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Physiological Reviews Jul 2003The calpain system originally comprised three molecules: two Ca2+-dependent proteases, mu-calpain and m-calpain, and a third polypeptide, calpastatin, whose only known... (Review)
Review
The calpain system originally comprised three molecules: two Ca2+-dependent proteases, mu-calpain and m-calpain, and a third polypeptide, calpastatin, whose only known function is to inhibit the two calpains. Both mu- and m-calpain are heterodimers containing an identical 28-kDa subunit and an 80-kDa subunit that shares 55-65% sequence homology between the two proteases. The crystallographic structure of m-calpain reveals six "domains" in the 80-kDa subunit: 1). a 19-amino acid NH2-terminal sequence; 2). and 3). two domains that constitute the active site, IIa and IIb; 4). domain III; 5). an 18-amino acid extended sequence linking domain III to domain IV; and 6). domain IV, which resembles the penta EF-hand family of polypeptides. The single calpastatin gene can produce eight or more calpastatin polypeptides ranging from 17 to 85 kDa by use of different promoters and alternative splicing events. The physiological significance of these different calpastatins is unclear, although all bind to three different places on the calpain molecule; binding to at least two of the sites is Ca2+ dependent. Since 1989, cDNA cloning has identified 12 additional mRNAs in mammals that encode polypeptides homologous to domains IIa and IIb of the 80-kDa subunit of mu- and m-calpain, and calpain-like mRNAs have been identified in other organisms. The molecules encoded by these mRNAs have not been isolated, so little is known about their properties. How calpain activity is regulated in cells is still unclear, but the calpains ostensibly participate in a variety of cellular processes including remodeling of cytoskeletal/membrane attachments, different signal transduction pathways, and apoptosis. Deregulated calpain activity following loss of Ca2+ homeostasis results in tissue damage in response to events such as myocardial infarcts, stroke, and brain trauma.
Topics: Animals; Calcium-Binding Proteins; Calpain; Humans; Protein Conformation; Substrate Specificity
PubMed: 12843408
DOI: 10.1152/physrev.00029.2002 -
International Journal of Molecular... Nov 2023Calpain is defined as a member of the superfamily of cysteine proteases possessing the CysPC motif within the gene. Calpain-1 and -2, which are categorized as... (Review)
Review
Calpain is defined as a member of the superfamily of cysteine proteases possessing the CysPC motif within the gene. Calpain-1 and -2, which are categorized as conventional isozymes, execute limited proteolysis in a calcium-dependent fashion. Accordingly, the calpain system participates in physiological and pathological phenomena, including cell migration, apoptosis, and synaptic plasticity. Recent investigations have unveiled the contributions of both conventional and unconventional calpains to the pathogenesis of cardiometabolic disorders. In the context of atherosclerosis, overactivation of conventional calpain attenuates the barrier function of vascular endothelial cells and decreases the immunosuppressive effects attributed to lymphatic endothelial cells. In addition, calpain-6 induces aberrant mRNA splicing in macrophages, conferring atheroprone properties. In terms of diabetes, polymorphisms of the calpain-10 gene can modify insulin secretion and glucose disposal. Moreover, conventional calpain reportedly participates in amino acid production from vascular endothelial cells to induce alteration of amino acid composition in the liver microenvironment, thereby facilitating steatohepatitis. Such multifaceted functionality of calpain underscores its potential as a promising candidate for pharmaceutical targets for the treatment of cardiometabolic diseases. Consequently, the present review highlights the pivotal role of calpains in the complications of cardiometabolic diseases and embarks upon a characterization of calpains as molecular targets.
Topics: Humans; Calpain; Endothelial Cells; Proteolysis; Atherosclerosis; Amino Acids
PubMed: 38069105
DOI: 10.3390/ijms242316782 -
Current Neuropharmacology 2019While the calpain system has now been discovered for over 50 years, there is still a paucity of information regarding the organization and functions of the signaling... (Review)
Review
While the calpain system has now been discovered for over 50 years, there is still a paucity of information regarding the organization and functions of the signaling pathways regulated by these proteases, although calpains play critical roles in many cell functions. Moreover, calpain overactivation has been shown to be involved in numerous diseases. Among the 15 calpain isoforms identified, calpain-1 (aka µ-calpain) and calpain-2 (aka m-calpain) are ubiquitously distributed in most tissues and organs, including the brain. We have recently proposed that calpain-1 and calpain- 2 play opposite functions in the brain, with calpain-1 activation being required for triggering synaptic plasticity and neuroprotection (Dr. Jekill), and calpain-2 limiting the extent of plasticity and being neurodegenerative (Mr. Hyde). Calpain-mediated cleavage has been observed in cytoskeleton proteins, membrane-associated proteins, receptors/channels, scaffolding/anchoring proteins, and protein kinases and phosphatases. This review will focus on the signaling pathways related to local protein synthesis, cytoskeleton regulation and neuronal survival/death regulated by calpain-1 and calpain-2, in an attempt to explain the origin of the opposite functions of these 2 calpain isoforms. This will be followed by a discussion of the potential therapeutic applications of selective regulators of these 2 calpain isoforms.
Topics: Amino Acid Sequence; Animals; Calpain; Humans; Neuronal Plasticity; Signal Transduction; Synapses
PubMed: 30819083
DOI: 10.2174/1570159X17666190228112451 -
Trends in Neurosciences Apr 2016Many signaling pathways participate in both synaptic plasticity and neuronal degeneration. While calpains participate in these phenomena, very few studies have evaluated... (Review)
Review
Many signaling pathways participate in both synaptic plasticity and neuronal degeneration. While calpains participate in these phenomena, very few studies have evaluated the respective roles of the two major calpain isoforms in the brain, calpain-1 and calpain-2. We review recent studies indicating that calpain-1 and calpain-2 exhibit opposite functions in both synaptic plasticity and neurodegeneration. Calpain-1 activation is required for the induction of long-term potentiation (LTP) and is generally neuroprotective, while calpain-2 activation limits the extent of potentiation and is neurodegenerative. This duality of functions is related to their associations with different PDZ-binding proteins, resulting in differential subcellular localization, and offers new therapeutic opportunities for a number of indications in which these proteases have previously been implicated.
Topics: Animals; Brain; Calpain; Humans; Nerve Degeneration; Neuronal Plasticity
PubMed: 26874794
DOI: 10.1016/j.tins.2016.01.007 -
Journal of Atherosclerosis and... 2013This review highlights the pro-atherogenic roles of Ca(2+)-sensitive intracellular protease calpains. Among more than ten species of calpain isozymes, µ- and m-calpains... (Review)
Review
This review highlights the pro-atherogenic roles of Ca(2+)-sensitive intracellular protease calpains. Among more than ten species of calpain isozymes, µ- and m-calpains have been characterized most extensively. These two isozymes are ubiquitously expressed in mammalian tissues, including blood vessels, and tightly regulate functional molecules in the vascular component cells through limited proteolytic cleavage. Indeed, previous cell-based experiments showed that calpains play significant roles in nitric oxide production in vascular endothelial cells (ECs), maintenance of EC barrier function and angiogenesis for maintaining vascular homeostasis. Recently, we demonstrated that modified-low density lipoprotein (LDL)-induced m-calpain causes hyperpermeability in ECs, leading to the infiltration of monocytes/macrophages and plasma lipids into the intimal spaces (Miyazaki T. et al., Circulation. 2011; 124: 2522-2532). Calpains also mediate oxidized LDL-induced apoptotic death in ECs. In monocytes/macrophages, calpains induce proteolytic degradation of ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1), which results in impaired cholesterol efflux and subsequent macrophage foam cell formation. In vascular smooth muscle cells, calpains may be involved in the conversion from contractile phenotype to proliferative phenotype. In hepatocytes, calpains disrupt the biogenesis of high-density lipoprotein via proteolytic degradation of ABCA1. Thus, calpains may serve as novel candidate molecular targets for control of atherosclerosis.
Topics: Atherosclerosis; Calpain; Humans; Macrophages; Monocytes
PubMed: 23171729
DOI: 10.5551/jat.14787 -
Cells Dec 2020Calpains are a family of soluble calcium-dependent proteases that are involved in multiple regulatory pathways. Our laboratory has focused on the understanding of the... (Review)
Review
Calpains are a family of soluble calcium-dependent proteases that are involved in multiple regulatory pathways. Our laboratory has focused on the understanding of the functions of two ubiquitous calpain isoforms, calpain-1 and calpain-2, in the brain. Results obtained over the last 30 years led to the remarkable conclusion that these two calpain isoforms exhibit opposite functions in the brain. Calpain-1 activation is required for certain forms of synaptic plasticity and corresponding types of learning and memory, while calpain-2 activation limits the extent of plasticity and learning. Calpain-1 is neuroprotective both during postnatal development and in adulthood, while calpain-2 is neurodegenerative. Several key protein targets participating in these opposite functions have been identified and linked to known pathways involved in synaptic plasticity and neuroprotection/neurodegeneration. We have proposed the hypothesis that the existence of different PDZ (PSD-95, DLG and ZO-1) binding domains in the C-terminal of calpain-1 and calpain-2 is responsible for their association with different signaling pathways and thereby their different functions. Results with calpain-2 knock-out mice or with mice treated with a selective calpain-2 inhibitor indicate that calpain-2 is a potential therapeutic target in various forms of neurodegeneration, including traumatic brain injury and repeated concussions.
Topics: Animals; Brain; Calpain; Cell Death; Humans; Neuronal Plasticity; Neurons; Neuroprotection
PubMed: 33339205
DOI: 10.3390/cells9122698 -
The Journal of Allergy and Clinical... Jun 2017Calpains are a family of intracellular, calcium-dependent cysteine proteases involved in a variety of regulatory processes, including cytoskeletal dynamics, cell-cycle... (Review)
Review
Calpains are a family of intracellular, calcium-dependent cysteine proteases involved in a variety of regulatory processes, including cytoskeletal dynamics, cell-cycle progression, signal transduction, gene expression, and apoptosis. These enzymes have been implicated in a number of disease processes, notably for this review involving eosinophilic tissue inflammation, such as eosinophilic esophagitis (EoE), a chronic inflammatory disorder triggered by allergic hypersensitivity to food and associated with genetic variants in calpain 14 (CAPN14). Herein we review the genetic, structural, and biochemical properties of CAPN14 and its gene product CAPN14, and its emerging role in patients with EoE. The CAPN14 gene is localized at chromosome 2p23.1-p21 and is most homologous to CAPN13 (36% sequence identity), which is located 365 kb downstream of CAPN14. Structurally, CAPN14 has classical calpain motifs, including a cysteine protease core. In comparison with other human calpains, CAPN14 has a unique expression pattern, with the highest levels in the upper gastrointestinal tract, particularly in the squamous epithelium of the esophagus. The CAPN14 gene is positioned in an epigenetic hotspot regulated by IL-13, a T2 cytokine with increased levels in patients with EoE that has been shown to be a mediator of the disease. CAPN14 induces disruptive effects on the esophageal epithelium by impairing epithelial barrier function in association with loss of desmoglein-1 expression and has a regulatory role in repairing epithelial changes induced by IL-13. Thus CAPN14 is a unique protease with distinct tissue-specific expression and function in patients with EoE and is a potential therapeutic target for EoE and related eosinophilic and allergic diseases.
Topics: Animals; Calpain; Eosinophilic Esophagitis; Humans; Protein Conformation
PubMed: 28131390
DOI: 10.1016/j.jaci.2016.09.027 -
International Journal of Molecular... Jul 2023The intercalated disk is a cardiac specific structure composed of three main protein complexes-adherens junctions, desmosomes, and gap junctions-that work in concert to... (Review)
Review
The intercalated disk is a cardiac specific structure composed of three main protein complexes-adherens junctions, desmosomes, and gap junctions-that work in concert to provide mechanical stability and electrical synchronization to the heart. Each substructure is regulated through a variety of mechanisms including proteolysis. Calpain proteases, a class of cysteine proteases dependent on calcium for activation, have recently emerged as important regulators of individual intercalated disk components. In this review, we will examine how calcium homeostasis regulates normal calpain function. We will also explore how calpains modulate gap junctions, desmosomes, and adherens junctions activity by targeting specific proteins, and describe the molecular mechanisms of how calpain dysregulation leads to structural and signaling defects within the heart. We will then examine how changes in calpain activity affects cardiomyocytes, and how such changes underlie various heart diseases.
Topics: Calpain; Calcium; Myocardium; Myocytes, Cardiac; Adherens Junctions
PubMed: 37511485
DOI: 10.3390/ijms241411726 -
The FEBS Journal Apr 2012Apparently unrelated systems often merge and work together to achieve diverse biological functions. This minireview series was aimed to unveil new facets of ESCRTs and...
Apparently unrelated systems often merge and work together to achieve diverse biological functions. This minireview series was aimed to unveil new facets of ESCRTs and calpains: ESCRT proteins in MVB formation, virus budding and cell division; the ambient pH sensing and adaptation in association with ESCRTs and the calpain system; evolutionary and physical linkage between calpains and PEF proteins.
Topics: Animals; Calpain; Endosomal Sorting Complexes Required for Transport; Humans; Multivesicular Bodies
PubMed: 22404913
DOI: 10.1111/j.1742-4658.2012.08561.x -
Biochimie Mar 2016Calpains are Ca(2+)-regulated proteolytic enzymes that are involved in a variety of biological phenomena. Calpains process substrates by limited proteolysis to modulate... (Review)
Review
Calpains are Ca(2+)-regulated proteolytic enzymes that are involved in a variety of biological phenomena. Calpains process substrates by limited proteolysis to modulate various protein functions in the cell, and are thus called "modulator proteases." CAPN3, previously called p94 or calpain-3, has unique features that are not found in any of the other 14 human calpains, or even in other proteases. For instance, CAPN3 undergoes extremely rapid and exhaustive autodegradation. CAPN3 is also the first (and so far, the only) intracellular enzyme found to depend on Na(+) for its activation. CAPN3 has both proteolytic and non-proteolytic functions. It has the interesting distinction of being the only protease, other than a few virus proteases, with the ability to regain protease function after its autolytic dissociation; this occurs through a process known as intermolecular complementation (iMOC). Gene mutations causing CAPN3 defects are responsible for limb-girdle muscular dystrophy type 2A (LGMD2A). Unusual characteristics of CAPN3 have fascinated researchers, but have also hampered conventional biochemical analysis. In this review, we describe significant findings about CAPN3 from its discovery to the present, and suggest promising avenues for future CAPN3 research.
Topics: Calpain; Gene Expression Profiling; Genetic Predisposition to Disease; Humans; Models, Genetic; Muscle Proteins; Muscular Dystrophies, Limb-Girdle; Mutation; Proteolysis; Sodium; Substrate Specificity
PubMed: 26363099
DOI: 10.1016/j.biochi.2015.09.010