deltaNp63 participates in the development and organization of Xenopus muciliary epithelium

CELESTE TRÍBULO; M. GUADALUPE BARRIONUEVO; EZEQUIEL R. CARRIZO; MANUEL J. AYBAR

Santos

Congreso; 8th Meeting of the Latin American Society of Developmental Biology; 2015

Latin American Society for Developmental Biology (LASDB)

It has been established in several models that the transcription factor deltaNp63 has an important role in the development of the epidermis and its derivatives. Our previous results demonstrated that deltaNp63 is regulated by BMP4 signaling pathway and participates in the early epidermis specification. The larval epidermis of Xenopus laevis is a bilayered epithelium which can be used as a model system for the study of the development and function of mucociliary epithelia. This tissue presents four different cellular types: Globet cells (GCs), ciliated cells (CCs), ionocytes (INCs) and small secretory cells (SSCs). GCs develop in the outer layer while CCs, INCs and SSCs sequentially intercalate from the inner to the outer layer. GCs are the most abundant and highest with a polygonal shape. CCs are placed in solitary and they are characterized by the presence of multiple apical cilia while INCs are generally situated in pairs and their surface present microvilli. Finally, SSCs have a triangular shape and big apical vesicles. We analyzed the participation of deltaNp63 during the specification of these cellular types. After loss of function experiments, we performed an ultraestructural analysis of Xenopus embryonic epidermis by scanning electron microscopy (SEM). Two different approaches were used to interfere with deltaNp63 function by means of different mechanisms. One of them consisted in the microinjection of an antisense morpholino oligonucleotide (deltaNp63MO) and the other in the overexpression of a C-terminally truncated form of deltaNp63 fused to a green fluorescent protein (deltaNp63(Ct)-GFP) which acts as a dominant negative. The inhibition of deltaNp63 leaded to alterations in the number, distribution and structure of epidermal cells. The number of CCs and INCs was augmented while SSCs number was diminished. Besides, INCs and GCs increased their size. CCs and INCs showed an abnormal spatial distribution, CCs were observed adjacent and INCs were disposed in groups. Further, GCs and CCs presented an altered morphology. GCs lost their polygonal shape while the alteration of CCs was characterized by the presence of few and short cilia. These results suggest that deltaNp63 is involved in the correct formation of mucociliary epithelia in Xenopus embryos.