Developmental switching between life-cycle stages is a common feature among parasitic pathogens to facilitate disease transmission and pathogenesis. The protozoan parasite Entamoeba switches between invasive trophozoites and dormant cysts, but the encystation process remains poorly understood despite being central to amoebic biology. We identify a transcription factor, Encystation Regulatory Motif-Binding Protein (ERM-BP), that regulates encystation. Down-regulation of ERM-BP decreases encystation efficiency resulting in abnormal cysts with defective cyst walls. We demonstrate that direct binding of NAD⁺ to ERM-BP affects ERM-BP conformation and facilitates its binding to promoter DNA. Additionally, cellular NAD⁺ levels increase during encystation and exogenous NAD⁺ enhances encystation consistent with the role of carbon source depletion in triggering Entamoeba encystation. Furthermore, ERM-BP catalyzes conversion of nicotinamide to nicotinic acid, which might have second messenger effects on stage conversion. Our findings link the metabolic cofactors nicotinamide and NAD⁺ to transcriptional regulation via ERM-BP and provide the first mechanistic insights into Entamoeba encystation.

Multinucleated Giant Cells (MGCs) are specialized cells that develop from the fusion of multiple cells, and their presence is commonly observed in human cells during various infections. However, MGC formation is not restricted to infections alone but can also occur through different mechanisms, such as endoreplication and abortive cell cycle. These processes lead to the formation of polyploid cells, eventually resulting in the formation of MGCs. In Entamoeba, a protozoan parasite that causes amoebic dysentery and liver abscesses in humans, the formation of MGCs is a unique phenomenon and not been reported in any other protozoa. This organism is exposed to various hostile environmental conditions, including changes in temperature, pH, and nutrient availability, which can lead to stress and damage to its cells. The formation of MGCs in Entamoeba is thought to be a survival strategy to cope with these adverse conditions. This organism forms MGCs through cell aggregation and fusion in response to osmotic and heat stress. The MGCs in Entamoeba are thought to have increased resistance to various stresses and can survive longer than normal cells under adverse conditions. This increased survival could be due to the presence of multiple nuclei, which could provide redundancy in case of DNA damage or mutations. Additionally, MGCs may play a role in the virulence of Entamoeba as they are found in the inflammatory foci of amoebic liver abscesses and other infections caused by Entamoeba. The presence of MGCs in these infections suggests that they may contribute to the pathogenesis of the disease. Overall, this article offers valuable insights into the intriguing phenomenon of MGC formation in Entamoeba. By unraveling the mechanisms behind this process and examining its implications, researchers can gain a deeper understanding of the complex biology of Entamoeba and potentially identify new targets for therapeutic interventions. The study of MGCs in Entamoeba serves as a gateway to exploring the broader field of cell fusion in various organisms, providing a foundation for future investigations into related cellular processes and their significance in health and disease.

Amoebae, fascinatingly diverse protists, showcase a dual nature that positions them as both friends and foes in our world. These organisms, defined by their distinctive pseudopodia, span a spectrum from harmful to helpful. On the darker side, species like Entamoeba histolytica pose serious health risks, causing intestinal and liver diseases, while the infamous “brain-eating” Naegleria fowleri leads to fatal primary amoebic meningoencephalitis (PAM), with a daunting 97% mortality rate. Other free-living amoebae, including Acanthamoeba castellanii and Balamuthia mandrillaris, also threaten the human central nervous system. Yet, beyond these dangers, amoebae play critical ecological roles. They function as nature’s recyclers, decomposing organic material and nourishing aquatic ecosystems, while also serving as food for various organisms. Moreover, certain amoebae help control plant pathogens and offer insight into human disease, proving valuable as model organisms in biomedical research. This review sheds light on the complex, multifaceted world of amoebae, highlighting their dual role as pathogens and as key contributors to vital ecological processes, as well as their significant impact on research and their promising potential for enhancing human well-being.

Increasing evidence demonstrates a robust link between environmental pollutants and allergic reactions, with air and indoor pollution exacerbating respiratory allergies and climate change intensifying seasonal allergies. Comprehensive action, including government regulations, public awareness, and individual efforts, is essential to mitigate pollution's impact on allergies and safeguard public health and ecological balance. Recent findings indicate a strong correlation between environmental pollutants and allergic reactions, with air pollution from vehicular emissions and industrial activities exacerbating respiratory allergies like asthma and allergic rhinitis. Additionally, indoor pollutants such as mold and volatile organic compounds are significant triggers of allergic responses, especially among vulnerable populations. Furthermore, climate change, driven by pollution, is intensifying seasonal allergies due to altered weather patterns and increased pollen production. This review emphasizes the critical importance of addressing pollution and allergies, highlighting the growing concerns in contemporary society. This review highlights the urgent need to address pollution and allergies, emphasizing their increasing significance in modern society and outlining effective allergy management strategies.