Publications by authors named "Hannah R Johnson"

4 Publications

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Investigating the Atomic and Mesoscale Interactions that Facilitate Spider Silk Protein Pre-Assembly.

Biomacromolecules 2021 Jul 12. Epub 2021 Jul 12.

Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, California 92182-1030, United States.

Black widow spider dragline silk is one of nature's high-performance biological polymers, exceeding the strength and toughness of most man-made materials including high tensile steel and Kevlar. Major ampullate (Ma), or dragline silk, is primarily comprised of two spidroin proteins (Sp) stored within the Ma gland. In the native gland environment, the MaSp1 and MaSp2 proteins self-associate to form hierarchical 200-300 nm superstructures despite being intrinsically disordered proteins (IDPs). Here, dynamic light scattering (DLS), three-dimensional (3D) triple resonance solution NMR, and diffusion NMR is utilized to probe the MaSp size, molecular structure, and dynamics of these protein pre-assemblies diluted in 4 M urea and identify specific regions of the proteins important for silk protein pre-assembly. 3D NMR indicates that the Gly-Ala-Ala and Ala-Ala-Gly motifs flanking the poly(Ala) runs, which comprise the β-sheet forming domains in fibers, are perturbed by urea, suggesting that these regions may be important for silk protein pre-assembly stabilization.
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http://dx.doi.org/10.1021/acs.biomac.1c00473DOI Listing
July 2021

Revealing the spatio-phenotypic patterning of cells in healthy and tumor tissues with mLSR-3D and STAPL-3D.

Nat Biotechnol 2021 Jun 3. Epub 2021 Jun 3.

Princess Máxima Center for Pediatric Oncology, Utrecht, the Netherlands.

Despite advances in three-dimensional (3D) imaging, it remains challenging to profile all the cells within a large 3D tissue, including the morphology and organization of the many cell types present. Here, we introduce eight-color, multispectral, large-scale single-cell resolution 3D (mLSR-3D) imaging and image analysis software for the parallelized, deep learning-based segmentation of large numbers of single cells in tissues, called segmentation analysis by parallelization of 3D datasets (STAPL-3D). Applying the method to pediatric Wilms tumor, we extract molecular, spatial and morphological features of millions of cells and reconstruct the tumor's spatio-phenotypic patterning. In situ population profiling and pseudotime ordering reveals a highly disorganized spatial pattern in Wilms tumor compared to healthy fetal kidney, yet cellular profiles closely resembling human fetal kidney cells could be observed. In addition, we identify previously unreported tumor-specific populations, uniquely characterized by their spatial embedding or morphological attributes. Our results demonstrate the use of combining mLSR-3D and STAPL-3D to generate a comprehensive cellular map of human tumors.
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http://dx.doi.org/10.1038/s41587-021-00926-3DOI Listing
June 2021

LGR6 marks nephron progenitor cells.

Dev Dyn 2021 Apr 13. Epub 2021 Apr 13.

Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands.

Background: Nephron progenitor cells (NPCs) undergo a stepwise process to generate all mature nephron structures. Mesenchymal to epithelial transition (MET) is considered a multistep process of NPC differentiation to ensure progressive establishment of new nephrons. However, despite this important role, to date, no marker for NPCs undergoing MET in the nephron exists.

Results: Here, we identify LGR6 as a NPC marker, expressed in very early cap mesenchyme, pre-tubular aggregates, renal vesicles, and in segments of S-shaped bodies, following the trajectory of MET. By using a lineage tracing approach in embryonic explants in combination with confocal imaging and single-cell RNA sequencing, we provide evidence for the multiple fates of LGR6+ cells during embryonic nephrogenesis. Moreover, by using long-term in vivo lineage tracing, we show that postnatal LGR6+ cells are capable of generating the multiple lineages of the nephrons.

Conclusions: Given the profound early mesenchymal expression and MET signature of LGR6 cells, together with the lineage tracing of mesenchymal LGR6 cells, we conclude that LGR6+ cells contribute to all nephrogenic segments by undergoing MET. LGR6+ cells can therefore be considered an early committed NPC population during embryonic and postnatal nephrogenesis with potential regenerative capability.
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http://dx.doi.org/10.1002/dvdy.346DOI Listing
April 2021

Anti-GD2-IRDye800CW as a targeted probe for fluorescence-guided surgery in neuroblastoma.

Sci Rep 2020 10 19;10(1):17667. Epub 2020 Oct 19.

Princess Máxima Center for Pediatric Oncology, Heidelberglaan 25, 3584 CS, Utrecht, The Netherlands.

Neuroblastoma resection represents a major challenge in pediatric surgery, because of the high risk of complications. Fluorescence-guided surgery (FGS) could lower this risk by facilitating discrimination of tumor from normal tissue and is gaining momentum in adult oncology. Here, we provide the first molecular-targeted fluorescent agent for FGS in pediatric oncology, by developing and preclinically evaluating a GD2-specific tracer consisting of the immunotherapeutic antibody dinutuximab-beta, recently approved for neuroblastoma treatment, conjugated to near-infrared (NIR) fluorescent dye IRDye800CW. We demonstrated specific binding of anti-GD2-IRDye800CW to human neuroblastoma cells in vitro and in vivo using xenograft mouse models. Furthermore, we defined an optimal dose of 1 nmol, an imaging time window of 4 days after administration and show that neoadjuvant treatment with anti-GD2 immunotherapy does not interfere with fluorescence imaging. Importantly, as we observed universal, yet heterogeneous expression of GD2 on neuroblastoma tissue of a wide range of patients, we implemented a xenograft model of patient-derived neuroblastoma organoids with differential GD2 expression and show that even low GD2 expressing tumors still provide an adequate real-time fluorescence signal. Hence, the imaging advancement presented in this study offers an opportunity for improving surgery and potentially survival of a broad group of children with neuroblastoma.
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http://dx.doi.org/10.1038/s41598-020-74464-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7573590PMC
October 2020
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