Calpain inhibitor inhibits secretory granule maturation and secretion of GH

Ohkawa, Kiyoshi; Takada, Koji; Asakura, Tadashi; Hashizume, Yukio; Okawa, Yutaka; Tashiro, Kojiro; Ueda, Junko; Itoh, Yoshitaka; Hibi, Nozomu

doi:10.1097/00001756-200012180-00021

Cited by 10 publications

(7 citation statements)

References 12 publications

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“…This nCL-2-mediated COPI disassembly model is consistent with the report that calpain may be involved in the maturation of secretory granules via clathrin-adaptin uncoating by the limited proteolysis of clathrin and the adaptins (54). Moreover, the relationship between membrane trafficking and the calpains has been confirmed recently, e.g.…”

Section: Discussionsupporting

confidence: 91%

Stomach-specific Calpain, nCL-2, Localizes in Mucus Cells and Proteolyzes the β-Subunit of Coatomer Complex, β-COP

Hata

Koyama

Kawahara

et al. 2006

Journal of Biological Chemistry

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Calpain is a Ca2؉ -regulated cytosolic protease. Mammals have 14 calpain genes, half of which are predominantly expressed in specific organ(s); the rest are expressed ubiquitously. A defect in calpains causes lethality/pathogenicity, indicating their physiological indispensability. nCL-2/calpain-8a was identified as a stomach-specific calpain, whose physiological functions are unclear. To elucidate these, we characterized nCL-2 in detail. Unexpectedly, nCL-2 was localized strictly to the surface mucus cells in the gastric epithelium and the mucus-secreting goblet cells in the duodenum. Yeast twohybrid screening identified several nCL-2-intracting molecules. Of these, the ␤-subunit of coatomer complex (␤-COP) occurs in the stomach pit cells and is proteolyzed by nCL-2 in vitro. Furthermore, ␤-COP and nCL-2 co-expressed in COS7 cells co-localized in the Golgi, and Ca 2؉ -ionophore stimulation caused the proteolysis of ␤-COP near the linker region, resulting in the dissociation of ␤-COP from the Golgi. These results strongly suggest novel functions for nCL-2 that involve the membrane trafficking of mucus cells via interactions with coat protein.Calpain (EC 3.4.22.17) is an intracellular Ca 2ϩ -regulated cysteine protease, comprising a superfamily in most organisms, including some bacteria, budding yeasts, fungi, plants, and animals. Calpains proteolyze specific substrates at very limited sites to irreversibly modify/modulate their functions, structures, and activities, and are thus called "modulator proteases." Fourteen calpain genes have been identified in humans and mice and can be classified into two categories according to their expression, i.e. ubiquitous or tissue-specific (1-3). Ubiquitous -and m-calpains, two major calpains in mammals, form a heterodimer composed of a distinct 80-kDa catalytic large subunit (abbreviated to "CL" and "mCL," respectively) 2 and a common 30-kDa regulatory small subunit (30K). Calpain three-dimensional structures define four (I-IV) and two (V and VI) domains in the large and small subunits, respectively: the regulatory N-terminal domain (I), the protease domain (II), the C2-domain-like Ca 2ϩ /phospholipid-binding domain (III), the penta-EF-hand domains (IV and VI), and the Glyclustering domain (V) (4, 5). In the absence of Ca 2ϩ , the protease domain (II) is further divided into two subdomains, IIa and IIb, which form a single active domain upon binding to Ca 2ϩ (6, 7). Genetic studies in mammals and other organisms have clearly shown the physiological indispensability of the calpains. A gene knock-out mouse with a mutation in the gene for 30K, Capn4, exhibits embryonic lethality (8); mutations in the human gene for skeletal-muscle-specific p94/calpain 3, CAPN3, are responsible for limb-girdle muscular dystrophy type 2A (9); and a single nucleotide polymorphism in intron 3 of the human gene for calpain 10, CAPN10, is associated with type 2 diabetes (10). Mutations in the calpain genes of various other organisms, including yeasts, plants, nematodes, and Drosophila, result in sign...

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Section: Discussionsupporting

confidence: 91%

Stomach-specific Calpain, nCL-2, Localizes in Mucus Cells and Proteolyzes the β-Subunit of Coatomer Complex, β-COP

Hata

Koyama

Kawahara

et al. 2006

Journal of Biological Chemistry

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“…Our study elucidates the specific calpain cleavage of ␣-and ␤2-adaptins, confirms the cleavage of CALM, and shows for the first time that the accessory adaptors AP180 and epsin 1 are susceptible to calpain proteolysis. Interestingly, calpain-mediated proteolysis has also been suggested to regulate trans-Golgi AP-1-dependent trafficking of growth hormone-containing secretory vesicles (37), and proteolysis of ␤1-adaptin (attributed to caspase-3) has been implicated in the maturation of mouse bone marrow-derived dendritic cells (38).…”

Section: Discussionmentioning

confidence: 99%

Calpain Hydrolysis of α- and β2-Adaptins Decreases Clathrin-dependent Endocytosis and May Promote Neurodegeneration

Rudinskiy

Grishchuk

Vaslin

et al. 2009

Journal of Biological Chemistry

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Clathrin-dependent endocytosis is mediated by a tightly regulated network of molecular interactions that provides essential protein-protein and protein-lipid binding activities. Here we report the hydrolysis of the ␣-and ␤2-subunits of the tetrameric adaptor protein complex 2 by calpain. Calcium-dependent ␣-and ␤2-adaptin hydrolysis was observed in several rat tissues, including brain and primary neuronal cultures. Neuronal ␣-and ␤2-adaptin cleavage was inducible by glutamate stimulation and was accompanied by the decreased endocytosis of transferrin. Heterologous expression of truncated forms of the ␤2-adaptin subunit significantly decreased the membrane recruitment of clathrin and inhibited clathrin-mediated receptor endocytosis. Moreover, the presence of truncated ␤2-adaptin sensitized neurons to glutamate receptor-mediated excitotoxicity. Proteolysis of ␣-and ␤2-adaptins, as well as the accessory clathrin adaptors epsin 1, adaptor protein 180, and the clathrin assembly lymphoid myeloid leukemia protein, was detected in brain tissues after experimentally induced ischemia and in cases of human Alzheimer disease. The present study further clarifies the central role of calpain in regulating clathrin-dependent endocytosis and provides evidence for a novel mechanism through which calpain activation may promote neurodegeneration: the sensitization of cells to glutamate-mediated excitotoxicity via the decreased internalization of surface receptors.

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“…Calpain 1 and 2 were found to be linked to coated vesicles in K562 cells and pituitary cells (Sato et al 1995;Ohkawa et al 2000). It was suggested that in mucosa cells calpain dissociates b-coat protein and triggers vesicular trafficking (Hata et al 2006).…”

Section: Possible Calpain Substrates That Regulate Facilitation and Ptpmentioning

confidence: 99%

Activity-dependent calpain activation plays a critical role in synaptic facilitation and post-tetanic potentiation

Khoutorsky¹,

Spira²

2009

Learn. Mem.

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Synaptic facilitation and post-tetanic potentiation (PTP) are believed to necessitate active regeneration of the release machinery and supply of synaptic vesicles to a ready-releasable site. The prevailing hypothesis assumes that synapsins play pivotal roles in these processes. Using a cholinergic synapse formed between cultured Aplysia neurons (B2 and MCn), we demonstrate here that the calcium-activated protease-calpain serves as a major regulating element in the cascade that links electrical activity, elevation of the free intracellular calcium concentration, and short-term synaptic enhancements such as facilitation and PTP. Our study revealed that calpain inhibitors (calpeptin and MG132) transform a facilitating synapse into a depressing one, and reduce its PTP by 80.6%. Inhibition of CaM kinases, PKA, and MAPK also reduced PTP at this synapse. When inhibitors of these kinases were applied together with calpeptin, tetanic stimuli led to synaptic depression. We concluded that at this synapse facilitation and PTP are mediated mainly by the calpain-dependent processes and to a smaller extent by the CaMKs/PKA/MAPK-dependent cascades.

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Calpain inhibitor inhibits secretory granule maturation and secretion of GH

Cited by 10 publications

References 12 publications

Stomach-specific Calpain, nCL-2, Localizes in Mucus Cells and Proteolyzes the β-Subunit of Coatomer Complex, β-COP

Stomach-specific Calpain, nCL-2, Localizes in Mucus Cells and Proteolyzes the β-Subunit of Coatomer Complex, β-COP

Calpain Hydrolysis of α- and β2-Adaptins Decreases Clathrin-dependent Endocytosis and May Promote Neurodegeneration

Activity-dependent calpain activation plays a critical role in synaptic facilitation and post-tetanic potentiation

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