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

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

FASEB bioAdvances (2018-12-03)
Zhenping Chen, Paul J Boor, Celeste C Finnerty, David N Herndon, Thomas Albrecht
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.

MATERIALS
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Sigma-Aldrich
Calpain-1, Human Erythrocytes, Calpain-1, Human Erythrocytes, is a native calpain-1. A heterodimeric cysteine proteinase with low Ca2+ requirement (EC₅₀ = 2 µM).