ABSTRACT
Nearly all persons with spinal cord injury (SCI) will develop osteoporosis following injury, and further, up to 50% of all persons with SCI will sustain a fracture during their lives. The unique mechanisms driving osteoporosis following SCI remain unknown. The cannabinoid system modulation of bone metabolism through cannabinoid 1/2 (CB1/2) has been of increasing interest for the preservation of bone mass and density in models of osteoporosis. Using a thoracic vertebral level 8 (T8) complete transection in a mouse model, we performed daily treatment with a selective CB2 receptor agonist, HU308, compared with SCI-vehicle-treated and naïve control animals either immediately after injury for 40 days, or in a delayed paradigm, following 3 months after injury. The goal was to prevent or potentially reverse SCI-induced osteoporosis. In the acute phase, administration of the CB2 agonist was not able to preserve the rapid loss of cancellous bone. In the delayed-treatment paradigm, in cortical bone, HU308 increased cortical-area to total-area ratio and periosteal perimeter in the femur, and improved bone density in the distal femur and proximal tibia. Further, we report changes to the metaphyseal periosteum with increased presence of adipocyte and fat mass in the periosteum of SCI animals, which was not present in naïve animals. The layer of fat increased markedly in HU308-treated animals compared with SCI-vehicle-treated animals. Overall, these data show that CB2 agonism targets a number of cell types that can influence overall bone quality.
ABSTRACT
The outbreak of the novel coronavirus (2019-nCoV) began in Wuhan, China and spread rapidly throughout the world. As of now, there have been numerous reports demonstrating clinical, radiological and pathological findings in adults. In children, the disease has essentially been seen as mild and self-limiting. However, more recently, children have been presenting with findings reminiscent of Kawasaki's disease. And secondary to this, the benign nature of COVID-19 disease in children is beginning to be challenged. This phenomenon is now referred to as multisystem inflammatory syndrome in children (MIS-C). Further understanding the clinical course in MIS-C and its temporal association with coronavirus disease 2019 will be paramount for treatment and public health decision making. This correspondence describes a case of MIS-C with gastrointestinal manifestations mimicking acute appendicitis in a child presenting from a COVID-19 endemic area.
ABSTRACT
The mammalian Fem1b gene encodes a homolog of FEM-1, a protein in the sex-determination pathway of the nematode Caenorhabditis elegans. Fem1b and FEM-1 proteins each contain a VHL-box motif that mediates their interaction with certain E3 ubiquitin ligase complexes. In C. elegans, FEM-1 negatively regulates the transcription factor TRA-1, and functions as an E3 ubiquitin ligase substrate recognition subunit to target TRA-1 for ubiquitylation. TRA-1 is homologous to the mammalian Gli1 protein, a transcription factor that mediates Hedgehog signaling as well as having Hedgehog-independent functions. Whether the interaction between nematode FEM-1 and TRA-1 proteins is conserved, between corresponding mammalian homologs, has not been reported. Herein, we show that Fem1b interacts with Gli1 within cells, and directly binds Gli1. Fem1b also promotes ubiquitylation of Gli1, suppresses transcriptional activation by Gli1, and attenuates an oncogenic Gli1 autoregulatory loop in cancer cells, all dependent on the VHL-box of Fem1b. These findings have implications for understanding the cellular functions of Fem1b, and the regulation of Gli1 oncoprotein activity.
