Biology subjects

Ting, K.

Publications and source records attributed to Ting, K..

5 recordsLinked to original sources

bioRxiv2024

Patterned wireless transcranial optogenetics generates artificial perception

Synthesizing perceivable artificial neural inputs independent of typical sensory channels remains a fundamental challenge in the development of next-generation brain-machine interfaces. Establishing a minimally invasive, wirelessly effective, and miniaturized platform with long-term stability is crucial for creating a clinically meaningful interface capable of mediating artificial perceptual feedback. In this study, we demonstrate a miniaturized fully implantable wireless transcranial optogenetic encoder designed to generate artificial perceptions through digitized optogenetic manipulation of large cortical ensembles. This platform enables the spatiotemporal orchestration of large-scale cortical activity for remote perception genesis via real-time wireless communication and control, with optimized device performance achieved by simulation-guided methods addressing light and heat propagation during operation. Cue discrimination during operant learning demonstrates the wireless genesis of artificial percepts sensed by mice, where spatial distance across large cortical networks and sequential order-based analyses of discrimination performance reveal principles that adhere to general perceptual rules. These conceptual and technical advancements expand our understanding of artificial neural syntax and its perception by the brain, guiding the evolution of next-generation brain-machine communication.

neuroscience↗

bioRxiv2024

Inhibition of heme biosynthesis triggers cuproptosis in acute myeloid leukaemia.

The ubiquitous metabolite heme has diverse enzymatic and signalling functions in most mammalian cells. Cells can salvage heme from the extracellular environment or synthesise heme de novo from succinyl-CoA and glycine through a series of 8 enzymatic reactions catalysed by heme biosynthesis enzymes (HBEs) localised in the mitochondria and the cytosol1,2. Through integrated analyses of mouse models, human cell lines and primary patient samples, we identify de novo heme biosynthesis as a selective dependency in acute myeloid leukaemia (AML). The dependency is underpinned by a propensity of AML cells, and especially leukaemic stem cells (LSCs) to downregulate HBEs. The resultant low heme state upregulates self-renewal genes via the heme sensing transcription factor BACH1, but also places leukaemia cells on the threshold of heme starvation. Genetic or pharmacological inhibition of HBEs induces cuproptosis, a form of programmed cell death caused by copper accumulation and oligomerisation of lipoylated proteins3. Moreover, we identify pathways that are synthetic lethal with heme biosynthesis, including glycolysis, which can be leveraged for combination strategies. Altogether, our work uncovers a heme rheostat that controls gene expression and drug sensitivity in AML and implicates HBE inhibition as a novel cuproptosis trigger.

cancer biology↗

bioRxiv2024

Intracellular accumulation of free cholesterol in macrophages triggers a PARP1 response to DNA damage and PARP1 impairs lipopolysaccharide-induced inflammatory response

The formation of macrophage (M{varphi}) foam cells is a hallmark of atherosclerosis, yet how the process of lipid loading can modulate M{varphi} inflammatory responses by rewiring their intracellular metabolic circuits is not well understood. Our previous studies have shown that the accumulation of oxidized LDL (oxLDL) or free cholesterol in M{varphi}s impaired their inflammatory response by suppressing HIF-1-mediated glycolysis and upregulating NRF2 antioxidative response. However, it remains unclear if other metabolic processes are also contributory. In this study, we found that the accumulation of free cholesterol, but not oxLDL, in primary murine thioglycolate-elicited peritoneal M{varphi}s (PM{varphi}s) enhanced a PARP1-dependent response associated with repair of DNA damage, which was characterized by poly ADP-ribosylation of proteins, phosphorylation of histone 2A.X and consumption of NAD+. Both oxLDL and cholesterol enhanced the PARP1 response after LPS stimulation. Treatment of PM{varphi}s with mitoTEMPO, a specific mitochondrial reactive oxygen species (mtROS) scavenger, alleviated mtROS during cholesterol loading, blocked the PARP1 response and partially restored LPS-induced inflammatory gene expression. In contrast to inhibition of PARP1 enzymatic activity, knockdown of PARP1 expression in RAW264.7 M{varphi}s with siRNA elevated LPS-induced inflammatory gene expression. Overall, our study suggests that cholesterol accumulation triggers a PARP1 response to DNA damage in M{varphi}s and that PARP1 inhibits LPS-mediated inflammation through a non-enzymatic function.

immunology↗

bioRxiv2022

NELL-1 regulates the matrisome to alter osteosarcoma disease progression

Sarcomas produce abnormal extracellular matrix (ECM) which in turn provides instructive cues for cell growth and invasion. Neural EGF Like-Like molecule 1 (NELL1) is a secreted glycoprotein characterized by its non-neoplastic osteoinductive effects, yet highly expressed in skeletal sarcomas. Here, NELL1 gene deletion markedly reduced invasive behavior across human osteosarcoma (OS) cell lines. This resulted in reduced OS disease progression, inhibited metastatic potential and improved survival in a xenograft model. These observations were recapitulated with Nell1 conditional knockout in mouse models of p53/Rb driven sarcomagenesis, including reduced tumor frequency, and extended tumor free survival. Transcriptomic and phospho-proteomic analysis demonstrated that NELL1 loss skews the expression of matricellular proteins associated with reduced FAK signaling. Culture on OS enriched matricellular proteins reversed phenotypic and signaling changes among NELL1 knockout sarcoma cells. These findings in mouse and human models suggest that NELL1 expression alters the sarcoma matrix, thereby modulating cellular invasive potential and prognosis. Disruption of NELL1 signaling may represent a novel therapeutic approach to short circuit sarcoma disease progression.

cancer biology↗

bioRxiv2021

Alternative Splicing Regulates the Physiological Adaptation of the Mouse Hind Limb Postural and Phasic Muscles to Microgravity

Muscle atrophy and fiber type alterations are well-characterized physiological adaptations to microgravity with both understood to be primarily regulated by differential gene expression (DGE). While microgravity-induced DGE has been extensively investigated, adaptations to microgravity due to alternative splicing (AS) have not been studied in a mammalian model. We sought to comprehensively elucidate the transcriptomic underpinnings of microgravity-induced muscle phenotypes in mice by evaluating both DGE and changes in AS due to extended spaceflight. Tissue sections and total RNA were isolated from the gastrocnemius and quadriceps, postural and phasic muscles of the hind limb, respectively, of 32-week-old female BALB/c mice exposed to microgravity or ground control conditions for nine weeks. Immunohistochemistry disclosed muscle type-specific physiological adaptations to microgravity that included i) a pronounced reduction in muscle fiber cross-sectional area in both muscles and ii) a prominent slow-to-fast fiber type transition in the gastrocnemius. RNA sequencing revealed that DGE and AS varied across postural and phasic muscle types with preferential employment of DGE in the gastrocnemius and AS in the quadriceps. Gene ontology analysis indicated that DGE and AS regulate distinct molecular processes. Various non-differentially expressed transcripts encoding musculoskeletal proteins (Tnnt3, Tnnt1, Neb, Ryr1, and Ttn) and muscle-specific RNA binding splicing regulators (Mbnl1 and Rbfox1) were found to have significant changes in AS that altered critical functional domains of their protein products. In striking contrast, microgravity-induced differentially expressed genes were associated with lipid metabolism and mitochondrial function. Our work serves as the first comprehensive investigation of coordinate changes in DGE and AS in large limb muscles across spaceflight. We propose that substantial remodeling of pre-mRNA by AS is a major component of transcriptomic adaptation of skeletal muscle to microgravity. The alternatively spliced genes identified here could be targeted by small molecule splicing regulator therapies to address microgravity-induced changes in muscle during spaceflight.

genomics↗