Mutants of human αB-crystallin cause enhanced protein aggregation and apoptosis in mammalian cells: influence of co-expression of HspB1

Biochem Biophys Res Commun. 2013 Jan 4;430(1):107-12. doi: 10.1016/j.bbrc.2012.11.051. Epub 2012 Nov 27.

Abstract

Mutations of human αB-crystallin cause congenital cataract and cardio-myopathy by protein aggregation and cell death. How mutations of αB-crystallin become pathogenic is poorly understood. To better understand the cellular events related to protein aggregation and cell death, we transfected cataract and cardio-myopathy causing mutants, R11H, P20S, R56W, D109H, R120G, D140N, G154S, R157H and A171T in HeLa cells and assessed protein aggregation and apoptosis by laser scanning confocal microspy (LSCM) and flow cytometry. Cells individually transfected with the mutants, D109H, R120G, D140N and R157H significantly showed more aggregates. Cells overexpressed with HspB1 (Hsp27) significantly sequestered aggregates in all mutants and suppressed apoptosis in mutants, P20S, D109H and A171T. Significant increases of apoptotic cells as stained with Annexin V were observed in mutants, D109H and A171T transfected cells. Cells positive for active caspase-3 was increased in the mutant, D109H. Thus the previously recognized anti-apoptotic functions of αB-crystallin were compromised in these mutants.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Apoptosis*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • HSP27 Heat-Shock Proteins / biosynthesis*
  • HSP27 Heat-Shock Proteins / genetics
  • HeLa Cells
  • Heat-Shock Proteins
  • Humans
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Molecular Chaperones
  • Mutant Proteins / genetics
  • Mutant Proteins / metabolism*
  • Mutation
  • alpha-Crystallin B Chain / genetics
  • alpha-Crystallin B Chain / metabolism*

Substances

  • Bacterial Proteins
  • HSP27 Heat-Shock Proteins
  • HSPB1 protein, human
  • Heat-Shock Proteins
  • Luminescent Proteins
  • Molecular Chaperones
  • Mutant Proteins
  • alpha-Crystallin B Chain
  • yellow fluorescent protein, Bacteria