A stem cell is a unique cell that has the ability to turn into any cell type and are also known as pluripotent cells. These cells have been used to generate and repair damaged tissues. All these years, embryonic cells were used as a basis for generating stem cells. While, in recent years, huge research has taken place to generate stem cells from the somatic cells.
Using certain genetic factors and controlled conditions, a somatic cell can be converted into a pluripotent cell and is termed as somatic cell reprogramming. Although this field remains undiscovered, a breakthrough by Dr. Karlen Gazarian has been made in this current research. The somatic cell reprogramming is a biphasic process, which includes an initiation phase and a maturation phase. Dr. Karlen Gazarian and his team at the Institute of Biomedical Research of Mexican National University) in the current study have scrutinized the role of different genes of the Wnt signaling pathway in each stage.
In general, under normal conditions, a Wnt signaling pathway is known to regulate and deregulate certain cellular process. For instance, in the absence of a Wnt protein, the B-catenins are ubiquitinated and there is suppression of targeted genes. Meanwhile, in the presence of a Wnt protein, the B-catenins are not ubiquitinated and are transported to the nucleus. Inside the nucleus, these B-catenin along with TCF (a transcription factor protein) regulates the expression of a targeted gene. This mechanism has been studied in depth in this research. Dr. Karlen gazarian and his team have manipulated the genes to understand the role of each gene of the Wnt signaling pathway in the different stages of formation of pluripotent cells from somatic cells.
Using his current research, he has made novel findings in understanding the contrasting nature of canonical Wnt signaling during human fibroblast reprogramming. Their research has contributed immensely in understanding the molecular mechanisms lying behind the pluripotent generation from human somatic cells. They have used Human dermal fibroblast cells as the somatic cells to generate pluripotent cells. To investigate the expression of each protein/gene in different stages of maturation, the authors have used numerous methodologies.
RT-PCR, a widely used technique to understand the RNA expression was used as a first step study. Further, state of the art techniques such as flow cytometry and immunohistochemistry were used to study the cells (cellular features in different stages of development). Finally, microarray analysis was employed to demonstrate the expression of various genes at different time intervals.
The results of this research lead to interesting findings. As stated early, Dr. Karlen gazarian and his team observed that the Wnt gene expression was most required during the initiation phase while was not required for the maturation phase. The TCF7 (a part of the Wnt signaling pathway) protein was required for maintaining the cellular colony during the initial phase. During the maturation phase, the role of TCF7 or Wnt proteins were not observed. In contrast, they observed that TCF7L1 protein was overexpressed which helped in encouraging the cells towards pluripotency acquisition. While, in few earlier studies (that were made in murine cells), the role of TCF7L1 proteins were found to be deleterious during the maturation phase which was disproven in the current study with the help of Human dermal fibroblast cells and advanced methodologies.
Therefore, Dr.Karlen Gazarian state that the role of Wnt pathway could be different in somatic cell reprogramming between the murine and the human cells. The overall significant findings of the entire research are that the Wnt signaling pathways are essential for the initiation phase, whereas it is no longer required during the maturation phase as this signaling pathway later leads to the mesodermal formation which is deleterious for pluripotency acquisition.
A study such as this can help in understanding the cellular mechanism underlying the formation and maintenance of pluripotent cells. Dr. Karlen Gazarian and his team have also thrown light on the important roles played by the Wnt signaling pathway in the development of pluripotent cells that were left untouched till now. A research on the various signaling pathways can help in enhancing the current procedure in somatic cell reprogramming. This outstanding research has been sponsored by the grants obtained from Mexican Consejo Nacional de Ciencia y Tecnologıa (CONACYT; #201382) and Programa de Apoyo a Proyectos de Investigacion e Innovaci on Tecnologica (DGAPA-PAPIIT; #IT200313).
The scheme demonstrating the discovered differential role of the Wnt/catenine signalling in the initiation (positive) and in the maturation (negative) phases of the human cell reprogramming to pluripotency.