The tail segments are required by the performance but not the accomplishment of various modes of Drosophila larval locomotion.

The tail plays important roles in locomotion control in many animals. But in animals with multiple body segments, the roles of the hind body segments and corresponding innervating neurons in locomotion control are not clear. Here, using the Drosophila larva as the model animal, we investigated the roles of the posterior terminal segments in various modes of locomotion and found that they participate in all of them. In forward crawling, paralysis of the larval tail by blocking the Abdb-Gal4 labeled neurons in the posterior segments of VNC led to a slower locomotion speed but did not prevent the initiation of forward peristalsis. In backward crawling, larvae with the Abdb-Gal4 neurons inhibited were unable to generate effective displacement although waves of backward peristalsis could be initiated and persist. In head swing where the movement of the tail is not obvious, disabling the larval tail by blocking Abdb-Gal4 neurons led to increased bending amplitude upon touching the head. In the case of larval lateral rolling, larval tail paralysis by inhibition of Abdb-Gal4 neurons did not prevent the accomplishment of rolling, but resulted in slower rolling speed. Our work reveals that the contribution of Drosophila larval posterior VNC segments and corresponding body segments in the tail to locomotion is comprehensive but could be compensated at least partially by other body segments. We suggest that the decentralization in locomotion control with respect to animal body parts helps to maintain the robustness of locomotion in multi-segment animals.

Zebrafish: A smart tool for heart disease research.

The increasing prevalence of heart disease poses a significant threat to human survival and safety. However, the current treatments available for heart disease are quite limited. Therefore, it is of great importance to utilize suitable animal models that can accurately simulate the physiological characteristics of heart disease. This would help improve our understanding of this disease and aid in the development of new treatment methods and drugs. Zebrafish hearts not only exhibit similarities to mammalian hearts, but they also share ~70% of homologous genes with humans. Utilizing zebrafish as an alternative to costly and time-consuming mammalian models offers numerous advantages. Zebrafish models can be easily established and maintained, and compound screening and genetic methods allow for the creation of various economical and easily controlled zebrafish and zebrafish embryonic heart disease models in a short period of time. Consequently, zebrafish have become a powerful tool for exploring the pathological mechanisms of heart disease and identifying new effective genes. In this review, we summarize recent studies on different zebrafish models of heart disease. We also describe the techniques and protocols used to develop zebrafish models of myocardial infarction, heart failure, and congenital heart disease, including surgical procedures, forward and reverse genetics, as well as drug and combination screening. This review aims to promote the utilization of zebrafish models in investigating diverse pathological mechanisms of heart disease, enhancing our knowledge and comprehension of heart disease, and offering novel insights and objectives for exploring the prevention and treatment of heart disease.

Sesamin Induces the Transdifferentiation of Type II Alveolar Epithelial Cells via AnnexinA1 and TRPV1.

PURPOSE: Acute lung injury (ALI) with high rates of morbidity is often accompanied by the apoptosis in the type I alveolar epithelial cells (ATIs). Thus, the transdifferentiation of type II alveolar epithelial cells (ATIIs) into ATIs is crucial for the maintenance of alveolar epithelial functions. We aimed to elucidate the role of sesamin in the transdifferentiation of ATIIs to ATIs and the involvement of the TRPV1/AKT pathway. METHODS: In vivo, the mouse model of ALI was simulated by intraperitoneal and intratracheal injections of lipopolysaccharide (LPS), respectively. The protective effects of sesamin on ALI were investigated using the survival rate, lung/body weight ratio, histological analysis of lung with HE staining, and mRNA levels of inflammatory factors. Western blot analysis and immunofluorescence detection of ATIs marker AQP5 were used to evaluate the protective effect of sesamin on ATIs. Western blot, EdU, and qPCR analyses were applied to detect changes in apoptosis, proliferation, and transdifferentiation markers of ATII A549 cell lines. Small interfering RNA (siRNA) was used to detect the involvement and relationships between the sesamin receptors (ANXA1 and TRPV1) and the AKT pathway in transdifferentiation. RESULTS: Sesamin (200 mg/kg) significantly improved LPS-induced ALI and inhibited LPS-induced ATIs reduction. A low concentration of sesamin (20 µM) promoted the transdifferentiation of ATIIs to ATIs. Both ANXA1 and TRPV1 were involved in sesamin-promoted transdifferentiation, while the P-AKT (S473) level was down-regulated by TRPV1 siRNA. CONCLUSION: Sesamin may promote transdifferentiation of ATII to ATI to ultimately rescue ALI, with TRPV1/AKT pathway involved in this transdifferentiation. This study revealed a novel role of sesamin in promoting the transdifferentiation of ATIIs to ATIs, providing experimental supports for the potential targets of ALI therapy.

TRIM25 participates in the fibrous tissue hyperplasia induced by ALV-J infection in chickens by targeting 14-3-3σ protein.

ALV-J-SD1005 strain was subcutaneously inoculated into the necks of 1-day-old HY-Line Brown chickens and caused severe growth retardation, viremia and subcutaneous fibrosarcomas in the necks of all infected chickens from 14 days post inoculation (DPI) to 21 DPI, and also significantly increased the expressions of TRIM25, P53, etc., but significantly decreased the expressions of 14-3-3σ, etc. Overexpression of chicken TRIM25 (chTRIM25) significantly promoted cell proliferation and improved the expressions of P53, CDC2, and CDK2 tumor factors; and significantly inhibited the expression of 14-3-3σ in ALV-J-SD1005-infected DF1 cells; but knockdown of chTRIM25 caused the opposite effects. The results of co-immunoprecipitation (Co-IP) and confocal microscopy confirmed that chTRIM25 can recognize and bind 14-3-3σ protein in ALV-J-SD1005-infected cells, and they were co-located in the cytoplasm. It can be concluded that chTRIM25 participates in the fibrous tissue hyperplasia induced by ALV-J-SD1005 infections in chickens by binding 14-3-3σ protein and regulating the expressions of 14-3-3σ, P53, CDC2, and CDK2.

MORN4 protects cardiomyocytes against ischemic injury via MFN2-mediated mitochondrial dynamics and mitophagy.

The imbalance of mitochondrial fission and fusion dynamics causes ischemic cardiomyocyte apoptosis and heart injury by affecting mitophagy. Regulation of mitochondrial dynamics is an important therapeutic strategy for ischemic heart diseases. Considering the important roles of MORN motifs in heart diseases and chloroplast fission, we aimed to investigate the possible role of MORN repeat-containing protein 4 (MORN4) in the progression of myocardial infarction (MI), ischemic cardiomyocyte apoptosis, mitochondrial dynamics, and mitophagy. We found that in the MI mouse, MORN4 knockdown remarkably accelerated cardiac injury and fibrosis with deteriorating cardiac dysfunction. Sphingosylphosphorylcholine (SPC) alleviated ischemic cardiomyocyte apoptosis and heart injury through increased level of MORN4, indicating a vital function of MORN4 in heart with SPC used to clarify the molecular mechanisms underlying the functions of MORN4. Mechanistically, we found that MORN4 directly binds to MFN2 and promotes the phosphorylation of MFN2 S442 through Rho-associated protein kinase 2 (ROCK2), which mediates beneficial mitophagy induced by mitochondrial dynamics, while SPC promoted the binding of MORN4 and MFN2 and the process. Taken together, our data reveal a new perspective role of MORN4 in ischemic heart injury, and report that SPC could regulate myocardial mitochondrial homeostasis by activating the MORN4-MFN2 axis during the ischemic situation, this finding provides novel targets for improving myocardial ischemia tolerance and rescue of acute myocardial infarction.

Sphingosylphosphorylcholine ameliorates doxorubicin-induced cardiotoxicity in zebrafish and H9c2 cells by reducing excessive mitophagy and mitochondrial dysfunction.

Doxorubicin (DOX, C27H29NO11), is an anthracycline tumor chemotherapy drug, which has significant side effects on many organs including the heart. In recent years, mitochondrial dysfunction caused by DOX was identified as an important reason for cardiotoxic injury. Sphingosylphosphorylcholine (SPC) is essential for mitochondrial homeostasis in our previous report, however, its role in DOX-caused cardiomyopathy has remained elusive. Herein, DOX treated zebrafish embryos (90 µM) and adult fish (2.5 µM/g) were used to simulate DOX-induced cardiotoxic damage. Histopathological and ultrastructural observations showed that SPC (2.5 µM) significantly ameliorated DOX-induced pericardial edema, myocardial vacuolization and apoptosis. Furthermore, SPC (2.5 µM) can significantly inhibit DOX-induced apoptosis and promote cell proliferation in DOX treated H9c2 cells (1 µM), which is dependent on the restoration of mitochondrial homeostasis, including restored mitochondrial membrane potential, mitochondrial superoxide and ATP levels. We finally confirmed that SPC restored mitochondrial homeostasis through ameliorating DOX-induced excessive mitophagy. Mechanistically, SPC reduced calmodulin (CaM) levels and thus inhibiting Parkin activation and Parkin-dependent mitophagy. These results suggest that reducing the cardiotoxicity of chemotherapeutic drugs by targeting SPC may be a new solution to rescue chemotherapy injury.

Membrane occupation and recognition nexus (MORN) motif controls protein localization and function.

The membrane occupation and recognition nexus (MORN) motif was first defined in 2000, when it was identified in the junctophilin protein family. Dozens of studies have been published ever since, mainly focusing on the function of a given MORN motif-containing protein in parasites, plants or animal cells. Proteins with MORN motifs are not only expressed in most animal and plant cell types, but also significantly differ in their intracellular localization, suggesting that the MORN motifs may fulfill multiple physiological functions. Recent studies have found that MORN motif-containing proteins junctophilin-1/2 and MORN3 play a role in cardiac hypertrophy, skeletal muscle fiber stability and cancer. Hence, MORN motif-containing proteins may be exploited to develop improved treatments for various pathological conditions, such as cardiovascular diseases. Here, we review current research on MORN motif-containing proteins in different organisms and provide both ideas and approaches for follow-up exploration of their functions and applications.

JNK-dependent phosphorylation and nuclear translocation of EGR-1 promotes cardiomyocyte apoptosis.

Myocardial apoptosis induced by myocardial ischemia and hyperlipemia are the main causes of high mortality of cardiovascular diseases. It is not clear whether there is a common mechanism responsible for these two kinds of cardiomyocyte apoptosis. Previous studies demonstrated that early growth response protein 1 (EGR-1) has a pro-apoptotic effect on cardiomyocytes under various stress conditions. Here, we found that EGR-1 is also involved in cardiomyocyte apoptosis induced by both ischemia and high-fat, but how EGR-1 enters the nucleus and whether nuclear EGR-1 (nEGR-1) has a universal effect on cardiomyocyte apoptosis are still unknown. By analyzing the phosphorylation sites and nucleation information of EGR-1, we constructed different mutant plasmids to confirm that the nucleus location of EGR-1 requires Ser501 phosphorylation and regulated by JNK. Furthermore, the pro-apoptotic effect of nEGR-1 was further explored through genetic methods. The results showed that EGR-1 positively regulates the mRNA levels of apoptosis-related proteins (ATF2, CTCF, HAND2, ELK1), which may be the downstream targets of EGR-1 to promote the cardiomyocyte apoptosis. Our research announced the universal pro-apoptotic function of nEGR-1 and explored the mechanism of its nucleus location in cardiomyocytes, providing a new target for the "homotherapy for heteropathy" to cardiovascular diseases.

MicroRNA-155-5p/EPAS1/interleukin 6 pathway participated in the protection function of sphingosylphosphorylcholine to ischemic cardiomyocytes.

AIM: Previous research in our laboratory found that a biologically active sphingomyelin metabolite, sphingosylphosphorylcholine (SPC), can inhibit myocardial cell apoptosis caused by ischemia with an unknown mechanism. Here, we aimed to study the possible participation of EPAS1 in the protection process of SPC. METHODS: The rat cardiomyocytes deprived of serum were used to mimic ischemic-caused apoptosis, then treated with or without SPC. The expression and nuclear shift of EPAS1 were detected by western blot and immunofluorescence, and its function was studied using its siRNA. KEY FINDING: Our research shows that SPC inhibited serum starvation caused cardiomyocyte apoptosis, accompanied by the up-regulation and nucleus translocation of EPAS1. EPAS1 levels did not change when its transcript was blocked by Actinomycin D, which prompted us to search for a post-transcription mechanism for its increased expression, and finally found that miR-155-5p, regulated by STAT3, was a new post-transcription regulator to EPAS1. Further investigation found that EPAS1 participated in the protective effect of SPC is mainly achieved by activating the downstream target gene, interleukin-6 (IL-6). SIGNIFICANCE: Our results expand our understanding of the biological functions of SPC, and bring a new pathway as a potential therapeutic target to the treatment of cardiovascular diseases caused by myocardial apoptosis.