Dissertation
Deciphering the tissue-specific roles of ARHGAP29 during palatogenesis
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2026
DOI: 10.25820/etd.008327
Abstract
Orofacial clefts, including cleft palate, are among the most common structural birth defects. Although mechanisms of palatogenesis are not fully understood, extensive morphological remodeling of the palatal shelves (PS) occurs as they move from a vertical to a horizontal position. These changes are driven in part by mechanical forces generated through modulation of cellular contractility and tissue stiffness. One of the major regulators of mechanical forces is the actin cytoskeleton via the small GTPase RhoA pathway. In this study I demonstrate that ARHGAP29, an inhibitor of RhoA involved in actin cytoskeleton remodeling, is required for proper palatogenesis in mice. I first asked the question in which cell type ARHGAP29 was required in for proper palatogenesis. Using the mouse as a model, I deleted Arhgap29 in different combinations of ectoderm-derived and neural crest-derived cells. I found that the loss of ARHGAP29 in the ectoderm is required for palatogenesis. To determine the mechanism by which ARHGAP29 contributed to palatogenesis I utilized histology, immunofluorescent microscopy, and high-resolution atomic force microscopy (AFM). I determined that 1.) WT palatal shelves increase in stiffness after they elevate and fuse and 2.) the loss of ARHGAP29 significantly increases palatal stiffness prior to palatal shelf elevation. To further investigate a potential role for ARHGAP29 in mechanical forces, I immunostained palatal shelves for phosphorylated myosin regulatory light chain (p-MRLC) and alpha smooth muscle actin (a-SMA), two markers of contractility. In WT palatal shelves, p-MRLC levels are low in the palatal mesenchyme and epithelium prior to elevation but increase in epithelial cells after fusion. Conversely, a-SMA is absent from both tissues before and after fusion. These results support the model that reduced palatal contractility facilitates palatal shelf elevation. However, this expression pattern of contractility proteins is altered in A29-EctCre embryos. Particularly, I observed an increase in epithelial p-MRLC expression before, during and after palatal fusion and ectopic a-SMA during palatal fusion. Collectively, these data support a model in which palatal shelves are soft and less contractile prior to elevation to promote their rapid elevation and become stiffer once the palate is formed. Deletion of Arhgap29 increases stiffness and contractility which may prevent proper shelf elevation and fusion thereby contributing to the altered palatogenesis observed in these animals. Collectively, my data show that a change in mechanical forces may contribute to cleft palate in mice.
Details
- Title: Subtitle
- Deciphering the tissue-specific roles of ARHGAP29 during palatogenesis
- Creators
- Emily Adelizzi
- Contributors
- Martine Dunnwald (Advisor)Andrew Frank (Committee Member)Douglas Houston (Committee Member)Eric Van Otterloo (Committee Member)Charles Yeaman (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Genetics
- Date degree season
- Spring 2026
- DOI
- 10.25820/etd.008327
- Publisher
- University of Iowa
- Number of pages
- xiv, 209 pages
- Copyright
- Copyright 2026 Emily Adelizzi
- Language
- English
- Date submitted
- 04/28/2026
- Description illustrations
- illustrations, graphs, tables
- Description bibliographic
- Includes bibliographical references.
- Public Abstract (ETD)
Craniofacial development is a highly complex process that involves the coordinated growth, migration, and fusion of developing facial structures. Craniofacial morphogenesis is strongly influenced by genetics therefore the focus of my thesis was to investigate the contribution of the gene Arhgap29 during this process. I specifically asked what roles ARHGAP29 plays in different cell types that give rise to the face and palate. I found that loss of ARHGAP29 from some, but not all cell types cause cleft palate. I next investigated the cellular mechanism by which ARHGAP29 contribute to palatal development. I found that the loss of ARHGAP29 in epithelial cells results in changes in their cell shape and properties, thereby altering their behavior during palatogenesis. This body of work contributes to the field by shedding light on the cellular mechanisms regulating palatal development and how these mechanisms are altered with clefting.
- Academic Unit
- Interdisciplinary Graduate Program in Genetics
- Record Identifier
- 9985177373602771
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