Nambiar, K. | Search bioRxiv

bioRxiv2025

SMURF2/USP7-mediated ubiquitination of KAP1 controls its SUMO E3 ligase activity and chromatin regulation

KRAB-associated protein 1 (KAP1) is a critical nuclear protein that regulates chromatin architecture and gene expression, primarily through its SUMOylation activity. However, the mechanisms controlling KAP1 remain poorly understood. In a recent study, we identified the E3 ubiquitin ligase SMURF2 as a direct interactor and ubiquitin ligase for KAP1. Here, we show that SMURF2-mediated ubiquitination of KAP1 at lysines K254, K319, and K779 regulates its SUMOylation activity. We further demonstrate that SMURF2 collaborates with the deubiquitinase USP7/HAUSP, recruiting it to KAP1, to regulate a dynamic ubiquitination-deubiquitination cycle at these key residues. Cells expressing a KAP1 mutant, resistant to SMURF2-USP7 regulation, exhibit profound alterations in chromatin structure, gene expression, protein-protein interactions, and elevated LINE-1 retrotransposon activity. Notably, disrupting the SMURF2-USP7-KAP1-SUMOylation axis in cancer cells reduces their malignancy and tumor growth in vivo. Collectively, these findings uncover a novel regulatory mechanism for KAP1, highlighting its pivotal role in orchestrating critical cellular processes.

molecular biology↗

bioRxiv2021

Intranasal gene therapy to prevent infection by SARS-CoV-2 variants

SARS-CoV-2 variants have emerged with enhanced pathogenicity and transmissibility, and escape from pre-existing immunity, suggesting first-generation vaccines and monoclonal antibodies may now be less effective. This manuscript demonstrates an approach for preventing clinical sequelae and the spread of SARS-CoV-2 variants. First, we affinity-matured an angiotensin-converting enzyme 2 (ACE2) decoy protein, achieving 1000-fold binding improvements that extend across a wide range of SARS-CoV-2 variants and distantly related, ACE2-dependent coronaviruses. Next, we demonstrated the expression of this decoy in proximal airway when delivered via intranasal administration of an AAV vector. This intervention significantly diminished clinical and pathologic consequences of SARS-CoV-2 challenge in a mouse model and achieved therapeutic levels of decoy expression at the surface of proximal airways when delivered intranasally to nonhuman primates. Importantly, this long-lasting, passive protection approach is applicable in vulnerable populations such as the elderly and immune-compromised that do not respond well to traditional vaccination. This approach could be useful in combating COVID-19 surges caused by SARS-CoV-2 variants and should be considered as a countermeasure to future pandemics caused by pre-emergent members, ACE2-dependent CoVs that are poised for zoonosis. Author summarySARS-CoV-2 variants have emerged with enhanced pathogenicity and transmissibility, and escape from pre-existing immunity, suggesting first-generation vaccines and monoclonal antibodies may now be less effective. This manuscript demonstrates an approach for preventing clinical sequelae and the spread of SARS-CoV-2 variants. First, we affinity-matured an angiotensin-converting enzyme 2 (ACE2) decoy protein, achieving 1000-fold binding improvements that extend across a wide range of SARS-CoV-2 variants and distantly related, ACE2-dependent coronaviruses. Next, we demonstrated the expression of this decoy in proximal airway when delivered via intranasal administration of an AAV vector. This intervention significantly diminished clinical and pathologic consequences of SARS-CoV-2 challenge in a mouse model and achieved therapeutic levels of decoy expression at the surface of proximal airways when delivered intranasally to nonhuman primates. Importantly, this long-lasting, passive protection approach is applicable in vulnerable populations such as the elderly and immune-compromised that do not respond well to traditional vaccination. This approach could be useful in combating COVID-19 surges caused by SARS-CoV-2 variants and should be considered as a countermeasure to future pandemics caused by pre-emergent members, ACE2-dependent CoVs that are poised for zoonosis.

genetics↗