Loss of Fbxw7 in Sertoli cells impairs testis development and causes infertility in mice†

Abstract

F-box and WD-40 domain protein 7 (Fbxw7) is a component of the Skp1-Cdc53/Cullin-F-box-protein complex (SCF/β-TrCP), which is an E3 ubiquitin ligase that mediates protein degradation. This complex has recently been shown to negatively regulate spermatogonial stem cell self-renewal; however, its roles in Sertoli cell (SC) proliferation, differentiation, and function remain to be established. In this study, we generated conditional mutant mice with SC-specific deletion of Fbxw7 via the Cre-loxP system. Fbxw7 deficiency in SCs impaired testis development, which is characterized by age-dependent tubular atrophy, excessive germ cell loss, and spermatogenic arrest, and the mutant males were infertile at 7 months old. Fbxw7 ablation also compromised cytoskeletal organization and cell polarity of SCs, as well as integrity of the blood-testis barrier. In addition, the transcript levels of cell markers for germ cells, Leydig cells, and SCs were significantly decreased in Fbxw7 mutant mice. Importantly, protein levels of GATA-4, a transcription factor that plays a crucial role in SC maturation and testis development, were progressively decreased in control SCs after postnatal day 14, whereas levels were aberrantly elevated in Fbxw7-deleted SCs. Interestingly, the Gata-4 messenger RNA levels remained stable following Fbxw7 deletion. Fbxw7 silencing in SCs also induced progressive Leydig cell inefficiency and testosterone insufficiency. Collectively, these results demonstrate that Fbxw7 expression is required for SC maturation and function, potentially through degradation of GATA-4, to support pubertal testis development and spermatogenesis.

Deletion of Fbxw7 in oocytes causes follicle loss and premature ovarian insufficiency in mice

“…These isoforms exhibit distinct subcellular localizations: FBXW7 α in the nucleus, FBXW7 β in the cytoplasm, and FBXW7 γ in the nucleolus. 20 Our findings indicate that FBXW7 primarily exists as α and β isoforms in oocytes. Research has demonstrated that deletion of FBXW7 in tumour cells leads to mitotic defects and chromosomal instability, promoting tumorigenesis.…”

“… 37 Our previous work established the role of FBXW7 in Sertoli cell differentiation in male gonads, with its absence disturbs Sertoli cell differentiation and thus disrupts testicular development. 20 Similarly, in the nematode Caenorhabditis elegans, the FBXW7 homologue SEL‐10 coordinates meiosis and post‐transcriptional gene expression during gametogenesis through the MPK‐1/MAPK pathway. 38 Moreover, during primordial follicle development, FBXW7 inhibits primordial follicle activation via the eNOS/cGMP/PKG pathway.…”

“…Growth differentiation factor 9 ( Gdf9 )‐Cre mice were obtained from the Jackson Laboratory (Stock number: 011062). Fbxw7 ‐loxP mice were used in our previous study, 20 and followed the same mating strategy to obtain female mice homozygous for Fbxw7 ‐loxP and heterozygous for Gdf9 ‐Cre ( Gdf9 ‐Cre + , Fbxw7 loxP/loxP ). These females carried an oocyte‐specific deletion of Fbxw7 , and were designated Fbxw7 OcKO mice and the females from the same litter homozygous for Fbxw7 ‐loxP but without Gdf9‐ Cre ( Gdf9 ‐Cre − , Fbxw7 loxP/loxP ) were used as control mice.…”

A homozygous loss‐of‐function mutation in FBXO43 causes human non‐obstructive azoospermia

“…39 Moreover, FBXW7 (also known as FBXO30), a component of the SCF E3 ligase, is also indispensable for mouse spermatogenesis via the regulation of spermatogonial stem cell self-renewal 40 and the maintenance of Sertoli cell maturation and function. 41 Thus, it seems reasonable to postulate that FBXO43 might modulate mammalian spermatogenesis as a core subunit of the SCF complex. The SCF E3 ligase consists of four major components: Cullin1 (CUL1), RING box subunits (RBX1), SKP1, and an F-box protein.…”

Protein expression pattern of calcium-responsive transactivator in early postnatal and adult testes

“…The specificity of the anti-CREST antibody (Proteintech, 12439-1-AP; immunogen: C-terminal amino acids 47-396 of human CREST) utilized in the present research has been tested on the human and mouse tissues by co-immunoprecipitation and immunohistochemistry analyses (Chesi et al 2013). The specificity of anti-WT1 antibody (Abcam, ab89901), anti-GATA-4 antibody (Abclonal, A3600), anti-Brg1 antibody (Santa Cruz, sc-17796) and anti-p300 antibody (Santa Cruz, sc-48343) has been tested on mouse tissues by immunofluorescence analysis (anti-WT1, anti-GATA-4 and anti-Brg1 antibodies) (Del Monte-Nieto et al 2018;Morohoshi et al 2019;Zhang et al 2019) and Western blot analysis (anti-WT1, anti-GATA-4, anti-Brg1 and anti-p300 antibodies) (Bao et al 2018;Dou et al 2018;Shorstova et al 2019;Zhang et al 2019). In addition, the specificity of the anti-CREST antibody was tested in the present study by Western blotting (Fig.…”