Galectin-3 interacts with components of the nuclear ribonucleoprotein complex

BMC Cancer. 2016 Jul 19;16:502. doi: 10.1186/s12885-016-2546-0.

Abstract

Background: The multifunctional β-galactoside-binding protein galectin-3 is found in many distinct subcellular compartments including the cell nucleus. Expression and distribution of galectin-3 between the cell nucleus and the cytosol changes during cell differentiation and cancer development. Nuclear functions of galectin-3 and how they contribute to tumorigenesis are not understood.

Methods: In order to identify nuclear galectin-3 interaction partners, we used affinity chromatography and co-immunoprecipitation. Spatial proximity in the nucleus was assessed by immunofluorescence and proximity ligation assay. We also investigated the function of galectin-3 on mRNA-export by fluorescence in situ hybridization and on mRNA-processing by RNA-sequencing.

Results: The heterogeneous ribonucleoprotein particle component hnRNPA2B1 was identified as a novel galectin-3 binding protein that associates with the lectin in a lactose-dependent manner in the cell nucleus. Specific individual depletion of galectin-3 does not affect the mRNA distribution between cytoplasm and nucleus. A significant alteration of this distribution was observed after combined depletion of galectin-1 and -3. However, silencing of galectin-3 was sufficient to alter the splicing patterns of several genes.

Conclusions: Galectin-3 and hnRNPA2B1 interact as members of the early splicing machinery. Galectin-3 and -1 have redundant functions in mRNA transport and at least in part in mRNA splicing. RNA-sequencing data points to a specific function of the hnRNPA2B1/galectin-3 interaction in the processing of transcripts coding for the nuclear oncoprotein SET.

Keywords: Galectin-1; Galectin-3; RNA-processing; Spliceosome; hnRNPA2B1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Nucleus / genetics*
  • Cell Nucleus / metabolism
  • Galectin 3 / genetics*
  • Galectin 3 / metabolism
  • HeLa Cells
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B / genetics*
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B / metabolism
  • Humans
  • Immunoblotting
  • Immunoprecipitation
  • In Situ Hybridization, Fluorescence
  • Microscopy, Fluorescence
  • Protein Binding
  • RNA Interference
  • RNA Splicing
  • RNA Transport
  • RNA, Messenger / genetics*
  • RNA, Messenger / metabolism
  • Sequence Analysis, RNA / methods

Substances

  • Galectin 3
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B
  • RNA, Messenger
  • hnRNP A2