No abstract

Sexual dimorphism exists in energy balance, but the underlying mechanisms remain unclear. Here we show that the female mice have more pro-opiomelanocortin (POMC) neurons in the arcuate nucleus of hypothalamus than males, and female POMC neurons display higher neural activities, compared to male counterparts. Strikingly, deletion of the transcription factor, TAp63, in POMC neurons confers “male-like” diet-induced obesity (DIO) in female mice associated with decreased POMC neural activities; but the same deletion does not affect male mice. Our results indicate that TAp63 in female POMC neurons contributes to the enhanced POMC neuron functions and resistance to obesity in females. Thus, TAp63 in POMC neurons is one key molecular driver for the sexual dimorphism in energy homeostasis.

Objectives. Bone destruction is a remarkable feature of inflammatory arthritis. It remains unknown why arthritis associated with the systemic autoimmune/inflammatory condition systemic lupus erythematosus (SLE) does not result in erosion and destruction. We aimed to determine the role of autoantibody in the pathogenesis of non-erosive arthritis in SLE. Methods. We analysed medical record of SLE patients, investigated whether autoantibody induces arthritis lacking bone destruction in animal models and determined whether SLE autoantibody inhibits osteoclastogenesis induced by RANKL in vitro experiments. Results. We found that arthritis lacking bone erosions is common in SLE patients and lupus-prone mice. Intraarticular injection of lupus serum or IgG induces immune complex deposition and arthritis, but does not result in bone destruction. Deposition of IgG, monocytes/macrophages and TNF-a is all required for the development of arthritis. Lupus serum or IgG inhibits RANKLinduced differentiation of monocytes into osteoclast in a dosedependent manner. FccR acts as co-receptors for RANKL and is involved in osteoclastogenesis. Deficiency of FccRII or FccRIII does not affect osteoclastogenesis in the presence of SLE IgG. However, lupus IgG competes for FccRI binding with RANKL, thereby reducing osteoclastogenesis. Conclusion. Observations from this study demonstrate that IgG from SLE patients can induce arthritis and inhibits RANKL-induced osteoclastogenesis through competitive occupation of FccRI on monocytes/macrophages. This study improves the understanding of the pathophysiology of SLEassociated arthritis and offers a protective mechanism (FccRI inhibition) that may be targeted in other forms of autoimmune/ inflammatory arthritis, such as RA, to prevent or limit bone erosion and inflammatory bone loss.

Background A variety of biological functions of estrogens, including regulation of energy metabolism, are mediated by neurons expressing estrogen receptor-α (ERα) in the brain. However, complex intracellular processes in these ERα-expressing neurons are difficult to unravel, due to the lack of strategy to visualize ERα-expressing neurons, especially in unfixed brain tissues. Results and Conclusions Here we generated a novel ERα-ZsGreen reporter mouse line in which expression of a green fluorescent reporter protein, ZsGreen, is driven by a 241 kb ERα gene promoter. We validated that ZsGreen is highly colocalized with endogenous ERα in the brain. Native ZsGreen signals were visualized in unfixed brain tissue, and were used to assist single cell collection and electrophysiological recordings. Finally, we demonstrated that this ERα-ZsGreen mouse allele can be used in combination with other genetic reporter alleles to allow experiments in highly selective neural populations.