A major
direction in medical research leading to clinical applications targets the
regulation of intracellular calcium and the various human diseases associated
with an altered homeostasis of this global second messenger. These diseases
include, for example, cardiomyopathy, inflammation, brain disorders, diabetes,
and cancer. After entering the cell, Ca 2+ binds reversibly to specific Ca 2+
-binding and sensor proteins that fulfill multiple cellular functions. The
human genome contains over 200 genes coding for this large protein family,
characterized by a common helix–loop–helix structural motif, the EF-hand.
In the 1960s
troponin was discovered by Ebashi [1] as the first intracellular Ca 2+ -sensor protein,
regulating muscle contraction. Today highly sensitive cardiac-specific troponin
assays are routinely used in most hospitals to diagnose patients with acute
coronary syndrome (ACS). Calmodulin interacts with more than 300 variable
target sequences, regulating many biological functions. New strategies are
described in this book to quantify calmodulin–target interactions. These
techniques can be applied to analyze the interaction between any calcium-binding
protein with its binding partner. In 1971 muscle parvalbumin was the first Ca
2+ -binding protein to have its amino acid sequence and 3D structure resolved.
On this basis, Kretsinger developed the concept of the EF-hand structural
motif. Today parvalbumin is known as a marker of a subpopulation of GABAergic
neurons in the brain and as a major food allergen sharing the allergenic potential
of many other Ca 2+ -binding proteins. Parvalbumin and S100A1, when introduced by
gene therapy, are able to restore heart function in animal models. These and
other examples, included in this book, underline the diagnostic and clinical importance
of this family of proteins in human diseases and as drug targets. For example, longistatin—a
plasminogen activator from vector ticks (blood-sucking ectoparasites affecting humans
and animals)—is a candidate for the development of anti-tick vaccines. S100
proteins constitute the largest family within this EF-hand superfamily. Most
S100 genes are clustered on a region of human chromosome 1q21 that is prone to
chromosomal rearrangements.
Several S100
proteins are secreted, and they exert the role of cytokines through the
activation of various cell surface receptors, e.g., the Receptor for Advanced
Glycation End products (RAGE), an immunoglobulin-like multi-ligand receptor for
AGEs, amyloid beta peptides, HMGB1, TTR, and several S100 proteins. This
receptor and its ligands are associated with Alzheimer’s disease, inflammation
and cancer. The interaction of RAGE with its ligands is described, using the
Surface Plasmon Resonance (SPR) technology. Site specific blocking of RAGE by
specific inhibitors, antibodies, or selected peptides that target RAGE or its
ligands is also described, using phage display technology. This approach is
presently discussed as a therapeutic strategy to attenuate cell toxicity.
This volume is a
collection of chapters written by leading experts in the field, containing state-of-the-art,
lab-based methods and easy-to-follow protocols for daily use. These methods and
techniques are generally applicable—after modifications—and are not restricted
to Ca2+ -binding proteins and their targets.
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