TY - JOUR T1 - Tfap2a is a novel gatekeeper of differentiation in renal progenitors during kidney development JF - bioRxiv DO - 10.1101/460105 SP - 460105 AU - Brooke E. Chambers AU - Gary F. Gerlach AU - Karen H. Chen AU - Eleanor G. Clark AU - Ignaty Leshchiner AU - Wolfram Goessling AU - Rebecca A. Wingert Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/11/02/460105.abstract N2 - Renal functional units known as nephrons undergo patterning events during development that create a segmental array of cellular populations with discrete physiological tasks. Knowledge about the terminal differentiation programs of each nephron segment has central importance for understanding kidney disease and to advance regenerative medicine, as mammalian nephrons grown in organoid cultures from pluripotent cells fail to terminally differentiate. Here, from a novel forward genetic screen using zebrafish we report the discovery that transcription factor AP-2 alpha (tfap2a) coordinates a gene regulatory network that controls the progression of nephron distal segment progenitors into the differentiated state. Overexpression of tfap2a rescued differentiation in mutants and caused ectopic expression of distal segment markers in wild-type nephrons, indicating tfap2a is sufficient to instigate the distal segment differentiation program. tfap2a/2b deficiency exacerbated distal nephron segment differentiation defects, revealing functional redundancy where tfap2a has a dominant role upstream of its family member. With further genetic studies, we assembled a blueprint of the tfap2a gene regulatory network during nephrogenesis. We demonstrate that tfap2a acts downstream of Iroquois homeobox 3b, a conserved distal lineage transcription factor. tfap2a controls a circuit consisting of irx1a, tfap2b, and genes encoding solute transporters that dictate the specialized metabolic functions of the distal nephron segments, and we show for the first time that this regulatory node is distinct from the pathway circuits controlling aspects such as apical-basal polarity and ciliogenesis during the differentiation process. Thus, our studies reveal new insights into the genetic control of differentiation, where tfap2a regulates the suite of segment transporter traits. These findings have relevance for understanding renal birth defects, as well as efforts to recapitulate nephrogenesis in vivo to make functional units that can facilitate organoid applications such as drug discovery and regenerative therapies.Summary Statement Here, we report for the first time that transcription factor AP-2 alpha (tfap2a) controls the progression from nephron progenitor into the fully differentiated state. This fundamentally deepens our knowledge about the genetic control of kidney development.(BOFS)branchio-oculo-facial syndrome(CS)corpuscle of Stannius(DE)distal early 27(DL)distal late(FISH)fluorescent whole mount in situ hybridization(IF)immunofluorescence(irx1a)iroquois homeobox 1a(irx3b)iroquois homeobox 3b(hpf)hours post fertilization(MET)mesenchymal to epithelial transition(MO)morpholino oligonucleotide(PCT)proximal convoluted tubule(PST)proximal straight tubule(ss)somite stage(TAL)thick ascending limb(tfap2a)transcription factor AP-2 alpha(tfap2b)transcription factor AP-2 beta(WISH)whole mount in situ hybridization(WT)wild-type(BOFS)branchio-oculo-facial syndrome(CS)corpuscle of Stannius(DE)distal early 27(DL)distal late(FISH)fluorescent whole mount in situ hybridization(IF)immunofluorescence(irx1a)iroquois homeobox 1a(irx3b)iroquois homeobox 3b(hpf)hours post fertilization(MET)mesenchymal to epithelial transition(MO)morpholino oligonucleotide(PCT)proximal convoluted tubule(PST)proximal straight tubule(ss)somite stage(TAL)thick ascending limb(tfap2a)transcription factor AP-2 alpha(tfap2b)transcription factor AP-2 beta(WISH)whole mount in situ hybridization(WT)wild-type ER -