Saddouk et al. report that, in established pulmonary hypertension, endothelial production of platelet-derived growth factor B is required for survival of pathological distal arteriole smooth muscle cells via the autophagy initiator Beclin1, thereby sustaining hemodynamic abnormalities. The cover image of the murine lung shows enhanced staining for proapoptotic marker activated BAX (red) in pulmonary arteriole smooth muscle cells (green) with deletion of Beclin1. Image credit: Fatima Z. Saddouk and Junichi Saito.
Caloric restriction improves metabolic health, but is often complicated by bone loss. We studied bone parameters in humans during a 10-day fast and identified candidate metabolic regulators of bone turnover. P1NP, a bone formation marker, decreased within 3 days of fasting. Whereas dual-energy X-ray absorptiometry measures of bone mineral density were unchanged after 10 days of fasting, high-resolution peripheral quantitative CT demonstrated remodeling of bone microarchitecture. Pathway analysis of longitudinal metabolomics data identified one-carbon metabolism as fasting-dependent. In cultured osteoblasts, we tested the functional significance of one-carbon metabolites modulated by fasting, finding that methionine — which surged after 3 days of fasting — impacted markers of osteoblast cell state in a concentration dependent manner, in some instances exhibiting a U-shaped response with both low and high concentrations driving putative anti-bone responses. Administration of methionine to mice for 5 days recapitulated some fasting effects on bone, including a reduction in serum P1NP. In conclusion, a 10-day fast in humans led to remodeling of bone microarchitecture, potentially mediated by a surge in circulating methionine. These data support an emerging model that points to a window of optimal methionine exposure for bone health.
Tânia Amorim, Naveen G.V. Kumar, Natalie L. David, William Dion, Trishya Pagadala, Nandini K. Doshi, Bokai Zhu, Andrey Parkhitko, Matthew L. Steinhauser, Pouneh K. Fazeli
Pathogenic variants in SCN8A, which encodes the voltage-gated sodium (NaV) channel NaV1.6, associate with neurodevelopmental disorders including developmental and epileptic encephalopathy. Previous approaches to determine SCN8A variant function may be confounded by use of a neonatal-expressed alternatively spliced isoform of NaV1.6 (NaV1.6N), and engineered mutations rendering the channel tetrodotoxin (TTX) resistant. We investigated the impact of SCN8A alternative splicing on variant function by comparing the functional attributes of 15 variants expressed in two developmentally regulated splice isoforms (NaV1.6N, NaV1.6A). We employed automated patch clamp recording to enhance throughput, and developed a novel neuronal cell line (ND7/LoNav) with low levels of endogenous NaV current to obviate the need for TTX-resistance mutations. Expression of NaV1.6N or NaV1.6A in ND7/LoNav cells generated NaV currents with small but significant differences in voltage-dependence of activation and inactivation. TTX-resistant versions of both isoforms exhibited significant functional differences compared to the corresponding wild-type (WT) channels. We demonstrated that many of the 15 disease-associated variants studied exhibited isoform-dependent functional effects, and that many of the studied SCN8A variants exhibited functional properties that were not easily classified as either gain- or loss-of-function. Our work illustrated the value of considering molecular and cellular context when investigating SCN8A variants.
Carlos G. Vanoye, Tatiana V. Abramova, Jean-Marc Dekeyser, Nora F. Ghabra, Madeleine J. Oudin, Christopher B. Burge, Ingo Helbig, Christopher H. Thompson, Alfred L. George Jr.
Hypotrichosis is a genetic disorder which characterized by a diffuse and progressive loss of scalp and/or body hair. Nonetheless, the causative genes for several affected individuals remain elusive, and the underlying mechanisms have yet to be fully elucidated. Here, we discovered a dominant variant in ADAM17 gene caused hypotrichosis with woolly hair. Adam17 (p.D647N) knock-in mice model mimicked the hair abnormality in patients. ADAM17 (p.D647N) mutation led to hair follicle stem cells (HFSCs) exhaustion and caused abnormal hair follicles, ultimately resulting in alopecia. Mechanistic studies revealed that ADAM17 binds directly to E3 ubiquitin ligase TRIM47. ADAM17 (p.D647N) variant enhanced the association between ADAM17 and TRIM47, leading to an increase in ubiquitination and subsequent degradation of ADAM17 protein. Furthermore, reduced ADAM17 protein expression affected Notch signaling pathway, impairing the activation, proliferation, and differentiation of HFSCs during hair follicle regeneration. Overexpression of NICD rescued the reduced proliferation ability caused by Adam17 variant in primary fibroblast cells.
Xiaoxiao Wang, Chaolan Pan, Luyao Zheng, Jianbo Wang, Quan Zou, Peiyi Sun, Kaili Zhou, Anqi Zhao, Qiaoyu Cao, Wei He, Yumeng Wang, Ruhong Cheng, Zhirong Yao, Si Zhang, Hui Zhang, Ming Li
Alloreactive memory, unlike naïve, CD8+ T cells resist transplantation tolerance protocols and are a critical barrier to long-term graft acceptance in the clinic. We here show that semi-allogeneic pregnancy successfully reprogrammed memory fetus/graft-specific CD8+ T cells (TFGS) towards hypofunction. Female C57BL/6 mice harboring memory CD8+ T cells generated by the rejection of BALB/c skin grafts and then mated with BALB/c males achieved rates of pregnancy comparable to naive controls. Post-partum fetus/graft-specific CD8+ T cells (TFGS) from skin-sensitized dams upregulated expression of T cell exhaustion (TEX) markers (Tox, Eomes, PD-1, TIGIT, and Lag3). Transcriptional analysis corroborated an enrichment of canonical T exhaustion (TEX) genes in post-partum memory TFGS and additionally, revealed a downregulation of a subset of memory-associated transcripts. Strikingly, pregnancy induced extensive epigenetic modifications of exhaustion- and memory-associated genes in memory TFGS, whereas minimal epigenetic modifications were observed in naive TFGS cells. Finally, post-partum memory TFGS durably expressed the exhaustion-enriched phenotype, and their susceptibility to transplantation tolerance was significantly restored compared to memory TFGS. These findings advance the concept of pregnancy as an epigenetic modulator inducing hypofunction in memory CD8+ T cells that has relevance not only for pregnancy and transplantation tolerance, but also for tumor immunity and chronic infections.
Jared M. Pollard, Grace Hynes, Dengping Yin, Malay Mandal, Fotini Gounari, Maria-Luisa Alegre, Anita S. Chong
Glycogen storage disease type III (GSDIII) is a rare metabolic disorder due to glycogen debranching enzyme (GDE) deficiency. Reduced GDE activity leads to pathological glycogen accumulation responsible for impaired hepatic metabolism and muscle weakness. To date, there is no curative treatment for GSDIII. We previously reported that two distinct dual AAV vectors encoding for GDE were needed to correct liver and muscle in a GSDIII mouse model. Here, we evaluated the efficacy of rapamycin in combination with AAV gene therapy. Simultaneous treatment with rapamycin and a novel dual AAV vector expressing GDE in the liver and muscle resulted in a synergic effect demonstrated at biochemical and functional levels. Transcriptomic analysis confirmed synergy and suggested a putative mechanism based on the correction of lysosomal impairment. In GSDIII mice liver, dual AAV gene therapy combined with rapamycin reduced the impact of the immune response to AAV observed in this disease model. These data provide proof of concept of an approach exploiting the combination of gene therapy and rapamycin to improve efficacy and safety and support clinical translation.
Louisa Jauze, Mallaury Vie, Quentin Miagoux, Lucille Rossiaud, Patrice Vidal, Valle Montalvo-Romeral, Hanadi Saliba, Margot Jarrige, Helene Polveche, Justine Nozi, Pierre-Romain Le Brun, Luca Bocchialini, Amandine Francois, Jeremie Cosette, Jérémy Rouillon, Fanny Collaud, Fanny Bordier, Emilie Bertil-Froidevaux, Christophe Georger, Laetitia Van Wittenberghe, Adeline Miranda, Nathalie Daniele, David Gross, Lucile Hoch, Xavier Nissan, Giuseppe Ronzitti