Publications by authors named "Vivian Leong"

The incidence of hepatocellular carcinoma (HCC) is rapidly increasing due to the prevalence of obesity and non-alcoholic fatty liver disease, but the molecular triggers that initiate disease development are not fully understood. We demonstrate that mice with targeted loss-of-function point mutations within the AMP-activated protein kinase (AMPK) phosphorylation sites on acetyl-CoA carboxylase 1 (ACC1 Ser79Ala) and ACC2 (ACC2 Ser212Ala) have increased liver de novo lipogenesis (DNL) and liver lesions. The same mutation in ACC1 also increases DNL and proliferation in human liver cancer cells.

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Our understanding regarding the function of YjeQ (also called RsgA), RbfA, RimM and Era in ribosome biogenesis has been derived in part from the study of immature 30S particles that accumulate in null strains lacking one of these factors. However, their mechanistic details are still unknown. Here, we demonstrate that these immature particles are not dead-end products of assembly, but progress into mature 30S subunits.

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Rvb1 and Rvb2 are conserved AAA+ (ATPases associated with diverse cellular activities) proteins found at the core of large multicomponent complexes that play key roles in chromatin remodeling, integrity of the telomeres, ribonucleoprotein complex biogenesis and other essential cellular processes. These proteins contain an AAA+ domain for ATP binding and hydrolysis and an insertion domain proposed to bind DNA/RNA. Yeast Rvb1 and Rvb2 proteins oligomerize primarily as heterohexameric rings.

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RNA metabolism is a critical but frequently overlooked control element affecting virtually every cellular process in bacteria. RNA processing and degradation is mediated by a suite of ribonucleases having distinct cleavage and substrate specificity. Here, we probe the role of two ribonucleases (RNase III and RNase J) in the emerging model system Streptomyces venezuelae.

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Article Synopsis
  • The assembly of Escherichia coli 30S ribosomal subunits involves various protein factors (RimM, YjeQ, RbfA, Era) that assist in the final stages of maturation.
  • The study compared immature 30S subunits from ribosomes lacking either RimM or YjeQ, revealing structural defects, such as missing rRNA helices and depleted ribosomal proteins.
  • The research supports an "early convergency model" suggesting that different assembly pathways merge into a late intermediate stage before reaching the mature 30S subunit, with specific factors aiding in the final maturation steps.
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Escherichia coli DegP protein is a periplasmic protein that functions both as a protease and as a chaperone. In the absence of substrate, DegP oligomerizes as a hexameric cage but in its presence DegP reorganizes into 12 and 24-mer cages with large chambers that house the substrate for degradation or refolding. Here, we studied the factors that determine the oligomeric state adopted by DegP in the presence of substrate.

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Background: In 2003, the government of British Columbia, Canada introduced a universal drug benefit plan to cover drug costs that are high relative to household income. Residents were required to register in order to be eligible for the income-based benefits. Given past research suggesting that registration processes may pose an access barrier to certain subpopulations, we aimed to determine whether registration rates varied across small geographic areas that differed in ethnic composition.

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DNA mismatch repair maintains genomic stability by correcting errors that have escaped polymerase proofreading. Defects on mismatch repair genes lead to an increased mutation rate, microsatellite instability and predisposition to human non-polyposis colorectal cancer (HNPCC). Human MutLalpha is a heterodimer formed by the interaction of MLH1 and PMS2 that coordinates a series of key events in mismatch repair.

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The Canadian context in which home-based healthcare services are delivered is characterised by limited resources and escalating healthcare costs. As a result, a financing shift has occurred, whereby care recipients receive a mixture of publicly and privately financed home-based services. Although ensuring that care recipients receive efficient and equitable care is crucial, a limited understanding of the economic outcomes and determinants of privately financed services exists.

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Home-based health services remain one of the fastest-growing sectors in the Canadian healthcare system. While there have been studies addressing the characteristics of home care users and the determinants of utilization, the costs associated with the use of home care services, particularly private costs, have been largely neglected. To gain a comprehensive appreciation of the financing context in which ambulatory and home-based care is delivered and received, it is imperative to assess costs incurred by clients and their family/friends.

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PDZ domains are modular protein interaction domains that are present in metazoans and bacteria. These domains possess unique structural features that allow them to interact with the C-terminal residues of their ligands. The Escherichia coli essential periplasmic protein DegP contains two PDZ domains attached to the C-terminal end of the protease domain.

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The Escherichia coli DegP protein is an essential periplasmic protein for bacterial survival at high temperatures. DegP has the unusual property of working as a chaperone below 28 degrees C, but efficiently degrading unfolded proteins above 28 degrees C. Monomeric DegP contains a protease domain and two PDZ domains.

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Infected-cell protein 27 (ICP27) is an essential herpes simplex virus type 1 (HSV-1) regulatory protein that activates a subset of viral delayed-early and late genes, at least in part through posttranscriptional mechanisms. Previous studies have shown that the amino (N)-terminal half of the protein contains important functional regions, including a leucine-rich nuclear export signal (NES). However, to date, the phenotype of an HSV-1 ICP27 NES mutant has not been reported.

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