title: Apoptosis in human myelodysplastic syndrome CD34+ cells is modulated by the upregulation of TLRs and histone H4 acetylation via a β-arrestin 1 dependent mechanism.
abstract: Excessive apoptosis of hematopoietic precursors in the bone marrow underlies the ineffective hematopoiesis characteristic of myelodysplastic syndrome (MDS). Toll-like receptor (TLR) signaling is abnormally activated in MDS and may be involved in excessive programmed cell death in the pathogenesis of MDS. TLRs expression and global histone H3/H4 acetylation were analyzed in bone marrow (BM) CD34+ cells from 20 lower-risk and 20 higher-risk MDS patients and 10 healthy controls. Apoptosis of BM CD34+ cells was examined by flow cytometry, and its correlation to histone acetylation and the expression of TLR2 and β-arrestin1 (β-arr1), measured by enzyme-linked immunosorbent assay and qRT-PCR, was assessed. TLR1, TLR2 and TLR6 expression and H4 acetylation levels were higher in lower-risk MDS patients than in higher-risk MDS patients or controls, and TLR2 expression and H4 acetylation levels were positively correlated with an increased rate of apoptosis. Lower-risk MDS was associated with increased β-arr1 expression and histone acetyltransferase p300 activity. In in vitro-cultured primary normal and lower-risk MDS CD34+ cells, TLR2 activation-induced apoptosis was mediated by the upregulation of β-arr1 leading to the recruitment of p300 and increased histone H4 acetylation. The nuclear accumulation of βarr1 following TLR2 activation promote H4 acetylation at specific target gene promoters and may thus affect transcription of target genes in BM CD34+ cells. The mechanisms underlying the deregulation of TLR2 and increased apoptosis in MDS may involve the β-arr1 mediated recruitment of p300 leading to increased levels of histone H4 acetylation.
authors.affiliation: Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Shu
authors.affiliation: Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200071, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Hu
authors.affiliation: Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China.
authors.forename: Shao-Hong
authors.initials: SH
authors.lastname: Zhou
authors.affiliation: Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China.
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Qian
authors.affiliation: Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Hu
authors.affiliation: Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China.
authors.forename: Ling-Yan
authors.initials: LY
authors.lastname: Hu
authors.affiliation: Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China.
authors.forename: Yu-Guang
authors.initials: YG
authors.lastname: Wang
authors.affiliation: Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China. Electronic address: Yongmingz@sohu.com.
authors.forename: Yong-Ming
authors.initials: YM
authors.lastname: Zhou
authors.affiliation: Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200071, China. Electronic address: Lujiahui73@163.com.
authors.forename: Jia-Hui
authors.initials: JH
authors.lastname: Lu
mesh_terms: D000107:Acetylation; D018952:Antigens, CD34 / Q000378:metabolism*; D017209:Apoptosis; D019390:Arrestins / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D009190:Myelodysplastic Syndromes / Q000378:metabolism* / Q000473:pathology*; D051193:Toll-Like Receptors / Q000378:metabolism*; D015854:Up-Regulation; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins
chemical_list: C000605253:ARRB1 protein, human; D018952:Antigens, CD34; D019390:Arrestins; D006657:Histones; D051193:Toll-Like Receptors; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins
keywords: Apoptosis; Histone acetylation; Myelodysplastic syndromes (MDS); Toll-like receptor; β-arrestin 1