Desmoplakin is required for epidermal integrity and morphogenesis in theXenopus laevisembryo

Abstract

Statement: Critical desmosomal protein, desmoplakin, is required for proper distribution and levels of cytoskeletal elements and e-cadherin. Thus embryos with decreased desmoplakin have defects in epidermal integrity and morphogenesis. AbstractDesmoplakin (Dsp) is a unique and critical desmosomal protein, however, it is unclear whether this protein and desmosomes themselves are required for epidermal morphogenesis. Using morpholinos or Crispr/Cas9 mutagenesis we decreased the function of Dsp in frog embryos to better understand its role during epidermal development. Dsp morphant and mutant embryos had developmental defects that mimicked what has been reported in mammals. Such defects included epidermal fragility which correlated with reduction in cortical keratin and junctional e-cadherin in the developing epidermis. Dsp protein sequence and expression are also highly similar with mammals and suggest shared function across vertebrates. Most importantly, we also uncovered a novel function for Dsp in the morphogenesis of the epidermis in X. laevis. Specifically, Dsp is required during the process of radial intercalation where basally located cells move into the outer epidermal layer. Once inserted these newly intercalated cells expand their apical surface and then they differentiate into specific epidermal cell types. Decreased levels of Dsp resulted in the failure of the radially intercalating cells to expand their apical surface, thereby reducing the number of differentiated multiciliated and secretory cells.Dsp is also required in the development of other ectodermally derived structures such as the mouth, eye and fin that utilize intercalating-like cell movements. We have developed a novel system, in the frog, to demonstrate for the first time that desmosomes not only protect against mechanical stress but are also critical for epidermal morphogenesis.

Optimization of CRISPR/Cas9‐mediated gene disruption in Xenopus laevis using a phenotypic image analysis technique

“…Clustered regulatory interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) has become a popular genome editing tool in Xenopus laevis (Aslan et al, 2017; Banach et al, 2017; Bharathan & Dickinson, 2019; Carr et al, 2021; Delay et al, 2018; Delay et al, 2019; Ezawa et al, 2021; Feehan et al, 2017; Jaffe et al, 2016; Kato et al, 2021; Kim et al, 2021; Ledford et al, 2017; Martin et al, 2020; Naert et al, 2020; Ochi et al, 2017; Pickett et al, 2017; Smith et al, 2020; Square et al, 2020; Tandon et al, 2017; Tsujioka et al, 2017; Viet et al, 2020; Wang et al, 2015; Wen et al, 2019; Wyatt et al, 2021). Importantly, most studies to date delivered the CRISPR reagents using a microinjection into fertilized eggs.…”

Desmoplakin and clinical manifestations of desmoplakin cardiomyopathy

“…Suppressed DSP levels were shown to result in the failure of radially intercalating cells to expand their apical surface, thereby reducing the number of differentiated multiciliated and secretory cells. [16] Underlying Mechanisms of DSP Cardiomyopathy…”

“…In frog embryos, DSP is required during the process of radial intercalation, where basally located cells move into the outer epidermal layer. Suppressed DSP levels were shown to result in the failure of radially intercalating cells to expand their apical surface, thereby reducing the number of differentiated multiciliated and secretory cells [16] …”

Scaling up single-cell mechanics to multicellular tissues – the role of the intermediate filament–desmosome network

“…In a sheet of migrating cells, local tugging forces on trailing cell-cell contacts use this mechanism to polarize and direct collective migration, which is likely important during embryogenesis and/or morphogenesis and wound healing (Weber et al, 2012). Interestingly, desmoplakin is required for not only epidermal integrity but also morphogenesis in Xenopus (Bharathan and Dickinson, 2019). Desmoplakin has been shown to promote apical cell expansion during epidermal stratification in Xenopus, which is known to be regulated by mechanical forces (Sedzinski et al, 2016;Sedzinski et al, 2017).…”