Optimization of NAMPT activators to achieve in vivo neuroprotective efficacy.

NAMPT is the rate-limiting enzyme in the NAD salvage pathway, which makes it an attractive target for the treatment of many diseases associated with NAD exhaustion such as neurodegenerative diseases. Herein, we present the systematic optimization of NAT, an initial hit of NAMPT activator discovered by us through high-throughput screening, based on the co-crystal structure of the NAMPT-NAT complex. Over 80 NAT derivatives have been designed and synthesized, among which compound 72 showed notably improved potency as NAMPT activator and effectively protected cultured cells from FK866-mediated toxicity. Moreover, compound 72 exhibited strong neuroprotective efficacy in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN) without any overt toxicity, which renders it a promising candidate for the development of novel neuroprotective agents.

Discovery of small-molecule activators of nicotinamide phosphoribosyltransferase (NAMPT) and their preclinical neuroprotective activity.

The decline of nicotinamide adenine dinucleotide (NAD) occurs in a variety of human pathologies including neurodegeneration. NAD-boosting agents can provide neuroprotective benefits. Here, we report the discovery and development of a class of potent activators (NATs) of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD salvage pathway. We obtained the crystal structure of NAMPT in complex with the NAT, which defined the allosteric action of NAT near the enzyme active site. The optimization of NAT further revealed the critical role of K189 residue in boosting NAMPT activity. NATs effectively increased intracellular levels of NAD and induced subsequent metabolic and transcriptional reprogramming. Importantly, NATs exhibited strong neuroprotective efficacy in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN) without any overt toxicity. These findings demonstrate the potential of NATs in the treatment of neurodegenerative diseases or conditions associated with NAD level decline.

A Direct RNA-to-RNA Replication System for Enhanced Gene Expression in Bacteria.

A long-standing objective of metabolic engineering has been to exogenously increase the expression of target genes. In this research, we proposed the permanent RNA replication system using DNA as a template to store genetic information in bacteria. We selected Qß phage as the RNA replication prototype and made many improvements to achieve target gene expression enhancement directly by increasing mRNA abundance. First, we identified the endogenous gene Rnc, the knockout of which significantly improved the RNA replication efficiency. Second, we elucidated the essential elements for RNA replication and optimized the system to make it more easily applicable. Combined with optimization of the host cell and the system itself, we developed a stable RNA-to-RNA replication tool to directly increase the abundance of the target mRNA and subsequently the target protein. Furthermore, it was proven efficient in enhancing the expression of specific proteins and was demonstrated to be applicable in metabolic engineering. Our system has the potential to be combined with any of the existing methods for increasing gene expression.

The complete chloroplast genome of the Taiwan red pine Pinus taiwanensis (Pinaceae).

The complete nucleotide sequence of the Taiwan red pine Pinus taiwanensis Hayata chloroplast genome (cpDNA) is determined in this study. The genome is composed of 119,741 bp in length, containing a pair of very short inverted repeat (IRa and IRb) regions of 495 bp, which was divided by a large single-copy (LSC) region of 65,670 bp and a small single-copy (SSC) region of 53,080 bp in length. The cpDNA contained 115 genes, including 74 protein-coding genes (73 PCG species), 4 ribosomal RNA genes (four rRNA species) and 37 tRNA genes (22 tRNA species). Out of these genes, 12 harbored a single intron, and one (rps12) contained a couple of introns. The overall AT content of the Taiwan red pine cpDNA is 61.5%, while the corresponding values of the LSC, SSC and IR regions are 62.2%, 60.6% and 63.6%, respectively. A maximum parsimony phylogenetic analysis suggested that the genus Pinus, Picea, Abies and Larix were strongly supported as monophyletic, and the cpDNA of P. taiwanensis is closely related to that of P. thunbergii.

The complete chloroplast genome of Armand pine Pinus armandii, an endemic conifer tree species to China.

The complete chloroplast genome (cpDNA) sequence of an endemic conifer species, Armand pine Pinus armandii Franch., is determined in this study. The cpDNA was 117,265 bp in length, containing a pair of 475 bp inverted repeat (IR) regions those distinguished in large and small single copy (LSC and SSC) regions of 64,548 and 51,767 bp in length, respectively. The cpDNA contained 114 genes, including 74 protein-coding genes (74 PCG species), 4 ribosomal RNA genes (four rRNA species) and 36 transfer RNA genes (33 tRNA species). Out of these genes, 12 harbor a single intron and most of the genes occurred in a single copy. The overall AT content of the Armand pine cpDNA was 61.2%, while the corresponding values of the LSC, SSC and IR regions were 62.0%, 60.2% and 62.7%, respectively. A phylogenetic analysis revealed that P. armandii chloroplast genome is closely related to that of the P. koraiensis within the genus Pinus.