We have collaborated with the Angerer lab (NIH) to examine the roles of GalNAc-Ts and mucin-type O-glycosylation during embryonic development of the sea urchin, S. purpuratus. One phenotype has been characterized in morphants in which SpGalNAc-T13 expression was attenuated. This results in a deficiency of embryonic skeleton and neurons, suggesting that mucin-type O-glycans play essential roles during embryonic development in S. purpuratus. A manuscript will be submitted shortly. Gaetan Herbomel, Duy Tran, Raul Rojas, Monica Ajinkya, and Lauren Beck challenged the hypothesis put forward by Gill et al., (The Journal of Cell Biology. 189:843, 2010) that growth factors EGF or PDGF, induce Golgi complex-to- endoplasmicreticulum (ER) relocation of both GalNAc-Ts and Tn antigen in HeLa cells,offering a mechanism for Tn antigen over-expression termed GALA. However, we were unable to reproduce these findings. Upon treatment of HeLa cells with either EGF or PDGF we observed no change in the co-localization of endogenous GalNAc-T1, GalNAc-T2 or Tn antigen with the Golgi complex marker TGN46. There was also no enhancement of localization with the ER marker calnexin. We conclude that growth factors do not cause redistribution of GalNAc-Ts from the Golgi complex to the ER in HeLa cells.We have placed a manuscript on the BioRxiv pre-print server (http://biorxiv.org/content/early/2016/08/23/071225) and have submitted the manuscript to JCB. Duy Tran, Gaetan Herbomel, Raul Rojas, and Jessi Becker are evaluating the studied the targeting signals in GalNAc-Ts that direct these enzymes from the endoplasmic reticulum to the Golgi and then retain them in the Golgi. They are also using super resolution microscopy to discern which compartments in the Golgi different GalNAc-Ts are retained in. Nadine Samara and Amy Fernandez are studying the structural basis for GalNAc-T substrate specificity using X-ray crystallography. We have a collaboration with Henrik Clausen in Denmark on the role of GalNAc-T11 in early mouse development.
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