Dmrt5, a Novel Neurogenic Factor, Reciprocally Regulates Lhx2 to Control the Neuron–Glia Cell-Fate Switch in the Developing Hippocampus

Abstract

Regulation of the neuron–glia cell-fate switch is a critical step in the development of the CNS. Previously, we demonstrated that Lhx2 is a necessary and sufficient regulator of this process in the mouse hippocampal primordium, such that Lhx2 overexpression promotes neurogenesis and suppresses gliogenesis, whereas loss of Lhx2 has the opposite effect. We tested a series of transcription factors for their ability to mimic Lhx2 overexpression and suppress baseline gliogenesis, and also to compensate for loss of Lhx2 and suppress the resulting enhanced level of gliogenesis in the hippocampus. Here, we demonstrate a novel function of Dmrt5/Dmrta2 as a neurogenic factor in the developing hippocampus. We show that Dmrt5, as well as known neurogenic factors Neurog2 and Pax6, can each not only mimic Lhx2 overexpression, but also can compensate for loss of Lhx2 to different extents. We further uncover a reciprocal regulatory relationship between Dmrt5 and Lhx2, such that each can compensate for loss of the other. Dmrt5 and Lhx2 also have opposing regulatory control on Pax6 and Neurog2, indicating a complex bidirectionally regulated network that controls the neuron–glia cell-fate switch.SIGNIFICANCE STATEMENT We identify Dmrt5 as a novel regulator of the neuron–glia cell-fate switch in the developing hippocampus. We demonstrate Dmrt5 to be neurogenic, and reciprocally regulated by Lhx2: loss of either factor promotes gliogenesis; overexpression of either factor suppresses gliogenesis and promotes neurogenesis; each can substitute for loss of the other. Furthermore, each factor has opposing effects on established neurogenic genes Neurog2 and Pax6. Dmrt5 is known to suppress their expression, and we show that Lhx2 is required to maintain it. Our study reveals a complex regulatory network with bidirectional control of a fundamental feature of CNS development, the control of the production of neurons versus astroglia in the developing hippocampus.Finally, we confirm that Lhx2 binds a highly conserved putative enhancer of Dmrt5, suggesting an evolutionarily conserved regulatory relationship between these factors. Our findings uncover a complex network that involves Lhx2, Dmrt5, Neurog2, and Pax6, and that ensures the appropriate amount and timing of neurogenesis and gliogenesis in the developing hippocampus.

Accelerated evolution of an Lhx2 enhancer shapes mammalian social hierarchies

“…39 Therefore, we speculated that Lhx2 modulates social hierarchy by regulating the Wnt pathway. Lhx2 is a selector gene in the cerebral cortex 53 and controls neuronal subtype specification, [54][55][56] axon projection, and dendritic arborization of neurons. 57,58 Taken together, we suggest that PAS1, the enhancer of Lhx2, acts as an ignition controller.…”

Potential involvement of a DMRT family member ( Mr‐Dsx ) in the regulation of sexual differentiation and moulting in the giant river prawn Macrobrachium rosenbergii

“…To date, our knowledge on the functions of Dmrt genes is largely derived from studies carried out in a few model organisms such as mice and zebrafish (Muralidharan et al, ; Urquhart et al, ; Young et al, ). The most‐studied functions of Dmrt homologues include its involvement in the development and functioning of neutral system, animal somitogenesis and sex differentiation (De Clercq et al, ; Muralidharan et al, ; Xu et al, ). In crustaceans, however, the functions of Dmrt homologues are poorly understood, and the involvement of Dmrt genes in the regulation of moulting, growth and sexual differentiation remains to be explored (Zhang & Qiu, ).…”

“…In addition to the well‐characterized roles of Dmrt genes in sex differentiation and development, there are a growing number of studies describing the functions of these transcription factors in other biological processes (De Clercq et al, ; Graf, Teo Qi‐Wen, Sarusie, Rajaei, & Winkler, ; Yoshizawa et al, ). Dmrt5 (also known as DmrtA2 ), for example, is a Dmrt gene with important roles in various processes including gonad development, neurogenesis, embryonic development and somite formation (De Clercq et al, ; Muralidharan et al, ; Urquhart et al, ). To date, most of our knowledge on Dmrt5 is derived from studies on a few model organisms such as mice and zebrafish, while information on the molecular characteristics and functions of Dmrt5 genes in crustaceans is quite scarce (Levy et al, ; Zhang & Qiu, ).…”

An Efficient System for Gene Perturbation in Embryonic Hippocampal Progenitors Using Ex Vivo Electroporation Followed by In Vitro Dissociated Cell Culture

“…This is particularly useful when combinations of different constructs need to be tested. In Muralidharan et al, 5 we used embryos from an Lhx2lox/lox background and electroporated either a construct encoding GFP (control) or Cre-GFP, which produced a loss-of-function phenotype. Then, in combination with Cre-GFP, we electroporated constructs that we wished to test for their ability to rescue this phenotype ( Figure 3 ).…”

“…Cells can be maintained at 37°C in a CO 2 incubator for as many days as required for the question being tested. For the neuron-glia cell fate assay in Muralidharan et al, 5 the cells were maintained 5 days in vitro.…”