Strategies for Elucidating Immunological Mechanisms in Intestinal Smooth Muscle Pathophysiology
William J. Snape, Stephen M. Collins in Effects of Immune Cells and Inflammation on Smooth Muscle and Enteric Nerves, 2020
Interestingly, a spectrum of growth factors, including: fibroblast growth factor (FGF), transforming growth factor (TGF)-β and insulin-like growth factor (IGF)-I and II can modulate the proliferation and differentiation of myoblasts.18 For example, IGF-I and II promote myoblast proliferation and differentiation by a mechanism that involves enhanced expression of the oncogene c-fos. By contrast, TGF-β blocks myogenic differentiation and FGF blocks differentiation and facilitates myoblast proliferation. Florini and Magri18 reviewed the information that, in addition to modulating the proliferation and differentiation of myoblasts, these growth factors influence the activities of mature skeletal and cardiac muscle cells in adult mammals. Whether or not these and other growth factors are an integral part of the altered functional phenotype of inflamed smooth muscle, either through actions directly on gene expression or responsiveness of the muscle, or indirectly through effects on the neural networks or interstitial cells, remains to be tested. Alterations in gene expression in muscle cells could regulate responsiveness through multiple pathways ranging from receptor numbers to the amounts or functions of contractile proteins.
Actin and Myosin
Masahiko Mori in Histochemistry of the Salivary Glands, 2019
In normal and abnormal salivary glands, myosin and actin were mainly demonstrable in myoepithelial cells and ductal segments. Myoepithelial cells are evident surrounding acinar cells and between basal lamina of exocrine glands (salivary, lacrimal, and mammary). Their biologic features differ from smooth muscle cells in that they exhibit epithelial features. Scanning electronmicroscopic studies of myoepithelial cells in submandibular glands reveal stellate shapes with many processes, but those in parotid glands lack the terminal portion.9 Electronmicroscopic features of myoepithelial cells in salivary glands have been described in detail.10–12 The histogenesis of myoepithelial cells has been reported.13–15 Tumor cells in salivary gland tumors also stained variably.22–25 These contractile proteins may contribute to contraction, and participate in the integration and regulation of cytoplasmic organelles in cells.26–28
Cardiac Subcellular Function During Diabetes
Grant N. Pierce, Robert E. Beamish, Naranjan S. Dhalla in Heart Dysfunction in Diabetes, 2019
Many individual proteins constitute the contractile protein complex. Because of this, it is possible to separate these proteins by various biochemical means into distinct preparations of varying purity.2 Several preparations of contractile proteins are presently examined routinely by many laboratories across the world but four fractions have achieved widespread use: myofibril, actomyosin, myosin, and the heavy meromyosin. The myofibrillar preparation contains a more complete complement of contractile proteins and, therefore, may represent a closer approximation of the physiological setting.2 However, many experiments require a purer preparation of contractile proteins to avoid possible errors in interpretation of results. The myosin or heavy meromyosin preparations represent attempts to purify the contractile proteins to a single protein or protein subunit. Each preparation has its own advantages and disadvantages2 and such considerations will limit the value of the conclusions which are obtained.
Modulation of the airway smooth muscle phenotype in a murine asthma model and effects of nuclear factor-κB inhibition
Published in Journal of Asthma, 2019
Chen Qiu, Jie Li, Jian Zhang, Qi He, Lingwei Wang, Xuanwen Weng, Minjie Guan
Three genes encoding the contractile proteins of ASMC were studied by real-time PCR: α-smooth muscle actin, calponin and SM-MHC. α-Smooth muscle actin, calponin and SM-MHC mRNAs were dramatically decreased in OVA + vehicle mice compared with those in naive controls in the chronic model (Figure 1(B)). In the acute model, only one out of three genes (calponin) was down-regulated with statistical significance in OVA + vehicle mice (Figure 1(C)). PDTC treatment partially reversed the down-regulation of contractile gene expression in both the acute and chronic models. We also assessed COLIA1 mRNA expression in the intrapulmonary airways. Although OVA + vehicle mice demonstrated increased expression of COLIA1 that was significantly decreased by PDTC treatment in the acute model, there were no significant differences between the groups in the chronic model.
Effects of chronic treatment with gold nanoparticles on inflammatory responses and oxidative stress in Mdx mice
Published in Journal of Drug Targeting, 2020
Daniela Pacheco dos Santos Haupenthal, Jonathann Corrêa Possato, Rubya Pereira Zaccaron, Carolini Mendes, Matheus Scarpatto Rodrigues, Renata Tiscoski Nesi, Ricardo Aurino Pinho, Paulo Emilio Feuser, Ricardo Andrez Machado-de-Ávila, Clarissa M. Comim, Paulo Cesar Lock Silveira
The aetiology of this myopathy is explained by a deficiency of dystrophin, a protein considered a key component of the glycoprotein complex present in the sarcolemma. This protein plays a crucial role in the protection and integrity of muscle fibres by providing a stabilising bond between the actin cytoskeleton and the cell membrane. The protein also mediates signalling between the extracellular matrix, the cell membrane and the cytoskeleton [2]. A deficiency in this protein impedes muscle contraction and causes cellular lesions. Subsequent damage to the membrane of muscle fibres leads to increased intracellular calcium concentrations and the activation of proteases, triggering inflammation, mitochondrial dysfunction, connective tissue proliferation, adipose infiltration and cell death [3]. According to Evans et al. [4], an increase in physical activity by patients with dystrophin deficiency increases the production of reactive oxygen species (ROS), which alters cell homeostasis and modifies the cells signalling state. In turn, the nuclear factor kappa B pathway (NF-kB) is activated. This factor is linked to the cellular inflammatory pathway and cell survival.
Human cochlear microanatomy – an electron microscopy and super-resolution structured illumination study and review
Published in Hearing, Balance and Communication, 2020
Wei Liu, Rudolf Glueckert, Annelies Schrott-Fischer, Helge Rask-Andersen
Contractile mechanisms along microtubule bundles seem to be of importance for active vibratory responses during hearing, in animals as well as in humans. Inner and OHCs stereocilia and cuticular plates contain contractile elements such as actin together with an intricate cross-linking molecular machinery whose organization is still poorly understood [9]. Actin filaments and microtubules can crosslink in OHCs [10,11]. Contractile proteins were described in supporting cells in guinea pigs by Flock et al. [12] and were noted to be giving stability to the cells. They contain non-muscle β- and γ actin isoforms and α-actinin [13,14] whereas the cuticular plate contains actin, α-actinin, myosin, tropomyosin, spectrin, profilin and fodrin [10,15]. Non-muscle actin subunits are present in human Deiters cells, IPCs and OPCs and contain a remarkable three-dimensional (3D) interacting skeletal system of actin strands and microtubules anchored to the plasma cell membranes (Figure 3). Opposing pillars appear to be coupled with functional elements to relay basilar membrane (BM) vibrations to the reticular lamina (RL) and sensory hair cells that have no direct contact with the BM (Figure 4). In humans, TEM shows a dense meshwork associated with cell junctional complexes at the plasma membrane referred to as surfoskelosomes [13]. These are located in the pillar heads and foot (basal bodies) that contain organized actin and are closely associated with microtubules [16]. Deiters’ cells also express organized actin in basal bodies. Border and phalangeal cells around the IHCs do not express cytoplasmic actin possibly since they are positioned on a rigid fundament operative as principal sensory receptors.
Related Knowledge Centers
- Actin
- Action Potential
- Motor Neuron
- Motor Protein
- Myosin
- Nervous System
- Physiology
- Synapse
- Muscle Cell
- Sliding Filament Theory