Nickel-Catalyzed Antibody Bioconjugation

New biocompatible methods for post-translational protein modification are challenging to develop but crucial to create improved chemical probes and optimize next-generation biologic therapies such as antibody-drug conjugates (ADCs). Herein, we describe the bottom-up construction of an aqueous nickel-catalyzed cross-coupling for the chemospecific arylation of cysteine residues on peptides and proteins and its use for the preparation of ADCs. A variety of arene linkages are exemplified, enabling the incorporation of small molecules, probes, and cytotoxic payloads. The utility of this new bioconjugation platform in a drug discovery setting is highlighted by the construction of novel ADCs with target-mediated in vitro cytotoxic activity.

[Efficacy of esophageal cancer screening program on population at high risk: a survey carried out in people aged 40-69 years in Yangzhong, Jiangsu province]

Objective: To understand the incidence of esophageal cancer in population at high risk in Yangzhong of Jiangsu province. Methods: Cluster random sampling method was conducted to select several natural villages from the high risk area of esophageal cancer in Yangzhong during 2011-2017. Local residents aged 40-69 years were selected as the target population and a total of 14 687 persons were diagnosed esophageal cancer by endoscopy and pathology. Results: Precancerous lesions were detected in 341 persons, with the detection rate as 2.32% (341/14 687). Among them, there were 234 (1.59%) cases with mild and 107 (0.73%) cases with moderate esophageal hyperplasia. There were 77 positive cases with esophageal hyperplasia and the detection rate was 0.52%. Among these positive cases, 41 showed severe esophageal hyperplasia/carcinoma in situ (0.28%), with another 19 as early esophageal cancer (0.13%) and 17 with invasive carcinoma (0.12%). The overall early detection rate of positivity through active screening was 77.92% (60/77), with trends of upwarding and then downwarding. The detection rate of esophageal lesions in men was higher than that in women (P<0.05), but without significant gender specific differences seen in the detection rates of early esophageal cancer or invasive carcinoma (P>0.05). The detection rates of all lesions other than invasive carcinoma, gradually increased with age (P<0.05). The detection rate of invasive carcinoma reached the highest (0.39%, 10/2 547) in the age group of 60-years and slightly decreased in the age group of 65-years old. Conclusions: Considerable numbers of patients with cancer and precancerous lesions in groups at high-risk can be found through the screening program for esophageal cancer, suggesting that the screening program is of great significance in improving the survival rate and quality of life. Attention should be paid to men, with elderly groups in particular, at high-risk in order to increase the detection rate of early cases.

[Status of non-steroidal anti-inflammatory drugs use in areas with a high incidence of upper gastrointestinal cancer in China: a multi-center cross-sectional survey]

Objective: To describe the status of non-steroidal anti-inflammatory drugs (NSAIDs) use in areas with a high incidence of upper gastrointestinal cancer in China. Methods: This study was based on the National Key Research and Development Program of "National Precision Medicine Cohort of Esophageal Cancer" and "Study on Identification and Prevention of High-risk Populations of Gastrointestinal Malignancies (Esophageal cancer, Gastric cancer and Colorectal cancer)" . From January 2017 to August 2018, 212 villages or communities with a high incidence of esophageal cancer or gastric cancer were selected from 12 regions in 6 provinces. A total of 35 910 residents aged between 40 and 69 years old who met the inclusion criteria and signed the informed consent were investigated and enrolled in this study. The use of NSAIDs, demographic characteristics, health-related habits, height, weight, and blood pressure were collected by the questionnaire and physical examination. The status of main NSAIDs (aspirin, acetaminophen and ibuprofen) use with the difference varying in genders, age groups and regions were analyzed by using χ(2) test and Cochran-Armitage trend analysis method. Results: Of 35 910 subjects, the mean age was (54.6±7.1) years old and males accounted for 43.42% (15 591). The overall prevalence of NSAIDs intake was 4.56% (1 638), but it significantly varied in different provinces (P<0.001). The overall prevalence of NSAIDs intake was 4.87% (1 750) in females, which was significantly higher than that in males 4.24% (1 524) (P<0.001). The prevalence of NSAIDs intake increased with age (P for trend <0.001). As the frequency of NSAIDs intake increased, the incidence of gastrointestinal symptoms, gastrointestinal ulcers and black stools increased (P for trend <0.05 for all). Conclusion: The use of NSAIDs is prevalent in some areas with a high incidence of upper gastrointestinal cancer in China. The increased use of NSAIDs may lead to more adverse effects related to the gastrointestinal tract.

[The analysis of the relationship between the fungal microbiota from soil and tongue coating of 18 patients with precancerous lesions of upper gastrointestinal]

The fungal microbiota from self-retained soil and tongue coating of 18 patients with precancerous lesions of upper gastrointestinal (PLUG) were sequenced. The diversity of α, β in and the structure of the microbial community were analyzed, and the association of them was quantified by using the Spearman rank correlation method. The richness index (1.67±2.79) and the diversity index (0.25±0.10) of the fungal microbiota from tongue coating of PLUG patients were significantly lower than those from soil (4.00±4.69; 0.99±0.18) (all P values<0.001). The relative abundance of 11 taxa from tongue coating of these PLUG patients was positively associated with that from soil (all P values<0.05).

Epithelial-Mesenchymal Micro-niches Govern Stem Cell Lineage Choices

Adult tissue stem cells (SCs) reside in niches, which, through intercellular contacts and signaling, influence SC behavior. Once activated, SCs typically give rise to short-lived transit-amplifying cells (TACs), which then progress to differentiate into their lineages. Here, using single-cell RNA-seq, we unearth unexpected heterogeneity among SCs and TACs of hair follicles. We trace the roots of this heterogeneity to micro-niches along epithelial-mesenchymal interfaces, where progenitors display molecular signatures reflective of spatially distinct local signals and intercellular interactions. Using lineage tracing, temporal single-cell analyses, and chromatin landscaping, we show that SC plasticity becomes restricted in a sequentially and spatially choreographed program, culminating in seven spatially arranged unilineage progenitors within TACs of mature follicles. By compartmentalizing SCs into micro-niches, tissues gain precise control over morphogenesis and regeneration: some progenitors specify lineages immediately, whereas others retain potency, preserving self-renewing features established early while progressively restricting lineages as they experience dynamic changes in microenvironment.

Rac1 plays an essential role in axon growth and guidance and in neuronal survival in the central and peripheral nervous systems

BACKGROUND

Rac1 is a critical regulator of cytoskeletal dynamics in multiple cell types. In the nervous system, it has been implicated in the control of cell proliferation, neuronal migration, and axon development.

RESULTS

To systematically investigate the role of Rac1 in axon growth and guidance in the developing nervous system, we have examined the phenotypes associated with deleting Rac1 in the embryonic mouse forebrain, in cranial and spinal motor neurons, in cranial sensory and dorsal root ganglion neurons, and in the retina. We observe a widespread requirement for Rac1 in axon growth and guidance and a cell-autonomous defect in axon growth in Rac1 (-/-) motor neurons in culture. Neuronal death, presumably a secondary consequence of the axon growth and/or guidance defects, was observed in multiple locations. Following deletion of Rac1 in the forebrain, thalamocortical axons were misrouted inferiorly, with the majority projecting to the contralateral thalamus and a minority projecting ipsilaterally to the ventral cortex, a pattern of misrouting that is indistinguishable from the pattern previously observed in Frizzled3 (-/-) and Celsr3 (-/-) forebrains. In the limbs, motor-neuron-specific deletion of Rac1 produced a distinctive stalling of axons within the dorsal nerve of the hindlimb but a much milder loss of axons in the ventral hindlimb and forelimb nerves, a pattern that is virtually identical to the one previously observed in Frizzled3 (-/-) limbs.

CONCLUSIONS

The similarities in axon growth and guidance phenotypes caused by Rac1, Frizzled3, and Celsr3 loss-of-function mutations suggest a mechanistic connection between tissue polarity/planar cell polarity signaling and Rac1-dependent cytoskeletal regulation.

Partial interchangeability of Fz3 and Fz6 in tissue polarity signaling for epithelial orientation and axon growth and guidance

In mammals, a set of anatomically diverse polarity processes - including axon growth and guidance, hair follicle orientation, and stereociliary bundle orientation in inner ear sensory hair cells - appear to be mechanistically related, as judged by their dependence on vertebrate homologues of core tissue polarity/planar cell polarity (PCP) genes in Drosophila. To explore more deeply the mechanistic similarities between different polarity processes, we have determined the extent to which frizzled 3 (Fz3) can rescue the hair follicle and Merkel cell polarity defects in frizzled 6-null (Fz6(-/-)) mice, and, reciprocally, the extent to which Fz6 can rescue the axon growth and guidance defects in Fz3(-/-) mice. These experiments reveal full rescue of the Fz6(-/-) phenotype by Fz3 and partial rescue of the Fz3(-/-) phenotype by Fz6, implying that these two proteins are likely to act in a conserved manner in these two contexts. Stimulated by these observations, we searched for additional anatomical structures that exhibit macroscopic polarity and that might plausibly use Fz3 and/or Fz6 signaling. This search has revealed a hitherto unappreciated pattern of papillae on the dorsal surface of the tongue that depends, at least in part, on redundant signaling by Fz3 and Fz6. Taken together, these experiments provide compelling evidence for a close mechanistic relationship between multiple anatomically diverse polarity processes.

Frizzled3 controls axonal development in distinct populations of cranial and spinal motor neurons

Disruption of the Frizzled3 (Fz3) gene leads to defects in axonal growth in the VII^th and XII^th cranial motor nerves, the phrenic nerve, and the dorsal motor nerve in fore- and hindlimbs. In Fz3^−/− limbs, dorsal axons stall at a precise location in the nerve plexus, and, in contrast to the phenotypes of several other axon path-finding mutants, Fz3^−/− dorsal axons do not reroute to other trajectories. Affected motor neurons undergo cell death 2 days prior to the normal wave of developmental cell death that coincides with innervation of muscle targets, providing in vivo evidence for the idea that developing neurons with long-range axons are programmed to die unless their axons arrive at intermediate targets on schedule. These experiments implicate planar cell polarity (PCP) signaling in motor axon growth and they highlight the question of how PCP proteins, which form cell–cell complexes in epithelia, function in the dynamic context of axonal growth.

DOI:http://dx.doi.org/10.7554/eLife.01482.001

For the nervous system to become wired up correctly, neurons within the developing embryo must project over long distances to form connections with remote targets. They do this by lengthening their axons—the ‘cables’ along which electrical signals flow—and some axons in adult humans can grow to be more than 1 metre long.

This type of long-range pathfinding activity is particularly common for neurons that control movement, as many of these neurons must establish connections with muscles that are some distance away from the brain. For example, motor neurons in the brainstem form connections with muscles in the face to control facial expressions, while motor neurons in parts of the spinal cord project to muscles in the limbs. Multiple signaling pathways tell the developing axons which direction to grow en route to their final targets.

Now, Hua et al. have shown that an evolutionarily conserved protein called Frizzled3 is also involved in this process. In mouse embryos that lacked Frizzled3, the motor nerves that control breathing and limb movements were thinner than those in normal mice. In the mutant animals, many motor axons failed to form connections with their targets. Instead, these axons came to an abrupt halt midway along their intended paths and the neurons from which they originated died soon afterwards. These experiments support the idea that developing neurons are programmed to die unless their axons progress on the appropriate schedule.

As well as increasing our knowledge of the networks of connections that form within the developing mammalian nervous system, the work of Hua et al. provides new insights into some of the molecular mechanisms by which these connections are established.

DOI:http://dx.doi.org/10.7554/eLife.01482.002

Ultrafast and Large Third-Order Nonlinear Optical Properties of CdS Nanocrystals in Polymeric Film

We report the ultrafast and large third-order nonlinear optical properties of CdS nanocrystals (NCs) embedded in a polymeric film. The CdS NCs of 2 nm radius are synthesized by an ion-exchange method and highly concentrated in the two layers near the surfaces of the polymeric film. The two-photon absorption coefficient and the optical Kerr coefficient are measured with laser pulses of 250 fs duration at 800 nm wavelength. The one-photon and two-photon figures of merit are determined to be 3.1 and 1.3, respectively, at irradiance of 2 GW/cm(2). The observed nonlinearities have a recovery time of approximately 1 ps. The two-photon-generated free carrier effects have also been observed and discussed. These results demonstrate that CdS NCs embedded in polymeric film are a promising candidate for optical switching applications.