Encystation commitment in Giardia duodenalis: a long and winding road
R Argüello-Garciá1, M L Bazán-Tejeda, G Ortega-Pierres
1Departamento de Genètica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del I.P.N., Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360 Mexico City, México.
Parasite (Paris, France)
|January 23, 2010
Summary
Bile salts and cholesterol modulate Giardia encystation. A Raf/MEK/ERK pathway may mediate cholesterol
Area of Science:
- Parasitology
- Molecular Biology
- Biochemistry
Background:
- Cholesterol and bile salts are known modulators of Giardia encystation.
- Signaling cascades and gene expression changes during encystation are observed, but interactions are unclear.
Purpose of the Study:
- To investigate the role of bile salts as natural stimuli in Giardia encystation.
- To explore the potential involvement of a Raf/MEK/ERK pathway in cholesterol-regulated gene expression during cyst formation.
Main Methods:
- Utilized recent experimental data and the Giardia Genome Project Database (GiardiaDB).
- Considered bile salts as natural stimuli.
- Hypothesized a Raf/MEK/ERK signaling pathway.
Main Results:
- Bile salts act as natural stimuli for Giardia encystation.
- A Raf/MEK/ERK pathway is implicated in regulating cyst-specific gene expression.
- Cholesterol influences the expression of cyst wall proteins (CWPs) and GalNAc homopolymer precursors.
Conclusions:
- Bile salts and cholesterol are key regulators of Giardia encystation.
- The Raf/MEK/ERK pathway is a potential mediator of cholesterol's effects.
- These findings offer targets for giardiasis diagnostics and therapeutics.
Related Concept Videos
01:12Giardiasis
Giardiasis is a globally prevalent intestinal infection caused by the protozoan parasite Giardia duodenalis (also known as G. lamblia or G. intestinalis). This flagellated protozoan is the most frequently identified intestinal parasite in the United States and worldwide. Transmission primarily occurs via the fecal-oral route, with infection arising from ingestion of water or food contaminated with cysts. Individuals in low-resource settings, international travelers, outdoor enthusiasts, daycare...
01:28Amebiasis
Entamoeba histolytica, a protozoan parasite, is responsible for intestinal and extraintestinal amebiasis. Though a significant proportion of infections remain asymptomatic, approximately 50 million individuals annually are estimated to present with clinical disease, resulting in up to 100,000 deaths globally. The disease burden is disproportionately high in regions with lower socioeconomic status, such as parts of India, Africa, Mexico, and Latin America.Etiology and TransmissionThe infective...
01:26Gastritis II: Pathophysiology
The pathophysiology of gastritis begins with the colonization of the stomach lining by Helicobacter pylori (H. pylori). This bacterium spreads mainly via the oral-oral route through saliva or shared utensils, and can also be transmitted in overcrowded or unhygienic environments through contaminated water, despite its brief survival outside the body.ColonizationOnce ingested, H. pylori enters the stomach and begins colonization by navigating through the mucus layer lining the stomach wall. It...
01:18Bacterial Gastroenteritis
Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...
01:15Diversity of Protists I
Excavata is a diverse group of protists that includes both chemoorganotrophic and phototrophic species, with some thriving in anaerobic environments. Among the key groups within Excavata are diplomonads and parabasalids, which are flagellated protists that lack mitochondria and chloroplasts. These microorganisms typically inhabit anoxic environments, such as the intestines of animals, where they exist either symbiotically or as parasites, relying on fermentation for energy production. Some...
01:18Trichomoniasis
Trichomonas vaginalis is a flagellated protozoan parasite and the causative agent of trichomoniasis, one of the most prevalent non-viral sexually transmitted infections in the United States. This extracellular parasite primarily colonizes the lower genitourinary tract in women—particularly the vagina—and in men, the urethra and prostate. Its structural and functional adaptations enable its survival, motility, and pathogenicity within the host environment.Structural Features and Host EntryT.