Biology subjects

Maxfield, A.

Publications and source records attributed to Maxfield, A..

3 recordsLinked to original sources

bioRxiv2023

RhoA GEF Mcf2lb regulates rosette integrity during collective cell migration

During development, multicellular rosettes serve as important cellular intermediates in the formation of diverse organ systems. Multicellular rosettes are transient epithelial structures that are defined by the apical constriction of cells towards the rosette center. Due to the important role these structures play during development, understanding the molecular mechanisms by which rosettes are formed and maintained is of high interest. Utilizing the zebrafish posterior lateral line primordium (pLLP) as a model system, we identify the RhoA GEF Mcf2lb as a regulator of rosette integrity. The pLLP is a group of [~]150 cells that migrates along the zebrafish trunk and is organized into epithelial rosettes; these are deposited along the trunk and will differentiate into sensory organs called neuromasts (NMs). Using single-cell RNA sequencing and whole-mount in situ hybridization, we showed that mcf2lb is expressed in the pLLP during migration. Given the known role of RhoA in rosette formation, we asked whether Mcf2lb plays a role in regulating apical constriction of cells within rosettes. Live imaging and subsequent 3D analysis of mcf2lb mutant pLLP cells showed disrupted apical constriction and subsequent rosette organization. This in turn resulted in a unique posterior Lateral Line phenotype: an excess number of deposited NMs along the trunk of the zebrafish. Cell polarity markers ZO-1 and Par-3 were apically localized, indicating that pLLP cells are normally polarized. In contrast, signaling components that mediate apical constriction downstream of RhoA, Rock-2a and non-muscle Myosin II were diminished apically. Altogether our results suggest a model whereby Mcf2lb activates RhoA, which in turn activates downstream signaling machinery to induce and maintain apical constriction in cells incorporated into rosettes.

developmental biology↗

bioRxiv2022

Type 2 Inflammation Drives an Airway Basal Stem Cell Program Through Insulin Receptor Substrate Signaling

BackgroundChronic rhinosinusitis with nasal polyposis (CRSwNP) is a type 2 (T2) inflammatory disease associated with an increased number of airway basal epithelial cells (BCs). Recent studies have identified transcriptionally distinct BCs, but functional data are lacking and the molecular pathways that support or inhibit human BC proliferation and differentiation are largely unknown. ObjectiveTo determine the role of T2 cytokines in regulating airway BCs MethodsSingle cell and bulk RNA-sequencing of sinus and lung airway epithelial cells was analyzed. Human sinus BCs were stimulated with IL-4 and IL-13 in the presence and absence of IL4R inhibitors. Confocal analysis of human sinus tissue and murine airway was performed. Murine BC subsets were sorted for RNA sequencing and functional assays. Fate labeling was performed in a murine model of tracheal injury and repair. ResultsHere we find two subsets of BCs in human and murine respiratory mucosa distinguished by the expression of BC adhesion molecule (BCAM). BCAM expression identifies airway stem cells among P63+KRT5+NGFR+ BCs. In the sinonasal mucosa, BCAMhi BCs expressing TSLP, IL33, CCL26, and the canonical BC transcription factor TP63 are increased in patients with CRSwNP. In cultured BCs, IL-4/13 increases expression of BCAM and TP63 through an Insulin Receptor Substrate (IRS)-dependent signaling pathway that is increased in CRSwNP. ConclusionsThese findings establish BCAM as a marker of airway stem cells among the BC pool and demonstrate that airway epithelial remodeling in T2 inflammation extends beyond goblet cell metaplasia to the support of a BC stem state poised to perpetuate inflammation. CAPSULE SUMMARYType 2 cytokines drive an airway stem cell program through IRS signaling KEY MESSAGESO_LITwo subsets of airway BCs have distinct transcriptional signatures and function C_LIO_LIHigh levels of BCAM expression mark the earliest BC progenitor C_LIO_LIIL-4 and IL-13 upregulate BCAM and P63 in an IRS-dependent fashion which prevents BC differentiation to secretory epithelial cells C_LIO_LIBCAMhi BCs are increased in CRSwNP C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/512129v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@16e78e8org.highwire.dtl.DTLVardef@1c40393org.highwire.dtl.DTLVardef@1c6bc4aorg.highwire.dtl.DTLVardef@73b9db_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

Olfactory microvillar tuft cells direct neurogenesis during allergic inflammation

The olfactory neuroepithelium serves as a sensory organ for odors and is part of the nasal mucosal barrier. Olfactory sensory neurons are surrounded and supported by epithelial cells. A subset of these, microvillous cells (MVCs), are strategically positioned at the apical surface but their specific functions are still enigmatic and their relationship to the rest of the solitary chemosensory cell family is unclear. Here, we establish that the larger family of MVCs comprises tuft cells and ionocytes in both mice and humans. Olfactory TRPM5+ tuft-MVCs share a core transcriptional profile with the chemosensory tuft family, prominently including the machinery for lipid mediator generation. Integrating analysis of the respiratory and olfactory epithelium, we define the unique receptor expression of TRPM5+ tuft-MVC compared to the G[a]-gustducin+ respiratory tuft cells and characterize a new population of glandular DCLK1+ tuft cells. To establish how allergen sensing by tuft-MVCs might direct olfactory mucosal responses, we employed an integrated single-cell transcriptional and protein analysis. We defined a remodeling olfactory epithelial switch pathway with induction of Chil4 and a distinct pathway of proliferation of the quiescent olfactory horizontal basal stem cell (HBC), both triggered in the absence of significant olfactory apoptosis. While the Chil4 pathway was dependent on STAT6 signaling and innate lymphocytes, neither were required for HBC proliferation. HBC proliferation was dependent on tuft-MVCs, establishing these specialized epithelial cells as both sensors for allergens and regulators of olfactory stem cell responses. Together our data provide high resolution characterization of the nasal tuft cell heterogeneity and uncover a novel mechanism by which TRPM5+ tuft cells direct the olfactory mucosal response to allergens. One Sentence SummaryWe identify the enigmatic TRPM5+ olfactory microvillous cells as tuft cells, and show their functional role as regulators of olfactory stem cell proliferation in response to environmental signals.

immunology↗