Biology subjects

Ho, T. T.

Publications and source records attributed to Ho, T. T..

4 recordsLinked to original sources

bioRxiv2023

Autophagy counters inflammation-driven glycolytic impairment in aging hematopoietic stem cells

Aging of the hematopoietic system promotes various blood, immune and systemic disorders and is largely driven by hematopoietic stem cell (HSC) dysfunction (1). Autophagy is central for the benefits associated with activation of longevity signaling programs (2), and for HSC function and response to nutrient stress (3,4). With age, a subset of HSCs increases autophagy flux and preserves some regenerative capacity, while the rest fail to engage autophagy and become metabolically overactivated and dysfunctional (4). However, the signals that promote autophagy in old HSCs and the mechanisms responsible for the increased regenerative potential of autophagy-activated old HSCs remain unknown. Here, we demonstrate that autophagy activation is an adaptive survival response to chronic inflammation in the aging bone marrow (BM) niche (5). We find that inflammation impairs glucose metabolism and suppresses glycolysis in aged HSCs through Socs3-mediated impairment of AKT/FoxO-dependent signaling. In this context, we show that inflammation-mediated autophagy engagement preserves functional quiescence by enabling metabolic adaptation to glycolytic impairment. Moreover, we demonstrate that transient autophagy induction via a short-term fasting/refeeding paradigm normalizes glucose uptake and glycolytic flux and significantly improves old HSC regenerative potential. Our results identify inflammation-driven glucose hypometabolism as a key driver of HSC dysfunction with age and establish autophagy as a targetable node to reset old HSC glycolytic and regenerative capacity. One-Sentence SummaryAutophagy compensates for chronic inflammation-induced metabolic deregulation in old HSCs, and its transient modulation can reset old HSC glycolytic and regenerative capacity.

cell biology↗

bioRxiv2021

Stromal inflammation is a targetable driver of hematopoietic aging

Hematopoietic aging is marked by a loss of regenerative capacity and skewed differentiation from hematopoietic stem cells (HSC) leading to dysfunctional blood production. Signals from the bone marrow (BM) niche dynamically tailor hematopoiesis, but the effect of aging on the niche microenvironment and the contribution of the aging niche to blood aging still remains unclear. Here, we characterize the inflammatory milieu in the aged marrow cavity that drives both stromal and hematopoietic remodeling. We find decreased numbers and functionality of osteogenic mesenchymal stromal cells (MSC) at the endosteum and expansion of pro-inflammatory perisinusoidal MSCs with deterioration of sinusoidal endothelium in the central marrow, which together create a degraded and inflamed old niche. Molecular mapping at single cell resolution confirms disruption of cell identities and enrichment of inflammatory response genes in niche populations. Niche inflammation, in turn, drives chronic activation of emergency myelopoiesis pathways in old HSCs and multipotent progenitors (MPP), which promotes myeloid differentiation at the expense of lymphoid and erythroid commitment and hinders hematopoietic regeneration. Remarkably, niche deterioration, HSC dysfunction and defective hematopoietic regeneration, can be improved by blocking inflammatory IL-1 signaling. Our results demonstrate that targeting niche inflammation is a tractable strategy to restore blood production during aging.

cell biology↗

bioRxiv2020

An aminoacylation independent activity of PheRS/FARS promotes growth and proliferation

Summary / AbstractAminoacyl-tRNA synthetases (aaRSs) not only load the appropriate amino acid onto their cognate tRNA, but many of them perform additional functions that are not necessarily related to their canonical activities. Phenylalanyl-tRNA synthetase (PheRS/FARS) levels are elevated in various cancer cells compared to their normal cell counterparts. However, whether and how these levels might contribute to tumor formation was not clear. Here, we show that PheRS is required for cell growth and proliferation. Interestingly, elevated expression of the -PheRS subunit alone stimulates cell growth and proliferation. In the wing discs system, this leads to a strong increase of mitotic cells. Clonal analysis of twin spots in dividing follicle cells revealed that elevated expression of the -PheRS subunit causes cells to grow and proliferate about 25% faster than their normal twin cells. Importantly, this stimulation of growth and proliferation neither required the {beta}-PheRS subunit nor the aminoacylation activity, and it did not visibly stimulate translation. These results, therefore, revealed a non-canonical function of an ancient housekeeping enzyme, providing novel insight into its roles in health and diseases.

cell biology↗

bioRxiv2020

WHOLE-GENOME SEQUENCING AND DE NOVO ASSEMBLY OF A 2019 NOVEL CORONAVIRUS (SARS-COV-2) STRAIN ISOLATED IN VIETNAM

The pandemic COVID-19 caused by the zoonotic virus SARS-CoV-2 has devastated countries worldwide, infecting more than 4.5 million people and leading to more than 300,000 deaths. Whole genome sequencing (WGS) is an effective tool to monitor emerging strains and provide information for intervention, thus help to inform outbreak control decisions. Here, we reported the first effort to sequence and de novo assemble the whole genome of SARS-CoV-2 using PacBios SMRT sequencing technology in Vietnam. We also presented the annotation results and a brief analysis of the variants found in our SARS-CoV-2 strain, which was isolated from a Vietnamese patient. The sequencing was successfully completed and de novo assembled in less than 30 hours, resulting in one contig with no gap and a length of 29,766 bp. All detected variants as compared to the NCBI reference were highly accurate as confirmed by Sanger sequencing. The results have shown the potential of long read sequencing to provide high quality WGS data to support public health responses, and advance understanding of this and future pandemics.

genomics↗