Histone acetyltransferase HAT4 modulates navigation across G2/M and re-entry into G1 in Leishmania donovani

Abstract

Histone acetyltransferases impact multiple processes. This study investigates the role of histone acetyltransferase HAT4 in Leishmania donovani. Though HAT4 was dispensable for survival, its elimination decreased cell viability and caused cell cycle defects, with HAT4-nulls experiencing an unusually long G2/M. Survival of HAT4-nulls in macrophages was also substantially compromised. DNA microarray analysis revealed that HAT4 modestly regulated the expression of only a select number of genes, thus not being a major modulator of global gene expression. Significantly, cdc20 was among the downregulated genes. To ascertain if decreased expression of cdc20 was responsible for HAT4-null growth and cell cycle defects we expressed LdCdc20 ectopically in HAT4-nulls. We found this to alleviate the aberrant growth and cell cycle progression patterns displayed by HAT4-nulls, with cells navigating G2/M phase and re-entering G1 phase smoothly. HAT4-nulls expressing LdCdc20 ectopically showed survival rates comparable to wild type within macrophages, suggesting that G2/M defects were responsible for poor survival of HAT4-nulls within host cells also. These are the first data analyzing the in vivo functional role of HAT4 in any trypanosomatid. Our results directly demonstrate for the first time a role for Cdc20 in regulating trypanosomatid G2/M events, opening avenues for further research in this area.

Cell cycle stage-specific transcriptional activation of cyclins mediated by HAT2-dependent H4K10 acetylation of promoters in Leishmania donovani

“…In this case, a successful replacement could be obtained ( S3C Fig ). The importance of LdHAT2 in mediating cell survival was in contrast to LdHAT3 and LdHAT4, both of which are dispensable [ 9 , 10 ]. Expression of HAT2 in LdHAT2-hKO:hyg cells was ~0.6 of that seen in wild type cells ( Fig 2A ), and western blot analysis revealed that H4K10 acetylation was reduced by ~ 50% in LdHAT2-hKO cells while H4K4 acetylation levels remained unaltered ( Fig 2B ).…”

“…This is in keeping with findings in Trypanosoma cruzi where overexpression of histone H4 that is non-acetylatable at the 10 th and 14 th residues leads to reduced uptake of EU and EdU, suggesting that H4K10 acetylation is important for replication and transcription [ 15 ]. The survival of LdHAT2-hKO:hyg parasites within host cells was examined by infecting macrophages with metacyclic promastigotes [ 10 ]. Depletion of HAT2 did not impair their ability to infect macrophages, with the number of parasites per 100 macrophages at the end of the five-hour infection period being the same as in control promastigotes ( Fig 2G, 0h time-point).…”

“…EdU labeling analysis was done as detailed earlier [ 10 ]. Briefly, Ld1S-hyg and LdHAT2-hKO:hyg promastigotes were synchronized using hydroxyurea, released into drug-free medium, and aliquots of cells pulsed with 5-ethynyl-2-deoxyuridine (EdU) at different time-points after release.…”

“…LdHAT3 has been identified as an essential player in UV-induced DNA damage repair pathway, via its mediation of PCNA acetylation that must precede PCNA monoubiquitination in order for translesion DNA synthesis-based repair to occur efficiently [ 9 ]. Leishmania donovani HAT4 acetylates H4K14 in vitro , and its deletion leads to prolonged G2/M phase due to down regulation of Cdc20 [ 10 ]. Trypanosoma brucei HAT1 and HAT2 have been found to be essential, with TbHAT1 knockdown compromising DNA replication as well as telomeric silencing [ 11 ].…”

Silsesquioxane‐Containing Hybrid Nanomaterials: Fascinating Platforms for Advanced Applications

“…The improved thermal stability was attributed mainly to the formation of a silicon-containing heat shield layer at high temperatures. [58] Ph-POSS-TiO 2 organic-inorganic hybrid nanomaterials were incorporated into an epoxy resin to form epoxy/POSS-TiO 2 nanocomposites. The addition of POSS-TiO 2 improved the thermal stability of the epoxy resin matrix, which could be used in satellites to enhance their adaptability to the space environment and extend their service life.…”