The utterly unforeseen livelihood shock: COVID-19 and street vendor coping mechanisms in Hanoi, Chiang Mai and Luang Prabang.

Well before COVID-19, municipal governments in Vietnam, Thailand and Laos were enacting policies that made street vendor livelihoods increasingly challenging. Yet, vending continues to support tens of thousands of urban households in these three countries. Vendors are often rural-to-urban migrants lacking the formal education skills necessary to secure 'modern' urban employment, and despite ongoing government disapproval, vending provides a relatively low entry-cost opportunity for them to support their household's financial needs. Now add to this complex situation the livelihood shocks associated with the COVID-19 pandemic, as well as additional government restrictions across these three countries to mitigate the pandemic's impacts. Drawing on interviews with 61 street vendors in Hanoi, Chiang Mai and Luang Prabang, and rooted in conceptual discussions regarding urban livelihood shocks, we examine how street vendors, especially rural-to-urban migrants, experienced and responded to the 'first wave' of COVID-19, including additional government-imposed constraints on their livelihoods and mobility. We find that a diverse range of responses helped some-but not all-vendors overcome the initial shocks to their livelihoods and household responsibilities. Yet, we also note that the pandemic's onset altered urban-rural connections and mobility, with many vendors who turned to formerly dependable rural-urban ties for support facing unexpected barriers.

Mechanism of dominant-negative telomerase function.

Human telomerase uses its integral core components, hTR and hTERT, to maintain telomeres in many cell types. Expression of a dominant-negative mutant of the catalytic subunit of telomerase, DN-hTERT, has been shown to cause telomere shortening and ultimately cell death in a number of tumor-derived cell lines. However, the mechanism of dominant-negative hTERT function and its fate inside the cell are still unknown. In order to understand the effect of the dominant-negative on wild-type hTERT, each was fused with GFP and expressed in telomerase-positive cells. GFP-DN-hTERT expression resulted in cytoplasmic exportation and degradation via ubiquitination. Co-expression of wild-type GFP-hTERT with an untagged DN-hTERT resulted in decreased wild-type hTERT levels, export to the cytoplasm, and increased ubiquitination, suggesting that DN-hTERT complexes with wild-type hTERT to induce cytoplasmic localization. Based on the cytoplasmic degradation, we propose two new mechanisms of dominant-negative hTERT, employing the theory of interactive dimerization. First, the heterodimer of DN-hTERT with wild-type hTERT is exported to the cytoplasm for ubiquitin-mediated protein degradation, and second, the heterodimer may be degraded at a faster rate than the wild-type hTERT homodimer. Understanding mechanisms of telomerase degradation will guide future drug design to target sites on telomerase important for catalytic activity and protein stability.

Genetic inhibition of telomerase results in sensitization and recovery of breast tumor cells.

Telomerase, a ribonucleoprotein enzyme minimally composed of an RNA template (human telomerase RNA) and a catalytically active protein subunit (human telomerase reverse transcriptase), synthesizes telomeric repeats onto chromosome ends and is obligatory for continuous tumor cell proliferation. Telomerase is an attractive anticancer therapeutic target because its activity is present in >90% of human cancers, including >95% of breast carcinomas. Traditional chemotherapies lack the ability to effectively control and cure breast cancer, in part because residual cells are often resistant to DNA-damaging modalities. Although numerous telomerase inhibition strategies cause cancer cells to undergo apoptosis or senescence, there is often a lag period between the beginning of the treatment regimen and a biological effect. Thus, our goal for these studies was to show that effectively blocking telomerase genetically together with standard chemotherapeutic agents, doxorubicin/Adriamycin or Taxol, would increase the sensitization and efficacy for triggering senescence and/or apoptosis in cultures of breast cancer cells while reducing toxicity. We find that blocking telomerase in breast tumor cells substantially increases the sensitization at lower doses of Adriamycin or Taxol and that the kinetics of senescence/apoptosis is more rapid at higher concentrations. Combined with telomerase inhibition, Taxol treatment induced both apoptosis (its typical cell fate) and senescence, both at high enough levels to suggest that these two cellular responses are not mutually exclusive. Genetic inhibition of telomerase is eventually reversed due to up-regulation of endogenous telomerase activity without a net change in telomere length, suggesting that telomerase inhibition itself, not necessarily short telomeres, is important for sensitization.