Biology subjects

Lo, S.-C.

Publications and source records attributed to Lo, S.-C..

3 recordsLinked to original sources

bioRxiv2026

Development of autotrophy in Escherichia coli through adaptive laboratory evolution

Enabling heterotrophic Escherichia coli to use CO2 as its only carbon source remains a great challenge, and previous studies approached autotrophy conversion by metabolic engineering. Although its native carbon fixation routes were identified, the potential to reach autotrophy by itself has long been overlooked. In this study, autotrophy in E. coli was developed through adaptive laboratory evolution. After 1,000 days of consecutive inorganic subculturing, missense mutations were found in isocitrate dehydrogenase icd and isocitrate dehydrogenase kinase/phosphatase aceK genes, determining the metabolic switch between the citrate cycle and the glyoxylate shunt. By transcriptomic comparison of the adapted E. coli between inorganic and organic cultivations, two CO2 fixing enzymes activated in autotrophic mode were found, including the upregulated pyruvate:ferredoxin oxidoreductase YdbK and phosphoenolpyruvate carboxykinase Pck. Connected by the upregulated phosphoenolpyruvate synthase PpsA, a carbon fixation module was constituted, which was the shared foundation of the aspartate-threonine cycle and the citrate-glyoxylate-methylcitrate cycle, and thus integrating into an autotrophic network. By comparing the 13C enrichment patterns in inorganic cultivations between the adapted and initial E. coli, the favorable direction of the autotrophic network was confirmed. IMPORTANCEThis is the first study to accomplish autotrophy in E. coli through long-term evolution alone. Besides missense mutations in icd and aceK genes, adapted E. coli also actively regulated its gene expression to respond to inorganic environment, such as directing the metabolic switch towards the glyoxylate shunt. For biomass formation, a carbon fixation module consisted of the upregulated YdbK, PpsA, and Pck produced pyruvate and oxaloacetate as precursors for two cycles. The aspartate-threonine cycle with a replenishment side loop further accumulated these precursors, and the citrate-glyoxylate-methylcitrate cycle was driven by four overexpressed enzymes to catalyze six reactions. These metabolic pathways were integrated into a novel autotrophic network, and by understanding the nature of E. coli, rational designs for its carbon fixation optimization become attainable by using compatible mechanisms.

microbiology↗

bioRxiv2025

Comparative snRNAseq study of C9orf72, SOD1, and sALS spinal cord

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the loss of motor neurons, yet the cell-type specific molecular alterations within the spinal cords are not well characterized. In this study, we conducted deep molecular profiling of spinal cord tissues donated by people living with sporadic, C9orf72, and SOD1-ALS using single-nucleus RNA sequencing (snRNAseq). We observed numerous distinct gene expression patterns and enriched pathways among ALS types. However, when focusing on common features, we identified activation of stress-response and inflammatory pathways in specific microglia subtypes, as well as disrupted vesicle transport and synaptic function in a ventral inhibitory neuronal subtype. Notably, CPLX3, a SNARE regulator, was uniquely expressed in alpha-motor neurons and was commonly downregulated across all ALS types. While this study uncovers the molecular heterogeneity underlying ALS, it also highlights shared pathways within specific cell types, especially in the ventral inhibitory neurons that have been less explored in ALS research.

neuroscience↗

bioRxiv2024

Cis-regulatory elements driving motor neuron-restricted viral payload expression within the mammalian spinal cord

Spinal motor neuron (MN) dysfunction is the cause of a number of clinically significant movement disorders. Despite the recent approval of gene therapeutics targeting these MN-related disorders, there are no viral delivery mechanisms that achieve MN-restricted transgene expression. In this study, chromatin accessibility profiling of genetically defined mouse MNs was used to identify candidate cis-regulatory elements (CREs) capable of driving MN-selective gene expression. Subsequent testing of these candidates identified two CREs that confer MN-selective gene expression in the spinal cord as well as reduced off-target expression in dorsal root ganglia. Within one of these candidate elements, we identified a compact core transcription factor (TF)-binding region that drives MN-selective gene expression. Finally, we demonstrate that selective spinal cord expression of this mouse CRE is preserved in non-human primates. These findings suggest that the generation of cell-type-selective viral reagents, in which cell-type-selective CREs drive restricted gene expression, will be valuable research tools in mice and other mammalian species, with potentially significant therapeutic value in humans. SIGNIFICANCE STATEMENTMotor neurons transduce the motor outputs of nervous system activity to muscle and are the vulnerable neurons in a number of clinically significant degenerative conditions, including spinal muscular atrophy and amyotrophic lateral sclerosis. A recent strategy for treating motor neuron degenerative diseases has been to use viruses to introduce genes into motor neurons to inhibit the degenerative process. However, we still lack viral reagents that promote gene expression in motor neurons without potentially toxic off-target expression in other cell types. Our study identifies cis-regulatory elements capable of conferring motor neuron-selective transgene expression in a viral context. These findings have important implications for future gene therapeutics for motor neuron-related disorders.

neuroscience↗