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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Cbx4 Sumoylates Prdm16 To Regulate Adipose Tissue Thermogenesis, Qingbo Chen, Lei Huang, Dongning Pan, Lihua (Julie) Zhu, Yong-Xu Wang Mar 2018

Cbx4 Sumoylates Prdm16 To Regulate Adipose Tissue Thermogenesis, Qingbo Chen, Lei Huang, Dongning Pan, Lihua (Julie) Zhu, Yong-Xu Wang

Open Access Articles

Transcriptional co-activator Prdm16 controls brown fat development and white fat browning, but how this thermogenic function is modulated post-translationally is poorly understood. Here, we report that Cbx4, a Polycomb group protein, is a SUMO E3 ligase for Prdm16 and that Cbx4-mediated sumoylation of Prdm16 is required for thermogenic gene expression. Cbx4 expression is enriched in brown fat and is induced in adipose tissue by acute cold exposure. Sumoylation of Prdm16 at lysine 917 by Cbx4 blocks its ubiquitination-mediated degradation, thereby augmenting its stability and thermogenic function. Moreover, this sumoylation event primes Prdm16 to be further stabilized by methyltransferase Ehmt1. Heterozygous ...


Phopsphorylation And Ubiquitin Modification At Dna Damage Sites In Response To Double-Strand Breaks, Atanu Paul May 2017

Phopsphorylation And Ubiquitin Modification At Dna Damage Sites In Response To Double-Strand Breaks, Atanu Paul

UT GSBS Dissertations and Theses (Open Access)

Genomes of all organisms are continuously damaged by numerous exogenous and endogenous sources leading to different kinds of DNA lesions, which if not repaired efficiently may trigger wide-scale genomic instability, a hallmark of cancer development. To overcome this, cells have evolved a sophisticated sensory network called the DNA damage response (DDR) comprised of a large number of distinct protein complexes categorized as sensor, mediator, transducer and effector proteins that amplify the DNA damage signal and activate cell cycle checkpoint to initiate DNA repair or trigger apoptosis where the defect is beyond repair. This intricate signaling pathway is tightly regulated by ...


Rad Gtpase: Identification Of Novel Regulatory Mechanisms And A New Function In Modulation Of Bone Density And Marrow Adiposity, Catherine Nicole Kaminski Withers Jan 2017

Rad Gtpase: Identification Of Novel Regulatory Mechanisms And A New Function In Modulation Of Bone Density And Marrow Adiposity, Catherine Nicole Kaminski Withers

Theses and Dissertations--Molecular and Cellular Biochemistry

The small GTP-binding protein Rad (RRAD, Ras associated with diabetes) is the founding member of the RGK (Rad, Rem, Rem2, and Gem/Kir) family that regulates voltage-dependent calcium channel function. Given its expression in both excitable and non-excitable cell types, the control mechanisms for Rad regulation and the potential for novel functions for Rad beyond calcium channel modulation are open questions. Here we report a novel interaction between Rad and Enigma, a scaffolding protein that also binds to the E3 ubiquitin ligase Smad ubiquitin regulatory factor 1 (Smurf1). Overexpression of Smurf1, but not of a ...


Novel Posttranslational Modification In Lkb1 Activation And Function, Szu-Wei Lee Dec 2014

Novel Posttranslational Modification In Lkb1 Activation And Function, Szu-Wei Lee

UT GSBS Dissertations and Theses (Open Access)

Cancer cells display dramatic alterations in cellular metabolism to meet their needs of increased growth and proliferation. In the last decade, cancer research has brought these pathways into focus, and one emerging issue that has come to attention is that many oncogenes and tumor-suppressors are intimately linked to metabolic regulation (Jones and Thompson, 2009). One of the key tumor-suppressors involved in metabolism is Liver Kinase B1 (LKB1). LKB1 is the major upstream kinase of the evolutionarily conserved metabolic sensor—AMP-activated protein kinase (AMPK). Activation of the LKB1/AMPK pathway provides a survival advantage for cells under energy stress. LKB1 forms ...


Control Of The Tumor Suppressor P53 By Regulating Mdm2 Activity And Stability, Ruchira S. Ranaweera Jan 2013

Control Of The Tumor Suppressor P53 By Regulating Mdm2 Activity And Stability, Ruchira S. Ranaweera

Publicly Accessible Penn Dissertations

p53 is a tumor suppressor that is widely mutated or deleted in cancer cells. Mdm2, an E3 ubiquitin ligase, is the master regulator of p53. It targets p53 for proteasomal degradation, restraining the potent activity of p53 and enabling cell survival and proliferation. There are complex regulatory mechanisms balancing the activity and stability of Mdm2 in a cell. Mdm2 has an extremely short half-life in the unstressed cell and its regulation is not well understood. Like most E3 ligases, Mdm2 can autoubiquitinate. Previously, the sole function of autoubiquitination was thought to be to signal Mdm2 degradation. Here I show that ...


Regulation Of The Glycine Transporter 1 (Glyt1) By Pkca-Dependent Ubiquitination, Susana Barrera Jan 2013

Regulation Of The Glycine Transporter 1 (Glyt1) By Pkca-Dependent Ubiquitination, Susana Barrera

Open Access Theses & Dissertations

Glycine is one of the major inhibitory neurotransmitters in the central nervous system. It is implicated in the regulation of motor-sensory function such as; pain perception, reflex responses, and is essential for early development of the CNS. In addition to its inhibitory actions, it acts as an obligatory co-agonist for the activation of glutamatergic NMDARs, which are of pivotal importance in the process of learning and memory, its dysfunction leads to several neurodegenerative diseases. Two high affinity Na+/Cl- dependent transporters GlyT1 and GlyT2 tightly regulate the availability of glycine present at the synapse for the activation of NMDARs and ...


The Role Of Mitochondrial Omi/Htra2 Protease In Protein Quality Control And Mitophagy, Camilla Ambivero Jan 2013

The Role Of Mitochondrial Omi/Htra2 Protease In Protein Quality Control And Mitophagy, Camilla Ambivero

Electronic Theses and Dissertations

Omi/HtrA2 is a mitochondrial serine protease with a dual and opposite function depending on its subcellular localization. Most of the previous studies focused on Omi/HtrA2’s pro-apoptotic function when the protein is released to the cytoplasm. It is becoming apparent that the main function of Omi/HtrA2 is within the mitochondria, where it has a pro-survival role. However, its mechanism is still poorly understood. To this end, we used the yeast two-hybrid system to dissect the Omi/HtrA2 pathway by identifying novel interactors and substrates. Our studies revealed a novel function of Omi/HtrA2 in the regulation of ...


Regulation Of Set1-Mediated Methylation Of Dam1, John A. Latham May 2011

Regulation Of Set1-Mediated Methylation Of Dam1, John A. Latham

UT GSBS Dissertations and Theses (Open Access)

Eukaryotic genomes exist within a dynamic structure named chromatin in which DNA is wrapped around an octamer of histones forming the nucleosome. Histones are modified by a range of posttranslational modifications including methylation, phosphorylation, and ubiquitination, which are integral to a range of DNA-templated processes including transcriptional regulation. A hallmark for transcriptional activity is methylation of histone H3 on lysine (K) 4 within active gene promoters. In S. cerevisiae, H3K4 methylation is mediated by Set1 within the COMPASS complex. Methylation requires prior ubiquitination of histone H2BK123 by the E2-E3 ligases Rad6 and Bre1, as well as the Paf1 transcriptional elongation ...


Mechanisms Of The Downregulation Of Prolactin Receptor And Their Role In Cell Proliferation, Bentley J. Varghese May 2010

Mechanisms Of The Downregulation Of Prolactin Receptor And Their Role In Cell Proliferation, Bentley J. Varghese

Publicly Accessible Penn Dissertations

Cells react to diverse stimuli by expressing specific receptors that recognize these stimuli and initiate specific signaling pathways that enable a cell to change with the environment. Downregulation of these signaling receptors represents the most direct method for limiting the magnitude and duration of downstream signal transduction. For cell surface transmembrane receptors, ligand-stimulated endocytosis is a major mechanism by which the ability of a cell to react to a ligand is restricted. In order to investigate the downregulation of the prolactin receptor (PRLr), we investigated the mechanism and key determinants in the endocytosis and downregulation of PRLr. In Chapter 2 ...