Editorial highlights

Abstract

Every organism is a model organism for understanding development, evolution, disease, and regeneration, and we have only begun to scratch the surface of the interdisciplinary genetic, molecular, cellular, and developmental mechanisms that regulate these biological processes. These “Highlights” denote exciting advances recently reported in Developmental Dynamics that illustrate the complex dynamics of developmental biology.

Skin Development “Denticleless E3 ubiquitin protein ligase (DTL) maintains the proliferation and differentiation of epidermis and hair follicles during skin development by Yanhui Lin, Weibo Tang, Peijun Huang, Zhendong Wang, Lian Duan, Chonghui Jia, Ruizhen Sun, Li Liu and Jingling Shen; DevDyn 253:7, pp. 635-647. https://doi.org/10.1002/dvdy.682. The skin acts as a protective barrier between an organism and its environment. A precise balance between the proliferation and differentiation of epidermal progenitors during embryogenesis is required to form and then maintain the skin and its barrier function, and this process is tightly controlled via cell cycle progression. DTL, is a substrate receptor of CUL4-DDB1 ubiquitin ligase, is involved in cell cycle progression through the degradation of cell cycle-related proteins. However, the essential role of DTL in the differentiation and proliferation of epidermal progenitor cells remains incompletely understood. In this study, Dtl was conditionally knocked out in keratin14 positive epidermal cells, resulting in mice with a thinner epidermis and loss of hair follicles. These phenotypes are associated with perturbed proliferation and differentiation of keratinocytes. Deletion of DTL resulted in the induction of p53 and p53-transactivated proapoptotic genes, cell cycle arrest and increased apoptosis. Deletion of p53 in Dtl mutant mice rescued the epithelial progenitor cells from apoptosis but had no effect on the proliferation and differentiation of keratinocytes, which implies p53-independent mechanisms are also important for the proliferation and differentiation of epidermal cells during the skin epidermis and hair follicle development.

Neuronal Development “Trim46 knockout impaired neuronal architecture and caused hypoactive behavior in rats” by Feifei Guan, Shan Gao, Hanxuan Sheng, Yuanwu Ma, Wei Chen, Xiaolong Qi, Xu Zhang, Xiang Gao, Shuo Pang, Lianfeng Zhang, and Li Zhang; DevDyn 253:7, pp. 659-676. https://doi.org/10.1002/dvdy.687. Tripartite motif (TRIM) proteins play important roles in numerous biological processes including the regulation of cell cycle progression, neurogenesis and oncogenesis. Variants in the C-I subgroup of TRIM proteins, of which there are six members, have been associated with brain disorders including X-linked 101 mental retardation, Opitz GBBB syndrome, dementia, spatial memory impairments, and sensorimotor gating defects. However, the function of the C-I subgroup member, TRIM46, has not yet been defined. TRIM46 is expressed in the proximal region of axons and is thought to be important for neuronal polarity. To study the role of TRIM46 in brain development, the authors generated a Trim46 knockout in rat via CRISPR/cas9 gene editing. Trim46 loss-of-function resulted in rats with smaller hippocampal volume, decreased dendritic complexity and dendritic spine density, and a disordered axon initial segment. Collectively, this reveals a novel potential association of TRIM46 with dendritic development and neuropsychiatric behavior, providing new insights into the role of TRIM46 in brain structure and behavioral function.

Advances in High-Resolution Imaging “Tetrahedral serial multiview microscopy and image fusion for improved resolution and extent in stained zebrafish embryos” by Johanna Kroll, Anna Cha, Alon Oyler-Yaniv, Talley Lambert, Ian Swinburne, Andrew Murphy and Sean Megason; DevDyn 253:7, pp. 690-704. https://doi.org/10.1002/dvdy.683.

Zebrafish are a unique model organism in biomedical research in the study of developmental processes and human diseases. In particular, the transparency of zebrafish embryos has made this aquatic organism very amenable to live imaging. Characterizing the spatial patterns and subcellular localization of mRNAs, proteins, and other molecules has provide the basis for numerous fundamental discoveries in biology. However, the detection of labeled molecules in thick samples such as in zebrafish embryos can be limited by numerous extraneous factors. In this study, the authors use a standard single objective confocal microscope to perform serial 40 multiview imaging (SMIM). Initially the fixed sample is embedded in an agarose tetrahedron, and then each face is sequentially imaged. The sample is manually rotated in between each image to generate Multiple views. Computational image fusion facilitates the generation of a joint 3D image from multiple tiled z-stacks acquired from different angles. The resulting fused image has improved resolution and imaging extent. With this technique, multiview imaging can be performed on a variety of common single objective microscopes, facilitating high-resolution imaging of whole embryos.