TβRII Regulates the Proliferation of Metanephric Mesenchyme Cells through Six2 In Vitro.

Zhaomin Mao,Yaguang Weng,Zhongshi Lyu,Qin Zhou,Liyuan Huang

doi:10.3390/ijms18040853

Zhaomin Mao, Yaguang Weng + Show 3 more

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https://doi.org/10.3390/ijms18040853

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Abstract

The transforming growth factor-β (TGFβ) family signaling pathways play an important role in regulatory cellular networks and exert specific effects on developmental programs during embryo development. However, the function of TGFβ signaling pathways on the early kidney development remains unclear. In this work, we aim to detect the underlying role of TGFβ type II receptor (TβRII) in vitro, which has a similar expression pattern as the crucial regulator Six2 during early kidney development. Firstly, the 5-ethynyl-2′-deoxyuridine (EdU) assay showed knock down of TβRII significantly decreased the proliferation ratio of metanephric mesenchyme (MM) cells. Additionally, real-time Polymerase Chain Reaction (PCR) and Western blot together with immunofluorescence determined that the mRNA and protein levels of Six2 declined after TβRII knock down. Also, Six2 was observed to be able to partially rescue the proliferation phenotype caused by the depletion of TβRII. Moreover, bioinformatics analysis and luciferase assay indicated Smad3 could transcriptionally target Six2. Further, the EdU assay showed that Smad3 could also rescue the inhibition of proliferation caused by the knock down of TβRII. Taken together, these findings delineate the important function of the TGFβ signaling pathway in the early development of kidney and TβRII was shown to be able to promote the expression of Six2 through Smad3 mediating transcriptional regulation and in turn activate the proliferation of MM cells.

Highlights

The transforming growth factor-β (TGFβ) family signaling pathways are composed of various closely related proteins which share some structural homology but have separate receptors and take part in different functions; for example, activated TGFβ ligands bind to type 2 TGFβ receptor, which is a kinase, which recruits, phosphorylates, and activates the type 1 receptor that phosphorylates receptor-regulated Smads to bind the co-Smads, acting as transcriptional factors [1]
These findings delineate the important function of the TGFβ signaling pathway in the early development of kidney and TβRII was shown to be able to promote the expression of Six2 through Smad3 mediating transcriptional regulation and in turn activate the proliferation of MM cells
There is a balance between consumption and self-renewal of Six2 positive mesenchymal nephron progenitor-cells in order to form the full complement of nephrons and nephron endowment

Summary

Introduction

The transforming growth factor-β (TGFβ) family signaling pathways are composed of various closely related proteins which share some structural homology but have separate receptors and take part in different functions; for example, activated TGFβ ligands bind to type 2 TGFβ receptor, which is a kinase, which recruits, phosphorylates, and activates the type 1 receptor that phosphorylates receptor-regulated Smads to bind the co-Smads, acting as transcriptional factors [1] This leads to the activation of different downstream target genes that function in many cellular processes, including proliferation, differentiation, apoptosis, cell growth, and other cellular functions both in embryo and adult organism [1,2]. Six knockout mice display ectopic differentiation, depletion of metanephric mesenchyme cells, and kidney hypoplasia and dysplasia [5,12]

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