The E3 ligase RNF32 controls the IκB kinase complex and NF-κB signaling in intestinal stem cells

  • Mol Cell. 2025 Oct 29:S1097-2765(25)00822-6. doi: 10.1016/j.molcel.2025.10.005.
Angela Lauriola  1 ,  Juliana Haydeé Enriqué Steinberg  1 ,  Motoharu Sarubo  2 ,  Elena Maspero  3 ,  Fabiana Alejandra Rossi  4 ,  Yasuhiro Mouri  2 ,  Marco Pedretti  1 ,  Mohsen Hajisadeghian  1 ,  Vincenzo Taibi  3 ,  Andrea Vettori  1 ,  Nicola Vitulo  1 ,  Michael Assfalg  1 ,  Mariapina D'Onofrio  1 ,  Mario Rossi  4 ,  Akihiro Yasue  5 ,  Alessandra Astegno  1 ,  Simona Polo  3 ,  Spartaco Santi  6 ,  Yasusei Kudo  7 ,  Daniele Guardavaccaro  8
Affiliations
  • 1. Department of Biotechnology, University of Verona, 37134 Verona, Italy.
  • 2. Department of Oral Bioscience, Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8504, Japan.
  • 3. IFOM ETS, The AIRC Institute of Molecular Oncology, 20139 Milan, Italy.
  • 4. Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET, Universidad Austral, B1629AHJ Pilar, Argentina; Facultad de Ciencias Biomédicas, Universidad Austral, B1629AHJ Pilar, Argentina.
  • 5. Nakano-Cho niconicoKamKam Dental and Orthodontics, 1-31 Nakano-cho, Tokushima 770-0932, Japan.
  • 6. Consiglio Nazionale delle Ricerche (CNR) Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", 40136 Bologna, Italy.
  • 7. Department of Oral Bioscience, Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8504, Japan; Institute of Photonics and Human Health Frontier, Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8504, Japan. Electronic address: [email protected].
  • 8. Department of Biotechnology, University of Verona, 37134 Verona, Italy. Electronic address: [email protected].
PMID: 41167191 DOI: 10.1016/j.molcel.2025.10.005
Abstract

Nuclear factor κB (NF-κB) signaling is a central pathway regulating a plethora of cellular functions. Here, we find that RNF32, a RING E3 ubiquitin Ligase whose expression is enriched in murine intestinal stem cells, regulates the activity of the IκB kinase (IKK) complex, the signal integration hub for NF-κB activation. The E3 Ligase activity of RNF32 depends on Calmodulin, the primary calcium sensor in eukaryotic cells. Increased levels of intracellular calcium ion (CA2+) induce RNF32 binding to Calmodulin, RNF32 activation, and autoubiquitylation. In turn, polyubiquitin chains conjugated to RNF32 recruit NEMO, the regulatory subunit of the IKK complex. Moreover, CA2+ rise triggers RNF32 phase separation, which is required for the formation of NEMO condensates and IKK activation. Finally, we show that RNF32 is required for NF-κB activation triggered by Bacterial lipopolysaccharides. Collectively, our findings uncover a mechanism controlling NF-κB signaling in the intestinal epithelium.

Products