Nerve growth factor (NGF) signaling is a clinically validated target for the treatment of several prevalent types of chronic pain; however, addressing safety concerns remain a key challenge. In this issue of the JCI, Peach et al. take a major step forward in this area by deciphering complexities in the signaling of the NGF receptor TrkA, finding that neuropilin 1 (NRP1) acted as a coreceptor for NGF actions at TrkA and the receptor complex required scaffolding from GIPC1. Using a mix of techniques, including animal behavioral models, electrophysiology on mouse and human dorsal root ganglion (DRG) neurons, and elegant biochemical pharmacology, the authors demonstrated that this therapeutic target might more safely manipulate NGF signaling to achieve pain alleviation. While there are still important questions to answer, the innovative work paves the way for the development of nonopioid pain therapeutics.
Andi Wangzhou, Theodore J. Price
Chronic pain is a debilitating condition that affects up to 1.5 billion people globally. Advancing pain management depends on a thorough understanding of the types of pain experienced by patients and the underlying mechanisms driving it. N-type calcium channels play a crucial role as therapeutic targets for managing chronic pain. In this issue of the JCI, Tang et al. introduce C2230, an N-type calcium channel blocker that inhibited CaV2.2 channels during high frequency stimulation with little effect on other ion channels in the pain pathway across multiple models. C2230 offers a promising analgesic for use in therapeutic intervention.
Maria A. Gandini, Gerald W. Zamponi
Truncation variants in the gene TTN encoding titin are the most common cause of familial dilated cardiomyopathy (DCM), with both haploinsufficiency and “poison peptide” implicated as contributory mechanisms of disease. In this issue of the JCI, Kim et al. identify a highly conserved enhancer element approximately 500 bp downstream of the transcriptional start site of TTN in intron 1, which they demonstrated to be critical in regulating TTN expression. This work helps to further clarify the relative role of haploinsufficiency in TTN-related DCM and provides a potential target for therapies aimed at treating TTN-related DCM.
Dominic E. Fullenkamp
Lysosome storage dysfunction plays a central role in numerous human diseases, but a lack of appropriate tools has hindered lysosomal content profiling in clinical settings. In this issue of the JCI, Saarela et al. introduce a method called tagless LysoIP that enabled rapid isolation of intact lysosomes from blood and brain cells via immunoprecipitation of the endogenous protein TMEM192. Applied to the neurodegenerative lysosomal storage disorder known as Batten disease (caused by mutations in the CLN3 gene), tagless LysoIP revealed substantial accumulation of glycerophosphodiesters (GPDs) in patient lysosomes. These findings highlight the role of CLN3 in GPD clearance and present an innovative method that will enable biomarker discovery and therapeutic advancement in lysosomal diseases.
Ali Shilatifard, Issam Ben-Sahra
Serologic biomarkers for the early diagnosis of EBV-associated nasopharyngeal carcinoma (NPC) have been identified from population studies, but a protective antibody signature in cancer-free seropositive carriers remains undefined. In this issue of the JCI, Kong et al. show that high levels of IgG against EBV glycoprotein 42 (gp42) were associated with reduced NPC risk in three independent prospective cohorts from southern China. EBV virions contain gp42, which complexes with gH-gL to facilitate fusion with B cells by binding to HLA class II (HLA-II). In this study, HLA-II was detected on non-antigen-presenting cells in a proportion of premalignant nasopharyngeal tissues, which may prime the nasopharyngeal epithelium for infection. In vitro, HLA-II expression in a nasopharyngeal cell line encouraged infection by EBV derived from B cells or epithelial cells. These findings suggest that a vaccine that stimulates gp42-IgG production may reduce the risk of EBV-associated NPC in endemic regions.
Benjamin E. Warner, Kathy H.Y. Shair
The precise mechanisms of blood pressure (BP) regulation are not fully elucidated, and understanding BP regulation is crucial for managing hypertension and improving outcomes for cardiovascular disease. In this issue of the JCI, Wang et al. identified the transcription factor PR domain–containing protein 16 (PRDM16) as a regulator of both vascular smooth muscle cell contraction and the circadian response to BP control. PRDM16 directly transcriptionally controlled the expression of the adrenergic receptor α 1d and several clock genes crucial for BP circadian regulation. These findings identify a mechanism of how molecular pathways govern circadian BP variation, highlighting PRDM16 as a potential target for hypertension.
M. Adriana Cuibus, Omar Abdel-Wahab
Colorectal cancer is the second leading cause of cancer death in the United States. The adenomatous polyposis coli (APC) pathway plays a critical role in colorectal tumorigenesis, but the mechanism is not fully understood. In this issue of the JCI, Luo and colleagues used genetically engineered mouse models to show that high mobility group A (HMGA1) is a critical mediator in the development of colon tumors driven by the loss of the Apc gene. HMGA1 activated the transcription of Achaete-Scute Family BHLH Transcription Factor 2 (ASCL2), which regulated intestinal stemness and promoted colon tumorigenesis.
Yuxiang Wang, Mikayla Ybarra, Zhenghe Wang
Heterozygous loss-of-function variants in the SLC6A1 gene, encoding GAT1, which is the main GABA transporter in the brain, lead to a broad spectrum of neuropsychiatric and neurodevelopmental disorders including epilepsy, developmental delay, intellectual disability, and autism. Gene-replacement strategies involving adeno-associated viruses (AAV) require the delivery of genes to specific types of neurons or areas in the brain, likely during certain developmental time points. In this issue of the JCI, Guo and colleagues from the Gray lab evaluated two promoters, three injection modalities, and various timing strategies for replacement of GAT1 via AAV type 9 in heterozygous and homozygous knockout mouse models. Intrathecal administration of vectors containing either promoter at postnatal day 5 achieved high expression and was the best tolerated approach. Notably, gene-replacement therapy failed at later disease stages, suggesting the importance of early gene reconstitution and confirming the importance of GABA metabolism in early brain development.
Holger Lerche, Ulrike B.S. Hedrich, Thomas V. Wuttke
Sensorineural hearing loss (SNHL) is the most prevalent form of permanent hearing impairment, arising from factors such as aging, exposure to loud noise, disease, ototoxic medications, and genetic mutations. Despite extensive research, effective treatments or cures for SNHL remain elusive. In this issue of the JCI, Lee et al. reveal a link between mutations in ATF6 and SNHL in patients with achromatopsia. The study also shows that Atf6-deficient (Atf6–/–) mice exhibit disorganized stereocilia and age-related loss of outer hair cells. Additionally, the researchers show that Atf6 is critical for cochlear hair cell function. Mice lacking Atf6 expression experienced ER stress, which ultimately led to SNHL. Collectively, these findings enhance our understanding of the emerging role of protein homeostasis and ER stress in the pathogenesis of SNHL.
Yuvraj Joshi, Jeffrey N. Savas
Superantigen-induced (Sag-induced) autoimmunity has been proposed as a mechanism for many human disorders, without a clear understanding of the potential triggers. In this issue of the JCI, McCarthy and colleagues used the SKG mouse model of rheumatoid arthritis to characterize the role of Sag activity in inflammatory arthritis by profiling arthritogenic naive CD4+ T cells. Within the diseased joints, they found a marked enrichment of T cell receptor–variable β (TCR-Vβ) subsets that were reactive to the endogenously encoded mouse mammary tumor virus (MMTV) Sag. Arthritis was improved using reverse transcriptase inhibitors. Moreover, depletion of MMTV Sag-activated TCR-Vβ subsets affected the ability of transferred activated CD4+ T cells to induce disease in mice with severe combined immunodeficiency (SCID). Further virological studies should determine whether endogenous or exogenous MMTV is necessary or sufficient to trigger inflammatory arthritis in the SKG model.
Andrew L. Mason, Doaa Waly, Mohammed S. Osman
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