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Supplemental Digital Content is available in the text.

The organization of the membrane cytoskeleton of red blood cells allows them to tolerate constant exposure to mechanical stresses. We demonstrated that the proper organization of the membrane cytoskeleton of red blood cells requires Ttll4. Red blood cells from Ttll4-knockout mice showed an abnormal arrangement of the membrane cytoskeleton.

In this study, we directly imaged subnanometer-scale structures of tubulins by performing frequency modulation atomic force microscopy (FM-AFM) in liquid. Individual α-helices at the surface of a tubulin protofilament were imaged as periodic corrugations with a spacing of 0.53 nm, which corresponds to the common pitch of an α-helix backbone (0.54 nm). The identification of individual α-helices allowed us to determine the orientation of the deposited tubulin protofilament. As a result, C-terminal domains of tubulins were identified as protrusions with a height of 0.4 nm from the surface of the tubulin. The imaging mechanism for the observed subnanometer-scale contrasts is discussed in relation to the possible structures of the C-terminal domains. Because the C-terminal domains are chemically modified to regulate the interactions between tubulins and other biomolecules (e.g., motor proteins and microtubule-associated proteins), detailed structural information on individual C-terminal domains is valuable for understanding such regulation mechanisms. The results obtained in this study demonstrate that FM-AFM is capable of visualizing the structural variation of tubulins with subnanometer resolution. This is an important first step toward using FM-AFM to analyze the functions of tubulins.

Background: The indication for endoscopic resection for submucosally invasive colorectal cancer (T1-CRC) depends on the preoperative diagnosis of invasion depth. The aim of this investigation was to evaluate the association between barium enema examination (BE) profile views and depth of submucosal (SM) invasion in CRCs. Methods: We reviewed the radiographic and endoscopic findings of 145 T1-CRCs diagnosed from 2008 to 2019. We measured the widths of horizontal and vertical rigidity under a BE profile view corresponding to CRC and compared the values with SM invasion depth. Horizontal rigidity was defined as the horizontal length and vertical rigidity as the vertical width of the barium defect corresponding to each target lesion. The most appropriate cut-off values for predicting SM invasion ≥1.8 mm were calculated by receiver operating characteristic curve analysis. Results: Values of horizontal rigidity (r= 0.626, P< 0.05) and vertical rigidity (r= 0.482, P< 0.05) correlated significantly with SM invasion depth. The most appropriate cut-off values for the prediction of SM invasion depth ≥ 1.8 mm were 4.5 mm for horizontal rigidity, with an accuracy of 80.7%; and 0.7 mm for vertical rigidity, with an accuracy of 77.9%. The prevalence of lympho-vascular invasion was significantly different when those cut-off values were applied (43.2% vs. 17.5% for horizontal rigidity, P< 0.005). Conclusions: In T1-CRC, values of horizontal and vertical rigidities under a BE profile view were correlated with SM invasion depth. While the accuracy of the rigidities for the prediction of SM invasion depth ≥ 1.8 mm was not high, horizontal rigidity may be predictive of lympho-vascular invasion, thus aiding in therapeutic decision-making.

The cholestane amide conjugate MCC-257 has been shown to augment the effects of nerve growth factor (NGF) on cell survival and on tyrosine phosphorylation of the TrkA receptor in PC12 cells. Recent findings suggest that signaling pathways downstream of Trk are regulated independently. We describe here our finding that the NGF-induced phosphorylation of both ERK and Akt are accelerated by MCC-257. Analysis of the common features of the augmented pathways suggests that TrkA is most likely to be the primary target of MCC-257 and that both ERK and Akt may be involved in the cellular effects of this compound.

Aspartate aminotransferase (AspAT) was purified to homogeneity from cell extracts of the non-N2-fixing cyanobacterium Phormidium lapideum. The NH2-terminal sequence of 25 amino acid residues was different from the sequences of the subfamily Iα of AspATs from eukaryotes and Escherichia coli, but it was similar to sequences of the subfamily Iγ of AspATs from archaebacteria and eubacteria. The enzyme was most active at 80°C and was stable at up to 75°C. Thermal inactivation (60-85°C) of the enzyme followed first-order kinetics, with 2-oxoglutarate causing a shift of the thermal inactivation curves to higher temperatures. However, at 25°C the kcatof P. lapideumAspAT was nearly equal to the values of AspATs from mesophilic organisms. The enzyme used L-aspartate and L-cysteine sulfinate as amino donors and 2-oxoglutarate as an amino acceptor. The Kmvalues were 5.0 mMfor L-aspartate, 5.7 mMfor L-glutamate, 0.2 mMfor 2-oxoglutarate, and 0.032 mMfor oxaloacetate.