calcium Archives - Center for Tropical and Emerging Global Diseases

Membrane contact activation of Piezo2 drives lysosome-mitochondrion Ca2+ transfer and signaling in Trypanosoma cruzi

Donna Huber on October 20, 2026

Calcium ion (Ca2+) transfer from other organelles is central to mitochondrial metabolism and cell survival, yet how mechanical forces regulate interorganelle communication remains unclear. Here we report a lysosome-to-mitochondrion pathway in Trypanosoma cruzi, the etiologic agent of Chagas disease, mediated by the mechano/osmosensitive channel TcPiezo2. Using ultrastructural, biochemical, and live-cell superresolution imaging, we define …

Molecular recognition of myosin L by the Toxoplasma gondii calmodulin

Donna Huber on September 29, 2026

Calmodulin is a conserved EF-hand Ca2+ sensor that transduces intracellular Ca2+ signals through interactions with target proteins. Recent cryo-electron microscopy studies revealed the Toxoplasma gondii calmodulin (TgCaM) as a light chain associated with the neck of the unconventional myosin MyoL within the preconoidal P2 ring , a key component of the conoid involved in parasite …

Imaging Ca2+ Signaling in Trypanosoma cruzi with Genetically Encoded Ca2+ Indicators

Donna Huber on February 3, 2026

Genetically encoded calcium indicators (GECIs) are proteins used to monitor calcium ion (Ca2+) changes in living cells. They can be targeted to the cytosol or to organelles for continuous measurements in vivo. In this chapter, we present an overview of the methods that our lab used to detect Ca2+ changes in Trypanosoma cruzi elicited by stimulation …

Calcium transfer from the ER to other organelles for optimal signaling in Toxoplasma gondii

Donna Huber on November 12, 2025

Ca2+ signaling in cells begins with the opening of Ca2+ channels in either the plasma membrane (PM) or endoplasmic reticulum (ER), leading to a sharp increase in the physiologically low (<100 nM) cytosolic Ca2+ level. The temporal and spatial regulation of Ca²+ is crucial for the precise activation of key biological processes. In the …

Lysosome and plasma membrane Piezo channels of Trypanosoma cruzi are essential for proliferation, differentiation and infectivity

Donna Huber on April 23, 2025

Trypanosoma cruzi, the causative agent of Chagas disease, is a parasitic protist that affects millions of people worldwide. Currently there are no fully effective drugs or vaccines available. Contact of T. cruzi infective forms with their host cells or with the extracellular matrix increases their intracellular Ca2+ concentration suggesting a mechano-transduction process. We report here …

Regulation of Calcium entry by cyclic GMP signaling in Toxoplasma gondii

Donna Huber on February 19, 2024

Ca2+ signaling impacts almost every aspect of cellular life. Ca2+ signals are generated through the opening of ion channels that permit the flow of Ca2+ down an electrochemical gradient. Cytosolic Ca2+ fluctuations can be generated through Ca2+ entry from the extracellular milieu or release from intracellular stores. In Toxoplasma gondii, Ca2+ ions play critical …

Advances in the cellular biology, biochemistry, and molecular biology of acidocalcisomes

Donna Huber on December 15, 2023

Acidocalcisomes are organelles conserved during evolution and closely related to the so-called volutin granules of bacteria and archaea, to the acidocalcisome-like vacuoles of yeasts, and to the lysosome-related organelles of animal species. All these organelles have in common their acidity and high content of polyphosphate and calcium. They are characterized by a variety of functions …

Praziquantel target validation of a Ca2+ permeable channel in schistosomes

Donna Huber on January 18, 2023

Highlights Schistosomiasis is a devastating neglected helminthic disease. Praziquantel (PZQ) is the most important drug against schistosomiasis. Previous work identified a TRP channel of the melastatin type as a PZQ target. Molecular studies now reveal the basis for varied PZQ sensitivity of different helminths. Roberto Docampo. Cell Calcium. 2023 Jan 18;110:102698. doi: 10.1016/j.ceca.2023.102698

Calcium signaling in intracellular protist parasites

Donna Huber on September 24, 2021

Calcium ion (Ca2+) signaling is one of the most frequently employed mechanisms of signal transduction by eukaryotic cells, and starts with either Ca2+ release from intracellular stores or Ca2+ entry through the plasma membrane. In intracellular protist parasites Ca2+ signaling initiates a sequence of events that may facilitate their invasion of host cells, respond to environmental changes within …

Ca2+ entry at the plasma membrane and uptake by acidic stores is regulated by the activity of the V‐H+‐ATPase in Toxoplasma gondii

Donna Huber on April 1, 2021

Ca2+ is a universal intracellular signal that regulates many cellular functions. In Toxoplasma gondii, the controlled influx of extracellular and intracellular Ca2+ into the cytosol initiates a signaling cascade that promotes pathogenic processes like tissue destruction and dissemination. In this work we studied the role of proton transport in cytosolic Ca2+ homeostasis and the initiation of Ca2+ signaling. We …

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