LDH) in metastatic CRPC patients. CONCLUSIONS: Our results illustrate the potential use of CTCs as a non-invasive, real-time liquid biopsy to determine PTEN gene status. The prognostic and predictive value of PTEN in CTCs warrants investigation in CRPC clinical trials of PI3K/AKT-targeted therapies.

Near-field investigation of the effect of the array edge on the resonance of loop frequency selective surface elements at mid-infrared wavelengths.

Mid-infrared scattering scanning near-field optical microscopy, in combination with far-field infrared spectroscopy, and simulations, was employed to investigate the effect of mutual-element coupling towards the edge of arrays of loop elements acting as frequency selective surfaces (FSSs). Two different square loop arrays on ZnS over a ground plane, resonant at 10.3 µm, were investigated. One array had elements that were closely spaced while the other array had elements with greater inter-element spacing. In addition to the dipolar resonance, we observed a new emergent resonance associated with the edge of the closely-spaced array as a finite size effect, due to the broken translational invariance.

Cxcr4 regulation of interneuron migration is disrupted in 22q11.2 deletion syndrome.

Interneurons are thought to be a primary pathogenic target for several behavioral disorders that arise during development, including schizophrenia and autism. It is not known, however, whether genetic lesions associated with these diseases disrupt established molecular mechanisms of interneuron development. We found that diminished 22q11.2 gene dosage-the primary genetic lesion in 22q11.2 deletion syndrome (22q11.2 DS)-specifically compromises the distribution of early-generated parvalbumin-expressing interneurons in the Large Deletion (LgDel) 22q11.2DS mouse model. This change reflects cell-autonomous disruption of interneuron migration caused by altered expression of the cytokine C-X-C chemokine receptor type 4 (Cxcr4), an established regulator of this process. Cxcr4 is specifically reduced in LgDel migrating interneurons, and genetic analysis confirms that diminished Cxcr4 alters interneuron migration in LgDel mice. Thus, diminished 22q11.2 gene dosage disrupts cortical circuit development by modifying a critical molecular signaling pathway via Cxcr4 that regulates cortical interneuron migration and placement.

Array truncation effects in infrared frequency selective surfaces.

A metasurface consisting of an infinite array of square loops was designed for maximal absorptivity for s-polarized light at a wavelength of 10.6 µm and 60 degrees off-normal. We investigate the effects of array truncation in finite arrays of this design using far-field FTIR spectroscopy and scattering scanning near-field optical microscopy. The far-field spectra are observed to blue-shift with decreasing array size. The near-field images show a corresponding decrease in uniformity of the local electric field amplitude and phase spatial distributions. Simulations of the far-field absorption spectra and local electric field are consistent with the measured results.

Proliferative and transcriptional identity of distinct classes of neural precursors in the mammalian olfactory epithelium.

Neural precursors in the developing olfactory epithelium (OE) give rise to three major neuronal classes - olfactory receptor (ORNs), vomeronasal (VRNs) and gonadotropin releasing hormone (GnRH) neurons. Nevertheless, the molecular and proliferative identities of these precursors are largely unknown. We characterized two precursor classes in the olfactory epithelium (OE) shortly after it becomes a distinct tissue at midgestation in the mouse: slowly dividing self-renewing precursors that express Meis1/2 at high levels, and rapidly dividing neurogenic precursors that express high levels of Sox2 and Ascl1. Precursors expressing high levels of Meis genes primarily reside in the lateral OE, whereas precursors expressing high levels of Sox2 and Ascl1 primarily reside in the medial OE. Fgf8 maintains these expression signatures and proliferative identities. Using electroporation in the wild-type embryonic OE in vitro as well as Fgf8, Sox2 and Ascl1 mutant mice in vivo, we found that Sox2 dose and Meis1 - independent of Pbx co-factors - regulate Ascl1 expression and the transition from lateral to medial precursor state. Thus, we have identified proliferative characteristics and a dose-dependent transcriptional network that define distinct OE precursors: medial precursors that are most probably transit amplifying neurogenic progenitors for ORNs, VRNs and GnRH neurons, and lateral precursors that include multi-potent self-renewing OE neural stem cells.

Near- and far-field spectroscopic imaging investigation of resonant square-loop infrared metasurfaces.

Optical metamaterials have unique properties which result from geometric confinement of the optical conductivity. We developed a series of infrared metasurfaces based on an array of metallic square loop antennas. The far-field absorption spectrum can be designed with resonances across the infrared by scaling the geometric dimensions. We measure the amplitude and phase of the resonant mode as standing wave patterns within the square loops using scattering-scanning near-field optical microscopy (s-SNOM). Further, using a broad-band synchrotron-based FTIR microscope and s-SNOM at the Advanced Light Source, we are able to correlate far-field spectra to near-field modes of the metasurface as the resonance is tuned between samples. The results highlight the importance of multi-modal imaging for the design and characterization of optical metamaterials.

Online interactive medical neuroimaging exercise to identify human brain structures.

A persisting need remains for developing methods for inspiring and teaching undergraduate medical students to quickly learn to identify the hundreds of human brain structures, tracts and spaces that are clinically relevant (viewed as three-dimensional volumes or two-dimensional neuroimages), and to accomplish this with the option of virtual on-line methods. This notably includes teaching the essentials of recommended diagnostic radiology to allow students to be familiar with patient neuroimages routinely acquired using magnetic resonance imaging (MRI) and computed tomography (CT). The present article includes a brief example video plus details a clinically oriented interactive neuroimaging exercise for first year medical students (MS1s) in small groups, conducted with instructors either in-person or as an entirely online virtual event. This "find-the-brain-structure" (FBS) event included teaching students to identify brain structures and other regions of interest in the central nervous system (and potentially in head and neck gross anatomy), which are traditionally taught using brain anatomy atlases and anatomical specimens. The interactive, small group exercise can be conducted in person or virtually on-line in as little as 30 min depending on the scope of objectives being covered. The learning exercise involves coordinated interaction between MS1s with one or several non-clinical faculty and may include one or several physicians (clinical faculty and/or qualified residents). It further allows for varying degrees of instructor interaction online and is easy to convey to instructors who do not have expertise in neuroimaging. Anonymous pre-event survey (n = 113, 100% response rate) versus post-event surveys (n = 92, 81% response rate) were attained from a cohort of MS1s in a neurobiology course. Results showed multiple statistically significant group-level shifts in response to several of the questions, showing an increase in MS1 confidence with reading MRI images (12% increase shift in mean, p < 0.001), confidence in their approaching physicians for medical training (9%, p < 0.01), and comfort levels in working online with virtual team-based peers and with team-based faculty (6%, p < 0.05). Qualitative student feedback revealed highly positive comments regarding the experience overall, encouraging this virtual medium as a desirable educational approach.

Diminished dosage of 22q11 genes disrupts neurogenesis and cortical development in a mouse model of 22q11 deletion/DiGeorge syndrome.

The 22q11 deletion (or DiGeorge) syndrome (22q11DS), the result of a 1.5- to 3-megabase hemizygous deletion on human chromosome 22, results in dramatically increased susceptibility for "diseases of cortical connectivity" thought to arise during development, including schizophrenia and autism. We show that diminished dosage of the genes deleted in the 1.5-megabase 22q11 minimal critical deleted region in a mouse model of 22q11DS specifically compromises neurogenesis and subsequent differentiation in the cerebral cortex. Proliferation of basal, but not apical, progenitors is disrupted, and subsequently, the frequency of layer 2/3, but not layer 5/6, projection neurons is altered. This change is paralleled by aberrant distribution of parvalbumin-labeled interneurons in upper and lower cortical layers. Deletion of Tbx1 or Prodh (22q11 genes independently associated with 22q11DS phenotypes) does not similarly disrupt basal progenitors. However, expression analysis implicates additional 22q11 genes that are selectively expressed in cortical precursors. Thus, diminished 22q11 gene dosage disrupts cortical neurogenesis and interneuron migration. Such developmental disruption may alter cortical circuitry and establish vulnerability for developmental disorders, including schizophrenia and autism.

Terminal alkynes as an ink or background SAM in replacement lithography: adventitious versus directed replacement.

Self-assembled monolayers (SAMs) comprised from n-alkanethiols and terminal alkynes were subjected to solutions containing ferrocene-terminated thiol, thioacetate, and terminal alkyne. The rate and extent of chemical exchange were monitored by scanning tunneling microscopy (STM). In several cases, a rate constant for exchange could be obtained by fitting to a model for exchange. In each case where this could be accomplished, a different rate model gave the best fit to the data, suggesting that the mechanism of exchange depended on either or both the original SAM and the incoming molecule. In scenarios where the rate of exchange was slow, directed exchange was accomplished via STM tip-induced lithographic patterning (replacement lithography). The extent of exchange was independent of the incoming molecule, suggesting that tip-induced desorption was the limiting factor in this process.

JNK Signaling Regulates Cellular Mechanics of Cortical Interneuron Migration.

Aberrant migration of inhibitory interneurons can alter the formation of cortical circuitry and lead to severe neurologic disorders including epilepsy, autism, and schizophrenia. However, mechanisms involved in directing the migration of interneurons remain incompletely understood. Using a mouse model, we performed live-cell confocal microscopy to explore the mechanisms by which the c-Jun NH2-terminal kinase (JNK) pathway coordinates leading process branching and nucleokinesis, two cell biological processes that are essential for the guided migration of cortical interneurons. Pharmacological inhibition of JNK signaling disrupts the kinetics of leading process branching, rate and amplitude of nucleokinesis, and leads to the rearward mislocalization of the centrosome and primary cilium to the trailing process. Genetic loss of Jnk from interneurons also impairs leading process branching and nucleokinesis, suggesting that important mechanics of interneuron migration depend on the intrinsic activity of JNK. These findings highlight key roles for JNK signaling in leading process branching, nucleokinesis, and the trafficking of centrosomes and cilia during interneuron migration, and further implicates JNK signaling as an important mediator of cortical development.

Molecular specification and patterning of progenitor cells in the lateral and medial ganglionic eminences.

We characterized intrinsic and extrinsic specification of progenitors in the lateral and medial ganglionic eminences (LGE and MGE). We identified seven genes whose expression is enriched or restricted in either the LGE [biregional cell adhesion molecule-related/downregulated by oncogenes binding protein (Boc), Frizzled homolog 8 (Fzd8), Ankrd43 (ankyrin repeat domain-containing protein 43), and Ikzf1 (Ikaros family zinc finger 1)] or MGE [Map3k12 binding inhibitory protein 1 (Mbip); zinc-finger, SWIM domain containing 5 (Zswim5); and Adamts5 [a disintegrin-like and metallopeptidase (reprolysin type) with thrombospondin type 1 motif, 5]]. Boc, Fzd8, Mbip, and Zswim5 are apparently expressed in LGE or MGE progenitors, whereas the remaining three are seen in the postmitotic mantle zone. Relative expression levels are altered and regional distinctions are lost for each gene in LGE or MGE cells propagated as neurospheres, indicating that these newly identified molecular characteristics of LGE or MGE progenitors depend on forebrain signals not available in the neurosphere assay. Analyses of Pax6(Sey/Sey), Shh(-/-), and Gli3(XtJ/XtJ) mutants suggests that LGE and MGE progenitor identity does not rely exclusively on previously established forebrain-intrinsic patterning mechanisms. Among a limited number of additional potential patterning mechanisms, we found that extrinsic signals from the frontonasal mesenchyme are essential for Shh- and Fgf8-dependent regulation of LGE and MGE genes. Thus, extrinsic and intrinsic forebrain patterning mechanisms cooperate to establish LGE and MGE progenitor identity, and presumably their capacities to generate distinct classes of neuronal progeny.

Reversible addition-fragmentation chain transfer polymerization in DNA biosensing.

Reversible addition-fragmentation chain transfer polymerization is employed here to allow detector-free visualization of specific DNA sequences for which dynamic polymer growth is used in signal amplification. In particular, surface-initiated polymer growth was regulated by the immobilization of chain transfer agents on the Au surface where DNA hybridization occurred. A linear polymer growth was observed as a function of the reaction time, characteristic of "living" polymer reactions. Significant improvement in assay sensitivity was realized in comparison to the previously reported polymerization-based sensing method by enhancing polymer growth rate and reducing background noises caused by nonspecific adsorption. Direct visualization of fewer than 2,000 copies of a short oligonucleotide sequence was demonstrated in a detector-free fashion.

Remapping worker citizenship in contemporary occupational health and safety regimes.

The article draws on the rapidly growing field of citizenship studies to map and explore the dynamics of contemporary occupational health and safety (OHS) regulation. Using two key dimensions of OHS regulation (protection and participation), the author constructs four ideal types of worker citizenship (market, public, private industrial, and public industrial citizens). Historically, workers have been written into OHS regulatory regimes in each of these ways. Most recently lawmakers have created a new species of OHS regimes, best described as mandated partial self-regulation. Its distinguishing characteristic is its flexibility, such that worker citizenship can take on any of the forms previously described, often without changing the statutory framework. Using Ontario as an example, the study finds that in the late 20th century, workers made significant strides toward public industrial citizenship and, surprisingly, even under a neoconservative government, workers successfully defended their participatory rights and saw their right to protection modestly strengthened through increased enforcement. The conditions under which this regime operates, however, constantly threaten to undermine the efficacy of worker participation rights and to weaken the enforcement effort. Some suggestions are made about using a citizenship discourse to revitalize the worker OHS movement and strengthen OHS rights.