The majority of human skeleton develops through the endochondral pathway, in which cartilage-forming chondrocytes proliferate and enlarge into hypertrophic chondrocytes that eventually undergo apoptosis and are replaced by bone. Although at a terminal differentiation stage, hypertrophic chondrocytes have been implicated as the principal engine of bone growth. Abnormal chondrocyte hypertrophy has been seen in many skeletal dysplasia and osteoarthritis. Meanwhile, as a specific marker of hypertrophic chondrocytes, the type X collagen gene (COL10A1) is also critical for endochondral bone formation, as mutation and altered COL10A1 expression are often accompanied by abnormal chondrocyte hypertrophy in many skeletal diseases. However, how the type X collagen gene is regulated during chondrocyte hypertrophy has not been fully elucidated. We have recently demonstrated that Runx2 interaction with a 150-bp mouse Col10a1 cis-enhancer is required but not sufficient for its hypertrophic chondrocyte-specific reporter expression in transgenic mice, suggesting requirement of additional Col10a1 regulators. In this study, we report in silico sequence analysis of this 150-bp enhancer and identification of its multiple binding factors, including AP1, MEF2, NFAT, Runx1 and TBX5. Using this enhancer as bait, we performed yeast one-hybrid assay and identified multiple candidate Col10a1-interacting genes, including cyclooxygenase 1 (Cox-1) and Cox-2. We have also performed mass spectrometry analysis and detected EF1-alpha, Fus, GdF7 and Runx3 as components of the specific complex formed by the cis-enhancer and nuclear extracts from hypertrophic MCT (mouse chondrocytes immortalized with large T antigen) cells that express Col10a1 abundantly. Notably, some of the candidate genes are differentially expressed in hypertrophic MCT cells and have been associated with chondrocyte hypertrophy and Runx2, an indispensible Col10a1 regulator. Intriguingly, we detected high-level Cox-2 expression in hypertrophic MCT cells. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays confirmed the interaction between Cox-2 and Col10a1 cis-enhancer, supporting its role as a candidate Col10a1 regulator. Together, our data support a Cox-2-containing, Runx2-centered Col10a1 regulatory mechanism, during chondrocyte hypertrophic differentiation.

Fuel spray characteristics is known to significantly affect the combustion and emission processes in diesel engines. High-pressure common-rail system can supply so high injection pressure for getting the better spray characteristics to enhance combustion efficiency and reduce emission. With the fuel injection pressure increasing, spray process becomes more and more complex which makes the study on atomization mechanism more challenging. Under the super high injection pressure, the internal turbulent flow and cavitating flow of the nozzle will greatly influence the subsequent fuel atomization process and spray characteristics, especially the cavitation has been the key to relating internal flow of nozzle and atomization behavior. So it is necessary to simulate the fuel spray process considering of internal cavitating flow of the nozzle. In this paper, firstly, the high-precision three-dimension structure of nozzle with detailed internal geometry information were obtained using synchrotron radiation x-ray phase contrast imaging technology, which was used for the mesh generation of three-dimensional numerical simulation of the cavitating flow in the nozzle. Then the spray model coupled with nozzle cavitating flow was setup in FIRE v2010 and validated by the spray experimental data got from the high-speed imaging technology on a high-pressure common-rail injection system. The spray simulations coupled with cavitating flow showed that the cavitating flow characteristics in nozzles have a large effect on both macroscopic properties and microscopic properties. Finally basing on the above verified spray model, multi-scheme simulations with various geometry parameters of nozzle were performed and the effect of nozzle geometries on the spray characteristics was analyzed and it was concluded that the nozzle sac volume, hole inlet curvature, hole inclination angle, injector needle lift and needle eccentricity had obvious effects on the nozzle flow and subsequent spray, and there was an opposite trend between the spray penetration and Sauter mean diameter, which provided a certain reference value for structure optimization of the fuel system.

Vacuolar protein sorting 4 (Vps4) not only functions with its positive regulator vacuolar protein sorting 20‐associated 1 (Vta1) in the multivesicular body (MVB) pathway but also participates alone in MVB‐unrelated cellular processes. However, its physiological roles at the organism level remain rarely explored. We previously identified their respective homologues Bombyx mori Vps4 (BmVps4) and BmVta1 from the silkworm, a model organism for insect research. In this study, we performed fluorescence quantitative real‐time PCR and Western blot to globally characterize the transcription and protein expression profiles of BmVps4 and BmVta1 during silkworm development and in different silkworm tissues and organs. The results showed that they were significantly up‐regulated in metamorphosis, adulthood and embryogenesis relative to larval stages, and displayed a roughly similar tissue‐and‐organ specificity for transcriptions in silkworm larvae. Importantly, BmVps4 was down‐regulated during the early period of the fifth instar, reaching the lowest level of transcription on Day 6, then up‐regulated from Day 7 to the wandering, spinning and pupal stages, and down‐regulated again in adulthood. Moreover, knocking down BmVps4 by RNA interference significantly inhibited silk gland growth, shortened spinning time, prolonged pupation, reduced pupal size and weight, and increased moth wing defects. Together, our data demonstrate the critical and broad requirements for BmVps4 in silkworm metamorphosis.

T cells synthesize a large number of proteins during their development, activation, and differentiation. The build‐up of misfolded and unfolded proteins in the endoplasmic reticulum, however, causes endoplasmic reticulum (ER) stress. Thus, T cells can maintain ER homeostasis via endoplasmic reticulum‐associated degradation, unfolded protein response, and autophagy. In T cell‐mediated diseases, such as rheumatoid arthritis, systemic lupus erythematosus, Sjogren's syndrome, type 1 diabetes and vitiligo, ER stress caused by changes in the internal microenvironment can cause disease progression by affecting T cell homeostasis. This review discusses ER stress in T cell formation, activation, differentiation, and T cell‐mediated illnesses, and may offer new perspectives on the involvement of T cells in autoimmune disorders and cancer.

No abstract