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Structure-Based Mechanism For Early Plp-Mediated Steps Of Rabbit Cytosolic Serine Hydroxymethyltransferase Reaction, Martino L. Di Salvo, J. Neel Scarsdale, Galina Kazanina, Roberto Contestabile, Verne Schirch, H. Tonie Wright

Biochemistry and Molecular Biology Publications

Serine hydroxymethyltransferase catalyzes the reversible interconversion of L-serine and glycine with transfer of one-carbon groups to and from tetrahydrofolate. Active site residue Thr254 is known to be involved in the transaldimination reaction, a crucial step in the catalytic mechanism of all pyridoxal 5′-phosphate- (PLP-) dependent enzymes, which determines binding of substrates and release of products. In order to better understand the role of Thr254, we have expressed, characterized, and determined the crystal structures of rabbit cytosolic serine hydroxymethyltransferase T254A and T254C mutant forms, in the absence and presence of substrates. These mutants accumulate a kinetically stable gem-diamine intermediate, and their …

Osu-03012 Sensitizes Breast Cancers To Lapatinib-Induced Cell Killing: A Role For Nck1 But Not Nck2, N. Winston West, Aileen Garcia-Vargas, Charles E. Chalfant, Margaret A. Park

Biochemistry and Molecular Biology Publications

Background

Lapatinib is characterized as an ErbB1/ErbB2 dual inhibitor and has recently been approved for the treatment of metastatic breast cancer. In this study, we examined mechanisms associated with enhancing the activity of lapatinib via combination with other therapies.

Methods

In the present studies, estrogen receptor (ER) positive and ER negative breast cancer cells were genetically manipulated to up- or downregulate eIF2-alpha, its phospho-mutant, Nck1, or Nck2, then treated with OSU-03012, lapatinib or the combination and assayed for cytotoxicity/cytostaticity using clonogenic assays.

Results

Treatment of breast cancer cell lines with lapatinib and OSU-03012 (a small molecule derivative of the Cox-2 …

The Geometry Of Locomotive Behavioral States In C. Elegans, Thomas Gallagher, Theresa Bjorness, Robert Greene, Young-Jai You, Leon Avery

Biochemistry and Molecular Biology Publications

We develop a new hidden Markov model-based method to analyze C elegans locomotive behavior and use this method to quantitatively characterize behavioral states. In agreement with previous work, we find states corresponding to roaming, dwelling, and quiescence. However, we also find evidence for a continuum of intermediate states. We suggest that roaming, dwelling, and quiescence may best be thought of as extremes which, mixed in any proportion, define the locomotive repertoire of C elegans foraging and feeding behavior.

Light-Induced Translocation Of Rgs9-1 And Gβ5l In Mouse Rod Photoreceptors, Mei Tian, Marisa Zallocchi, Weimin Wang, Ching-Kang Chen, Krzysztof Palczewski, Duane Delimont, Dominic Cosgrove, You-Wei Peng

Biochemistry and Molecular Biology Publications

The transducin GTPase-accelerating protein complex, which determines the photoresponse duration of photoreceptors, is composed of RGS9-1, Gβ5L and R9AP. Here we report that RGS9-1 and Gβ5L change their distribution in rods during light/dark adaptation. Upon prolonged dark adaptation, RGS9-1 and Gβ5L are primarily located in rod inner segments. But very dim-light exposure quickly translocates them to the outer segments. In contrast, their anchor protein R9AP remains in the outer segment at all times. In the dark, Gβ5L's interaction with R9AP decreases significantly and RGS9-1 is phosphorylated at S475 to a significant degree. Dim light exposure leads to quick de-phosphorylation of …

Hif- And Non-Hif-Regulated Hypoxic Responses Require The Estrogen-Related Receptor In Drosophila Melanogaster, Yan Li, Divya Padmanabha, Luciana B. Gentile, Catherine I. Dumur, Robert B. Beckstead, Keith D. Baker

Biochemistry and Molecular Biology Publications

Low-oxygen tolerance is supported by an adaptive response that includes a coordinate shift in metabolism and the activation of a transcriptional program that is driven by the hypoxia-inducible factor (HIF) pathway. The precise contribution of HIF-1a in the adaptive response, however, has not been determined. Here, we investigate how HIF influences hypoxic adaptation throughout Drosophila melanogaster development. We find that hypoxic-induced transcriptional changes are comprised of HIF-dependent and HIF-independent pathways that are distinct and separable. We show that normoxic set-points of carbohydrate metabolites are significantly altered in sima mutants and that these animals are unable to mobilize glycogen in hypoxia. …

A Networks Method For Ranking Microrna Dysregulation In Cancer, William Budd, Sarah Seashols, Danielle Weaver, Cyriac Joseph, Zendra E. Zehner

Biochemistry and Molecular Biology Publications

Background

Despite the lack of agreement on their exact roles, it is known that miRNAs contribute to cancer progression. Many studies utilize methods to detect differential regulation of miRNA expression. It is prohibitively expensive to examine all potentially dysregulated miRNAs and traditionally, researchers have focused their efforts on the most extremely dysregulated miRNAs. These methods may overlook the contribution of less differentially expressed but more functionally relevant miRNAs. The purpose of this study was to outline a method that not only utilizes differential expression but ranks miRNAs based on the functional relevance of their targets. This work uses a networks …