Drosophila homolog of the intellectual disability-related long-chain acyl-CoA synthetase 4 is required for neuroblast proliferation

Brain microRNA profiles after exposure to heroin in rats

Heroin addiction is one of the neuropsychiatric burdens that affects many genetic and epigenetic systems. While it is known that heroin may change the expressions of some genes in the brain during dependence, there is no detailed study related to which gene are mostly affected. Therefore, in the current study, we aimed to determine alterations in the miRNA profiles of rats' brains for providing a detailed analysis of molecular mechanisms in heroin addiction-related toxicology. Next generation global miRNA sequencing was used to predict potential miRNAs in prefrontal cortex (PC), hippocampus, ventral tegmental area (VTA), striatum, and Nucleus accumbens (NA) of rats that exposed to heroin by intravenous injections. The total daily dose was started with 2 mg/kg and ended with 10 mg/kg on the 10th day. In the striatum, miR-18a, miR-17-5p, miR-20a-5p, miR-106a, miR-301a-3p, miR872-5p, miR-15a-5p, miR-500-3p, and miR-339-5p expressions were upregulated by nearly 2-to-4 times with heroin. The expressions of hippocampal miR-153-3p, miR-130a-3p, miR-204-5p, miR-15b-5p, and miR-137-3p and the expressions of miR-872, miR-183-5p, miR-20a-5p, miR-325-5p, miR-379-5p, and miR-340-5p in the VTA were 2-times higher in the heroin-addicted rats. While there was nearly 2-times increase in the miR-129-1-3p and miR-3068-3p expressions in the NA, no change was noted in the PC due to heroin. The only heroin-dependent downregulation was observed in the expressions of striatal miR-450b-3p and miR-103-1-5p of VTA. These results suggested that heroin addiction might give harm to brain by altering cytokine balance and increasing neuroinflammation and apoptosis. In addition, neurons also try to compensate these abnormalities by enhancing neurogenesis and angiogenesis through several miRNAs in the different brain regions. In conclusion, the present study may provide a more integrated view of the molecular mechanism and a potential biomarker that will aid in clinical diagnosis and treatment of heroin-dependence.

A Pvr-AP-1-Mmp1 signaling pathway is activated in astrocytes upon traumatic brain injury

Traumatic brain injury (TBI) caused by external mechanical forces is a major health burden worldwide, but the underlying mechanism in glia remains largely unclear. We report herein that Drosophila adults exhibit a defective blood-brain barrier, elevated innate immune responses, and astrocyte swelling upon consecutive strikes with a high-impact trauma device. RNA sequencing (RNA-seq) analysis of these astrocytes revealed upregulated expression of genes encoding PDGF and VEGF receptor-related (Pvr, a receptor tyrosine kinase), adaptor protein complex 1 (AP-1, a transcription factor complex of the c-Jun N-terminal kinase pathway) composed of Jun-related antigen (Jra) and kayak (kay), and matrix metalloproteinase 1 (Mmp1) following TBI. Interestingly, Pvr is both required and sufficient for AP-1 and Mmp1 upregulation, while knockdown of AP-1 expression in the background of Pvr overexpression in astrocytes rescued Mmp1 upregulation upon TBI, indicating that Pvr acts as the upstream receptor for the downstream AP-1-Mmp1 transduction. Moreover, dynamin-associated endocytosis was found to be an important regulatory step in downregulating Pvr signaling. Our results identify a new Pvr-AP-1-Mmp1 signaling pathway in astrocytes in response to TBI, providing potential targets for developing new therapeutic strategies for TBI.

An update on the therapeutic implications of long-chain acyl-coenzyme A synthetases in nervous system diseases

Long-chain acyl-coenzyme A synthetases (ACSLs) are a family of CoA synthetases that activate fatty acid (FA) with chain lengths of 12-20 carbon atoms by forming the acyl-AMP derivative in an isozyme-specific manner. This family mainly includes five members (ACSL1, ACSL3, ACSL4, ACSL5, and ACSL6), which are thought to have specific and different functions in FA metabolism and oxidative stress of mammals. Accumulating evidence shows that the dysfunction of ACSLs is likely to affect cell proliferation and lead to metabolic diseases in multiple organs and systems through different signaling pathways and molecular mechanisms. Hence, a central theme of this review is to emphasize the therapeutic implications of ACSLs in nervous system disorders.

Lipophorin receptors regulate mushroom body development and complex behaviors in Drosophila

BACKGROUND

Drosophila melanogaster lipophorin receptors (LpRs), LpR1 and LpR2, are members of the LDLR family known to mediate lipid uptake in a range of organisms from Drosophila to humans. The vertebrate orthologs of LpRs, ApoER2 and VLDL-R, function as receptors of a glycoprotein involved in development of the central nervous system, Reelin, which is not present in flies. ApoER2 and VLDL-R are associated with the development and function of the hippocampus and cerebral cortex, important association areas in the mammalian brain, as well as with neurodevelopmental and neurodegenerative disorders linked to those regions. It is currently unknown whether LpRs play similar roles in the Drosophila brain.

RESULTS

We report that LpR-deficient flies exhibit impaired olfactory memory and sleep patterns, which seem to reflect anatomical defects found in a critical brain association area, the mushroom bodies (MB). Moreover, cultured MB neurons respond to mammalian Reelin by increasing the complexity of their neurite arborization. This effect depends on LpRs and Dab, the Drosophila ortholog of the Reelin signaling adaptor protein Dab1. In vitro, two of the long isoforms of LpRs allow the internalization of Reelin, suggesting that Drosophila LpRs interact with human Reelin to induce downstream cellular events.

CONCLUSIONS

These findings demonstrate that LpRs contribute to MB development and function, supporting the existence of a LpR-dependent signaling in Drosophila, and advance our understanding of the molecular factors functioning in neural systems to generate complex behaviors in this model. Our results further emphasize the importance of Drosophila as a model to investigate the alterations in specific genes contributing to neural disorders.

MiR‐130a‐3p regulates neural stem cell differentiation in vitro by targeting Acsl4

In the adult mammalian brain, neural stem cells (NSCs) are the precursor cells of neurons that contribute to nervous system development, regeneration, and repair. MicroRNAs (miRNAs) are small non‐coding RNAs that regulate cell fate determination and differentiation by negatively regulating gene expression. Here, we identified a post‐transcriptional mechanism, centred around miR‐130a‐3p that regulated NSC differentiation. Importantly, overexpressing miR‐130a‐3p promoted NSC differentiation into neurons, whereas inhibiting miR‐130a‐3p function reduced the number of neurons. Then, the quantitative PCR, Western blot and dual‐luciferase reporter assays showed that miR‐130a‐3p negatively regulated acyl‐CoA synthetase long‐chain family member 4 (Acsl4) expression. Additionally, inhibition of Acsl4 promoted NSC differentiation into neurons, whereas silencing miR‐130a‐3p partially suppressed the neuronal differentiation induced by inhibiting Acsl4. Furthermore, overexpressing miR‐130a‐3p or inhibiting Acsl4 increased the levels of p‐AKT, p‐GSK‐3β and PI3K. In conclusion, our results suggested that miR‐130a‐3p targeted Acsl4 to promote neuronal differentiation of NSCs via regulating the Akt/PI3K pathway. These findings may help to develop strategies for stem cell‐mediated treatment for central nervous system diseases.