2.3.3 Chromatin assembly factor 1 (CAF1)
Yuchen Zhang et al 58, via a genome-wide human CRISPR
screen, observed that an essential element in preserving Burkitt latency
is the chromatin assembly factor CAF1. Its depletion leads to the
conversion of Burkitt cells from latency to lysis, ensuing in the
expression of early Burkitt cell BZLF1, BMRF1, and the secretion of
viral particle. Meanwhile it reduced histone 3.1 and 3.3 as well as
inhibited tri-methylation of lysine 4 on histone H3 and histone H3
lys-27-specific trimethylation (H3K9me3 and H3K27me3) occupy several
regulatory elements of the viral genomic cleavage cycle. The CAF1
complicated is composed of three subunits, CHAF1A, CHAF1B, and RBBP4,
and their depletion similarly inhibits the expression of EBV lytic
genes. EBV The predominantly expressed protein elements are EBNA2 and
EBNA-LP, and inactivation of EBNA2 reduces the expression of CAF1
subunit mRNA 59. In addition, EBNA-LP, EBNA3A, EBNA3C
and LMP1-activated NF-κB subunits co-occupy the CHAF1A, CHAF1B and RBBP4
promoters, suggesting that they may support CAF1 expression. The loss of
histone chaperone is similar to that of CAF1, which can up-regulate
BZLF1 and BMRF1, but weaker than CAF1.