Link between Lipid Second Messengers and Osmotic Stress in Plants.

Plants are subject to different types of stress, which consequently affect their growth and development. They have developed mechanisms for recognizing and processing an extracellular signal. Second messengers are transient molecules that modulate the physiological responses in plant cells under stress conditions. In this sense, it has been shown in various plant models that membrane lipids are substrates for the generation of second lipid messengers such as phosphoinositide, phosphatidic acid, sphingolipids, and lysophospholipids. In recent years, research on lipid second messengers has been moving toward using genetic and molecular approaches to reveal the molecular setting in which these molecules act in response to osmotic stress. In this sense, these studies have established that second messengers can transiently recruit target proteins to the membrane and, therefore, affect protein conformation, activity, and gene expression. This review summarizes recent advances in responses related to the link between lipid second messengers and osmotic stress in plant cells.

In vitro histomorphometric comparison of dental pulp tissue in different teeth.

BACKGROUND: Dental pulp (DP) represents an accessible and valuable source promising of stem cells for clinical application. However, there are some disadvantages associated with the isolation of dental pulp stem cells (DPSCs), which include the size and weight of the pulp tissue needed to yield sufficient cells for culturing in vitro. Therefore, the objective of this study was to compare in vitro histomorphometry of DP from permanent (premolars, third molar), supernumerary and deciduous teeth of patients between 5 and 25 years old with regards to weight, length, width and the cell density in the four regions of the DP in order to obtain quantitative parameters in a tissue that represents a valuable source of stem cells. METHODS: DPs were obtained from 10 central incisors deciduous, 20 permanent teeth (10 premolars, 10 third molars) and 10 supernumeraries (six mesiodents and four inferior premolar shapes). The pulps were carefully removed, and the entire tissue was weighed. The pulp length and the width were measured with a digital Vernier caliper. The cellular density analysis was performed according to the four regions of the DP (coronal, cervical, medial and apical) in histological slides using photography and the ImageJ® program for quantification. RESULTS: The Pearson correlation test revealed that DP weight among different types of teeth is correlated with age in male patients. A significant positive correlation was noted between length and width of the DP with age in both genders. The mean DP weight for supernumerary and third molar teeth was greater than deciduous and premolar teeth. Finally, the histological analysis showed that the coronal and apical portions of DP in supernumerary and premolar teeth have the highest cell density. CONCLUSIONS: The DP of supernumerary teeth has quantitatively the best morphometric parameters and cell density comparable with the quality of DP obtained from deciduous teeth.

Stem Cells from Dental Pulp: What Epigenetics Can Do with Your Tooth.

Adult stem cells have attracted scientific attention because they are able to self-renew and differentiate into several specialized cell types. In this context, human dental tissue-derived mesenchymal stem cells (hDT-MSCs) have emerged as a possible solution for repairing or regenerating damaged tissues. These cells can be isolated from primary teeth that are naturally replaced, third molars, or other dental tissues and exhibit self-renewal, a high proliferative rate and a great multilineage potential. However, the cellular and molecular mechanisms that determine lineage specification are still largely unknown. It is known that a change in cell fate requires the deletion of existing transcriptional programs, followed by the establishment of a new developmental program to give rise to a new cell lineage. Increasing evidence indicates that chromatin structure conformation can influence cell fate. In this way, reversible chemical modifications at the DNA or histone level, and combinations thereof can activate or inactivate cell-type-specific gene sequences, giving rise to an alternative cell fates. On the other hand, miRNAs are starting to emerge as a possible player in establishing particular somatic lineages. In this review, we discuss two new and promising research fields in medicine and biology, epigenetics and stem cells, by summarizing the properties of hDT-MSCs and highlighting the recent findings on epigenetic contributions to the regulation of cellular differentiation.