Smooth muscle is a primary determinant of physiology as its ability to contract affords dynamic control of diameter of the hollow organs it encircles including the airways. Mature airway smooth muscle (ASM) cells are phenotypically plastic, enabling them to subserve contractile, proliferative, migratory and secretory roles that relates to its function in health and disease. ASM cells can control airway diameter both acutely, via reversible contraction, and chronically, by driving fixed changes in structure and function properties of the airway wall. However, the scope of research on ASM biology and function has broadened greatly in the past two decades, embracing the now recognized dynamic and multifunctional behavior, but there is always a need to investigate the role of new proteins regulating ASM phenotype in vitro and lung function in vivo. The multimeric dystrophin-glycoprotein complex (DGC) links the extracellular matrix (ECM) and actin cytoskeleton while caveolae form membrane arrays on ASM cells. Using ASM cells and tissues from human and canine and intact mouse for lung physiology, we investigated the role of DGC in phenotype maturation. We also investigated the mechanism for the organization of DGC with caveolae and further tested whether this is functionally important in mobilizing intracellular calcium in ASM cells, contraction of ASM tissue and finally its role in airway physiology. Our data demonstrate that the expression of DGC is an integral feature and a key determinant for phenotype maturation of human ASM cells. Our new data reveals an interaction between caveolin-1 and DGC and indicate that this association, in concert with anchoring to the actin cytoskeleton, underpins the spatial organization of caveolae on the membrane and has a functional role in receptor-mediated calcium release in ASM in vitro, ASM contraction ex vivo and lung function in vivo. Collectively our study indicates that the organization of caveolae and DGC, and its link from ECM to the actin cytoskeleton with in caveolae are a determinant of phenotype and functional properties of ASM, which underpins its role in physiology and pathophysiology of chronic airway diseases such as asthma.

Smooth muscle is a primary determinant of physiology as its ability to contract affords dynamic control of diameter of the hollow organs it encircles including the airways. Mature airway smooth muscle (ASM) cells are phenotypically plastic, enabling them to subserve contractile, proliferative, migratory and secretory roles that relates to its function in health and disease. ASM cells can control airway diameter both acutely, via reversible contraction, and chronically, by driving fixed changes in structure and function properties of the airway wall. However, the scope of research on ASM biology and function has broadened greatly in the past two decades, embracing the now recognized dynamic and multifunctional behavior, but there is always a need to investigate the role of new proteins regulating ASM phenotype in vitro and lung function in vivo. The multimeric dystrophin-glycoprotein complex (DGC) links the extracellular matrix (ECM) and actin cytoskeleton while caveolae form membrane arrays on ASM cells. Using ASM cells and tissues from human and canine and intact mouse for lung physiology, we investigated the role of DGC in phenotype maturation. We also investigated the mechanism for the organization of DGC with caveolae and further tested whether this is functionally important in mobilizing intracellular calcium in ASM cells, contraction of ASM tissue and finally its role in airway physiology. Our data demonstrate that the expression of DGC is an integral feature and a key determinant for phenotype maturation of human ASM cells. Our new data reveals an interaction between caveolin-1 and DGC and indicate that this association, in concert with anchoring to the actin cytoskeleton, underpins the spatial organization of caveolae on the membrane and has a functional role in receptor-mediated calcium release in ASM in vitro, ASM contraction ex vivo and lung function in vivo. Collectively our study indicates that the organization of caveolae and DGC, and its link from ECM to the actin cytoskeleton with in caveolae are a determinant of phenotype and functional properties of ASM, which underpins its role in physiology and pathophysiology of chronic airway diseases such as asthma.

Vascular smooth muscle cells display a certain level of phenotype plasticity. Under specific conditions fully differentiated cells are able to undergo dedifferentiation and to restart growth and proliferation. An organ culture method is a useful technique for the analysis of dedifferentiation of vascular smooth muscle cells, because it provides an opportunity for studying the changes in cell phenotype. The aim of this study was to investigate the basic contractile characteristics in rat femoral arteries cultured for different time periods (from one to three days). In addition, the effects of fetal bovine serum (FBS), that contains various growth factors and other biological active molecules, on contractile function were studied. We also tried to attenuate cell dedifferentiation by lowering the calcium influx, because calcium is an important second messenger participating in cell growth and proliferation. To achieve this goal we used cultivation with nifedipine, a voltage-dependent calcium channel inhibitor. The cultivation without FBS slightly decreased arterial contractility, whereas the cultivation with FBS decreased arterial contractility considerably. The major change in contractility of arteries cultivated with FBS occurred approximately within 24 hours of cultivation. The cultivation with...

[Truncated abstract] This study focussed on how isolation and environmental heterogeneity in salt lakes has influenced intraspecific variation in the calanoid copepod Calamoecia clitellata. Calamoecia clitellata relies on passive vectors for dispersal, and this, coupled with the insular nature of salt lakes, may promote genetic divergence at a molecular level. When contrasting environments are involved, genetic divergence may also occur at the life history level, possibly due to local adaptation. I examined the distribution of genetic variation among 14 populations in Western Australia using molecular genetic markers, and examined variation in life history traits among contrasting environments. To ascertain how isolation had influenced molecular genetic variation, I determined population genetic structure and used a phylogeographic approach to infer the impact of historical events. Environmentally induced variation was also evident in the field, with a switch from subitaneous egg production to resting egg production coinciding with changing environmental conditions. It is proposed that plasticity in life history traits has evolved in response to temporal environmental heterogeneity … It can be concluded that isolation in salt lakes in Western Australia has influenced molecular and phenotypic variation in C. clitellata in contrasting ways. At the molecular level, contemporary and historical isolation have promoted genetic divergence of populations, yet when coupled with environmental heterogeneity, marked phenotype plasticity has arisen. This study raises questions as to whether phenotype plasticity is a widespread phenomena in zooplankton found in temporary saline waters and an adaptive strategy to tolerate marked temporal environmental heterogeneity