Изоформы актина и неопл астическая трансформация

The cytoplasmic actins (β and γ) play crucial roles during key cellular processes like adhesion, migration, polarization and cytokinesis. The understanding of their specific underlying mechanisms would be of major relevance not only for fundamental research but also for clinical applications, since modulations of actin isoforms are directly or indirectly correlated with severe pathologies. The major goal of the research was to elucidate the function of the actin isoforms during motile activities, adhesions and cell division and to investigate whether their expression and/or structural organization is related to pathological function. Selective depletion of β- and γ-cytoplasmic actins allowed attributing functional diversities of β- and γ-сytoplasmic actins. β-Сytoplasmic actin plays a preferential role in contractile activities, whereas γ-cytoplasmic actin mainly participates in the formation of a submembranous network necessary for cell shape flexibility and motile activity. The roles of isoforms in regulating the integrity of adherens and tight junctions respectively were demonstrated. Unique roles of β- and γ-cytoplasmic actins in normal cells were shown. Similar results were obtained in cancer cells compared with normal epithelial cells in culture and in human pathological tissue sections of mammary gland, colon, lung and cervix. Malignant cell transformation requires changes in the ability of cells to migrate. The disruption of actin cytoskeleton and intercellular adhesions is an important component of the acquisition of invasive properties in epithelial malignancies.Цитоплазматические изоформы актина (β и γ) играют важную роль в ключевых клеточных процессах, таких как адгезия, миграция, поляризация и цитокинез. Понимание специфических механизмов, лежащих в основе этих процессов, является связующим звеном между фундаментальными и клиническими исследованиями, так как модуляции актиновых изоформ прямо или косвенно связаны с различными патологиями. Исследованию функций цитоплазматических изоформ актина, связанных с подвижностью и делением нормальных и опухолевых клеток, адгезионными структурами, а также изучению соответствия их экспрессии и / или структурной организации нормальным и патологическим функциям клеток посвящен данный обзор. Селективная редукция β- или γ-цитоплазматических актинов позволила определить функциональные различия между этими изоформами. Преимущественную роль в сократительных и адгезионных активностях играет β-актин, тогда как цитоплазматический γ-актин участвует в образовании подмембранной сети, необходимой для клеточной пластичности и подвижности. Определяющую роль в установлении и поддержании нормальной архитектуры и динамики эпителиальных плотных и адгезионных межклеточных контактов играет связь с актиновым цитоскелетом. Продемонстрирована уникальная роль β- и γ-актинов в регуляции и поддержании целостности адгезионных и плотных межклеточных контактов соответственно. Похожие результаты были получены при сравнении опухолевых клеток с нормальными эпителиальными клетками в культуре и на срезах патологических тканей молочной железы, кишечника, легких и шейки матки человека. Изоформ-специфичная перестройка актинового цитоскелета и адгезионных межклеточных контактов является важным шагом в приобретении инвазивности эпителиальными опухолями

Reviving grain quality in wheat through non-destructive phenotyping techniques like hyperspectral imaging

A long-term goal of breeders and researchers is to develop crop varieties that can resist environmental stressors and produce high yields. However, prioritising yield often compromises improvement of other key traits, including grain quality, which is tedious and time-consuming to measure because of the frequent involvement of destructive phenotyping methods. Recently, non-destructive methods such as hyperspectral imaging (HSI) have gained attention in the food industry for studying wheat grain quality. HSI can quantify variations in individual grains, helping to differentiate high-quality grains from those of low quality. In this review , we discuss the reduction of wheat genetic diversity underlying grain quality traits due to modern breeding, key traits for grain quality, traditional methods for studying grain quality and the application of HSI to study grain quality traits in wheat and its scope in breeding. Our critical review of literature on wheat domes-tication, grain quality traits and innovative technology introduces approaches that could help improve grain quality in wheat. K E Y W O R D S grain quality, hyperspectral imaging, plant breeding, whea

PDGF-Rα gene expression predicts proliferation, but PDGF-A suppresses transdifferentiation of neonatal mouse lung myofibroblasts

<p>Abstract</p> <p>Background</p> <p>Platelet-derived growth factor A (PDGF-A) signals solely through PDGF-Rα, and is required for fibroblast proliferation and transdifferentiation (fibroblast to myofibroblast conversion) during alveolar development, because <it>pdgfa</it>-null mice lack both myofibroblasts and alveoli. However, these PDGF-A-mediated mechanisms remain incompletely defined. At postnatal days 4 and 12 (P4 and P12), using mouse lung fibroblasts, we examined (a) how PDGF-Rα correlates with ki67 (proliferation marker) or alpha-smooth muscle actin (αSMA, myofibroblast marker) expression, and (b) whether PDGF-A directly affects αSMA or modifies stimulation by transforming growth factor beta (TGFβ).</p> <p>Methods</p> <p>Using flow cytometry we examined PDGF-Rα, αSMA and Ki67 in mice which express green fluorescent protein (GFP) as a marker for PDGF-Rα expression. Using real-time RT-PCR we quantified αSMA mRNA in cultured Mlg neonatal mouse lung fibroblasts after treatment with PDGF-A, and/or TGFβ.</p> <p>Results</p> <p>The intensity of GFP-fluorescence enabled us to distinguish three groups of fibroblasts which exhibited absent, lower, or higher levels of PDGF-Rα. At P4, more of the higher than lower PDGF-Rα + fibroblasts contained Ki67 (Ki67+), and Ki67+ fibroblasts predominated in the αSMA + but not the αSMA- population. By P12, Ki67+ fibroblasts comprised a minority in both the PDGF-Rα + and αSMA+ populations. At P4, most Ki67+ fibroblasts were PDGF-Rα + and αSMA- whereas at P12, most Ki67+ fibroblasts were PDGF-Rα- and αSMA-. More of the PDGF-Rα + than - fibroblasts contained αSMA at both P4 and P12. In the lung, proximate αSMA was more abundant around nuclei in cells expressing high than low levels of PDGF-Rα at both P4 and P12. Nuclear SMAD 2/3 declined from P4 to P12 in PDGF-Rα-, but not in PDGF-Rα + cells. In Mlg fibroblasts, αSMA mRNA increased after exposure to TGFβ, but declined after treatment with PDGF-A.</p> <p>Conclusion</p> <p>During both septal eruption (P4) and elongation (P12), alveolar PDGF-Rα may enhance the propensity of fibroblasts to transdifferentiate rather than directly stimulate αSMA, which preferentially localizes to non-proliferating fibroblasts. In accordance, PDGF-Rα more dominantly influences fibroblast proliferation at P4 than at P12. In the lung, TGFβ may overshadow the antagonistic effects of PDGF-A/PDGF-Rα signaling, enhancing αSMA-abundance in PDGF-Rα-expressing fibroblasts.</p

Rac Inhibition Reverses the Phenotype of Fibrotic Fibroblasts

Background: Fibrosis, the excessive deposition of scar tissue by fibroblasts, is one of the largest groups of diseases for which there is no therapy. Fibroblasts from lesional areas of scleroderma patients possess elevated abilities to contract matrix and produce alpha-smooth muscle actin (alpha-SMA), type I collagen and CCN2 (connective tissue growth factor, CTGF). The basis for this phenomenon is poorly understood, and is a necessary prerequisite for developing novel, rational anti-fibrotic strategies.Methods and Findings: Compared to healthy skin fibroblasts, dermal fibroblasts cultured from lesional areas of scleroderma (SSc) patients possess elevated Rac activity. NSC23766, a Rac inhibitor, suppressed the persistent fibrotic phenotype of lesional SSc fibroblasts. NSC23766 caused a decrease in migration on and contraction of matrix, and alpha-SMA, type I collagen and CCN2 mRNA and protein expression. SSc fibroblasts possessed elevated Akt phosphorylation, which was also blocked by NSC23766. Overexpression of rac1 in normal fibroblasts induced matrix contraction and alpha-SMA, type I collagen and CCN2 mRNA and protein expression. Rac1 activity was blocked by PI3kinase/Akt inhibition. Basal fibroblast activity was not affected by NSC23766.Conclusion: Rac inhibition may be considered as a novel treatment for the fibrosis observed in SSc

Cancer Cell Invasion Is Enhanced by Applied Mechanical Stimulation

Metastatic cells migrate from the site of the primary tumor, through the stroma, into the blood and lymphatic vessels, finally colonizing various other tissues to form secondary tumors. Numerous studies have been done to identify the stimuli that drive the metastatic cascade. This has led to the identification of multiple biochemical signals that promote metastasis. However, information on the role of mechanical factors in cancer metastasis has been limited to the affect of compliance. Interestingly, the tumor microenvironment is rich in many cell types including highly contractile cells that are responsible for extensive remodeling and production of the dense extracellular matrix surrounding the cancerous tissue. We hypothesize that the mechanical forces produced by remodeling activities of cells in the tumor microenvironment contribute to the invasion efficiency of metastatic cells. We have discovered a significant difference in the extent of invasion in mechanically stimulated verses non-stimulated cell culture environments. Furthermore, this mechanically enhanced invasion is dependent upon substrate protein composition, and influenced by topography. Finally, we have found that the protein cofilin is needed to sense the mechanical stimuli that enhances invasion. We conclude that other types of mechanical signals in the tumor microenvironment, besides the rigidity, can enhance the invasive abilities of cancer cells in vitro. We further propose that in vivo, non-cancerous cells located within the tumor micro-environment may be capable of providing the necessary mechanical stimulus during the remodeling of the extracellular matrix surrounding the tumor