Regulation of chromatin structure during thymic T cell development

Development is the process whereby a multipotent cell gives rise, through series of divisions, to progeny with successively restricted potentials. During T cell development, the process begins with a multipotent hematopoietic stem cell (HSC) in the bone marrow, moves to the thymus where early T cells or thymocytes pass through signal‐initiated developmental checkpoints, and ends in the periphery where mature T cells reside. At each step along this developmental pathway, T lymphocyte progenitors must be able to turn genes on and off, creating a specialized program of gene expression, to allow further development. How is gene expression coordinated? This review will summarize what has been learned about the function of chromatin structure in generating a “blueprint” of gene expression during T cell development. This will include discussion of mechanisms of chromatin remodeling, histone modification, and heritable gene silencing. In many cases, these processes are carried out by multi‐protein complexes whose components are largely ubiquitously expressed. The spatial and temporal specificity of these complexes is contributed by sequence specific DNA binding factors, some of which are cell type restricted in their expression. This review will summarize research underway to identify these key genetic “targeters.” Taken together, the research reviewed here provides a glimpse into the importance of regulation of chromatin structure in T cell development and the “players” involved. © 2005 Wiley‐Liss, Inc.     

The many faces of plant chromatin: Meeting summary of the 4th European workshop on plant chromatin 2015, Uppsala,Sweden

In June 2015, the fourth European Workshop on Plant Chromatin took place in Uppsala, Sweden, bringing together 80 researchers studying various aspects of plant chromatin and epigenetics. The intricate relationships between plant chromatin dynamics and gene expression change, chromatin organization within the plant cell nucleus, and the impact of chromatin structure on plant development were discussed. Among the main highlights of the meeting were an ever-growing list of newly identified players in chromatin structure establishment and the development of novel tools and approaches to foster our understanding of chromatin-mediated gene regulation, taking into account the context of the plant cell nucleus and its architecture. In this report, we summarize some of the main advances and prospects of plant chromatin research presented at this meeting.     

A computational approach to characterization of bovine sperm chromatin alterations

We describe here a computational morphology-based approach to the investigation of possible causes of chromatin alterations in sperm. A comprehensive set of state-of-the-art and geometric measures are computationally extracted from toluidine blue stained images and analyzed to infer the possible processes leading to normal and abnormal chromatin formation while seeking a possible taxonomy of chromatin alterations and their influence on sperm head morphology. Using this methodology, we have identified higher chromatin fragility at some specific points of the sperm head. Despite the lack of correlation between morphologies of sperm head and chromatin structure, four main morphological types of chromatin alterations in bull spermatozoa have been identified and their possible causes discussed.     

30nm染色质纤维结构与表观遗传调控

真核生物的DNA以染色质形式通过逐级折叠压缩形成高级结构存在于细胞核中。染色质高级结构直接参与了真核基因的转录调控和其它与DNA相关的生物学事件,因此研究染色质高级结构对了解表观遗传学分子机制有着至关重要的作用。近些年,研究者们针对30 nm染色质高级结构提出了两个模型:螺线管模型和Zig-Zag模型。2014年,我们利用体外染色质组装体系重建了30 nm染色质纤维,运用高精度冷冻电镜技术得到了分辨率为11?的30 nm染色质纤维的精细结构,提出了30 nm染色质高级结构的左手双螺旋Zig-Zag模型。本文综述了30 nm染色质纤维结构研究方面的相关进展,并对30 nm染色质高级结构的表观遗传调控机理以及单分子成像和操纵技术在研究30 nm染色质高级结构中潜在的应用作出讨论和展望。     

Epithelial stem cells: An epigenetic and wnt‐centric perspective

Epithelial stem cells, such as those present in mammalian skin, intestine, or mammary gland, are tissue stem cells capable of both long‐term self‐renewal and multi‐lineage differentiation. Here we review studies implicating epigenetic control mechanisms in mammalian epithelial stem cell development and homeostasis. We also provide an update of recent progresses in the involvement of canonical Wnt signaling and note an interesting link between the Wnt pathway and chromatin regulation in epithelial stem cells. We anticipate that epigenetic and epigenomic studies of these cells will increase exponentially in the near future. J. Cell. Biochem. 106: 1279–1287, 2010. © 2010 Wiley‐Liss, Inc.