Identification of Protein Arginine Methyltransferase 5 as a Regulator for Encystation of <i>Acanthamoeba</i>

Abstract

Encystation is an essential process for Acanthamoeba survival under nutrient-limiting conditions and exposure to drugs. The expression of several genes has been observed to increase or decrease during encystation. Epigenetic processes involved in regulation of gene expression have been shown to play a role in several pathogenic parasites. In the present study, we identified the protein arginine methyltransferase 5 (PRMT5), a known epigenetic regulator, in Acanthamoeba castellanii. PRMT5 of A. castellanii (AcPRMT5) contained domains found in S-adenosylmethionine-dependent methyltransferases and in PRMT5 arginine-N-methyltransferase. Expression levels of AcPRMT5 were increased during encystation of A. castellanii. The EGFP-PRMT5 fusion protein was mainly localized in the nucleus of trophozoites. A. castellanii transfected with siRNA designed against AcPRMT5 failed to form mature cysts. The findings of this study lead to a better understanding of epigenetic mechanisms behind the regulation of encystation in cyst-forming pathogenic protozoa.

Identification and Characterization of Protein Arginine Methyltransferase 1 in Acanthamoeba castellanii

“…AcPRMT1 was localized both in the cytoplasm and the nucleus (Fig. 3), while we have previously identified that AcPRMT5 was localized mainly in the nucleus [19]. However, the substrates of PRMT1 and PRMT5 of A. castellanii have yet to be identified.…”

“…2 ). The previously identified PRMT5 of A. castellanii (AcPRMT5) also showed increased expression patterns during encystation [ 19 ]. However, AcPRMT1 was expressed higher than AcPRMT5 during encystation of A. castellanii ( Fig.…”

“…3 ). Previously it was found that the EGFP-AcPRMT5 fusion protein was mainly localized in the nucleus of Acanthamoeba [ 19 ]. However, AcPRMT1 was localized in both the cytoplasm and the nucleus of Acanthamoeba trophozoite ( Fig.…”

“…To investigate the intracellular localization of PRMT1, the gene was cloned into the pGAPDH vector using enhanced green fluorescent protein (EGFP) as a marker [ 19 ]. The pGAPDHgPRMT1 plasmid was transfected into live cells of A. castellanii .…”

DNA Methylation of Gene Expression in Acanthamoeba castellanii Encystation

“…Geyer et al [ 15 ] have shown evidence of cytosine methylation in Schistosoma mansoni , suggesting the presence of a functional DNA methylation machinery. However, methylated cytosine and DNA methyltransferase have not been reported in Acanthamoeba yet, although protein arginine methyltransferase 5 has been identified [ 16 ].…”