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Welcome to the Integrated Department of Immunology at the University of Colorado - School of Medicine and National Jewish Health.

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Anne-Laure Perraud PhD

Associate Professor of Immunology


 Anne-Laure Perraud

 

 

 

 

Education: Max-Planck Institute Marburg, Germany-MS  Microbiology (1994), Biozentrum Wuerzburg, Germany-Ph.D. Microbiology 1998
E-mail: perrauda@NJHealth.org
Phone: 303-270 2078 (office), 303-270 2072 (lab) 
Dr. Perraud's National Jewish Health webpage

Receptor mediated oscillations or sustained increases in cytosolic free Ca2+ are a ubiquitous signaling mechanism in immune cells. The crucial role of Ca2+ in this context is illustrated by severe immunodeficiencies in patients with genetic defects in molecules involved in Ca2+-homeostasis regulation in immune cells. These signals are generated both by release of Ca2+ from intracellular stores (mainly from the ER) and by entry of extracellular Ca2+.

 

Ca2+ entry can be induced by the stimulation of receptors such as the B-cell (BCR) or T-cell receptor (TCR), or by non-receptor mediated events, such as stress due to oxidants or elevated temperatures. Whereas the molecular events leading to the first phase of cytoplasmic Ca2+ elevation through depletion of the intracellular stores are better understood, less is known about the mechanisms underlying Ca2+ entry from the outside. Molecular characterization of multiple ion channel families in the past two decades led to the surprising finding that immune cells, like excitable cells such as neurons, also have a great variety of different ion channels to their disposal.

 

Our research group is focusing on various aspects of Ca2+ signaling and more generally ion homeostasis regulation in immune cells. To this aim, we use a combinatory approach including genetics, biochemistry, and biophysical characterization of ion entry pathways in lymphocytes as well as in cells of the myleoid lineage.

 

 

The ADP-ribose and oxidant gated TRPM2 channel in immune cells and lung inflammation - In an effort to identify new potential ion channel candidates, using a bioinformatics screen, we identified, cloned, and completed a primary characterization of several members of a novel family of cation-channels (recently renamed TRPM) expressed in the immune context. Three members of this family show a feature unique among known channels, the presence of an active enzymatic domain, located at their C-terminus (“chanzymes”).

 

TRPM2 contains a so-called NUDIX domain showing ADP-ribose (ADPR) hydrolase activity. Based on this observation, we hypothesized that ADPR might also be involved in channel regulation and could show in patch-clamp experiments that TRPM2 is a Ca2+-permeable channel intracellularly gated by ADPR, a metabolite of NAD-metabolism.

 

One circumstance under which ADPR might be produced is oxidative stress, as known consequences include NAD depletion and breakdown in the mitochondrial subcompartment, as well as in the nucleus. In experiments using the fluorescent calcium indicator dye Fura-2 to monitor cytoplasmic Ca2+ concentration changes, only HEK293 cells overexpressing TRPM2 show cytoplasmic Ca2+ elevation following oxidative stress through external application of H2O2. These results support the idea of TRPM2 and ADPR as part of a novel signaling pathway directly linking oxidative stress to Ca2+ entry from the extracellular space via the ADPR gating of the TRPM2 channels located in the plasma membrane.

 

In order to define the biological function of TRPM2, we study the signaling properties of ADPR and related compounds. Research projects include the characterization of ADPR-metabolism and its regulation using biochemical, cellular, molecular and genetic approaches to measure spatial and temporal patterns of ADPR-production in immune cells. Furthermore, we have started extensive structure-function relationship studies of TRPM2, as well as analyses of TRPM2 in vivo expression in immunocytes, utilizing TRPM2-deficient mouse strains in combination with models of infection or of other diseases. We find that TRPM2 plays en essential role in innate immunity, partly by regulating the production of cytokines.

Another project focuses on understanding the role of TRPM2 in the lung. In particular, we would like to investigate the role of TRPM2 in the context of the healthy lung in comparison to the lung of cystic fibrosis or asthma patients.

 

L-type channel variants in the immune system: Originally thought to be signature molecules of excitability, variants of the voltage-gated Ca2+-channels of the “L-type” have unexpectedly also been found to be expressed in immune cells. As these channels have been used already for decades as therapeutic targets to treat hypertension and other cardiac ailments, it is important to explore their potential as immunomodulatory drugs. Patients with known genetic deficiencies in these channels have severe cardiac malfunctions, but also immune deficiencies. We aim at elucidating the role these channels are playing in B-lymphocyte function in cellular and mouse models.

 

Mg2+-homeostasis regulation in the immune system: Hypomagnesia is very common, affecting a vast proportion of the US population, mostly because of nutritional deficiencies in this vital ion. Clinically, Mg2+-deficiency has been associated with multiple conditions, including exacerbation of asthma, diabetes, heart diseases, and weakening of the immune response. Despite the abundance and ubiquitous use of Mg2+ in all forms of life, and the well documented, crucial role of this cation in cellular physiology and human health, extremely little is known about molecular components and mechanisms acting to regulate Mg2+-homeostasis, especially in vertebrates. Over the last two decades, a growing number of studies in different cellular systems have demonstrated that Mg2+ homeostasis is a very dynamic process, with multiple and complex forms of regulation that plays an underestimated role in managing cell function and metabolism. Several projects in the lab aim at understanding how various transporters in the plasma membrane as well as in intracellular membranes from organelles impact Mg2+-homeostasis and immune cell function.

 

 

View of Recent Publications in PubMed