Recent BCR stimulation induces a negative autoregulatory loop via FBXO10 mediated degradation of HGAL

Leukemia. 2020 Feb;34(2):553-566. doi: 10.1038/s41375-019-0579-5. Epub 2019 Sep 30.

Abstract

Regulating B-cell receptor (BCR) signaling after antigenic stimulation is essential to properly control immune responses. Currently known mechanisms of inhibiting BCR signaling are via co-receptor stimulation and downstream immunoreceptor tyrosine-based inhibition motif (ITIM) phosphorylation. Herein we demonstrate that BCR stimulation induces rapid and reversible palmitoylation of the SCF-FBXO10 ubiquitin E3 ligase. This results in FBXO10 relocation to the cell membrane, where it targets the human germinal center-associated lymphoma (HGAL) protein for ubiquitylation and degradation, leading to decreases in both BCR-induced calcium influx and phosphorylation of proximal BCR effectors. Importantly, FBXO10 recognition and degradation of HGAL is phosphorylation independent and instead relies on a single evolutionarily conserved HGAL amino acid residue (H91) and FBXO10 relocalization to the cytoplasmic membrane. Together our findings demonstrate the first evidence of negative BCR signaling regulation from direct BCR stimulation and define the temporospatial functions of the FBXO10-HGAL axis. FBXO10 is infrequently mutated in DLBCL but some of these mutations deregulate BCR signaling. These observations may have important implications on lymphomagenesis and other immune processes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • B-Lymphocytes / metabolism
  • Cell Membrane / metabolism
  • F-Box Proteins / metabolism*
  • Germinal Center / metabolism*
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Lymphoma, Large B-Cell, Diffuse / metabolism
  • Microfilament Proteins / metabolism*
  • Neoplasm Proteins / metabolism
  • Phosphorylation / physiology
  • Receptors, Antigen, B-Cell / metabolism*
  • Signal Transduction / physiology
  • Ubiquitin-Protein Ligases / metabolism

Substances

  • F-Box Proteins
  • FBXO10 protein, human
  • GCSAM protein, human
  • Intracellular Signaling Peptides and Proteins
  • Microfilament Proteins
  • Neoplasm Proteins
  • Receptors, Antigen, B-Cell
  • Ubiquitin-Protein Ligases