Origin, specification and differentiation of a rare supporting-like lineage in the developing mouse gonad

Abstract

Gonadal sex determination represents a unique model for studying cell fate decisions. However, a complete understanding of the different cell lineages forming the developing testis and ovary remains elusive. Here, we investigated the origin, specification, and subsequent sex-specific differentiation of a previously uncharacterized population of supporting-like cells (SLCs) in the developing mouse gonads. The SLC lineage is closely related to the coelomic epithelium and specified as early as E10.5, making it the first somatic lineage to be specified in the bipotential gonad. SLC progenitors are localized within the genital ridge at the interface with the mesonephros and initially coexpress Wnt4 and Sox9 . SLCs become sexually dimorphic around E12.5, progressively acquire a more Sertoli- or pregranulosa-like identity and contribute to the formation of the rete testis and rete ovarii. Last, we found that WNT4 is a crucial regulator of the SLC lineage and is required for normal development of the rete testis.

Integration of mouse ovary morphogenesis with developmental dynamics of the oviduct, ovarian ligaments, and rete ovarii

“…The CR and IOR also expressed several ovarian markers, including RUNX1, SF-1, and GATA4, reinforcing the notion that cells of the IOR are closely related to ovarian cells ( Figure 6—figure supplement 2E,F,G ). This is consistent with a recent single-cell transcriptomic study of mouse gonad development showing that cells of the RO were closely related to pre-supporting cells, and even gave rise to a subset of pre-granulosa cells during early differentiation of the ovary Mayère et al, 2022 . While expression of RUNX1 was lower in the CR, this was the only gonadal marker to be expressed in the tubular cells of the EOR ( Figure 6—figure supplement 2E ).…”

“…Pax2 and Pax8 are essential genes during the development of the urogenital system, and null alleles for both of these have been shown to impact the development of the kidneys and the reproductive ducts in mice ( Torres et al, 1995 ; Mittag et al, 2007 ). While Pax8 is expressed in all three regions of the RO, Pax2 is not expressed in the intraovarian progenitors of the RO ( Mayère et al, 2022 ). Both genes are expressed in cells of the oviduct throughout development ( Torres et al, 1995 ).…”

“…In XX embryos, the gonads develop into ovaries, where supporting cells become granulosa cells, interstitial cells become theca cells and other stromal cell types, and germ cells become oocytes ( Nef et al, 2019 ; Rastetter et al, 2014 ; Stévant et al, 2019 ; Wilhelm et al, 2013 ). As these cells undergo differentiation between E11.5 and birth, they progressively assemble into individual ovarian follicles, characterized by the presence of one oocyte surrounded by two or three pre-granulosa cells ( Lei and Spradling, 2016 ; Lei and Spradling, 2013 ; Liu et al, 2010 ; Mork et al, 2012 ; Pepling and Lei, 2018 ; Pepling, 2012 ; Zheng et al, 2014 ).The advent of single-cell transcriptomics has provided a wealth of information on the cellular profiles and gene expression trajectories within the developing ovary, presenting an unprecedented view of the molecular and cellular pathways at play during mammalian ovary differentiation and follicle formation ( Li et al, 2017 ; Liu et al, 2010 ; Mayère et al, 2022 ; Niu and Spradling, 2020 ; Stévant et al, 2019 ). However, transcriptomics alone do not address the spatial and structural components that underlie ovary regionalization and patterning.…”

Deciphering the origins and fates of steroidogenic lineages in the mouse testis

“…Consistent with previously published studies, our transcriptomic analysis suggests that SPs have a dual origin, some from the CE and others from the gonad/mesonephros border (DeFalco et al, 2011;Karl and Capel, 1998;Kumar and DeFalco, 2018;Rotgers et al, 2018). CE-derived progenitors are multipotent and give rise sequentially to several somatic lineages, such as the supporting-like cell lineage required for rete testis formation around E10.5 and then the supporting lineage and Sertoli cells around E11.0-E11.5 (Maye `re et al, 2022;Nef et al, 2019;Stevant et al, 2018). Finally, around E11.5-E12.5, these CE-derived progenitors adopt a steroidogenic progenitor identity characterized by the expression of markers such as Arx and Wnt5a.…”

“…Single-cell RNA sequencing analysis Demultiplexing, alignment, barcodes filtering, quality checks, data aggregation, gene filtering, normalization and dimensionality reduction, batch correction neighbor graph generation, annotation were performed as described in (Maye `re et al, 2022).…”