Functional diversity among cardiolipin binding sites on the mitochondrial ADP/ATP carrier.

Lipid-protein interactions play a multitude of essential roles in membrane homeostasis. Mitochondrial membranes have a unique lipid-protein environment that ensures bioenergetic efficiency. Cardiolipin (CL), the signature mitochondrial lipid, plays multiple roles in promoting oxidative phosphorylation (OXPHOS). In the inner mitochondrial membrane, the ADP/ATP carrier (AAC in yeast; adenine nucleotide translocator, ANT in mammals) exchanges ADP and ATP, enabling OXPHOS. AAC/ANT contains three tightly bound CLs, and these interactions are evolutionarily conserved. Here, we investigated the role of these buried CLs in AAC/ANT using a combination of biochemical approaches, native mass spectrometry, and molecular dynamics simulations. We introduced negatively charged mutations into each CL-binding site of yeast Aac2 and established experimentally that the mutations disrupted the CL interactions. While all mutations destabilized Aac2 tertiary structure, transport activity was impaired in a binding site-specific manner. Additionally, we determined that a disease-associated missense mutation in one CL-binding site in human ANT1 compromised its structure and transport activity, resulting in OXPHOS defects. Our findings highlight the conserved significance of CL in AAC/ANT structure and function, directly tied to specific lipid-protein interactions.

Juvenile eosinophilic fasciitis: a single center case series.

BACKGROUND: Eosinophilic fasciitis (EF) is a rare disease characterized by skin induration and musculoskeletal abnormalities. Diagnostic criteria for EF are based on adult populations. There is a need to expand the literature on EF in children due to limited reported cases and potential differences compared to adults. METHODS: We conducted a retrospective review of medical records for six pediatric patients diagnosed with EF at our institution between November 2011 and April 2023. Inclusion criteria required patients to be under 18 years of age at the time of diagnosis and to have confirmed diagnosis through clinical history, imaging, and histology. RESULTS: Most of our cohort were female (83%) and non-Hispanic white (50%). Age at diagnosis ranged from 4 to 16 years. Duration of symptoms before diagnosis varied from 1 to 12 months. Follow-up periods ranged from 14 to 123 months. Concurrent medical conditions included localized scleroderma, acquired thrombophilia, and juvenile idiopathic arthritis. Patients presented with progressive painful swelling, severe joint limitations, and positive prayer sign. Initial regimens involved corticosteroids and methotrexate. Hydroxychloroquine, immunoglobulin, mycophenolate mofetil, rituximab, and tocilizumab were also used depending on the patient's disease severity and course. CONCLUSIONS: Juvenile EF may manifest as swelling and progressive induration without apparent skin abnormalities. Unlike adult populations, no underlying malignancies or associations with trauma were observed in our cohort. Our cases did not exhibit systemic involvement observed in previous studies on juvenile EF. While non-specific, the prayer sign may aid in early recognition of juvenile EF and help prevent long-term disability.