Cellular mechanisms that mediate the collecting duct (CD) formation during postnatal renal development

EDITH DEL VALLE GUAYTIMA; YAMILA ROMINA BRANDÁN; JERÓNIMO VALLS; NICOLÁS OCTAVIO FAVALE; BRUNO JAIME SANTACREU; NORMA BEATRIZ STERIN-SPEZIALE; MARÍA GABRIELA MÁRQUEZ

Cuidad Autónoma de Buenos Aires

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

SOCIEDADES DE BIOCIENCIAS

In mammals, nephrogenesis is completed postnatally. In previous works, we have shown that primary cultures of renal papillary CD cells from neonatal rats, display a phenotype of migratory sheet of epithelial cells. Now, we investigated the mechanisms involved in the postnatal CD formation. In order to evaluatethe differentiation degree of primary cultured CD cells, the ability of DBA (a CD marker) and BSL-I (a renal interstice marker)-binding, together with the expression of epithelial (cytokeratin-7, CK7, and adherens junction proteins, AJ) and mesenchymal biomarkers (vimentin and α-smooth muscle actin, α-SMA) were analyzed by immunofluorescence. We observed the coexistence of CD cells withdifferent degree of differentiation in the same colony. Those of higher differentiation were DBA (+), intermediate filaments CK7 (+) and exhibited assembled AJs. While those of lower differentiation were vimentin (+), cytosolic CK7 (+), DBA/BSL-I (+), only BSL-I (+), or DBA/BSL-I (-), and they lacked mature AJs. The analysis of overlapping cells showed a mesenchymal phenotype. 3D reconstructions and xz profiles of confocal microscopy images showed thatthey were located adjacent to or below the plane of the colonies. Cell behavior studies in real time by phase contrast microscopy revealed that they could be inserted between the CD cells from the basal plane through a mesenchymal-epithelial transition, acquiring the epithelial phenotype of the cells that surround them. Taking into account the above results, we suggest that overlapping cells could originate in situ through an epithelial-mesenchymal transition from CD cells. Therefore, our results suggest the existence of a ?dynamic balance? between CD and mesenchymal cells, strongly displacedtowards the former. Most likely, between CD cells and the mesenchymal cells generated de novo, the mutual induction described above could occur.