Actin smooth muscle

In Section II, we will concentrate on characterizing smooth muscle actin and its isoforms, primarily from a biochemical perspective. In Section III, we will present our current understanding of the structure of native actin assemblies, that is, of thin filaments, which is based largely on analysis of electron microscope images. 

Different smooth muscles all contain large quantities of actin ranging from about 30 to 50 mg/g wet weight, corresponding to approximately 0.9-1.6 mM in situ (Murphy et al., 1977 Hartshorne, 1987). Actin consequently accounts for between 30 and 50% of the total noncollagenous proteins in smooth muscle. As with skeletal muscle, smooth muscle actin can exist in vitro in two forms, namely, monomeric- globular G-actin and polymeric-filamentous F-actin. The mo- 

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Considering the ubiquitous distribution of actin and its highly conserved amino acid sequence, it is not surprising that actin is a poor antigen, regardless of its source. Cavadore et al. (1987), however, were able 

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The superstructure of smooth muscle actin filaments is differentiated from those of striated muscle by the absence of the troponins and the lateral organization by association of the filaments with dense bodies instead of with the Z-line. How these differences are encoded is again not at all clear. However, the myofibrillar structure and the alignment of the alternating actin and myosin filaments is apparently due primarily to dense bodies and the actin-actinin macrostructures. As the bent dumbbell shaped actins assemble into filaments they are all oriented in the same direction. The S-1 fragments of myosin will bind to actin filaments in vitro and in... 

Gallucci RM, Lee EG, Tomasek JJ. IL-6 modulates alpha-smooth muscle actin expression in dermal fibroblasts from IL-6-deficient mice. J Invest Dermatol 2006 126(3) 561-568. 

Fig. 5.2 Immunofluorescent demonstration of smooth muscle actin (FITC, green channel) in the blood vessel wall of the human kidney. Red autofluorescence of erythrocytes, elastic lamellae and kidney tubules was captured with a filter exciting the autofluorescence in red spectrum under a longer exposure than with the filter exciting specific fluorescence in the green spectrum. Nuclei are counterstained with DAPI (blue channel)...

Immunohistochemical analyses were performed using antibodies recognizing smooth muscle actin (SMA), troponin-T (Trop-T), troponin T-C (Trop T-C), myosin heavy chain (MHC), muscle actin (MA), a-actinin, a-SR-1, desmin, connexin-43, fibroblasts (all antibodies from Dako, Denmark). For fluorescent immunohistochemistry the AlexaFluor 594 goat anti mouse secondary antibody (Molecular Probes, Leiden, The Netherlands) was used. In addition, cell nuclei were stained using DAPI. 

Fig. 7.4 Top) Dil-positive stem cells (red) in the midmyocardium of the anterolateral wall. Middle) a-Smooth muscle actin staining with FITC green) showing cross-section of vessel wall. Bottom) Stained areas show colocalization yellow) of stem cells and smooth muscle cells, suggesting transformation of stem cells into smooth muscle cells. The vessel shown is in the myocardial interstitium. Arrows point to vessel media. Reprinted from [63]...

Fig. 7.15 Number of capillaries per mm in anterolateral, posterior, and septal walls of studied heart. (A) Anti-factor Vlll-associated antigen counterstained with hematoxylin. (B) Anti-smooth muscle-actin antigen counterstained with hematoxylin. (C) Capillaries reacted with anti-factor VIII-associated antigen inside fibrotic areas only in anterolateral and posterior walls, n = 108 microscope fields for A 96...

Additional information <1> (<1> isozyme of calmodulin-dependent multifunctional protein kinase II in smooth-muscle [5] <1> caldesmon is not a substrate of smooth-muscle myosin light-chain kinase [3] <1> no substrates are bovine cardiac C-protein, bovine brain fodrin, rabbit skeletal muscle glycogen synthase, phosphorylase B, troponon (I -I- T -I- C), actin, tropomyosin, smooth-muscle actin, filamin, vinculin, cr-actinin, protamine or phosvitin [1]) [1-3]... 

Ngai, P.K. Walsh, M.P. Inhibition of smooth muscle actin-activated myosin Mg -ATPase activity by caldesmon. J. Biol. Chem., 259, 13656-13659 (1984)... 

Accurate flow cytometric measurements depend on clear discrimination between intact cells and cellular debris. Both cytoplasmic (bcl-2, CD68, lipocortin-1, a-smooth muscle actin, and desmin) and nuclear antigens (p53, PCNA, Ki-67) have been simultaneously detected with this combined protocol (Lan et al., 1996 Millard et al., 1998). 

By using antibodies to alpha smooth muscle actin, we were able to identify activated fibroblasts (myofibroblasts). These contractile fibroblasts actively make collagen in contrast to quiescent fibroblasts. The increase in number of myofibroblasts after implantation was very similar to the increase in response to TGF-p,16 and this finding is consistent with the concept that one of the major roles of TGF-p is to activate fibroblasts in part to stimulate the formation of collagen. 

L. RubbiaBrandt, G. Mentha, A. Desmouliere, A. M. A. Costa, E. Giostra, G. Mo-las, H. Enzan, and G. Gabbiani, Hepatic stellate cells reversibly express alpha-smooth muscle actin during acute hepatic ischemia, Transplant Proc. 29 2390-2395 (1997). 

Willems, I.E., Havenith, M.G., De Mey, J.G., and Daemen, M.J. 1994. The alpha-smooth muscle actin-positive cells in healing human myocardial scars. Am. J. Pathol. 145 868-875. 

SMA SSEA-I smooth muscle actin stage-specific embryonic antigen characterized as a glycosphingolipid similar to Ii (MHC invariant chain)... 

Isolated chondrocytes grown in type I and type II collagen-glycosaminoglycan matrices contract the matrix and immunochemically stain for alpha-smooth muscle actin. These results suggest that chondrocytes can also generate active tension and may be responsible for maintaining the tension in articular cartilage. 

Yonenaga Y, Mori A, Onodera H, Yasuda S, Oe H, Fujimoto A, et al. Absence of smooth muscle actin-positive pericyte coverage of tumor vessels correlates with hematogenous metastasis and prognosis of colorectal cancer patients. Oncology 2005 69 159-166. 

Johnson RJ, llda H, Alpers CE, Majesky MW, Schwartz SM, Pritzl P, Gordon K, and Gown AM. Expression of smooth muscle cell phenotype by rat mesangial cells In Immune complex nephritis. Alpha-smooth muscle actin Is a marker of mesangial cell proliferation. J Clin Invest 87 847-858,1991. 

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