Project description:Rad6 E2 ubiquitin-conjugating enzyme and Bre1 E3 ubiquitin ligase catalyze histone H2B Lysine-123 monoubiquitination (H2Bub1), which stabilizes nucleosomes and regulates the trans-histone H3K4 and K79 methylation during gene transcription and other nuclear processes. The interaction interfaces within the Rad6-Bre1-containing H2B ubiquitin-conjugating complex has remained unknown. By solving the crystal structure of Rad6 along with a non-RING domain N-terminal region of Bre1, we report a beta-turn in Rad6's so-called backside region away from catalytic pocket as a binding site for a homodimer of Bre1 E3 ligase. Using quantitative ChIP-seq or ChIP-Rx, we further demonstrate that Rad6's backside beta-turn residues also govern the chromatin binding dynamics of the Rad6-Bre1 complex.
Project description:Spermatogenesis is a complex process of sperm generation, including mitosis, meiosis, and spermiogenesis. During spermiogenesis, histones in post-meiotic spermatids are removed from chromatin and replaced by protamines. Although histone-to-protamine exchange is important for sperm nuclear condensation, the underlying regulatory mechanism is still poorly understood. Here, we identify PHD finger protein 7 (PHF7) as an E3 ubiquitin ligase for histone H3K14 in post-meiotic spermatids. Generation of Phf7-deficient mice and Phf7 C160A knockin mice with impaired E3 ubiquitin ligase activity reveals defects in histone-to-protamine exchange caused by dysregulation of histone removal factor Bromodomain, testis-specific (BRDT) in early condensing spermatids. Surprisingly, E3 ubiquitin ligase activity of PHF7 on histone ubiquitination leads to stabilization of BRDT by attenuating ubiquitination of BRDT. Collectively, our findings identify PHF7 as a critical factor for sperm chromatin condensation and contribute to mechanistic understanding of fundamental phenomenon of histone-to-protamine exchange and potential for drug development for the male reproduction system.
Project description:FBXW7 is and E3 ubiquitin ligase and is highly mutated in colorectal cancer. We used human colon organoids with engineered FBXW7 hotspot mutations to investigate novel targets of E3 ligase activity with a combined transcriptomic and proteomic approach uncovering the EGFR-MAPK pathway as highly regulated by the E3 ligase activity.
Project description:Rad6 E2 ubiquitin-conjugating enzyme and Bre1 E3 ubiquitin ligase catalyze histone H2B Lysine-123 monoubiquitination (H2Bub1), which stabilizes nucleosomes and regulates the trans-histone H3K4 and K79 methylation during gene transcription and other nuclear processes. The interaction interfaces within the Rad6-Bre1-containing H2B ubiquitin-conjugating complex have remained unknown. By solving the crystal structure of Rad6 along with a non-RING domain N-terminal region of Bre1, we report a beta-turn in Rad6's so-called backside region away from catalytic pocket as a binding site for a homodimer of Bre1 E3 ligase. Using quantitative ChIP-seq or ChIP-Rx, we further demonstrate that Rad6's backside beta-turn residues also govern the chromatin binding dynamics and transcriptional regulatory functions of the Rad6-Bre1 complex.
Project description:An antisense oligonucleotide (ASO) against E3 ubiquitin ligase IDOL in the brain significantly decreased Aβ pathology, and improved spatial learning and memory in APP/PS1 mice.
Project description:It has been recognized that BRCA1, in the form of the BRCA1/BARD1 heterodimer, acting as an ubiquitin E3 ligase offered a possible mechanism to explain its pleiotrophic nature of BRCA1 activity. Our observation that mice lacking BRCA1 enzymatic activity are viable apart from male sterility was unexpected. Our results suggest that the E3 ligase activity of BRCA1 is largely dispensable for normal development and is not essential for all BRCA1 functions. Thus, many of the known and unknown functions of BRCA1 are likely to be mediated independent of its ability to catalyze ubiquitination. The genome copy number patterns were studied on the mice tumors that lacks E3 ubiqitin ligase activity of BRCA1 and were compared to copy number profile of mice lacking p53 and both brca1 and p53.