Molecular mechanisms of transcription factor mediated cell reprogramming: conversion of liver to pancreas

Unraveling the Complexity and Advancements of Transdifferentiation Technologies in the Biomedical Field and Their Potential Clinical Relevance

Chronic diseases such as cancer, autoimmunity, and organ failure currently depend on conventional pharmaceutical treatment, which may cause detrimental side effects in the long term. In this regard, cell-based therapy has emerged as a suitable alternative for treating these chronic diseases. Transdifferentiation technologies have evolved as a suitable therapeutic alternative that converts one differentiated somatic cell into another phenotype by using transcription factors (TFs), small molecules, or small, single-stranded, non-coding RNA molecules (miRNA). The transdifferentiation techniques rely on simple, fast, standardized, and versatile protocols with minimal chance of tumorigenicity and genotoxicity. However, there are still challenges and limitations that need to be addressed to enhance their clinical translation percentage in the near future. Taking this into account, we have delineated the features and strategies used in the transdifferentiation techniques. Then, we delved into different intermediate states that were attained during transdifferentiation. Advancements in transdifferentiation techniques in the field of tissue engineering, autoimmunity, and cancer therapy were dissected. Furthermore, limitations, challenges, and future perspectives are outlined in this review to provide a whole new picture of the transdifferentiation techniques. Advancements in molecular biology, interdisciplinary research, bioinformatics, and artificial intelligence will push the frontiers of this technology further to establish new avenues for biomedical research.

Angiotensin (1-7) Improves Pancreatic Islet Function via Upregulating PDX-1 and GCK: A Dose-Dependent Study in Mice

Purpose: This study aimed to verify the effect of angiotensin (1-7) on improving islet function and further explore the signaling pathway that may be involved in this improvement. It also aimed to explore the effects of angiotensin (1-7) on blood glucose levels, islet function, and morphological changes in db/db mice and its potential signal pathway. Methods: Forty-five db/db mice were divided randomly into a model control group and different doses of angiotensin (1-7) intervention groups (0, 150, 300, and 600 μg/kg/d), while seven db/m mice were assigned as the normal control group. The angiotensin (1-7) intervention groups received daily intraperitoneal administration for 8 weeks, whereas the normal control group was injected intraperitoneally with an equal volume of normal saline every day for 8 weeks. Changes in weight and food intake of mice were detected. Effect of angiotensin (1-7) on lipid metabolism, islet function, the morphology of pancreatic islets, and β-cell mass on mice were evaluated. The expression of PDX-1 and GCK in pancreatic tissue was verified. Results: The group receiving angiotensin (1-7) at a dosage of 600 μg/kg/d showed a significant decrease in body weight, triglyceride levels, and fasting blood glucose, along with an improvement in glucose tolerance. In the 300 μg/kg/d group, angiotensin (1-7) tended to increase the total volume of islets. Moreover, the intervention groups exhibited a significant increase in the ratio of β cells, small islets (30-80 μm in diameter), as well as the expression levels of PDX-1 and GCK in pancreatic tissue. Conclusion: Angiotensin (1-7) could improve glucose and lipid metabolism and islet function by promoting the expression of PDX-1 and GCK genes in the pancreas of db/db mice.

Expression and clinicopathological characteristics of PDX1, PTF1A, and SALL4 in large and small ducts of ectopic pancreas located in gastro-duodenum and jejunum

An ectopic pancreas is defined as pancreatic tissue outside its normal location, anatomically separated from the pancreas. The transcription factor pancreas/duodenum homeobox protein 1 (PDX1) is involved in maintaining the pancreas and functions in early pancreatic development, beta cell differentiation, and endocrine non beta cells. Pancreatic transcription factor 1 subunit alpha (PTF1A) affects exocrine cell formation and regulation of acinar cell identity, and is expressed in exocrine cells as a transcription factor. The depletion of SALL4 disrupts self-renewal and induces differentiation. To clarify which of PDX1, PTF1A, or SALL4 determines the difference in Heinrich's classification, we examined the localization and number of positive cells. We analyzed the differential expression of PDX1, PTF1A, and SALL4 in large and small ducts in ectopic pancreas by immunohistochemistry. Results showed that the number of PTF1A-positive cells in large ducts was more widespread in type I than in type II in the gastro-duodenum, and more SALL4-positive cells were noticed in large ducts than in small ducts in the gastro-duodenum of type II. Our results revealed that PTF1A might promote exocrine differentiation in developing the pancreatic tissues, and that those with widespread expression differentiate into exocrine cells.

MyoD-Induced Trans-Differentiation: A Paradigm for Dissecting the Molecular Mechanisms of Cell Commitment, Differentiation and Reprogramming

The discovery of the skeletal muscle-specific transcription factor MyoD represents a milestone in the field of transcriptional regulation during differentiation and cell-fate reprogramming. MyoD was the first tissue-specific factor found capable of converting non-muscle somatic cells into skeletal muscle cells. A unique feature of MyoD, with respect to other lineage-specific factors able to drive trans-differentiation processes, is its ability to dramatically change the cell fate even when expressed alone. The present review will outline the molecular strategies by which MyoD reprograms the transcriptional regulation of the cell of origin during the myogenic conversion, focusing on the activation and coordination of a complex network of co-factors and epigenetic mechanisms. Some molecular roadblocks, found to restrain MyoD-dependent trans-differentiation, and the possible ways for overcoming these barriers, will also be discussed. Indeed, they are of critical importance not only to expand our knowledge of basic muscle biology but also to improve the generation skeletal muscle cells for translational research.