The Cul3 Ubiquitin Ligase: an Essential Regulator of Diverse Cellular Processes

Cul3 forms E3 ubiquitin ligase complexes that regulate a variety of cellular processes. This dissertation describes Cul3\u27s role in several of these pathways and provides new mechanistic details regarding the role of Cul3 in eukaryotic cells. Cyclin E is an example of a protein that is regulated in a Cul3-dependent manner. Cyclin E is a cell cycle regulator that controls the beginning of DNA replication in mammalian cells. Increased levels of cyclin E are found in some cancers, in addition, proteolytic removal of the cyclin E N-terminus occurs in some cancers and is associated with tumorigenesis. Cyclin E levels are tightly regulated and controlled in part through ubiquitin-mediated degradation initiated by one of two E3 ligase complexes, Cul1 and Cul3. Cul1 mediated degradation of cyclin E is triggered by cyclin E phosphorylation, however the mechanism Cul3 uses to ubiquitinate cyclin E is poorly understood. In order to gain a better understanding of how Cul3 mediates cyclin E destruction we identified the degron on cyclin E that is important in Cul3 dependent degradation. In addition, we show this degron is lacking in LMW cyclin E (found in abundance in breast cancer), providing a novel mechanism for how these cyclin E modifications result in increased cyclin E levels by avoiding the Cul3 degradation pathway

Estudio de la viabilidad comercial para la creación de un spa para hombres de 25 a 59 años en la ciudad de Chiclayo, 2015

La presente tesis tuvo como objetivo principal investigar la viabilidad comercial de implementar un Spa exclusivamente para hombres en la ciudad de Chiclayo, debido a que diversos estudios indicaron que en la actualidad los índices de estrés, ya sea laboral o psicológico, son elevados y se requiere desarrollar modelos de negocio que permitan atenuarlos. Por ello, la presente investigación, basándose en una segmentación que abarca hombres de 25 a 59 años, de estilos de vida sofisticados y progresistas, realizó mediante encuestas, entrevistas y grupos focales, un estudio para verificar la viabilidad de ejecución del spa masculino, del cual se obtuvo resultados positivos con respecto al crecimiento de éste sector, demostrando la aceptación del proyecto como parte del cuidado masculino, de modo que éste pueda brindar un servicio innovador, exclusivo y necesario, que ayude a mejorar la calidad de vida y satisfacción de los clientes, a través de las preferencias, características y sugerencias recolectadas en el estudio y análisis del mercado Chiclayano, por lo que se concluyó del estudio que sí es viable la creación de un spa para hombres en dicha ciudad.Tesi

Cul3 Regulates Cyclin E1 Protein Abundance via a Degron Located within the N-terminal Region of cyclin E

mammalian cells. Increased levels of cyclin E are found in some cancers. Additionally, proteolytic removal of the cyclin E N-terminus occurs in some cancers and is associated with increased cyclin E–Cdk2 activity and poor clinical prognosis. Cyclin E levels are tightly regulated and controlled in part through ubiquitin-mediated degradation initiated by one of two E3 ligases, Cul1 and Cul3. Cul1 ubiquitylates phosphorylated cyclin E, but the mechanism through which Cul3 ubiquitylates cyclin E is poorly understood. In experiments to ascertain how Cul3 mediates cyclin E destruction, we identified a degron on cyclin E that Cul3 targets for ubiquitylation. Recognition of the degron and binding of Cul3 does not require a BTB domain-containing adaptor protein. Additionally, this degron is lacking in N-terminally truncated cyclin E. Our results describe a mechanism whereby N-terminally truncated cyclin E can avoid the Cul3-mediated degradation pathway. This mechanism helps to explain the increased activity that is associated with the truncated cyclin E variants that occurs in some cancers

Multiple domains of the integral KREPA3 protein are critical for the structure and precise functions of RNA editing catalytic complexes in Trypanosoma brucei.

The gRNA directed U-insertion and deletion editing of mitochondrial mRNAs that is essential in different life-cycle stages for the protozoan parasite Trypanosoma brucei is performed by three similar multiprotein catalytic complexes (CCs) that contain the requisite enzymes. These CCs also contain a common set of eight proteins that have no apparent direct catalytic function, including six that have an OB-fold domain. We show here that one of these OB-fold proteins, KREPA3 (A3), has structural homology to other editing proteins, is essential for editing, and is multifunctional. We investigated A3 function by analyzing the effects of single amino acid loss of function mutations, most of which were identified by screening bloodstream form (BF) parasites for loss of growth following random mutagenesis. Mutations in the zinc fingers (ZFs), an intrinsically disordered region (IDR), and several within or near the carboxy-terminal OB-fold domain variably impacted CC structural integrity and editing. Some mutations resulted in almost complete loss of CCs and its proteins and editing, whereas others retained CCs but had aberrant editing. All but a mutation which is near the OB-fold affected growth and editing in BF but not procyclic form (PF) parasites. These data indicate that multiple positions within A3 have essential functions that contribute to the structural integrity of CCs, the precision of editing and the developmental differences in editing between BF and PF stages