Abstract Fetal Alcohol Syndrome (FAS) is characterized by disrupted fetal brain development and postnatal cognitive impairment. The targets of alcohol are diverse and it is not clear whether there are common underlying molecular mechanisms producing these disruptions. Prior work established that acute ethanol exposure causes a transient increase in tyrosine phosphorylation of multiple proteins in cultured embryonic cortical cells. In this study we show a similar tyrosine phosphorylation transient occurs in the fetal brain after maternal dosing with ethanol. Using phospho-specific antibodies and immunohistochemistry, we mapped regions of highest tyrosine phosphorylation in the fetal cerebral cortex and found that areas of dendritic and axonal growth showed elevated tyrosine phosphorylation 10 min after maternal ethanol exposure. These were also areas of Src expression and Src Family Kinase (SFKs) activation loop phosphorylation (pY416) expression. Importantly, maternal pretreatment with the SFK inhibitor Dasatinib completely prevents both the pY416 increase and the tyrosine phosphorylation response. The phosphorylation response was observed in the perisomatic region and neurites of immature migrating and differentiating primary neurons. Importantly, the initial phosphotyrosine transient (~ 30 min) targets both Src and Dab1, two critical elements in Reelin-signaling, a pathway required for normal cortical development. This initial phosphorylation response is followed by sustained reduction in Ser3 phosphorylation of n-cofilin, a critical actin severing protein and an identified downstream effector of Reelin-signaling. This biochemical disruption is associated with sustained reduction F-actin content and disrupted Golgi-apparatus morphology in developing cortical neurons. The finding outlines a model in which the initial activation of SFKs by ethanol has the potential to disrupt multiple developmentally important signaling systems for several hours after maternal exposure.
Calcium ions play critical roles in neuronal differentiation. We have recorded transient, repeated elevations of calcium in embryonic Xenopus spinal neurons over periods of 1 h in vitro and in vivo, confocally imaging fluo 3-loaded cells at 5 s intervals. Calcium spikes and calcium waves are found both in neurons in culture and in the intact spinal cord. Spikes rise rapidly to approximately 400% of baseline fluorescence and have a double exponential decay, whereas waves rise slowly to approximately 200% of baseline fluorescence and decay slowly as well. Imaging of fura 2-loaded neurons indicates that intracellular calcium increases from 50 to 500 nM during spikes. Both spikes and waves are abolished by removal of extracellular calcium. Developmentally, the incidence and frequency of spikes decrease, whereas the incidence and frequency of waves are constant. Spikes are generated by spontaneous calcium-dependent action potentials and also utilize intracellular calcium stores. Waves are produced by a mechanism that does not involve classic voltage-dependent calcium channels. Spikes are required for expression of the transmitter GABA and for potassium channel modulation. Waves in growth cones are likely to regulate neurite extension. The results demonstrate the roles of a novel signaling system in regulating neuronal plasticity, that operates on a time scale 10(4) times slower than that of action potentials.
Mast cell colonies were obtained when lymph node cells of horse serum-immunized Balb/c mice were cultured in a horse serum-containing medium on embryonic fibroblast monolayer. In order to characterize precursors of mast cells, mesenteric lymph node cells from the immunized mice were fractionated to obtain nonadherent cells, a B cell-depleted fraction and a T cell-depleted fraction; and each fraction was cultured on fibroblast monolayer. Mast cell colonies developed from nonadherent cells and from the B cell-depleted fraction but not from the T cell-depleted fraction. However, cultures of the same T cell-depleted fraction developed mast cell colonies if cell-free supernatant obtained from culture of horse serum-primed T cells was added. Soluble factors promoting mast cell growth were not obtained when the same T cells were incubated in horse serum-free medium. It appears that the majority of mast cell precursors in the lymph nodes are nonadherent cells and bear neither immunoglobulin nor Thy 1 antigen. The results also suggested that soluble factor(s) released from antigen-stimulated T cells enhanced the differentiation of the precursors to mature mast cells.
Fetal alcohol syndrome (FAS) is characterized by disrupted fetal brain development and postnatal cognitive impairment. The targets of alcohol are diverse, and it is not clear whether there are common underlying molecular mechanisms producing these disruptions. Prior work established that acute ethanol exposure causes a transient increase in tyrosine phosphorylation of multiple proteins in cultured embryonic cortical cells. In this study, we show that a similar tyrosine phosphorylation transient occurs in the fetal brain after maternal dosing with ethanol. Using phospho-specific antibodies and immunohistochemistry, we mapped regions of highest tyrosine phosphorylation in the fetal cerebral cortex and found that areas of dendritic and axonal growth showed elevated tyrosine phosphorylation 10 min after maternal ethanol exposure. These were also areas of Src expression and Src family kinase (SFK) activation loop phosphorylation (pY416) expression. Importantly, maternal pretreatment with the SFK inhibitor dasatinib completely prevents both the pY416 increase and the tyrosine phosphorylation response. The phosphorylation response was observed in the perisomatic region and neurites of immature migrating and differentiating primary neurons. Importantly, the initial phosphotyrosine transient (~ 30 min) targets both Src and Dab1, two critical elements in Reelin signaling, a pathway required for normal cortical development. This initial phosphorylation response is followed by sustained reduction in Ser3 phosphorylation of n-cofilin, a critical actin severing protein and an identified downstream effector of Reelin signaling. This biochemical disruption is associated with sustained reduction of F-actin content and disrupted Golgi apparatus morphology in developing cortical neurons. The finding outlines a model in which the initial activation of SFKs by ethanol has the potential to disrupt multiple developmentally important signaling systems for several hours after maternal exposure.
Abstract Primary tumors grow and invade into surrounding tissues/stroma, frequently resulting in metastasis to distant organs. Tumor cell-stroma crosstalk plays a crucial, but incompletely understood role during tumor progression and metastasis. For example, increased stromal matrix density and/or rigidity correlates with poor prognosis in human breast cancer patients. Previous studies have implicated Hic-5, a focal adhesion scaffold protein, in tumor cell invasion, proliferation and metastasis. To investigate the role of Hic-5 in mammary tumor progression, Hic-5 -/- mice were generated and crossed with mice expressing Polyoma Middle T Antigen (PyMT) driven by the MMTV promoter. The PyMT mouse is a well-established model for human breast cancer progression. Tumors from the Hic-5 -/- PyMT mice demonstrated an increased latency and had reduced growth as compared to Hic-5 +/- PyMT controls. The absence of Hic-5 did not affect the progression of the tumor to a carcinoma stage, but there was a decrease in metastasis to the lungs. Immunohistochemical analysis showed that Hic-5 is primarily expressed in the cancer associated fibroblasts (CAFs) and the Hic-5 -/- PyMT tumor stroma exhibits reduced extracellular matrix (ECM) deposition. Furthermore, 3D cell-derived matrices (CDM) generated in vitro using isolated CAFs, confirmed that Hic-5 -/- PyMT CAFs do not efficiently deposit and organize ECM. The organization of the stromal matrix has been shown previously to increase the rigidity of the tumor, which in turn promotes FAK Y397 phosphorylation in the tumor cells to promote cell invasion and proliferation. Accordingly, the Hic-5 -/- PyMT tumors exhibited a reduction in FAK phospho-Y397 staining and attenuation of downstream ERK activation, suggesting that their stromal matrix is not optimally organized for tumor cell signaling. Taken together, these data demonstrate that Hic-5 expression in CAFs is important for stromal matrix organization/remodeling during tumor progression and that the loss of the organization of the ECM in the Hic-5 -/- tumor stroma may contribute to the reduced tumor growth and metastasis observed in these animals. Supported by NIH CA163296 to CET, NS066071 to EO and Carol M. Baldwin Breast Cancer Fund to CET. Citation Format: Gregory J. Goreczny, Jessica Ouderkirk, Eric Olson, Mira Krendel, Christopher Turner. Hic-5 modulation of the stromal matrix is required for mammary tumor progression. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5095.
For more than a decade, various approaches have been taken to teach anatomy using immersive virtual reality. This is the first complete anatomy course we are aware of which directly substitutes immersive virtual reality via stereo volume visualization of clinical radiological datasets for cadaver dissection. The students valued highly the new approach and the overall course was very well received. Students performed well on examinations. The course efficiently added human anatomy to the University of Chicago undergraduate biology electives.
