Neuroscience
Abstract
Identifying factors that govern retinal ganglion cells’ (RGCs) ability to extend axons is an important step in developing therapies to achieve recovery after optic nerve injury. Here we report that the intracellular domain of the leukemia inhibitory factor receptor (LIFR/CD118) is essential for mature RGCs’ ability to regenerate injured axons independent of the cognate ligand (LIF) and other therapies. Overexpression of LIFR in adult RGCs induces neurite outgrowth in cultured RGCs and axon regeneration in vivo while strongly amplifying RGCs’ response to LIF itself and to unrelated growth factors. Conversely, downregulation of LIFR strongly suppresses the pro-regenerative effects of Pten deletion and other potent stimuli. LIFR modulation alters the constitutive activity of the MAP kinase pathway, in contrast to LIF itself, which primarily activates pSTAT3. The extracellular-domain-truncated LIFR construct retains substantial pro-regenerative activity, whereas mutation of intracellular signaling motifs reduces the full regenerative effect of LIFR. Together, these findings identify LIFR as a key cell-autonomous regulator of optic nerve regeneration in mature RGCs.
Authors
Qian Jiang, Cong Wang, Yuerong Ren, Peiyun Duan, Ke Tian, Xiangwei Duan, Binghan Cai, Changzhong Xu, Ke Liu, Jian Li, Larry Benowitz, Ningli Wang, Bing Jiang, Lili Xie
Abstract
Rationale: Persistent monocyte activation contributes to HIV-associated neurocognitive disorders (HAND), yet biomarkers that predict neurocognitive impairment before and after antiretroviral therapy (ART) remain incompletely defined. Objectives: We evaluated monocyte subsets and activation markers in participants from the SEARCH007 cohort prior to ART initiation and at 6 and 12 months following treatment. Methods and Results: Increased frequencies of CD14+CD16+ monocytes and elevated CD163 expression were associated with worsening neurocognitive performance and HAND severity. Plasma soluble CD163 levels increased with neurocognitive impairment and correlated with plasma HIV RNA levels, while CCR2 expression was associated with NPZ Global scores. Notably, CD169 expression was elevated across all monocyte subsets and demonstrated a stepwise increase with worsening neurocognitive impairment. Although ART reduced overall monocyte activation, elevated CD169 expression persisted in some individuals despite virologic suppression. Bayesian kernel machine regression and random forest analyses identified CD169 expression as one of the strongest predictors of cognitive impairment, surpassing plasma viral load, CD4+ T-cell count, and several established monocyte activation markers. Conclusions: These findings identify monocyte CD169 expression as a biomarker of neurocognitive dysfunction before and during the first year of ART and support further investigation of its role in HAND pathogenesis.
Authors
Hai Duc Nguyen, Andrew K. Ding-Su, Caroline Soulas, Tricia H. Burdo, Patrick Autissier, Pasiri Sithinamsuwan, Nitiya Chomchey, Jintanat Ananworanich, Victor Valcour, Silvia Ratto-Kim, Woong-Ki Kim, Kenneth C. Williams
Abstract
Noise-induced hearing loss (NIHL) is a major public health problem caused by damage to cochlear hair cells, synapses, and spiral ganglion neurons (SGNs). Since effective treatments are lacking, we investigated cellular stress responses induced by moderate and loud noise in a mouse model of cochlear synaptopathy. RNA sequencing and spatial transcriptomics revealed that noise exposure elicited a robust but transient upregulation of endoplasmic reticulum chaperones and proteasome subunits in SGNs and their supporting cells. To target this response, we administered TRC051384, a small-molecule activator of the heat shock transcription factor Hsf1, prior to noise exposure. TRC051384 crossed the blood–labyrinth barrier and reached the cochlea, induced heat shock protein gene expression, and restored ubiquitin–proteasome function in SGNs. Notably, TRC051384 treatment enhanced auditory brainstem response threshold recovery, preserved Wave I amplitudes, and maintained ribbon synapse density. Together with the existing literature, these findings identify proteotoxic stress in spiral ganglion neurons as a contributor to noise-induced hearing loss and support pharmacological activation of HSF1 as a promising therapeutic strategy.
Authors
Jintao Yu, Miguel A. Ramirez, Yi-Zhi Wang, Seby Edassery, Maxwell Shramuk, SangEun Yeom, Casey Jiaxi Li, Yuvraj Joshi, Mary Ann Cheatham, Mark A. Rutherford, Leah J. Welty, Jeffrey N. Savas
Abstract
Authors
Xiao Yang, Sameen Fatima, Salvador Sampere-Birlanga, Akshay Ware, Mariana Shumliakivska, Lukas Zanders, Srisurekha Radhakrishnan, Guillermo Luxán, David John, Stefan Günther, Silvia Mas-Peiro, Stefanie Dimmeler, Andreas M. Zeiher, Wesley T. Abplanalp
Abstract
Autosomal dominant leukodystrophy (ADLD) is a fatal-adult-onset CNS demyelinating disorder for which no treatment exists. The majority of ADLD cases are caused by duplications of the lamin B1 (LMNB1) gene, resulting in increased LMNB1 expression. While reducing LMNB1 levels represents a logical therapeutic strategy, its efficacy has not been previously demonstrated in any in vivo model. Mouse models with oligodendrocyte-specific human LMNB1 (hLMNB1) overexpression recapitulate salient features of ADLD. Using a modified version of this model, where hLMNB1 can be inducibly downregulated, we demonstrated that hLMNB1 reduction can prevent or substantially ameliorate disease progression. Therapeutic effects were maximized when hLMNB1 reduction was induced before expected symptom onset, resulting in improvements in behavioral, biochemical, histopathological, and survival measures relative to untreated animals. Reducing hLMNB1 levels after symptom onset led to improved survival, but mixed results for other disease phenotypes. In addition, we identified potential biomarkers that track disease progression. Furthermore, we demonstrated that near-complete knockdown of murine LMNB1 expression in adulthood did not result in any overt CNS phenotype. Together, these results provide a proof of concept supporting LMNB1 reduction as a therapeutic strategy and offer a rationale for treatments aimed at lowering levels of this protein in ADLD.
Authors
Nathan Herdman, Kaveh Moradi, Bruce Nmezi, Anushe Munir, Krizchelle A. Magtoto, Fang Liu, Mara Sullivan, Xuemei Zeng, Thomas K. Karikari, Quasar S. Padiath
Abstract
Authors
Ewa A. Ziółkowska, Letitia L. Williams, Elizabeth M. Eultgen, Grace R. Kick, Xukai Ding, Alexander Sorensen, Steven Q. Le, Balraj Doray, Patricia I. Dickson, Robert O. Heuckeroth, Jonathan D. Cooper
Abstract
The hypothalamic changes that occur after the loss of ovarian estrogen remain poorly characterized. Here, we performed a comprehensive temporal characterization of the mouse hypothalamus following ovariectomy (OVX), combining physiological measurements with bulk RNA-sequencing of the posterior hypothalamus (PH) and preoptic area (POA) at short-term (14 days) and long-term (4 months) post-OVX. Serum LH levels rose progressively and then declined, while core temperature peaked early and subsequently normalized, recapitulating the endocrine and thermoregulatory dynamics of reproductive aging in humans. Transcriptomic analysis revealed time-dependent activation of inflammatory pathways, glial markers, and KNDy neuron-related gene networks, with the most pronounced changes emerging at 4 months post-OVX, particularly in the PH. Immunofluorescence confirmed increased NKB release, declining KNDy neuronal activity, and heightened astrocytic reactivity in the arcuate nucleus after prolonged estrogen withdrawal. To contextualize these findings, we analyzed publicly available human hypothalamic RNA-seq data across chronological age. Age-related transcriptomic patterns in women, including progressive inflammatory signaling, glial activation, and altered KNDy gene expression, showed significant correlation with the OVX mouse model, particularly at the pathway level. These findings establish a temporal framework for hypothalamic molecular changes after estrogen withdrawal, identify conserved neuroinflammatory signatures across species, and provide a preclinical platform for testing interventions targeting menopausal-associated hypothalamic dysfunction.
Authors
Jordana C.B. Bloom, Encarnación Torres, Sidney A. Pereira, Liliana Arvizu-Sanchez, Audrey N. Fontes, Hadine Joffe, David C. Page, Victor M. Navarro
Abstract
Authors
Lun Li, Rhonda Lightle, Bader Ali, Georgeio Sader, Robert Shenkar, Sean P. Polster, Douglas A. Marchuk, Jan-Karl Burkhardt, Issam A. Awad, Mark L. Kahn
Abstract
Charcot-Marie-Tooth Disease (CMT) is a group of inherited progressive conditions affecting distal motor and sensory neurons, leading to muscle weakness, pain and loss of sensation in limbs. CMT type 2A (CMT2A) is the most common form of axonal CMT and is associated with a more severe clinical manifestation. However, there are no treatments currently available. To investigate disease mechanisms and facilitate treatment discovery, we developed an in vitro model for CMT2A by introducing the patient-specific MFN2R94Q/+ variant into human embryonic stem cells (hESCs). Isogenic variant and wild-type hESCs differentiated to spinal motor neurons with similar efficiency and gave rise to functional motor neurons in vitro. However, MFN2R94Q/+ spinal motor neurons displayed impaired mitochondrial trafficking, resulting in altered distribution of mitochondria in axons. Unbiased quantitative proteomic profiling of the endogenous MFN2 interactome revealed dose-dependent remodelling by the R94Q variant across 412 proteins, highlighting candidate mechanisms in disease pathology. Importantly, we showed that mitochondrial trafficking defects could be alleviated by treatment with an HDAC6 inhibitor. Chemical inhibition of HDAC6 also rescued the motor phenotype in a zebrafish CMT2A model. Taken together, our study reveals a variant-specific insight into CMT2A disease mechanisms and confirms HDAC6 as a promising target for further therapeutic development.
Authors
Lydia H. Jestice, Larissa Butler, Rebecca A. Lea, Kathryn I. Adamson, Jonas Van Lent, Stuart L. Johnson, Hollie Weedon, Eldriena D’Silva, Gabriele Gelezauskaite, Bob Asselbergh, Eloise Brown, Owen Laing, Christopher J. Price, Dylan Stavish, Anestis Tsakiridis, Mark O. Collins, Vincent Timmerman, Kurt J. De Vos, Alison E. Twelvetrees, Andrew J. Grierson, Ivana Barbaric
Abstract
Authors
Enrique Gonzalez Saez-Diez, Xutong Xue, Amy Tam, Hyo-Min Kim, Siofra Carty, Joshua Rong, Monica Ferrer-Socorro, Kathryn Yang, Darius Ebrahimi-Fakhari
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