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.

Ciliogenesis in Development and Disease “Actin cytoskeletal regulation of ciliogenesis in development and disease” by Brittany Hufft-Martinez, Henry Wang, Irfan Saadi, and Pamela Tran; Dev Dyn 253:12, pp. 1076–1093. https://doi.org/10.1002/dvdy.724. Primary cilia are antenna-like sensory organelles, comprised of microtubule-based cellular projections, which serve both motile and non-motile sensory functions. Cilia are required for reproduction and regulate multiple cellular processes, including cell motility, cell cycle, cell differentiation, autophagy, and cell–cell communication. Their evolutionary conservation from algae to mammals, has informed our understanding of the basic biology of mammalian primary cilia, organismal development, and the genetic etiology of ciliopathies. This review discusses studies that have revealed the importance of regulating the actin cytoskeleton in ciliary homeostasis, including centrosome migration and positioning, vesicle transport to the basal body, ectocytosis, and ciliary-mediated signaling. It also highlights both conserved and divergent mechanisms in algae and mammalian cells. Finally, the authors compare the phenotypic manifestations of patients with ciliopathies, to those with mutations in actin and actin-associated genes and propose that primary cilia defects caused by genetic alteration of the actin cytoskeleton may underlie specific birth defects.

Organogenesis, Teeth, and Retinoic Acid “Differential retinoic acid sensitivity of oral and pharyngeal teeth in medaka (Oryzias latipes) supports the importance of pouch–cleft contacts in pharyngeal tooth initiation” by Daria Loarinova and Ann Huysseune; Dev Dyn 253:12, pp. 1094–1105. https://doi.org/10.1002/dvdy.723. In early actinopterygian evolution, the dentition was widespread throughout the oropharynx, encompassing teeth on each pharyngeal arch. This wide distribution was reduced over time, as teeth were retained only on the most anterior and most posterior parts of the visceral skeleton, establishing an oral and a pharyngeal dentition, respectively. However, advanced teleost such as medaka, have retained both oral dentition and pharyngeal dentition, whereas less advanced teleosts such as zebrafish have lost oral dentition, retaining teeth exclusively on the last pharyngeal arch. Learn how previous studies claiming that pharyngeal teeth in medaka (Oryzias latipes) were induced independent of retinoic acid signaling unlike in zebrafish (Danio rerio) prompted the authors to explore genetic or molecular mechanisms that could explain the distinct distribution patterns. The authors discovered that the requirement for retinoic acid during pharyngeal tooth formation is equivalent between zebrafish and medaka. However, the differential response of the oral versus pharyngeal teeth in medaka could be due to the distinct germ layer origin of the epithelia involved in tooth formation.

Regeneration in Zebrafish “Disruption of the <fcreb3l1> gene causes defects in caudal fin regeneration and patterning in zebrafish ‘Danio rerio’” by Peyton VanWinkle, Eunjoo Lee, Bridge Wynn, Tomasz Nawara, Holly Thomas, John Parant, Cecilia Alvarez, Rosa Serra, Elizabeth Sztu; Dev Dyn 253:12, pp. 1106–1129. https://doi.org/10.1002/dvdy.726. Complex programs that regulate cell fate determination and tissue patterning are a central part of normal cell and tissue homeostasis and are often temporarily reactivated during tissue repair and regeneration. This is particularly true for bone, which may seem relatively static, but requires dynamic expression of many interacting proteins, together with rigid mineralized structures to support vertebrate animal bodies. Of note, Creb3l1 is a member of the ATF/CREB family of transmembrane transcription factors, and variants with CREB3L1 mutations have been linked to osteogenesis imperfecta. However, the mechanism through which Creb3l1 regulates bone development is not fully understood. Learn how the authors generated novel creb3l1 mutant fish, which express Creb3l1 but lack most of its coding region and the essential DNA-binding bZIP domain. The authors then demonstrate that Creb3l1 plays an important role in the development and regeneration of the zebrafish caudal fin. More specifically, the authors show that Creb3l1 participates in re-establishing the proximo-distal axis during fin regeneration by impacting the shha signaling pathway. Finally, the authors suggest that shha-Creb3l1 signaling interactions have important implications for therapeutic approaches to fracture healing in mammals.