Hax-1 is rapidly degraded by the proteasome dependent on its PEST sequence

BMC Cell Biol. 2012 Jul 24;13:20. doi: 10.1186/1471-2121-13-20.

Abstract

Background: HS-1-associated protein X-1 (Hax-1), is a multifunctional protein that has sequence homology to Bcl-2 family members. HAX-1 knockout animals reveal that it plays an essential protective role in the central nervous system against various stresses. Homozygous mutations in the HAX-1 gene are associated with autosomal recessive forms of severe congenital neutropenia along with neurological symptoms. The protein level of Hax-1 has been shown to be regulated by cellular protease cleavage or by transcriptional suppression upon stimulation.

Results: Here, we report a novel post-translational mechanism for regulation of Hax-1 levels in mammalian cells. We identified that PEST sequence, a sequence rich in proline, glutamic acid, serine and threonine, is responsible for its poly-ubiquitination and rapid degradation. Hax-1 is conjugated by K48-linked ubiquitin chains and undergoes a fast turnover by the proteasome system. A deletion mutant of Hax-1 that lacks the PEST sequence is more resistant to the proteasomal degradation and exerts more protective effects against apoptotic stimuli than wild type Hax-1.

Conclusion: Our data indicate that Hax-1 is a short-lived protein and that its PEST sequence dependent fast degradation by the proteasome may contribute to the rapid cellular responses upon different stimulations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / antagonists & inhibitors
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Apoptosis / drug effects
  • Cell Line
  • Humans
  • Mice
  • Mutation
  • Proteasome Endopeptidase Complex / metabolism*
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Staurosporine / pharmacology
  • Ubiquitin / metabolism
  • Ubiquitination

Substances

  • Adaptor Proteins, Signal Transducing
  • HAX1 protein, human
  • RNA, Small Interfering
  • Ubiquitin
  • Proteasome Endopeptidase Complex
  • Staurosporine