Immunohistochemical staining was performed using modified standard techniques and well\characterized monoclonal (mAb) and polyclonal (pAb) antibodies (Abs)

Immunohistochemical staining was performed using modified standard techniques and well\characterized monoclonal (mAb) and polyclonal (pAb) antibodies (Abs). nNOS was generally weak or absent, \dystroglycan and caveolin\3 showed a stronger immunostaining. The absence or a low expression of cytoskeletal proteins otherwise considered ubiquitous and important for integration and contraction of muscle cells indicate a unique cytoarchitecture designed to meet the intricate demands of the upper airway muscles. It can be concluded that a subgroup of muscle fibers in the human soft palate appears to have special biomechanical properties, and their LDN193189 Tetrahydrochloride unique cytoarchitecture must be taken into account while assessing function and pathology in oropharyngeal muscles. strong class=”kwd-title” Keywords: cytoskeleton, desmin, dystrophin, muscle fiber, palatopharyngeus, sleep apnea, soft palate, uvula Introduction The human soft palate is involved in diverse and intricate oropharyngeal functions, such as respiration, speech, swallowing and ventilation of the ear. Five pairs of muscles contribute to the formation and movements of the soft palate. Three of these, musculus uvula (UV), tensor veli palatini and levator veli palatini arise from bony attachment in the skull, while two, musculus palatopharyngeus (PP) and palatoglossus, ascend from the pharyngeal walls and the tongue, respectively. This special anatomy with lack of firm attachment at least at one end is a trait that palate muscles share with orofacial muscles. It has previously been shown that each of the palate muscles has a distinct morphological and molecular identity, and that they generally have more structural similarities with orofacial than with the limb muscles (St?l et?al. 1987, 1990, 1994, 1995; Kuehn & Kahane, 1990; St?l & Lindman, 2000). In recent years, the muscles of the soft palate have generated interest among researchers studying their role in sleep\disordered breathing as well as in the pathophysiology of swallowing and speech disorders. The internal framework of the muscle cell, the cytoskeleton, is composed of a network of protein filaments that extends throughout the cytosol of the cell. These proteins play an important role in sarcomeric movements by linking the contractile apparatus to the sarcolemma and extracellular matrix LDN193189 Tetrahydrochloride (ECM). The cytoskeleton also has important roles in cell shape, signal transduction, growth, division and differentiation, as well as in the movement of organelles within the cell (Capetanaki et?al. 2007). In skeletal muscles the major elements of the cytoskeleton are the intermediate filaments (IFs; Paulin & Li, 2004). Desmin is the most abundant IF in mature muscles, and it plays a central role in the integration of structure and function of the muscles. This protein is located at the periphery LDN193189 Tetrahydrochloride of the Z\disc and links the entire contractile apparatus to the subsarcolemmal cytoskeleton, the cell nuclei and to other organelles (Small et?al. 1992; Fuchs & Weber, 1994). The network of desmin filaments helps in maintaining the structural and mechanical integrity of the cell during contraction, contributes to force transmission and longitudinal load bearing (Paulin SOX18 & Li, 2004; Shah et?al. 2004). Another vital protein that connects the cytoskeleton of a muscle fiber to the surrounding ECM through the cell membrane is dystrophin (Campbell, 1995; Srivastava & Yu, 2006). Dystrophin binds to the membrane\spanning dystrophin\associated protein complex (DAPC) through its C\terminus domain, LDN193189 Tetrahydrochloride whereas its N\terminus interacts with actin filaments. The DAPC is composed of membrane\related proteins, such as dystroglycans, sarcoglycans, caveolin\3, neuronal nitric oxide synthase (nNOS) and laminin containing the \2 chain (Davies & Nowak, 2006). The DAPC has important roles in stabilizing sarcolemma and transmitting force generated in the muscle sarcomere to the ECM (Petrof et?al. 1993). In order to elucidate if the unique anatomy, morphology and function of the.