In mammals, female development has traditionally been considered a default process in the absence of the testis-determining gene, Sry. Recently, it has been documented that the gene for R-spondin1 (RSPO1), a novel class of soluble activator for Wnt/beta-catenin signaling, is mutated in two Italian families with female-to-male (XX) sex reversal. To elucidate the role of Rspo1 as a candidate female-determining gene in a mouse model, we generated Rspo1-null (Rspo1(-/-)) mice and found that Rspo1(-/-) XX mice displayed masculinized features including pseudohermaphroditism in genital ducts, depletion of fetal oocytes, male-specific coelomic vessel formation and ectopic testosterone production in the ovaries. Thus, although Rspo1 is required to fully suppress the male differentiation program and to maintain germ cell survival during the development of XX gonads, the loss of its activity has proved to be insufficient to cause complete XX sex reversal in mice. Interestingly, these partial sex-reversed phenotypes of Rspo1(-/-) XX mice recapitulated those of previously described Wnt-4(-/-) XX mice. In accordance with this finding, the expression of Wnt-4 and its downstream genes was deregulated in early Rspo1(-/-) XX gonads, suggesting that Rspo1 may participate in suppressing the male pathway in the absence of Sry and maintaining oocyte survival through positively regulating Wnt-4 signaling.

Acetylcholinesterase inhibitors (AChEIs) are widely used to compensate for acetylcholine (ACh) depletion in the Alzheimer's disease (AD) brain. Some clinical and experimental studies, however, have suggested that AChEIs also provide neuroprotection. To assess the effect of AChEIs on neurodegeneration, donepezil (DZ), an AChEI, was administered to FTDP-17 model mice with a P301S tau mutation (line PS19). Eight months of DZ treatment resulted in amelioration of neuroinflammation, tau pathology, synaptic loss, and neuronal loss, as well as decreased tau insolubility and phosphorylation. Tau kinase activity analysis demonstrated significantly suppressed c-Jun N-terminal kinase (JNK) in the brains of DZ-treated PS19 mice. Recently, ACh has been shown to suppress inflammation, which plays a role in neurodegeneration. To confirm the anti-inflammatory effect of DZ, PS19 mice were injected with lipopolysaccharide, in combination with or without DZ, for one month. Results demonstrated that DZ suppressed IL-1β and COX-2 expression in the brain, as well as the spleen, suggesting that DZ directly prevents systemic inflammation. These data indicated that ACh did not act just as a cognition-linking neurotransmitter, but might suppress pathological mechanisms of neurodegeneration via anti-inflammatory action.

Anticholinergics, and drugs with anticholinergic properties, are widely and frequently prescribed, especially to the elderly. It is well known that these drugs decrease cognitive function and increase the risk of dementia. Although the mechanism of anticholinergic drug-induced cognitive impairment has been assumed to be functionally reduced acetylcholine (ACh) neurotransmission, some data have indicated that anticholinergics might enhance the pathology of Alzheimer's disease. In this study, we investigated the pathological effects of anticholinergics on neurodegeneration. We chronically administered two anticholinergics, trihexyphenidyl (TP) and propiverine (PP) (the latter with less central anticholinergic action), to neurodegenerative tauopathy model mice 2 to 10 months old. Furthermore, because the ACh nervous system regulates both central and peripheral inflammation, we administered TP or PP to PS19 mice in which we had artificially induced inflammation by lipopolysaccharide injection. Tau pathology, synaptic loss, and neurodegeneration in the hippocampal region, as well as tau insolubility and phosphorylation, were markedly increased in TP-treated mice and mildly increased in PP-treated mice. Furthermore, immunohistochemical analysis revealed microglial proliferation and activation. Moreover, anticholinergics increased interleukin-1β expression in both the spleen and brain of the tauopathy model mice intraperitoneally injected with lipopolysaccharide to induce systemic inflammation. Interestingly, these alterations were more strongly observed in TP-treated mice than in PP-treated mice, consistent with the level of central anticholinergic action. Anticholinergic drugs not only impair cognitive function by decreased ACh neurotransmission, but also accelerate neurodegeneration by suppressing an ACh-dependent anti-inflammatory system. Anticholinergics should be less readily prescribed to reduce the risk of dementia.

Polyinosinic:polycytidylic acid (poly I:C), a synthetic double-stranded RNA, acts on myeloid cells and induces potent antitumor immune responses including natural killer (NK) cell activation. Myeloid-derived suppressor cells (MDSCs) systemically exist in tumor-bearing hosts and have strong immunosuppressive activity against antitumor effector cells, thereby dampening the efficacy of cancer immunotherapy. Here we tested what happened in MDSCs in poly I:C-treated mice. NK-sensitive syngenic tumor (B16)-bearing C57BL/6 mice were employed for this study. Intraperitoneal poly I:C treatment induced MDSC activation, driving CD69 expression and interferon (IFN)-γ production in NK cells. IFN-γ directly inhibited proliferation of B16 cells. This NK cell priming led to growth retardation of B16 tumors, although no direct tumoricidal activity was induced in NK cells. Mechanistic analysis using KO mice and function-blocking monclonal antibody revealed that MDSCs produced IFN-α via the mitochondrial antiviral signaling protein (MAVS) pathway after in vivo administration of poly I:C, and activated NK cells through the IFNAR pathway. MDSC-mediated NK cell priming was reconstituted by IFN-α in a coculture system. Either the MAVS or IFNAR signaling pathway was required for activation of MDSCs that led to growth retardation of B16 tumor in vivo. The results infer that MDSC is a target of poly I:C to prime NK cells, which exert antitumor activity to NK-sensitive tumor cells.

The number of patients with Alzheimer's disease (AD) is increasing worldwide, and available drugs have shown limited efficacy. Hence, preventive interventions and treatments for presymptomatic AD are currently considered very important. Obesity rates have also been increasing dramatically and it is an independent risk factor of AD. Therefore, for the prevention of AD, it is important to elucidate the pathomechanism between obesity and AD. We generated high calorie diet (HCD)-induced obese tauopathy model mice (PS19), which showed hyperleptinemia but limited insulin resistance. HCD enhanced tau pathology and glial activation. Conversely, voluntary exercise with a running wheel normalized the serum leptin concentration without reducing body weight, and restored the pathological changes induced by HCD. Thus, we speculated that persistent hyperleptinemia played an important role in accelerating pathological changes in PS19 mice. Leptin primarily regulates food intake and body weight via leptin receptor b (LepRb). Interestingly, the nuclear staining for p-STAT3, which was activated by LepRb, was decreased in hippocampal neurons in HCD PS19 mice, indicating leptin resistance. Meanwhile, astroglial activation and the astrocytic expression of a short LepR isoform, LepRa, were enhanced in the hippocampus of HCD PS19 mice. Real-time PCR analysis demonstrated that leptin increased mRNA levels for pro-inflammatory cytokines including IL-1β and TNF-α in primary cultured astrocytes from wild type and LepRb-deficient mice. These observations suggest that persistent hyperleptinemia caused by obesity induces astrocytic activation, astrocytic leptin hypersensitivity with enhanced LepRa expression, and enhanced inflammation, consequently accelerating tau pathology in PS19 mice.