Changing patterns of gap junctional intercellular communication and connexin distribution in mouse epidermis and hair follicles during embryonic development

Department of Dermatology, University of Glasgow, Scotland.
Developmental Dynamics (Impact Factor: 2.38). 12/1997; 210(4):417-30. DOI: 10.1002/(SICI)1097-0177(199712)210:4<417::AID-AJA6>3.0.CO;2-J
Source: PubMed


In the mouse embryo between embryonic days 12 (E12) and 16, regular arrays of epidermal placodes on the mystacial pad develop into whisker follicles. This system was chosen for analysis of gap junctional intercellular communication during differentiation. The patterns of communication were studied by microinjection of the tracers Lucifer yellow-CH (LY-CH) and neurobiotin (NB), while immunofluorescent staining was used to study distribution of connexins 26 and 43. Extensive communication was seen between keratinocytes in developing hair pegs or, in later-stage hair follicles, in the germinative matrix. Coupling between adjacent hair pegs via interfollicular epidermis was not observed. Coupling also became restricted as follicular cells differentiated to form outer root sheath, inner root sheath, and hair shaft. Extensive gap junctional coupling is characteristic of keratinocytes that are rapidly proliferating (as in hair pegs and germinative matrix). Follicular keratinocytes commence differentiation shortly before restriction of gap junctional coupling becomes evident. Dermal mesenchymal cells undergoing different modes of differentiation also exhibit differences in gap junctional coupling, as evidenced by poor transfer of LY-CH between cells in dermal condensations of hair follicles compared with extensive transfer elsewhere in the dermis. LY-CH and NB were not transferred between epidermal or follicular epithelium and mesenchyme, arguing against a direct role for gap junctions permeable to known second messenger molecules or nucleotides in epithelial-mesenchymal interactions in this system. The distribution of connexins 26 and 43 in epidermis and hair follicles changed during differentiation but there was no correlation with changing patterns of dye transfer, indicating an unexpected degree of complexity in the relationship between gap junctional intercellular communication and connexin protein distribution during development.

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    • "Since cells expressing both the Cx43 and Δ244* constructs developed a larger stratum corneum, we suggest that functional Cx43 levels can enhance the differentiation state of the epidermis. This is also supported by evidence that Cx43 is enhanced during restratification of the epidermis during development and after wound healing [38–41]. "
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    ABSTRACT: Although there are currently 62 mutants of Cx43 (connexin43) that can cause ODDD (oculodentodigital dysplasia), only two mutants have also been reported to cause palmar plantar hyperkeratosis. To determine how mutants of Cx43 can lead to this skin disease, REKs (rat epidermal keratinocytes) were engineered to express an ODDD-associated Cx43 mutant always linked to skin disease (fs260), an ODDD-linked Cx43 mutant which has been reported to sometimes cause skin disease (fs230), Cx43 mutants which cause ODDD only (G21R, G138R), a mouse Cx43 mutant linked to ODDD (G60S), a non-disease-linked truncated Cx43 mutant that is trapped in the endoplasmic reticulum (Delta244*) or full-length Cx43. When grown in organotypic cultures, of all the mutants investigated, only the fs260-expressing REKs consistently developed a thinner stratum corneum and expressed lower levels of Cx43, Cx26 and loricrin in comparison with REKs overexpressing wild-type Cx43. REKs expressing the fs260 mutant also developed a larger organotypic vital layer after acetone-induced injury and exhibited characteristics of parakeratosis. Collectively, our results suggest that the increased skin disease burden exhibited in ODDD patients harbouring the fs260 mutant is probably due to multiple additive effects cause by the mutant during epidermal differentiation.
    Biochemical Journal 08/2010; 429(3):473-83. DOI:10.1042/BJ20100155 · 4.40 Impact Factor
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    • "This suggests that the role of CX43 in the lower layer of the oral epithelium is as a negative regulator of the cell cycle, inhibiting excessive proliferation. Furthermore, our results also showed that reactivity for CX26 occurred in the upper area of the prickle cell layer in epidermal and corneal keratinocytes, which is consistent with the findings of earlier studies (Kamibayashi et al., 1993; Goliger and Paul, 1994; Choudhry et al., 1997; Wiszniewski et al., 2000). These results suggest that CX43 is associated with the regulation of cell proliferation, and that increased CX26 expression is associated with the differentiation of keratinocytes. "
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    ABSTRACT: We investigated the expression and localization of connexins (CX) 26 and 43 in the rat gingival epithelium. RT-PCR analysis revealed CX26 gene expression in both the upper and lower layers of the gingival epithelium and in the total epithelial layer, whereas CX43 gene expression was limited to the lower layer and the total epithelial layer. Immunoreactivity for CX43 was observed in the membranes of adjacent cells from the basal layer to the middle of the prickle cell layer, while immunoreactivity for CX26 was observed in the granular cell layer and lower part of the squamous cell layer. Merged images revealed the co-localization of CX26 and CX43 in the middle of the prickle cell layer. By immuno-electron microscopy, gap junctions appeared curved, hemi-circular, or annular within the cytoplasm, and gold particles indicating the presence of CX43 were localized at the outer edges of these cytoplasmic formations. These results suggest that CX43 is associated with the regulation of cell proliferation and that increased CX26 expression is associated with differentiation of keratinocytes. Thus, degradation of CX43 is considered to play an essential role in differentiation of the rat gingival epithelium.
    Archives of Histology and Cytology 11/2008; 71(3):147-54. DOI:10.1679/aohc.71.147 · 0.60 Impact Factor
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    • "Keratinocytes spatially express Cxs in specific and often overlapping patterns within the differentiating layers of the epidermis (Salomon et al., 1994). Reverse transcription-PCR analysis (data not shown) revealed that the Cx expression profile of primary mouse keratinocytes included all the epidermal Cxs reported from previous literature (Cx26, Cx30, Cx31, Cx43) and also those not (Cx37, Cx40, Cx45) previously reported (Kamibayashi et al., 1993; Butterweck et al., 1994; Goliger and Paul, 1995; Choudhry et al., 1997; Kretz et al., 2003). A major advantage of our model is its ability to evaluate the tissue architecture and spatial localisation of a varied spectrum of epidermal proteins by whole-mount immunolocalisation. "
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    ABSTRACT: Three-dimensional (3D) organotypic models are increasingly used to study the aspects of epidermal organisation and cutaneous wound-healing events. However, these are largely dependent on laborious histological analysis and immunohistochemical approaches. Despite the large resource of transgenic and knockout mice harboring mutations relevant to skin disorders, few organotypic mouse skin models are available. We have developed a versatile in vitro 3D organotypic mouse skin equivalent that reflects epidermal organisation in vivo. The system is optically transparent and ideally suited to real-time analysis using a variety of integrated in situ imaging techniques. As a paradigm for coordination of cellular events, the epidermal gap junction network was investigated and the model displayed predominant connexin 43 (Cx43) expression in basal proliferating cells and Cx26 and Cx30 expression in differentiated keratinocytes. We show that attenuation of Cx43-mediated communication by a Cx mimetic peptide enhanced wound closure rates in keratinocyte monocultures and in the living skin equivalent system, emphasising the utility of the model to systematically unravel the molecular mechanisms underlying epidermal morphogenesis, assess promising therapeutic strategies, and reduce animal experimentation. Furthermore, we visualise epidermal regeneration following injury in real time, thereby facilitating avenues to explore distinctive modes of wound re-epithelialisation in a non-invasive manner.
    Journal of Investigative Dermatology 05/2008; 128(4):1039-49. DOI:10.1038/sj.jid.5701125 · 7.22 Impact Factor
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