Characterization of a cysteine proteinase inhibitor induced during neuronal cell differentiation

J Neurochem. 2002 Jun;81(5):922-34. doi: 10.1046/j.1471-4159.2002.00882.x.


A rat homolog of human cystatin E/M was identified by differential display of transcripts induced during neuronal cell differentiation. A member of the family 2 cystatins, rat cystatin E/M is secreted, glycosylated and developmentally regulated. Rat cystatin E/M is expressed in brain, and is induced during differentiation of a conditionally immortalized E17 rat hippocampal cell line (H19-7) by bFGF or activated Raf via MEK-dependent and -independent signaling pathways. Rat cystatin E/M protein is increased post-transcriptionally in PC12 cells, and the protein is secreted into the medium of primary embryonal hippocampal cultures. Analysis of the K (i) of recombinant His-tagged rat cystatin E/M toward cathepsins B and H revealed that rat cystatin E/M has an inhibitor profile distinct from that of other members of the cystatin family. Motif swapping between rat cystatin E/M and human cystatin C, a well-characterized cystatin, identified some residues that can contribute to the specificity of inhibition. Taken together, these results describe a member of the cystatin family that has a distinct inhibitor profile and may play a role in neuronal development.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Cathepsins / antagonists & inhibitors
  • Cell Differentiation / physiology
  • Cells, Cultured
  • Cloning, Molecular
  • Cystatin M
  • Cystatins / genetics
  • Cystatins / metabolism
  • Cysteine Proteinase Inhibitors / genetics*
  • Cysteine Proteinase Inhibitors / metabolism*
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Profiling
  • Gene Expression Regulation
  • Gene Expression Regulation, Developmental
  • Glycosylation
  • Hippocampus / metabolism
  • Humans
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Molecular Sequence Data
  • Neurons / cytology
  • Neurons / metabolism*
  • Organ Specificity
  • PC12 Cells
  • Rats
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Homology, Amino Acid


  • CST6 protein, human
  • Cystatin M
  • Cystatins
  • Cysteine Proteinase Inhibitors
  • Enzyme Inhibitors
  • Recombinant Fusion Proteins
  • Mitogen-Activated Protein Kinase Kinases
  • Cathepsins