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Ankana Ganguly, Jennifer A Tamblyn, Alexandra Shattock, Annsha Joseph, Dean P Larner, Carl Jenkinson, Janesh Gupta, Janesh R Gross, and Martin Hewison

. These include a potential role as a macrophage-activation factor ( Benis & Schneider 1996 ), and in fatty acid transport ( Calvo & Ena 1989 ). DBP also binds the monomeric, globular form of actin (G-actin) with high affinity, allowing DBP to compete with

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M Yoneda, T Nishizaki, K Tasaka, H Kurachi, A Miyake, and Y Murata

Using digitonin-permeabilized GH3 cells, we investigated both the release of prolactin (PRL) and changes in the cytoskeleton. We determined that permeabilized GH3 cells released PRL in a dose-dependent manner upon addition of micromolar Ca(2+). Phalloidin, a filamentous actin (F-actin) stabilizing agent, inhibited both Ca(2+)-dependent and -independent PRL release, whereas cytochalasin B, a destabilizing agent, had almost no effect on the release. Observation with a confocal laser scanning microscope revealed that F-actin existed mainly in the cortical region in the quiescent state. Increased cytosolic Ca(2+) induced a change in F-actin distribution: F-actin in the cortical region decreased, whereas F-actin inside the cells increased. This change in F-actin distribution was not observed when phalloidin was added. Addition of cytochalasin B induced patchy F-actin spots, but the pattern of the changes of F-actin distribution did not change. The time course of change in F-actin distribution showed that the F-actin network in the cortical region was reduced within 1 min, and Ca(2+)-dependent release of PRL continued for up to 20 min. These results suggest that the F-actin network near the membrane acts as a barrier to exocytosis and that Ca(2+) directly controls the cytoskeletal changes.

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S Welle and C Thornton

Growth hormone (GH) increases the amount of insulin-like growth factor-I (IGF-I) mRNA in rat skeletal muscle, but this effect has not been demonstrated in human muscle. An autocrine effect of IGF-I produced in muscle may be an important determinant of the increased muscle mass associated with GH therapy. Thus, we examined IGF-I mRNA abundance in skeletal muscle biopsy samples taken 10 h after a subcutaneous injection of GH (0.03 mg/kg, n = 6) or placebo (normal saline, n = 5) in men and women over 60 years of age. Relative tissue concentrations of IGF-I mRNA were evaluated with a competitive reverse transcriptase-polymerase chain reaction assay. Mean plasma IGF-I concentrations rose steadily after the GH injection, and were 74% higher in the GH group than in the control group at the time of the muscle biopsies. There was no consistent difference between the GH and control groups in muscle IGF-I mRNA abundance when expressed in relation to total RNA or polyadenylated RNA. However, one GH-treated subject had three times more IGF-I mRNA, relative to polyadenylated RNA, than the average control subject. There was no effect of GH on levels of mRNAs encoding the most abundant myofibrillar proteins, actin and myosin heavy chain. These data do not support the hypothesis that increased IGF-I mRNA abundance in skeletal muscle is required for the anabolic effect of GH in people over 60 years of age.

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P Sluka, L O’Donnell, J R Bartles, and P G Stanton

). Typical AJs are found between Sertoli cells and are akin to those found in all classical epithelia. AJs are characterised by the presence of transmembrane, calcium-dependent cadherins that link to the actin cytoskeleton via catenins (see Lui et al

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Xiang Xiao, C Yan Cheng, and Dolores D Mruk

to associate with the actin cytoskeleton by binding various proteins such as α-actinin ( Heiska et al . 1996 ), ezrin ( Helander et al . 1996 ), radixin ( Hamada et al . 2001 ), and moesin ( Yonemura et al . 1998 ). Interestingly, ICAM2 clustering

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Kotaro Horiguchi, Tom Kouki, Ken Fujiwara, Takehiro Tsukada, Floren Ly, Motoshi Kikuchi, and Takashi Yashiro

studies that used living-cell imaging in primary culture of anterior pituitary cells to investigate FS cell network formation and found that FS cells extend and contract their cytoplasmic processes by rearranging their actin cytoskeleton, thereby

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Charlotte E Combs, Karen Fuller, Hashethra Kumar, Anthony P Albert, Grisha Pirianov, James McCormick, Ian C Locke, Timothy J Chambers, and Kevin M Lawrence

by a ruffled border and actin reorganisation ( Väänänen et al . 2000 ). Excessive resorption by these cells is the cause of several common diseases of bone, including osteoporosis. In this study we investigated the effects of UCN on the formation and

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Elizabeth I Tang, Dolores D Mruk, and C Yan Cheng

Introduction Eukaryotic cells, including those in health (e.g. spermatogenesis) and in disease (e.g. cancer cells during tumorigenesis), are structurally supported by three extensive cytoskeletal networks, which are composed of the actin

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Svetlana I Sofronova, Dina K Gaynullina, Anastasia A Shvetsova, Anna A Borzykh, Ekaterina K Selivanova, Daria S Kostyunina, Anna P Sharova, Andrey A Martyanov, and Olga S Tarasova

using test strips from Diacont (Moscow, Russia). qPCR mRNA contents of deiodinase 1 (D1), deiodinase 2 (D2), deiodinase 3 (D3), thyroid hormone receptor α 1 (TRα 1 ), α-actin, β-actin, SM22α, smooth muscle myosin heavy chains (SM-MHC), non

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Margarida Sancho, Joaquim Miguel Vieira, Cristina Casalou, Marta Mesquita, Teresa Pereira, Branca Maria Cavaco, Sérgio Dias, and Valeriano Leite

TCSISP2), with 63×1.4 oil objectives. Acquisition and image treatment were performed with the LSC software (Leica) and with ImageJ 1.33u software (USA). Actin polymerization assay TPC-1 cells, grown until 70% confluent