Blockade of endoplasmic reticulum stress‐induced cell death by Ureaplasma parvum vacuolating factor

Abstract

Previously, we found that Ureaplasma parvum internalised into HeLa cells and cytosolic accumulation of galectin-3. U. parvum induced the host cellular membrane damage and survived there. Here, we conducted vesicular trafficking inhibitory screening in yeast to identify U. parvum vacuolating factor (UpVF). U. parvum triggered endoplasmic reticulum (ER) stress and upregulated the unfolded protein response-related factors, including BiP, P-eIF2 and IRE1 in the host cells, but it blocked the induction of the downstream apoptotic factors. MicroRNA library screening of U. parvuminfected cells and UpVF-transfected cells identified miR-211 and miR-214 as the negative regulators of the apoptotic cascade under ER stress. Transient expression of UpVF induced HeLa cell death with intracellular vacuolization; however, some stable UpVF transformant survived. U. parvum-infected cervical cell lines showed resistance to actinomycin D, and UpVF stable transformant cell lines exhibited resistance to Xray irradiation, as well as cisplatin and paclitaxel. UpVF expressing cervical cancer xenografts in nude mice also acquired resistance to cisplatin and paclitaxel. A mycoplasma expression vector based on Mycoplasma mycoides, Syn-MBA (multiple banded antigen)-UpVF, reduced HeLa cell survival compared with that of Syn-MBA after 72 hr of infection. These findings together suggest novel mechanisms for Ureaplasma infection and the possible implications for cervical cancer malignancy. Take Aways• Ureaplasmal novel virulence factor, UpVF, was identified.• UpVF triggered ER stress but suppressed apoptotic cascade via miR-211 and -214.• UpVF conferred resistance to anticancer treatments both in vivo and in vitro.• Dual expression of MBA and UpVF in JCVI-syn3B showed host cell damage.

Differences in the characteristics and pulmonary toxicity of nano- and micron-sized respirable coal dust

“…In the process of cell culture, due to insufficient serum concentration, drug action, external stimuli, and other factors affecting cell metabolism, cell vacuolization will occur under stress of the endoplasmic reticulum [ 30 , 31 ]. The accumulation of unfolded proteins within the endoplasmic reticulum creates stress, and the unfolded protein response stimulates inflammatory pathways to alert surrounding cells of potential danger [ 32 ].…”

Minimal cell JCVI-syn3B as a chassis to reveal the mechanisms behind Mycoplasma host–pathogen interactions

“…Furthermore, addition of a surface antigen gene called mba from the mycoplasma species Ureaplasma parvum serovar 3, restored the capacity of JCVI-syn3B to adhere to HeLa cells. We also showed that a JCVI-syn3B construct expressing U. parvum mba and a U. parvum gene proposed to be a virulence factor blocked endoplasmic reticulum stress-induced cell death, caused the formation of vacuoles in the HeLa cells and enabled proliferation of the mutant strain in co-culture with the cell host (Nishiumi et al ., 2021).…”

“…The use of contaminated cells has the potential to invalidate results because the mycoplasma contaminants can alter almost all aspects of cell physiology. While this can lead to erroneous results or causes the loss of unique cell lines, it also offers an opportunity to examine host-parasite interactions (Nishiumi et al, 2021).…”

“…mycoides). Lacking cell walls, mycoplasmas are atypical bacteria, the Mollicutes, named from the Latin "soft" (mollis) and "skin" (cutis) (Noccard and Roux, 1898).…”

“…In 2021 we reported that a minimized Mmc strains JCVI-syn3.0, JCVI-syn3A and JCVI-syn3B were unable to survive in co-culture with host cells such as HeLa (Nishiumi et al ., 2021). The JCVI-syn3A (Breuer et al ., 2019) and JCVI-syn3B strains differ from JCVI-syn3.0 by the presence of 19 additional non-essential genes that result in a more easily manipulated cell.…”