Unraveling the Determinants of Protrusion Formation

A computerized morphometric classification technique based on latent factors reveals major protrusion classes: factors 4, 5, and 7. Previous work showed that factor 4 represented filopodia, 5 the distribution of lamellar cytoplasm, and 7 a blunt protrusion. We explore the relationship of focal contact (FC) characteristics and their integrated actin cables to factors values. The results show that FC maturation/cytoskeletal integration affects factor 5, because FC elongation/integration was correlated with its values. On the contrary, 7 values decreased with maturation, so cable or FC size or their integration must be restricted to form these protrusions. Where integration did occur, the cables showed distinctive size and orientation, as indicated by correlation of 7 values with FC shape. Results obtained with myosin inhibitors support the interpretation that a central, isometric, contractile network puts constraints on both factor 5 and 7 protrusions. We conclude that cells establish functional domains by rearranging the cytoskeleton

Inflammatory responses to dietary and surgical weight loss in male and female mice

Abstract Background Weight loss by surgery or lifestyle changes is strongly recommended for obese individuals to improve metabolic health, but the underlying impairments that persist from a history of obesity remain unclear. Recent investigations demonstrate a persistent inflammatory state with weight loss and bariatric surgery, but the mechanism and impact are not fully understood. Additionally, these studies have not been performed in females although women are the majority of individuals undergoing weight loss interventions. Methods The goal of this study was to determine the sex differences in metabolically induced inflammation after dietary weight loss (WL) or bariatric surgery. Following a 60% high-fat diet (HFD) for 12 weeks, C57Bl/6j mice underwent either a dietary switch to normal chow for WL or vertical sleeve gastrectomy (VSG) and were evaluated 8 weeks after intervention. WL effects on myelopoiesis were further evaluated with bone marrow chimeras. Results Both sexes had a decrease in adiposity and total weight following WL or VSG intervention. With HFD, females had very little inflammation and no further increase with WL, but males had persistent inflammation even after WL despite metabolic improvement. Interestingly, after VSG, myeloid inflammation was increased in the livers of males and to a lesser extent in females. Conclusions These studies demonstrate that regardless of sex, it is critical to assess an individuals’ history of obesity rather than just rely on current weight status in medical decision-making. There are long-lasting effects on tissue inflammation in both sexes especially with surgical weight loss. Dietary change is overall most effective to improve meta-inflammation in obese males on its own or in combination with surgical weight loss.https://deepblue.lib.umich.edu/bitstream/2027.42/148527/1/13293_2019_Article_229.pd

To Be or Not To Be a Protrusion: Unraveling the Determinants of Protrusion Formation

Cellular edge features have been widely studied in recent years due to the interest in cell motility in normal and cancerous cells. Cues from cell interactions with the extracellular environment lead to overall cytoskeletal remodeling and consequently shape changes. The factors that determine the shape of a cell include actin polymerization, myosin II contraction and focal contacts (FCs). Actin based structures like lamellipodia (broad protrusions), ruffles (vertical protrusions) and filopodia (elongated, tapering protrusions) are the major protrusion types described in the scientific literature. However, their subjective classification is a problem when trying to understand mechanisms of protrusion formation in different cell types. The present study makes use of a previously determined computerized morphometric classification technique to distinguish features other than lamellipodia in 1000W rat tracheal epithelial cells. Some of the features identified through previous studies were factor 4, factor 5, factor 7 and factor 16. The aim of the present study was to explore the role of some of the structural components leading to the formation of a protrusion, particularly to a feature defined as factor 7. Integrated morphometry analysis with MetaMorph software was used to study the FC characteristics, while a geographical information system (GIS) software was used to study the FC orientation with respect to a protrusive feature. Small FCs favored factor 7 feature formation. High factor 7 values were observed when the class of FCs without actin became narrower. Paradoxically, where anchored actin cables on FCs showed a positive correlation with factor 7, the inner radius and width of the FC were the only elevated variables. The results suggested that certain populations of FCs with actin, which were narrow but varied in orientation, are important for factor 7 feature formation. It was observed that the most robust FCs with actin association were related to factor 5 values. The values of both factors 4 and 5 tended to increase with greater elongation of the FCs. FCs without actin cables affected the values of factor 4 and 5 to approximately the same extent. Factor 16 showed no correlations with any dimensioned or shape variable. Actin polymerization and myosin dependence in relationship to protrusions were studied with the aid of cytochalasins and myosin inhibitors, respectively. Cytochalasins inhibited ruffles and stress fibers but surprisingly enhanced factor 7 protrusions. Blebbistatin, SPC 16524, and H1152p, a Rho-kinase (ROCK) inhibitor, showed no ability to inhibit factor 7 features suggesting that myosin II was inessential to the features. The current study suggests that factor 7 feature resembles a pseudopodial feature enhanced by a Rho inhibitory p160/ROCK/p38 mitogen activated protein kinase signal transduction pathway in breast cancer invasiveness. Four models consistent with results were proposed for factor 7 formation. The activity of a minus-end directed motor was proposed in models II, III and IV, and no myosin function at all in model I. All the models ruled out myosin II activity, since the involvement of myosin II would require a contraction of stress fibers, a situation unlikely to generate a protrusion. Hence, the involvement of a minus-end directed motor is more probable. However, further data is required to rigorously test models II, III and IV. Since, model I, on the other hand was proposed to have no myosin activity, it still holds ground. The present study has enabled the identification of features that might aid as a tool in distinguishing normal and cancer cell populations. Disagreement with some aspects of protrusion formation suggests that not all protrusions are formed in the same manner and are under differential regulation. The study encourages the need to abandon subjective classifications of cellular edge features. There is certainly a..

To Be or Not To Be a Protrusion: Unraveling the Determinants of Protrusion Formation

Cellular edge features have been widely studied in recent years due to the interest in cell motility in normal and cancerous cells. Cues from cell interactions with the extracellular environment lead to overall cytoskeletal remodeling and consequently shape changes. The factors that determine the shape of a cell include actin polymerization, myosin II contraction and focal contacts (FCs). Actin based structures like lamellipodia (broad protrusions), ruffles (vertical protrusions) and filopodia (elongated, tapering protrusions) are the major protrusion types described in the scientific literature. However, their subjective classification is a problem when trying to understand mechanisms of protrusion formation in different cell types. The present study makes use of a previously determined computerized morphometric classification technique to distinguish features other than lamellipodia in 1000W rat tracheal epithelial cells. Some of the features identified through previous studies were factor 4, factor 5, factor 7 and factor 16. The aim of the present study was to explore the role of some of the structural components leading to the formation of a protrusion, particularly to a feature defined as factor 7. Integrated morphometry analysis with MetaMorph software was used to study the FC characteristics, while a geographical information system (GIS) software was used to study the FC orientation with respect to a protrusive feature. Small FCs favored factor 7 feature formation. High factor 7 values were observed when the class of FCs without actin became narrower. Paradoxically, where anchored actin cables on FCs showed a positive correlation with factor 7, the inner radius and width of the FC were the only elevated variables. The results suggested that certain populations of FCs with actin, which were narrow but varied in orientation, are important for factor 7 feature formation. It was observed that the most robust FCs with actin association were related to factor 5 values. The values of both factors 4 and 5 tended to increase with greater elongation of the FCs. FCs without actin cables affected the values of factor 4 and 5 to approximately the same extent. Factor 16 showed no correlations with any dimensioned or shape variable. Actin polymerization and myosin dependence in relationship to protrusions were studied with the aid of cytochalasins and myosin inhibitors, respectively. Cytochalasins inhibited ruffles and stress fibers but surprisingly enhanced factor 7 protrusions. Blebbistatin, SPC 16524, and H1152p, a Rho-kinase (ROCK) inhibitor, showed no ability to inhibit factor 7 features suggesting that myosin II was inessential to the features. The current study suggests that factor 7 feature resembles a pseudopodial feature enhanced by a Rho inhibitory p160/ROCK/p38 mitogen activated protein kinase signal transduction pathway in breast cancer invasiveness. Four models consistent with results were proposed for factor 7 formation. The activity of a minus-end directed motor was proposed in models II, III and IV, and no myosin function at all in model I. All the models ruled out myosin II activity, since the involvement of myosin II would require a contraction of stress fibers, a situation unlikely to generate a protrusion. Hence, the involvement of a minus-end directed motor is more probable. However, further data is required to rigorously test models II, III and IV. Since, model I, on the other hand was proposed to have no myosin activity, it still holds ground. The present study has enabled the identification of features that might aid as a tool in distinguishing normal and cancer cell populations. Disagreement with some aspects of protrusion formation suggests that not all protrusions are formed in the same manner and are under differential regulation. The study encourages the need to abandon subjective classifications of cellular edge features. There is certainly a..

Lactational High-Fat Diet Exposure Programs Metabolic Inflammation and Bone Marrow Adiposity in Male Offspring

Overnutrition during critical windows of development plays a significant role in life-long metabolic disease risk. Early exposure to excessive nutrition may result in altered programming leading to increased susceptibility to obesity, inflammation, and metabolic complications. This study investigated the programming effects of high-fat diet (HFD) exposure during the lactation period on offspring adiposity and inflammation. Female C57Bl/6J dams were fed a normal diet or a 60% HFD during lactation. Offspring were weaned onto a normal diet until 12 weeks of age when half were re-challenged with HFD for 12 weeks. Metabolic testing was performed throughout adulthood. At 24 weeks, adipose depots were isolated and evaluated for macrophage profiling and inflammatory gene expression. Males exposed to HFD during lactation had insulin resistance and glucose intolerance as adults. After re-introduction to HFD, males had increased weight gain and worsened insulin resistance and hyperglycemia. There was increased infiltration of pro-inflammatory CD11c+ adipose tissue macrophages, and bone marrow was primed to produce granulocytes and macrophages. Bone density was lower due to enhanced marrow adiposity. This study demonstrates that maternal HFD exposure during the lactational window programs offspring adiposity, inflammation, and impaired glucose homeostasis