Neurofibromatosis 1 - mutant microglia exhibit sexually-dimorphic cyclic AMP-dependent purinergic defects

As critical regulators of brain homeostasis, microglia are influenced by numerous factors, including sex and genetic mutations. To study the impact of these factors on microglia biology, we employed genetically engineered mice that model Neurofibromatosis type 1 (NF1), a disorder characterized by clinically relevant sexually dimorphic differences. While microglia phagocytic activity was reduced in both male and female heterozygous Nf1 mutant (Nf1+/-) mice, purinergic control of phagocytosis was only affected in male Nf1+/- mice. ATP-induced P2Y-mediated membrane currents and P2RY12-dependent laser lesion-induced accumulation of microglial processes were also only impaired in male, but not female Nf1+/-, microglia. These defects resulted from Nf1+/- male-specific defects in cyclic AMP regulation, rather than from changes in purinergic receptor expression. Cyclic AMP elevation by phosphodiesterase blockade restored the male Nf1+/- microglia defects in P2Y-dependent membrane currents and process motility. Taken together, these data establish a sex-by-genotype interaction important to microglia function in the adult mouse brain

Neurofibromatosis 1 (NF1) mutation results in impaired function of human induced pluripotent stem cell-derived microglia

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition caused by germline mutations in the NF1 gene. Children with NF1 are prone to the development of multiple nervous system abnormalities, including autism and brain tumors, which could reflect the effect of NF1 mutation on microglia function. Using heterozygous Nf1-mutant mice, we previously demonstrated that impaired purinergic signaling underlies deficits in microglia process extension and phagocytosis in situ. To determine whether these abnormalities are also observed in human microglia in the setting of NF1, we leveraged an engineered isogenic series of human induced pluripotent stem cells to generate human microglia-like (hiMGL) cells heterozygous for three different NF1 patient-derived NF1 gene mutations. While all NF1-mutant and isogenic control hiMGL cells expressed classical microglia markers and exhibited similar transcriptomes and cytokine/chemokine release profiles, only NF1-mutant hiMGL cells had defects in P2X receptor activation, phagocytosis and motility. Taken together, heterozygous NF1 mutation impairs a subset of human microglia functional properties, which could contribute to the neurological abnormalities seen in children with NF1

Notch1 in cancer therapy: possible clinical implications and challenges

The Notch family consists of four highly conserved transmembrane receptors, the release of the active intracellular domain requires the enzymatic activity of gamma secretase. Notch is involved in embryonic development and in many physiological processes of normal cells where it regulates growth, apoptosis and differentiation. Notch 1, a member of the Notch family, is implicated in many types of cancer, including breast cancer (especially triple negative breast cancer), leukemias, brain tumors, and many others. Notch 1 is tightly connected to many signaling pathways that are therapeutically involved in tumorigenesis. Together, they impact apoptosis, proliferation, chemosensitivity, immune-response and the population of cancer stem cells. Notch 1 inhibition can be achieved through various and diverse methods, among the most common are the gamma secretase inhibitors which produce a pan-Notch inhibition, or the use of Notch 1 siRNA or Notch 1 monoclonal antibodies (mAb) which produce a more specific blockade. Downregulation of Notch 1 can be used alone or in combination with chemotherapy where a synergistic effect and a decrease in chemoresistance can be achieved. Targeting Notch1 in cancers that harbor high expression levels of Notch 1 offers an addition to therapeutic strategies recruited for managing cancer. Considering available evidence, Notch 1 offers a legitimate target that might be incorporated in future strategies for combating cancer. In this review, the possible clinical applications of Notch 1 inhibition and the obstacles that hinder its clinical application are discussed. SIGNIFICANCE STATEMENT: Notch 1 plays an important role in different types of cancer. Numerous approaches of Notch 1 inhibition possess potential benefits in the management of various clinical aspects of cancer. The application of different Notch 1 inhibition modalities faces many challenges

Antiproliferative activity of the combination of doxorubicin/quercetin on MCF7 breast cancer cell line: a combined study using colorimetric assay and synchrotron infrared microspectroscopy

Breast cancer is the most common type of cancer among females worldwide. Doxorubicin (Dox) is one of the main chemotherapy drugs used in neoadjuvant and adjuvant breast cancer therapy. Dox-induced cardiotoxicity limits its use to a definite period and a definite cumulative dose. On the other hand, quercetin (Quer), a natural antioxidant, has been successfully reported to protect cardiomyocytes from Dox toxicity. Our aim is to optimize Dox regimen by assessing Quer effect on Dox cytotoxicity in a breast cancer cell model, MCF7 using a classic in vitro technique as well as Fourier Transform Infrared (FTIR) microspectroscopy. The cancer cells were exposed to Dox, Quer, or the combination of both agents for 72 incubation hours. Cell proliferation was assessed by using the classical colorimetric Sulforhodamine B (SRB) assay and JC1 dye. MCF7cells were further investigated by FTIR microspectroscopy to correlate SRB results with the changes in the distinctive IR spectra of the cells. Our results show that Quer exerts an antiproliferative effect and enhances the cytotoxicity of Dox in MCF7 cells. Results obtained from both the in vitro assays and FTIR microspectroscopy showed that Quer potentiates the effect of Dox in breast cancer cells

Tenascin C regulates multiple microglial functions involving TLR4 signaling and HDAC1

Tenascin C (Tnc) is an extracellular matrix glycoprotein, expressed in the CNS during development, as well as in the setting of inflammation, fibrosis and cancer, which operates as an activator of Toll-like receptor 4 (TLR4). Although TLR4 is highly expressed in microglia, the effect of Tnc on microglia has not been elucidated to date. Herein, we demonstrate that Tnc regulates microglial phagocytic activity at an early postnatal age (P4), and that this process is partially dependent on microglial TLR4 expression. We further show that Tnc regulates proinflammatory cytokine/chemokine production, chemotaxis and phagocytosis in primary microglia in a TLR4-dependent fashion. Moreover, Tnc induces histone-deacetylase 1 (HDAC1) expression in microglia, such that HDAC1 inhibition by MS-275 decreases Tnc-induced microglial IL-6 and TNF-α production. Finally, Tnc(-/-) cortical microglia have reduced HDAC1 expression levels at P4. Taken together, these findings establish Tnc as a regulator of microglia function during early postnatal development

The VGF-derived peptide TLQP21 impairs purinergic control of chemotaxis and phagocytosis in mouse microglia

Microglial cells are considered as sensors of brain pathology by detecting any sign of brain lesions, infections, or dysfunction and can influence the onset and progression of neurological diseases. They are capable of sensing their neuronal environment via many different signaling molecules such as neurotransmitters, neurohormones and neuropeptides. The neuropeptide VGF has been associated with many metabolic and neurological disorders. TLQP21 is a VGF-derived peptide and has been shown to signal via C3aR1 and C1qBP receptors. The effect of TLQP21 on microglial functions in health or disease is not known. Studying microglial cells in acute brain slices, we found that TLQP21 impaired metabotropic purinergic signaling. Specifically, it attenuated the ATP-induced activation of a K(+) conductance, the UDP-stimulated phagocytic activity and the ATP dependent laser lesion-induced process outgrowth. These impairments were reversed by blocking C1qBP, but not C3aR1 receptors. While microglia in brain slices from male mice lack C3aR1 receptors, both receptors are expressed in primary cultured microglia. In addition to the negative impact on purinergic signaling, we found stimulating effects of TLQP21 in cultured microglia which were mediated by C3aR1 receptors: it directly evoked membrane currents, stimulated basal phagocytic activity, evoked intracellular Ca(2+) transient elevations and served as a chemotactic signal. We conclude that TLQP21 has differential effects on microglia depending on C3aR1 activation or C1qBP-dependent attenuation of purinergic signaling. Thus, TLQP21 can modulate the functional phenotype of microglia which may have an impact on their function in health and disease.SIGNIFICANCE STATEMENT: The neuropeptide VGF and its peptides have been associated with many metabolic and neurological disorders. TLQP21 is a VGF-derived peptide that activates C1qBP receptors which are expressed by microglia. We show here for the first time that TLQP21 impairs P2Y-mediated purinergic signaling and related functions. These include modulation of phagocytic activity and responses to injury. As purinergic signaling is central for microglial actions in the brain, this TLQP21-mediated mechanism might regulate microglial activity in health and disease. We furthermore show that besides C1qBP, functional C3aR1 responses contribute to TLQP21 action on microglia. However, C3aR1 responses were only present in primary cultures but not in situ, suggesting that the expression of these receptors might vary between different microglial activation states

Emotion recognition from speech using spectrograms and shallow neural networks

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