Biology subjects

Boulard, M.

Publications and source records attributed to Boulard, M..

3 recordsLinked to original sources

bioRxiv2024

Genetic gradual reduction of OGT activity unveils the essential role of O-GlcNAc in the mouse embryo

The reversible glycosylation of nuclear and cytoplasmic proteins (O-GlcNAcylation) is catalyzed by a single enzyme, namely O-GlcNAc transferase (OGT). The mammalian Ogt gene is X-linked and it is essential for embryonic development and for the viability of proliferating cells. We perturbed OGTs function in vivo by creating a murine allelic series of four single amino acid substitutions reducing OGTs catalytic activity to a range of degrees. The severity of the embryonic lethality was proportional to the degree of impairment of OGTs catalysis, demonstrating that the O-GlcNAc modification itself is required for early development. We identified milder hypomorphic Ogt alleles that perturb O-GlcNAc homeostasis while being compatible with embryogenesis. The analysis of the transcriptomes of the mutant embryos at different stages suggested a sexually-dimorphic developmental delay caused by the decrease in O-GlcNAc. Furthermore, a mild reduction of OGTs enzymatic activity was sufficient to loosen the silencing of endogenous retroviruses in vivo.

developmental biology↗

bioRxiv2024

Trim66 paternal deficiency causes intrauterine overgrowth

The tripartite motif-containing protein 66 (TRIM66, also known as TIF1-delta) is a PHD-Bromo containing protein primarily expressed in post-meiotic male germ cells known as spermatids. Biophysical assays showed that TRIM66 PHD-Bromo domain binds to H3 N-terminus only when lysine 4 is unmethylated. We addressed TRIM66s role in reproduction by loss-of-function genetics in the mouse. Males homozygous for Trim66-null mutations produced functional spermatozoa. Round spermatids lacking TRIM66 upregulated a network of genes involved in histone acetylation and H3K4 methylation. Profiling of H3K4me3 patterns in the sperm produced by Trim66-null mutant showed minor alterations below statistical significance. Unexpectedly, Trim66-null males, but not females, sired pups overweight at birth, hence revealing that Trim66 mutations cause a paternal effect phenotype.

developmental biology↗

bioRxiv2024

Perturbing nuclear glycosylation in the mouse preimplantation embryo slows down embryonic growth

The only known form of intracellular protein glycosylation (O-GlcNAc) is reversible and has been mapped on thousands of cytoplasmic and nuclear proteins, including RNA polymerase II, transcription factors and chromatin modifiers. The O-GlcNAc modification is catalyzed by a single enzyme known as O-GlcNAc Transferase (OGT), that is required for mammalian early development. Remarkably, the regulatory function of protein O-GlcNAcylation in the embryo as well as the embryonic O-GlcNAc proteome remain unknown. Here, we devised a new method to enzymatically remove O-GlcNAc from preimplantation embryonic nuclei, where it accumulates coincidently with embryonic genome activation (EGA). Unexpectedly, the depletion of nuclear O-GlcNAc to undetectable levels has no impact on EGA, but dampens the transcriptional activation of the translational machinery, and triggers a spindle checkpoint response. These molecular alterations were phenotypically associated with a developmental delay starting from early cleavage stages and persisting after embryo implantation, establishing a novel link between nuclear glycosylation and embryonic growth.

developmental biology↗