Functional Characterization of Double Mutations T929I/K1774N in the Voltage-Gated Sodium Channel of Megalurothrips usitatus (Bagnall) Related to Pyrethroid Resistance.

Megalurothrips usitatus (Bagnall), the main pest on legume vegetables, is controlled by pyrethroids in the field. Field strains of M. usitatus resistant to pyrethroids were collected from three areas in Hainan Province (Haikou, Ledong, and Sanya City), and two mutations, T929I and K1774N, were detected in the voltage-gated sodium channel. In this study, the sodium channel in M. usitatus was first subcloned and successfully expressed in Xenopus oocytes. The single mutation (T929I or K1774N) and double mutation (T929I/K1774N) shifted the voltage dependence of activation in the hyperpolarization direction. The three mutants all reduced the amplitude of tail currents induced by type I (permethrin and bifenthrin) and type II (deltamethrin and λ-cyhalothrin) pyrethroids. Homology modeling analysis of these two mutations shows that they may change the local hydrophobicity and positive charge of the sodium channel. Our data can be used to reveal the causes of the resistance of M. usitatus to pyrethroids and provide guidance for the comprehensive control of M. usitatus in the future.

Sonic hedgehog signaling: Alternative splicing and pathogenic role in medulloblastoma.

Alternative splicing (AS) produces the different mRNA splicing bodies, which are then translated into multiple protein isoforms and participate in various biological functions. With a deeper understanding of alternative splicing through the study of transcriptomes using high-throughput sequencing-based methods, the correlation between aberrant AS and diseases triggered a great concern, especially abnormal AS and cancer. Medulloblastoma (MB) is an intracranial tumor in children. Sonic hedgehog MB (SHH-MB) accounted for approximately 30% of MB, which is associated with the activation of SHH signaling. Growing evidence shows that aberrant AS is closely related to the tumorigenesis of MB. Here, we briefly introduced the AS and its mechanism. Next, we described canonical/noncanonical hedgehog signaling and its correlation with MB. The main description focused on AS of various regulators in canonical hedgehog signaling in MB. In addition, we also described AS of various regulators in noncanonical hedgehog signaling. Meanwhile, activated hedgehog signaling also induces AS in MB. Then, we pointed out that aberrant AS of hedgehog signaling is associated with different MB subgroups. Finally, we summarized the therapeutic applications of targeted AS in cancer treatment. In summary, further understanding of AS in SHH-MB could develop therapeutic targets for splicing factors which may be a novel therapeutic strategy.

Detection of Putative Mutation I873S in the Sodium Channel of Megalurothrips usitatus (Bagnall) Which May Be Associated with Pyrethroid Resistance.

Pyrethroid resistance of thrips has been reported in many countries, and knockdown resistance (kdr) has been identified as a main mechanism against pyrethroids in many insects. To characterize pyrethroid resistance in Megalurothrips usitatus from the Hainan Province of China, we conducted a biological assay and sequenced the voltage-gated sodium channel gene domain II from M. usitatus field populations. It showed high resistance to the pyrethroids for 2019 and 2020, in which LC50 to lambda-cyhalothrin of M. usitatus was 1683.521 mg/L from Sanya in 2020. The LC50 value of deltamethrin was lower in Haikou than in other locations, which mean the south of Hainan has higher resistance than the north of Hainan. Two mutations of I873S and V1015M were detected in the domain II region of the sodium channel in M. usitatus; however, the mutation frequency of V1015M was only 3.33% and that of I873S was 100%. One is homozygous and the other is a heterozygous mutant type. The three thrips-sensitive strains of sodium channel 873 are highly conserved in amino acids (isoleucine), while the M. usitatus pyrethroid-resistant strains are all serine, so I873S may be related to the resistance of M. usitatus to pyrethroids. The present study will contribute to the understanding of the evolution of pyrethroids resistance and contribute to the development of resistance management of M. usitatus in Hainan.

Functional Characterization of Knockdown Resistance Mutation L1014S in the German Cockroach, Blattella germanica (Linnaeus).

The effectiveness of pyrethroid insecticides is seriously threatened by knockdown resistance (kdr), which is induced in insects by inherited single-nucleotide polymorphisms in the voltage-gated sodium channel (VGSC) gene. VGSC's L1014F substitution results in the classic kdr mutation, which is found in many pest species. Other substitutions of the L1014 locus, such as L1014S, L1014C, L1014W, and L1014H, were also reported. In 2022, a new amino acid substitute L1014S of Blattella germanica was first discovered in China. We modified the BgNav1-1 sodium channel from cockroaches with the L1014S mutation to study how pyrethroid sensitivity and channel gating were affected in Xenopus oocytes. The L1014S mutation reduced the half-maximal activation voltage (V1/2,act) from -19.0 (wild type) to -15.5 mV while maintaining the voltage dependency of activation. Moreover, the voltage dependence of inactivation in the hyperpolarizing shifts from -48.3 (wild type) to -50.9 mV. However, compared with wild type, the mutation L1014S did not cause a significant shift in the half activation voltage (V1/2,act). Notably, the voltage dependency of activation was unaffected greatly by the L1014S mutation. Tail currents are induced by two types of pyrethroids (1 µM): type I (permethrin, bifenthrin) and type II (deltamethrin, λ-cyhalothrin). All four pyrethroids produced tail currents, and significant differences were found in the percentages of channel modifications between variants and wild types. Further computer modeling showed that the L1014S mutation allosterically modifies pyrethroid binding and action on B. germanica VGSC, with some residues playing a critical role in pyrethroid binding. This study elucidated the pyrethroid resistance mechanism of B. germanica and predicted the residues that may confer the risk of pyrethroid resistance, providing a molecular basis for understanding the resistance mechanisms conferred by mutations at the 1014 site in VGSC.

HSP90ß chaperoning SMURF1-mediated LATS proteasomal degradation in the regulation of bone formation.

Heat shock protein 90 (HSP90) molecular chaperone is responsible for the stabilization and biological activity of a diverse set of client proteins. We have previously demonstrated that inhibition of HSP90 by 17-Demethoxy-17-allyaminogeldanmycin (17-AAG) not only reverses the glucocorticoid-induced bone loss but also enhances the basal level of bone mass in mice. Here, we investigate the potential mechanism underlying HSP90-associated osteoblast differentiation and bone formation. Knockdown of HSP90ß but not HSP90α or inhibition of HSP90 by 17-AAG or NVP-BEP800 negates the protein levels of large tumor suppressor (LATS), the core kinases of Hippo signaling, resulting in the inactivation of LATS and activation of Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), in the enhancement of osteoblastic differentiation. In contrast, genetic ablation of Lats1 in mesenchymal stem cells is sufficient to abolish the HSP90 inhibition-induced osteoblastic differentiation and bone formation. Mechanistically, HSP90ß but not HSP90α chaperones and prevents the SMAD specific E3 ubiquitin protein ligase 1 (SMURF1)-mediated and ubiquitination-dependent LATS protein proteasomal degradation, whereas 17-AAG abolishes these effects of HSP90ß. Thus, these results uncover the HSP90ß chaperoning SMURF1-mediated LATS protein proteasomal degradation and the subsequent YAP/TAZ activation as a hitherto uncharacterized mechanism controlling osteoblastic differentiation and bone formation.

Unique post-translational modifications diversify the sodium channels in peach aphid (Myzus persicae [Sulzer]).

BACKGROUND: Myzus persicae (Sulzer), a worldwide pest, has caused remarkable damage to agriculture. Among the various control methods, chemical control (especially pyrethroids) is most commonly used. The targets of pyrethroids are voltage-gated sodium channels (Nav s). Unlike those of other insects, all Nav s of aphids (including two genes), such as Myzus persicae, are unique. RESULTS: In this study, three interlock patterns, I(918)-F(1014), L(918)-L(1014), and T(918)-F(1014), were found at sites 918 and 1014 in the sensitive Myzus persicae strain. Similar to that of other aphids, the Nav of Myzus persicae (MpNav ) consisted of two parts, that is MpNav -I and MpNav -II, which were embedded with an atypical 'DENS' ion selectivity filter and a conventional 'MFM' inactivation gate, respectively. MpNav had 11 alternative exons, including two mutually exclusive exons (k and l) and three exons (w, x, and t), which were located in domains I and III, respectively. In addition, various RNA editing events, A503T and V588A, appearing between the connection of domains I and II and the S3 of domain IV, respectively, had been described. CONCLUSION: Overall, MpNav was characterized by unique post-translational regulation mode, 918 and 1014 interlocks, and unusually alternative exons. Our research provides a new perspective on the evolution and variation of insect Nav s. © 2021 Society of Chemical Industry.

Ellipsoidal Abstract and Illustrative Representations of Molecular Surfaces.

Molecular visualization is often challenged with rendering of large molecular structures in real time. The key to LOD (level-of-detail), a classical technology, lies in designing a series of hierarchical abstractions of protein. In the paper, we improved the smoothness of transition for these abstractions by constructing a complete binary tree of a protein. In order to reduce the degree of expansion of the geometric model corresponding to the high level of abstraction, we introduced minimum ellipsoidal enveloping and some post-processing techniques. At the same time, a simple, ellipsoid drawing method based on graphics processing unit (GPU) is used that can guarantee that the drawing speed is not lower than the existing sphere-drawing method. Finally, we evaluated the rendering performance and effect on series of molecules with different scales. The post-processing techniques applied, diffuse shading and contours, further conceal the expansion problem and highlight the surface details.

Prediction of Enzyme Function Based on Three Parallel Deep CNN and Amino Acid Mutation.

During the past decade, due to the number of proteins in PDB database being increased gradually, traditional methods cannot better understand the function of newly discovered enzymes in chemical reactions. Computational models and protein feature representation for predicting enzymatic function are more important. Most of existing methods for predicting enzymatic function have used protein geometric structure or protein sequence alone. In this paper, the functions of enzymes are predicted from many-sided biological information including sequence information and structure information. Firstly, we extract the mutation information from amino acids sequence by the position scoring matrix and express structure information with amino acids distance and angle. Then, we use histogram to show the extracted sequence and structural features respectively. Meanwhile, we establish a network model of three parallel Deep Convolutional Neural Networks (DCNN) to learn three features of enzyme for function prediction simultaneously, and the outputs are fused through two different architectures. Finally, The proposed model was investigated on a large dataset of 43,843 enzymes from the PDB and achieved 92.34% correct classification when sequence information is considered, demonstrating an improvement compared with the previous result.