Endothelin receptor type A expression defines a distinct cardiac subdomain within the heart field and is later implicated in chamber myocardium formation

The avian and mammalian heart originates from two distinct embryonic regions: an early differentiating first heart field and a dorsomedially located second heart field. It remains largely unknown when and how these subdivisions of the heart field divide into regions with different fates. Here, we identify in the mouse a subpopulation of the first (crescent-forming) field marked by endothelin receptor type A (Ednra) gene expression, which contributes to chamber myocardium through a unique type of cell behavior. Ednra-lacZ/EGFP-expressing cells arise in the ventrocaudal inflow region of the early linear heart tube, converge to the midline, move anteriorly along the outer curvature and give rise to chamber myocardium mainly of the left ventricle and both atria. This movement was confirmed by fluorescent dye-labeling and transplantation experiments. The Ednra-lacZ/EGFP-expressing subpopulation is characterized by the presence of Tbx5-expressing cells. Ednra-null embryonic hearts often demonstrate hypoplasia of the ventricular wall, low mitotic activity and decreased Tbx5 expression with reciprocal expansion of Tbx2 expression. Conversely, endothelin 1 stimulates ERK phosphorylation and Tbx5 expression in the early embryonic heart. These results indicate that early Ednra expression defines a subdomain of the first heart field contributing to chamber formation, in which endothelin 1/Ednra signaling is involved. The present finding provides an insight into how subpopulations within the crescent-forming (first) heart field contribute to the coordination of heart morphogenesis through spatiotemporally defined cell movements.     

NMR studies on domain diffusion and alignment in modular GB1 repeats

Modular proteins contain individual domains that are often connected by flexible, unstructured linkers. Using a model system based on the GB1 domain, we constructed tandem repeat proteins and investigated the rotational diffusion and long-range angular ordering behavior of individual domains by measuring NMR relaxation parameters and residual dipolar couplings. Although they display almost identical protein-solvent interfaces, each domain exhibits distinct rotational diffusion and alignment properties. The diffusion tensor anisotropy of the N-terminal domain (NTD) is D_‖/D_⊥ = 1.5-1.6, similar to that of single-GB1 domains (D_‖/D_⊥ = 1.6-1.7), whereas the value for the C-terminal domain (CTD) is D_‖/D_⊥ = 2.0-2.2. In addition, the two domains have different rotational correlation times. These effects are observed for linkers of three to 24 residues, irrespective of linker length. The NTD and CTD also differ in their degree of magnetic alignment, even with a flexible linker of 18 residues, exhibiting D_a values of 7.7 Hz and 9.7 Hz, respectively. Our results suggest that diffusion differences and long-range influences may persist in modular protein systems, even for systems that have highly flexible linkers and exhibit no domain-domain or domain-linker interactions.     

Jiraiya attenuates BMP signaling by interfering with type II BMP receptors in neuroectodermal patterning

During embryogenesis, bone morphogenetic protein (BMP) signaling needs to be finely tuned in a locally restricted manner. Here, we report a cell-intrinsic mode of BMP response control executed by the membrane protein Jiraiya. In the Xenopus embryo, zygotic Jiraiya, expressed exclusively in the neuroectoderm, is essential and sufficient for limiting dorsal neural development, which is dependent on BMP signals. In animal cap assays, Jiraiya selectively and cell-autonomously inhibits BMP signaling, while Jiraiya's knockdown enhances the signaling. In the cell, Jiraiya selectively forms a complex with type II BMP receptor (BMPRII) and downregulates the cell surface localization of functional BMPRII. This functional interaction with Jiraiya depends on the unique tail domain of BMPRII, and, in particular, the conserved EVNNNG motif, the function of which has been unknown. Thus, Jiraiya represents a cell-intrinsic cutoff mechanism for dynamic responsiveness to BMP signals via subtype-selective receptor control.     

Expression pattern of CUC3 ortholog in Zeylanidium tailichenoides (Podostemaceae) infers organization of a unique distichous shoot in Podostemoideae

Journal of Plant Research - Shoots of the aquatic eudicot family, Podostemaceae, exhibit unusual organogenesis with mixed leaf and stem identities. New shoots arise at the base of the older shoot...     

Interleukin‐17A‐producing T lymphocytes in chronic active Epstein–Barr virus infection

T helper (Th) 17 cells are reportedly effector T cells that produce interleukin (IL)‐17A and play a significant role in the development of autoimmune diseases and immune responses for antimicrobial host defense. Production of IL‐17A in chronic active Epstein–Barr virus infection (CAEBV) was studied to investigate its contribution to pathogenesis of this disease. Significantly more IL‐17A‐producing cells were detected in the peripheral blood of CAEBV patients than in that of healthy controls, although a significant difference in serum IL‐17A production was not confirmed. Of the IL‐17A‐producing cells, 91.8% were cluster of differentiation (CD)4‐positive Th17 cells. Moreover, there were significantly more IL‐17A‐producing cells among CD4⁺ cells in peripheral blood of CAEBV patients than in that of controls (1.97 ± 0.69% vs. 1.09 ± 0.53%, P = 0.0073). These data suggest that IL‐17A‐producing cells may influence the pathophysiology of CAEBV.     

Establishment and characterization of patient-derived xenograft and its cell line of primary leiomyosarcoma of bone

Primary leiomyosarcoma (LMS) of bone is a rare and aggressive mesenchymal malignancy that differentiates toward smooth muscle. Complete resection is the only curable treatment, and novel therapeutic approaches for primary LMS of bone have long been desired. Patient-derived xenografts (PDXs) and cell lines are invaluable tools for preclinical studies. Here, we established PDXs from a patient with primary LMS of bone and a cell line from an established PDX. Bone primary LMS tissue was subcutaneously implanted into highly immune-deficient mice. After two passages, a piece of the tumor was subjected to tissue culturing, and a morphological evaluation and proteomic analysis were performed on the PDX and the established cell line. Moreover, the responses of the established cell line to anti-cancer drugs were examined. Microscopic observations revealed that the PDX tumors retained their original histology. The cell line was established from the third-generation PDX and named NCC-LMS1-X3-C1. The cells were maintained for over 18 mo and 40 passages. The cells exhibited a spindle shape and aggressive growth. Mass spectrometric protein identification revealed that the original tumor tissue, PDX tumor tissue, and NCC-LMS1-X3-C1 cells had similar but distinct protein expression profiles. We previously established the cell line, NCC-LMS1-C1, from the tumor tissue of same patient. We found that the response to drug treatments was different between NCC-LMS1-X3-C1 and NCC-LMS1-C1, suggesting the heterogeneous traits of tumor cells in the identical tumor tissue. This set of PDXs and stable cell line will be a useful resource for bone LMS research.     

Proliferating cells in the rat anterior pituitary during the postnatal period: immunoelectron microscopic observations using monoclonal anti-bromodeoxyuridine antibody

Proliferating cells in the male rat anterior pituitary at 1, 3, 5, and 8 weeks of age were labeled with bromodeoxyuridine (BrdU) and studied by light and electron microscopic immunocytochemistry using anti-BrdU. They decreased in number from 402±31/mm² at 1 week to 50±1.5/mm² at 8 weeks, while their cell area increased by about twofold during this period. They had a slightly higher nucleus/whole cell (N/C) ratio than non-proliferating cells. According to their ultrastructure we classified them into granular and agranular cells. The percentage of granular cells ranged from 73% to 82% of all the proliferating cells during the period studied. They had many granules of various sizes and shapes, and some contained growth hormone and prolactin. Agranular cells, constituting 18–27% of proliferating cells, were small and had a high N/C ratio, indicating their immaturity. Moreover, they showed several features of folliculo-stellate (FS) cells: they showed no secretory granules in the cytoplasm, extended thin cytoplasmic processes, and sometimes they constructed a follicle among them. These results suggest: (1) the majority of proliferating cells were mature cells producing anterior pituitary hormone(s) and (2) most of the agranular proliferating cells maybe FS cells. The possibility of the latter is discussed.     

Thymocyte apoptosis induced by phosphorylation of histones is associated with the change in chromatin structure to allow easy accessibility of DNase

The inhibitors of protein phosphatase such as calyculin A and okadaic acid induce the apoptotic cell death in rat thymocytes. To clarify the molecular mechanism of these inhibitor-induced apoptosis, the effect of calyculin A on DNA fragmentation in the isolated nuclei were studied. A significant increase in DNA fragmentation was observed in the nuclei prepared from the cells treated with calyculin A that caused histone hyperphosphorylation. No changes of the activities of caspase-8 and -3 were observed in the extract from the cells treated with calyculin A. The circular dichroism analysis of soluble chromatin from calyculin A-treated thymocyte nuclei indicated that phosphorylation of histones decreased its alpha-helical content. Thus, the change in the chromatin structure may be due to the chemical modification of histones. Moreover, the structural change in chromatin preceded DNA fragmentation in the nuclei. Therefore, these results suggest that the change of chromatin structure allow easy accessibility of nuclear DNase to chromosomal DNA.