Calpain-mediated cleavage of p53 in human cytomegalovirus-infected lung fibroblasts

Zhenping Chen, Paul J. Boor, Celeste C. Finnerty, David Herndon, Thomas Albrecht

Research output: Contribution to journalArticlepeer-review

Abstract

Endogenous fragments of p53 protein were identified in human cytomegalovirus (HCMV)-infected human lung fibroblasts, particularly a 44-kDa N-terminal fragment [hereafter referred to as p53(ΔCp44)], generated via calpain cleavage. The fragment abundance increased in a biphasic manner, peaking at 6-9 hours and 48 hours post infection. Treatment of LU cells with calpain inhibitors eliminated most detectable p53 fragments. In cell-free experiments, exogenous m-calpain cleavage generated p53(ΔCp44). Attempts to preserve p53 proteins by treating cells with the calpain inhibitor E64d for 6 hours before harvesting increased the sensitivity of p53 to calpain cleavage. p53 in mock-infected cell lysates was much more sensitive to cleavage and degradation by exogenous calpain than that in HCMV-infected cells. The proteasome inhibitor MG132 stabilized p53(ΔCp44), particularly in mock-infected cells. p53(ΔCp44) appeared to be tightly associated with a chromatin-rich fraction. The abundance of p53β was unchanged over a 96-h time course and very similar in mock- and HCMV-infected cells, making it unlikely that p53(ΔCp44) was p53β. The biological activities of this and other fragments lacking C-terminal sequences are unknown, but deserve further investigation, given the association of p53(ΔCp44) with the chromatin-rich (or buffer C insoluble) fraction in HCMV-infected cells.

Original languageEnglish (US)
Pages (from-to)151-166
Number of pages16
JournalFASEB BioAdvances
Volume1
Issue number3
DOIs
StatePublished - Mar 2019

Keywords

  • calpain
  • endogenous N-terminal p53 fragments
  • human cytomegalovirus
  • p53
  • proteasome

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • Cancer Research
  • Molecular Medicine
  • Physiology

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