Disruption of Hox9,10,11 function results in cellular level lineage infidelity in the kidney

Keri A Drake,S Steven Potter,Mike Adam,Robert Mahoney

doi:10.1038/s41598-018-24782-5

Abstract

Hox genes are important regulators of development. The 39 mammalian Hox genes have considerable functional overlap, greatly confounding their study. In this report, we generated mice with multiple combinations of paralogous and flanking Abd-B Hox gene mutations to investigate functional redundancies in kidney development. The resulting mice developed a number of kidney abnormalities, including hypoplasia, agenesis, and severe cysts, with distinct Hox functions observed in early metanephric kidney formation and nephron progenitor maintenance. Most surprising, however, was that extensive removal of Hox shared function in these kidneys resulted in cellular level lineage infidelity. Strikingly, mutant nephron tubules consisted of intermixed cells with proximal tubule, loop of Henle, and collecting duct identities, with some single cells expressing markers associated with more than one nephron segment. These results indicate that Hox genes are required for proper lineage selection/maintenance and full repression of genes involved in cell fate restriction in the developing kidney.

Highlights

Hox genes encode highly conserved transcription factors critical for patterning the developing embryo[1]
The final bacterial artificial chromosomes (BACs) targeting construct was electroporated into embryonic stem cells (ESCs) which were screened by genomic DNA quantitative PCR to identify clones with only a single remaining wild type Hoxc[9] allele, indicating correct targeting (Fig. S1)
Due to decreased fertility in multi-Hox mutant combinations, we interbred double heterozygotes (e.g. Hoxa9,10,11+/− Hoxc9,10,11+/− crossed with Hoxa9,10,11+/− Hoxc9,10,11+/−) as described in methods to generate the heterozygous/homozygous and double homozygous mutant combinations examined in this study: Hoxa9,10,11−/− Hoxc9,10,11−/−, Hoxa9,10−/−11+/− Hoxc9,10,11−/−, Hoxa9,10−/−11+/+ Hoxc9,10,11−/−, Hoxa9,10,11−/− Hoxc9,10,11+/−, Hoxa9,10,11+/− Hoxc9,10,11−/−, Hoxc9,10,11−/− Hoxd9,10,11−/−, Hoxc9,10,11−/− Hoxd9,10,11+/, Hoxc9,10,11+/− Hoxd9,10,11−/−, and triple heterozygotes Hoxa9,10,11+/− Hoxc9,10,11+/−, Hoxd9,10,11+/−

Summary

Introduction

Hox genes encode highly conserved transcription factors critical for patterning the developing embryo[1]. In mammals the axial body segments show identity transformations in response to Hox mutations, with removal of multiple members of a paralogous group giving synergistic severity phenotypes[5,6,7]. While paralogous Hox genes show the greatest functional overlap, there is extensive evidence indicating that Hox genes near each other on a single cluster are partially redundant. Hox[11] genes are key regulators of SIX2 and GDNF expression[19], showing that they can function at multiple levels of developmental programs and not just in segment identity determination. The data suggest, that the mutation of novel combinations of paralogous and flanking Hox genes could reveal Hox functions in kidney development previously concealed by redundancy.

Methods

Results

Conclusion