Recent studies have shown that miRNAs can target the promoter and CDS region. Thus, we predicted miRNA target sites in the 5'-UTR, CDS and 3'-UTR of Homo sapiens, Mus musculus and Drosophila melanogaster using miRanda and TargetScan. Target-site densities normalized with the average region length were higher in the 5'-UTR than 3'-UTR in all three organisms but were lower in the negative data set. Interestingly, the putative target sites were more conserved than non-target regions in both the 5'-UTR and 3'-UTR, implying that target sites in the 5'-UTR are subject to high selective pressure and might be functional. In Drosophila, 48 of 78 (61.5%) miRNAs showed high similarities with predicted siRNAs. Based on the results of previous experimental studies and a large-scale statistical analysis, we conclude that miRNA-mediated regulation is not limited to the 3'-UTR. However, the functionality of target sites in the 5'-UTR and CDS requires thorough investigation.

Insulinoma-associated1a (insm1a) is a zinc-finger transcription factor playing a series of functions in cell formation and differentiation of vertebrate central and peripheral nervous systems and neuroendocrine system. However, its roles on the development of motor neuron have still remained uncovered. Here, we provided evidences that insm1a was a vital regulator of motor neuron development, and provided a mechanistic understanding of how it contributes to this process. Firstly, we showed the localization of insm1a in spinal cord, and primary motor neurons (PMNs) of zebrafish embryos by in situ hybridization, and imaging analysis of transgenic reporter line Tg(insm1a: mCherry)ntu805. Then we demonstrated that the deficiency of insm1a in zebrafish larvae lead to the defects of PMNs development, including the reduction of caudal primary motor neurons (CaP), and middle primary motor neurons (MiP), the excessive branching of motor axons, and the disorganized distance between adjacent CaPs. Additionally, knockout of insm1 impaired motor neuron differentiation in the spinal cord. Locomotion analysis showed that swimming activity was significantly reduced in the insm1a-null zebrafish. Furthermore, we showed that the insm1a loss of function significantly decreased the transcript levels of both olig2 and nkx6.1. Microinjection of olig2 and nkx6.1 mRNA rescued the motor neuron defects in insm1a deficient embryos. Taken together, these data indicated that insm1a regulated the motor neuron development, at least in part, through modulation of the expressions of olig2 and nkx6.1.

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Abstract:The control of cellular N-acetylmannosamine (ManNAc) levels has been postulated to be an effective way to modulate the decoration of cell surfaces with sialic acid. N-acetylglucosamine 2-epimerase catalyzes the interconversion of N-acetylglucosamine (GlcNAc) and ManNAc. Herein, we describe the cloning, expression, purification and biochemical characterization of an unstudied N-acetylglucosamine 2-epimerase from Pedobacter heparinus (PhGn2E). To further characterize the enzyme, several N-acylated glucosamine derivatives were chemically synthesized, and subsequently used to test the substrate specificity of PhGn2E. Furthermore, NMR studies of deuterium/hydrogen exchange at the anomeric hydroxy group and C-2 positions of the substrate in the reaction mixture confirmed for the first time the postulated epimerization reaction via ring-opening/enolate formation. Site-directed mutagenesis of key residues in the active site showed that Arg63 and Glu314 are directly involved in proton abstraction and re-incorporation onto the substrate. As all mechanistically relevant active site residues also occur in all mammalian isoforms, PhGn2E can serve as a model N-acetylglucosamine 2-epimerase for further elucidation of the active site mechanism in these enzymes.

MicroRNA (miRNA) transcription is still not well understood until now. To increase the miRNA abundance, we stimulated miRNA transcription with CuSO(4) and knocked down Drosha enzyme using dsRNA in Drosophila S2 cells. The full length transcripts of bantam, miR-276a and miR-277, the 5'-end of miR-8, the 3'-end of miR-2b and miR-10 were obtained. We also conducted a series of miRNA promoter analysis to prove the reliability of RACE results. Luciferase-reporter assays proved that both bantam and miR-276a promoters successfully drove the expressions of downstream luciferase genes. The promoter activities were impaired by introducing one or multiple mutations at predicted transcription factor binding sites. Chromatin immunoprecipitation analysis confirmed that hypophosphorylated RNA polymerase II and transcription factor c-Myc physically bind at miRNA promoter. RNA interference of transcription factors Mad and Prd led to down-expression of bantam, miR-277 and miR-2b but not miR-276a, whereas RNAi of Dorsal had the opposite effect.

Background: Nonsyndromic hearing loss is clinically and genetically heterogeneous. In this study, we characterized the clinical features of 12 Chinese Han deaf families in which mutations in common deafness genes GJB2, SLC26A4, and MT-RNR1 were excluded. Methods: Targeted next-generation sequencing of 147 known deafness genes was performed in probands of 10 families, while whole-exome sequencing was applied in those of the rest two. Results: Pathogenic mutations in a total of 11 rare deafness genes, OTOF, CDH23, PCDH15, PDZD7, ADGRV1, KARS, OTOG, GRXCR2, MYO6, GRHL2, and POU3F4, were identified in all 12 probands, with 16 mutations being novel.Intrafamilial cosegregation of the mutations and the deafness phenotype were confirmed by Sanger sequencing. Conclusion: Our results expanded the mutation spectrum and genotype-phenotype correlation of nonsyndromic hearing loss in Chinese Hans and also emphasized the importance of combining both next-generation sequencing and detailed auditory evaluation to achieve a more accurate diagnosis for nonsyndromic hearing loss. K E Y W O R D Sdeafness, gene mutation, next-generation sequencing (NGS), nonsyndromic, phenotype

Apoptosis of cochlear hair cells is a key step towards age-related hearing loss. Although numerous genes have been implicated in the genetic causes of late-onset, progressive hearing loss, few show direct links to the proapoptotic process. By genome-wide linkage analysis and whole exome sequencing, we identified a heterozygous p.L183V variant in THOC1 as the probable cause of the late-onset, progressive, non-syndromic hearing loss in a large family with autosomal dominant inheritance. Thoc1, a member of the conserved multisubunit THO/TREX ribonucleoprotein complex, is highly expressed in mouse and zebrafish hair cells. The thoc1 knockout ( thoc1 mutant) zebrafish generated by gRNA-Cas9 system lacks the C-startle response, indicative of the hearing dysfunction. Both Thoc1 mutant and knockdown zebrafish have greatly reduced hair cell numbers, while the latter can be rescued by embryonic microinjection of human wild-type THOC1 mRNA but to significantly lesser degree by the c.547C>G mutant mRNA. The Thoc1 deficiency resulted in marked apoptosis in zebrafish hair cells. Consistently, transcriptome sequencing of the mutants showed significantly increased gene expression in the p53-associated signaling pathway. Depletion of p53 or applying the p53 inhibitor Pifithrin-α significantly rescued the hair cell loss in the Thoc1 knockdown zebrafish. Our results suggested that THOC1 deficiency lead to late-onset, progressive hearing loss through p53-mediated hair cell apoptosis. This is to our knowledge the first human disease associated with THOC1 mutations and may shed light on the molecular mechanism underlying the age-related hearing loss.

Novel sialic acid scaffolds have great significance in the development of influenza neuraminidase inhibitors. Here the enzymatic synthesis of a wide range of 2‐keto‐3‐deoxy‐d‐glycero‐d‐galacto‐nononic acid (KDN) analogues via aldol addition of pyruvate to d‐mannose, d‐glucose, d‐galactose, 2‐deoxy‐d‐glucose, d‐arabinose, l‐arabinose and l‐rhamnose using a previously unstudied N‐acetylneuraminic acid (Neu5Ac) aldolase derived from the bacterium Dyadobacter fermentas is exemplified. Several of the synthesized KDN analogues showed comparable or better inhibitory activity than unstudied Neu5Ac against the mutated influenza neuraminidases (A/California/04/2009 and A/Anhui/1/2005), which both show resistance to Neu5Ac‐based neuraminidase inhibitors, demonstrating that these compounds are promising templates for the development of anti‐influenza drugs.magnified image