The spliceosome-associated protein Mfap1 binds to VCP in Drosophila

Valosin containing protein (VCP): initiator, modifier, and potential drug target for neurodegenerative diseases

The AAA+ ATPase valosin containing protein (VCP) is essential for cell and organ homeostasis, especially in cells of the nervous system. As part of a large network, VCP collaborates with many cofactors to ensure proteostasis under normal, stress, and disease conditions. A large number of mutations have revealed the importance of VCP for human health. In particular, VCP facilitates the dismantling of protein aggregates and the removal of dysfunctional organelles. These are critical events to prevent malfunction of the brain and other parts of the nervous system. In line with this idea, VCP mutants are linked to the onset and progression of neurodegeneration and other diseases. The intricate molecular mechanisms that connect VCP mutations to distinct brain pathologies continue to be uncovered. Emerging evidence supports the model that VCP controls cellular functions on multiple levels and in a cell type specific fashion. Accordingly, VCP mutants derail cellular homeostasis through several mechanisms that can instigate disease. Our review focuses on the association between VCP malfunction and neurodegeneration. We discuss the latest insights in the field, emphasize open questions, and speculate on the potential of VCP as a drug target for some of the most devastating forms of neurodegeneration.

Blocking Osa-miR1871 enhances rice resistance against Magnaporthe oryzae and yield

MicroRNAs (miRNAs) play vital roles in plant development and defence responses against various stresses. Here, we show that blocking miR1871 improves rice resistance against Magnaporthe oryzae and enhances grain yield simultaneously. The transgenic lines overexpressing miR1871 (OX1871) exhibit compromised resistance, suppressed defence responses and reduced panicle number resulting in slightly decreased yield. In contrast, the transgenic lines blocking miR1871 (MIM1871) show improved resistance, enhanced defence responses and significantly increased panicle number leading to enhanced yield per plant. The RNA-seq assay and defence response assays reveal that blocking miR1871 resulted in the enhancement of PAMP-triggered immunity (PTI). Intriguingly, miR1871 suppresses the expression of LOC_Os06g22850, which encodes a microfibrillar-associated protein (MFAP1) locating nearby the cell wall and positively regulating PTI responses. The mutants of MFAP1 resemble the phenotype of OX1871. Conversely, the transgenic lines overexpressing MFAP1 (OXMFAP1) or overexpressing both MFAP1 and miR1871 (OXMFAP1/OX1871) resemble the resistance of MIM1871. The time-course experiment data reveal that the expression of miR1871 and MFAP1 in rice leaves, panicles and basal internode is dynamic during the whole growth period to manipulate the resistance and yield traits. Our results suggest that miR1871 regulates rice yield and immunity via MFAP1, and the miR8171-MFAP1 module could be used in rice breeding to improve both immunity and yield.

UBL5/Hub1: An Atypical Ubiquitin-Like Protein with a Typical Role as a Stress-Responsive Regulator

Members of the ubiquitin-like protein family are known for their ability to modify substrates by covalent conjugation. The highly conserved ubiquitin relative UBL5/Hub1, however, is atypical because it lacks a carboxy-terminal di-glycine motif required for conjugation, and the whole E1-E2-E3 enzyme cascade is likely absent. Though the conjugation-mediated role of UBL5/Hub1 is controversial, it undoubtedly functions by interacting non-covalently with its partners. Several interactors of UBL5/Hub1 identified to date have suggested broad stress-responsive functions of the protein, for example, stress-induced control of pre-mRNA splicing, Fanconi anemia pathway of DNA damage repair, and mitochondrial unfolded protein response. While having an atypical mode of function, UBL5/Hub1 is still a stress protein that regulates feedback to various stimuli in a similar manner to other ubiquitin-like proteins. In this review, I discuss recent progress in understanding the functions of UBL5/Hub1 and the fundamental questions which remain to be answered.

Molecular structure and function of microfibrillar-associated proteins in skeletal and metabolic disorders and cancers

Microfibrillar-associated proteins (MFAPs) are extracellular matrix glycoproteins, which play a role in microfibril assembly, elastinogenesis, and tissue homeostasis. MFAPs consist of five subfamily members, including MFAP1, MFAP2, MFAP3, MFAP4, and MFAP5. Among these, MFAP2 and MFAP5 are most closely related, and exhibit very limited amino acid sequence homology with MFAP1, MFAP3, and MFAP4. Gene expression profiling analysis reveals that MFAP2, MFAP5, and MFAP4 are specifically expressed in osteoblastic like cells, whereas MFAP1 and MFAP3 are more ubiquitously expressed, indicative of their diverse role in the tropism of tissues. Molecular structural analysis shows that each MFAP family member has distinct features, and functional evidence reveals discrete purposes of individual MFAPs. Animal studies indicate that MFAP2-deficient mice exhibit progressive osteopenia with elevated receptor activator of NF-κB ligand (RANKL) expression, whereas MFAP5-deficient mice are neutropenic, and MFAP4-deficient mice displayed emphysema-like pathology and the impaired formation of neointimal hyperplasia. Emerging data also suggest that MFAPs are involved in cancer progression and fat metabolism. Further understanding of tissue-specific pathophysiology of MFAPs might offer potential novel therapeutic targets for related diseases, such as skeletal and metabolic disorders, and cancers.

Splicing Players Are Differently Expressed in Sporadic Amyotrophic Lateral Sclerosis Molecular Clusters and Brain Regions

Splicing is a tightly orchestrated process by which the brain produces protein diversity over time and space. While this process specializes and diversifies neurons, its deregulation may be responsible for their selective degeneration. In amyotrophic lateral sclerosis (ALS), splicing defects have been investigated at the singular gene level without considering the higher-order level, involving the entire splicing machinery. In this study, we analyzed the complete spectrum (396) of genes encoding splicing factors in the motor cortex (41) and spinal cord (40) samples from control and sporadic ALS (SALS) patients. A substantial number of genes (184) displayed significant expression changes in tissue types or disease states, were implicated in distinct splicing complexes and showed different topological hierarchical roles based on protein–protein interactions. The deregulation of one of these splicing factors has a central topological role, i.e., the transcription factor YBX1, which might also have an impact on stress granule formation, a pathological marker associated with ALS.

Integrated analysis of microfibrillar-associated proteins reveals MFAP4 as a novel biomarker in human cancers

Aim: The potential functions and underlying mechanism of microfibrillar-associated proteins (MFAPs) are explored in human cancers. Materials & methods: Here, we examined the expression profiles, prognostic values, epigenetic and genetic alterations of MFAPs in human cancers from public omics repository. Results: Among MFAPs family, MFAP4 was frequently downregulated in the most human cancers and high mRNA expression of MFAP4 significantly correlated with better overall survival in breast cancer. DNA hypermethylation in the promoter of MFAP4 decreased its mRNA expression. MFAP4 strongly associated with pathway in impairment and alteration of the elastic fibers. Conclusion: This integrated analysis provides new insights into MFAPs in human cancers and indicates that MFAP4 could be used as novel biomarker for developing therapies against human cancers.

The sulfite oxidase Shopper controls neuronal activity by regulating glutamate homeostasis in Drosophila ensheathing glia

Specialized glial subtypes provide support to developing and functioning neural networks. Astrocytes modulate information processing by neurotransmitter recycling and release of neuromodulatory substances, whereas ensheathing glial cells have not been associated with neuromodulatory functions yet. To decipher a possible role of ensheathing glia in neuronal information processing, we screened for glial genes required in the Drosophila central nervous system for normal locomotor behavior. Shopper encodes a mitochondrial sulfite oxidase that is specifically required in ensheathing glia to regulate head bending and peristalsis. shopper mutants show elevated sulfite levels affecting the glutamate homeostasis which then act on neuronal network function. Interestingly, human patients lacking the Shopper homolog SUOX develop neurological symptoms, including seizures. Given an enhanced expression of SUOX by oligodendrocytes, our findings might indicate that in both invertebrates and vertebrates more than one glial cell type may be involved in modulating neuronal activity.