Neural progenitors of the vertebrate CNS are defined by generic cellular characteristics, including their pseudoepithelial morphology and their ability to divide and differentiate. SOXB1 transcription factors, including the three closely related genes Sox1, Sox2, and Sox3, universally mark neural progenitor and stem cells throughout the vertebrate CNS. We show here that constitutive expression of SOX2 inhibits neuronal differentiation and results in the maintenance of progenitor characteristics. Conversely, inhibition of SOX2 signaling results in the delamination of neural progenitor cells from the ventricular zone and exit from cell cycle, which is associated with a loss of progenitor markers and the onset of early neuronal differentiation markers. The phenotype elicited by inhibition of SOX2 signaling can be rescued by coexpression of SOX1, providing evidence for redundant SOXB1 function in CNS progenitors. Taken together, these data indicate that SOXB1 signaling is both necessary and sufficient to maintain panneural properties of neural progenitor cells.

Zika virus (ZIKV), a mosquito-borne flavivirus with homology to Dengue virus (DENV), has become a public health emergency. By characterizing memory lymphocytes from ZIKV-infected patients, we dissected ZIKV-specific and DENV-cross-reactive immune responses. Antibodies to nonstructural protein 1 (NS1) were largely ZIKV-specific and were used to develop a serological diagnostic tool. In contrast, antibodies against E protein domain I/II (EDI/II) were cross-reactive and, although poorly neutralizing, potently enhanced ZIKV and DENV infection in vitro and lethally enhanced DENVdisease in mice. Memory Tcells against NS1 or E proteins were poorly cross-reactive, even in donors preexposed to DENV. The most potent neutralizing antibodies were ZIKV-specific and targeted EDIII or quaternary epitopes on infectious virus. An EDIII-specific antibody protected mice from lethal ZIKV infection, illustrating the potential for antibody-based therapy.A fter its introduction into Brazil in 2015, Zika virus (ZIKV) has spread rapidly, and in February 2016, the World Health Organization (WHO) declared it a Public Health Emergency of International Concern (1-3). The main route of ZIKV infection is through bites by Aedes mosquitos, but the virus may also be sexually (4) and vertically transmitted (5). Although most of the ZIKV infections are asymptomatic or cause only mild symptoms, there is evidence that ZIKV infection can lead to neurological complications, such as Guillain-Barré syndrome in adults (6) and congenital birth defects, including microcephaly in the developing fetus (5,7,8), likely through its ability to infect human neural progenitor cells (9).Whereas flavivirus envelope (E) proteins mediate fusion and are the main target of neutralizing antibodies, the nonstructural protein 1 (NS1) is secreted by infected cells and is involved in immune evasion and pathogenesis (10). Two recent studies showed a high level of structural similarity between the E protein of ZIKV and that of other flaviviruses-such as dengue virus (DENV), yellow fever virus (YFV), and West Nile virus (WNV)-but also revealed distinct features that may be related to the ZIKV neurotropism (11,12). Similarly, the structural analysis of ZIKV NS1 revealed conserved features with NS1 of other flaviviruses, although with different electrostatic characteristics (13).A phenomenon that is characteristic of certain flaviviruses is the disease-enhancing activity of cross-reactive antibodies elicited by previous infections by heterologous viruses, termed antibodydependent enhancement (ADE). In the case of DENV, for which four serotypes are known, there is epidemiological evidence that a primary infection protects from reinfection with the same serotype but represents a risk factor for the development of severe disease upon reinfection with a different serotype (14). The exacerbated disease is triggered by E-and prM-specific antibodies that fail to neutralize the incoming virus but instead enhance its capture by Fc receptor-expressing (FcR + ) cells, leading to enhanced vi...

It is now well established that stromal interaction molecule 1 (STIM1) is the calcium sensor of endoplasmic reticulum stores required to activate store-operated calcium entry (SOC) channels at the surface of non-excitable cells. However, little is known about STIM1 in excitable cells, such as striated muscle, where the complement of calcium regulatory molecules is rather disparate from that of non-excitable cells. Here, we show that STIM1 is expressed in both myotubes and adult skeletal muscle. Myotubes lacking functional STIM1 fail to show SOC and fatigue rapidly. Moreover, mice lacking functional STIM1 die perinatally from a skeletal myopathy. In addition, STIM1 haploinsufficiency confers a contractile defect only under conditions where rapid refilling of stores would be needed. These findings provide insight into the role of STIM1 in skeletal muscle and suggest that STIM1 has a universal role as an ER/SR calcium sensor in both excitable and non-excitable cells.

Zika virus (ZIKV) is a mosquito-borne pathogen which has recently spread beyond Africa and into Pacific and South American regions. Despite first being detected in 1947, very little information is known about the virus, and its spread has been associated with increases in Guillain-Barre syndrome and microcephaly. There are currently no known vaccines or antivirals against ZIKV infection. Progress in assessing interventions will require the development of animal models to test efficacies; however, there are only limited reports on in vivo studies. The only susceptible murine models have involved intracerebral inoculations or juvenile animals, which do not replicate natural infection. Our report has studied the effect of ZIKV infection in type-I interferon receptor deficient (A129) mice and the parent strain (129Sv/Ev) after subcutaneous challenge in the lower leg to mimic a mosquito bite. A129 mice developed severe symptoms with widespread viral RNA detection in the blood, brain, spleen, liver and ovaries. Histological changes were also striking in these animals. 129Sv/Ev mice developed no clinical symptoms or histological changes, despite viral RNA being detectable in the blood, spleen and ovaries, albeit at lower levels than those seen in A129 mice. Our results identify A129 mice as being highly susceptible to ZIKV and thus A129 mice represent a suitable, and urgently required, small animal model for the testing of vaccines and antivirals.

Background The largest West African monkeypox outbreak began September 2017, in Nigeria. Four individuals traveling from Nigeria to the UK (2), Israel, and Singapore became the first human monkeypox cases exported from Africa, and a related nosocomial transmission event in the UK became the first confirmed human-to-human monkeypox transmission event outside of Africa. Methods Epidemiological and molecular data for exported and Nigerian cases were analyzed jointly to better understand the exportations in the temporal and geographic context of the outbreak. Results Isolates from all travelers and a Bayelsa case shared a most recent common ancestor and traveled to Bayelsa, Delta, or Rivers states. Genetic variation for this cluster was lower than would be expected from a random sampling of genomes from this outbreak, but data did not support direct links between travelers. Conclusions Monophyly of exportation cases and the Bayelsa sample, along with the intermediate levels of genetic variation suggest a small pool of related isolates is the likely source for the exported infections. This may be the result of the level of genetic variation present in monkeypox isolates circulating within the contiguous region of Bayelsa, Delta, and Rivers states, or another more restricted, yet unidentified source pool.

Rationale Fibroblast growth factor homologous factors (FHFs), a subfamily of fibroblast growth factors (FGFs) that are incapable of functioning as growth factors, are intracellular modulators of Na+ channels and have been linked to neurodegenerative diseases. Although certain FHFs have been found in embryonic heart, they have not been reported in adult heart, and they have not been shown to regulate endogenous cardiac Na+ channels nor participate in cardiac pathophysiology. Objective We tested whether FHFs regulate Na+ channels in murine heart. Methods and Results We demonstrated that isoforms of FGF13 are the predominant FHFs in adult mouse ventricular myocytes. FGF13 binds directly to, and co-localizes with the Na 1.5 Na+ V channel in the sarcolemma of adult mouse ventricular myocytes. Knockdown of FGF13 in adult mouse ventricular myocytes revealed a loss-of-function of NaV1.5: reduced Na+ current (INa) density, decreased Na+ channel availability, and slowed INa recovery from inactivation. Cell surface biotinylation experiments showed a ~45% reduction in NaV1.5 protein at the sarcolemma after FGF13 knockdown, whereas no changes in whole-cell NaV1.5 protein nor mRNA level were observed. Optical imaging in neonatal rat ventricular myocyte monolayers demonstrated slowed conduction velocity and a reduced maximum capture rate after FGF13 knockdown. Conclusion These findings show that FHFs are potent regulators of Na+ channels in adult ventricular myocytes and suggest that loss-of-function mutations in FHFs may underlie a similar set of cardiac arrhythmias and cardiomyopathies that result from NaV1.5 loss-of-function mutations.

Rationale: Cardiac muscle adapts to increase workload by altering cardiomyocyte size and function resulting in cardiac hypertrophy. G protein-coupled receptor signaling is known to govern the hypertrophic response through the regulation of ion channel activity and downstream signaling in failing cardiomyocytes. Objective: Transient receptor potential canonical (TRPC) channels are G protein-coupled receptor operated channels previously implicated in cardiac hypertrophy. Our objective of this study is to better understand how TRPC channels influence cardiomyocyte calcium signaling. Methods and Results: Here, we used whole cell patch clamp of adult cardiomyocytes to show upregulation of a nonselective cation current reminiscent of TRPC channels subjected to pressure overload. This TRPC current corresponds to the increased TRPC channel expression noted in hearts of mice subjected to pressure overload. Importantly, we show that mice lacking TRPC1 channels are missing this putative TRPC current. Moreover, Trpc1 ؊/؊ mice fail to manifest evidence of maladaptive cardiac hypertrophy and maintain preserved cardiac function when subjected to hemodynamic stress and neurohormonal excess. In addition, we provide a mechanistic basis for the protection conferred to Trpc1 ؊/؊ mice as mechanosensitive signaling through calcineurin/NFAT, mTOR and Akt is altered in Trpc1 ؊/؊ mice. Conclusions: From these studies, we suggest that TRPC1 channels are critical for the adaptation to biomechanical stress and TRPC dysregulation leads to maladaptive cardiac hypertrophy and failure. (Circ Res. 2009;105:1023-1030.)Key Words: transient receptor potential channels Ⅲ G protein receptor signaling Ⅲ cardiac hypertrophy C ardiac myocytes respond to changing mechanical workloads by altering the frequency and amplitude of their calcium transients. 1,2 Encoded in these calcium transients are signals that alter not only the immediate contractile response but also initiate and maintain a remodeling response that adjusts cellular mass, ionic currents, kinetic properties of contractile proteins, and metabolic capacity. 3 It is likely that persistence of these signals modulate the calcium signaling events resulting in a hypertrophic response and adverse remodeling. To identify the proximal signals that regulate cardiac hypertrophy, attention has begun to focus on ion channels because they may link mechanical activity to cell signaling. 4 Recent work has raised the possibility that hypertrophic agonists linked to G-protein coupled receptors activate calcium entry through transient receptor potential canonical (TRPC) channels. [5][6][7][8][9][10] TRPC channels encompass a large family of nonselective cation channels found in many different cell types. 11 TRPC channels are activated downstream of G-protein receptor through the phospholipase C signaling by inositol trisphosphate (TRPC1/4/5) or by diacyl glycerol (TRPC3/6/7). 5,12 More recently TRPC1/6 channels were found to be mechanosensitive channels that mediate nonselective cation entry in response to i...

SUMMARY Zika virus (ZIKV), a mosquito-borne flavivirus, causes devastating congenital birth defects. We isolated a human monoclonal antibody (mAb), ZKA190, that potently cross-neutralizes multi-lineage ZIKV strains. ZKA190 is highly effective in vivo in preventing morbidity and mortality of ZIKV-infected mice. NMR and cryo-electron microscopy show its binding to an exposed epitope on DIII of the E protein. ZKA190 Fab binds all 180 E protein copies, altering the virus quaternary arrangement and surface curvature. However, ZIKV escape mutants emerged in vitro and in vivo in the presence of ZKA190, as well as of other neutralizing mAbs. To counter this problem, we developed a bispecific antibody (FIT-1) comprising ZKA190 and a second mAb specific for DII of E protein. In addition to retaining high in vitro and in vivo potencies, FIT-1 robustly prevented viral escape, warranting its development as a ZIKV immunotherapy.