Munc13 proteins are essential regulators of neurotransmitter release at nerve cell synapses. They mediate the priming step that renders synaptic vesicles fusion-competent, and their genetic elimination causes a complete block of synaptic transmission. Here we have described a patient displaying a disorder characterized by a dyskinetic movement disorder, developmental delay, and autism. Using whole-exome sequencing, we have shown that this condition is associated with a rare, de novo Pro814Leu variant in the major human Munc13 paralog UNC13A (also known as Munc13-1). Electrophysiological studies in murine neuronal cultures and functional analyses in
Noa Lipstein, Nanda M. Verhoeven-Duif, Francesco E. Michelassi, Nathaniel Calloway, Peter M. van Hasselt, Katarzyna Pienkowska, Gijs van Haaften, Mieke M. van Haelst, Ron van Empelen, Inge Cuppen, Heleen C. van Teeseling, Annemieke M.V. Evelein, Jacob A. Vorstman, Sven Thoms, Olaf Jahn, Karen J. Duran, Glen R. Monroe, Timothy A. Ryan, Holger Taschenberger, Jeremy S. Dittman, Jeong-Seop Rhee, Gepke Visser, Judith J. Jans, Nils Brose
An intracellular complement system (ICS) has recently been described in immune and nonimmune human cells. This system can be activated in a convertase-independent manner from intracellular stores of the complement component C3. The source of these stores has not been rigorously investigated. In the present study, Western blotting identified a band corresponding to C3 in freshly isolated human peripheral blood cells that was absent in corresponding cell lines. One difference between native cells and cell lines was the time absent from a fluid-phase complement source; therefore, we hypothesized that loading C3 from plasma was a route of establishing intracellular C3 stores. We found that many types of human cells specifically internalized C3(H2O), the hydrolytic product of C3, and not native C3, from the extracellular milieu. Uptake was rapid, saturable, and sensitive to competition with unlabeled C3(H2O), indicating a specific mechanism of loading. Under steady-state conditions, approximately 80% of incorporated C3(H2O) was returned to the extracellular space. These studies identify an ICS recycling pathway for C3(H2O). The loaded C3(H2O) represents a source of C3a, and its uptake altered the cytokine profile of activated CD4+ T cells. Importantly, these results indicate that the impact of soluble plasma factors should be considered when performing in vitro studies assessing cellular immune function.
Michelle Elvington, M. Kathryn Liszewski, Paula Bertram, Hrishikesh S. Kulkarni, John P. Atkinson
A highly orchestrated gene expression program establishes the properties that define mature adipocytes, but the contribution of posttranscriptional factors to the adipocyte phenotype is poorly understood. Here we have shown that the RNA-binding protein PSPC1, a component of the paraspeckle complex, promotes adipogenesis in vitro and is important for mature adipocyte function in vivo. Cross-linking and immunoprecipitation followed by RNA sequencing revealed that PSPC1 binds to intronic and 3′-untranslated regions of a number of adipocyte RNAs, including the RNA encoding the transcriptional regulator EBF1. Purification of the paraspeckle complex from adipocytes further showed that PSPC1 associates with the RNA export factor DDX3X in a differentiation-dependent manner. Remarkably, PSPC1 relocates from the nucleus to the cytoplasm during differentiation, coinciding with enhanced export of adipogenic RNAs. Mice lacking PSPC1 in fat displayed reduced lipid storage and adipose tissue mass and were resistant to diet-induced obesity and insulin resistance due to a compensatory increase in energy expenditure. These findings highlight a role for PSPC1-dependent RNA maturation in the posttranscriptional control of adipose development and function.
Jiexin Wang, Prashant Rajbhandari, Andrey Damianov, Areum Han, Tamer Sallam, Hironori Waki, Claudio J. Villanueva, Stephen D. Lee, Ronni Nielsen, Susanne Mandrup, Karen Reue, Stephen G. Young, Julian Whitelegge, Enrique Saez, Douglas L. Black, Peter Tontonoz
Defective apoptotic death of activated macrophages has been implicated in the pathogenesis of rheumatoid arthritis (RA). However, the molecular signatures defining apoptotic resistance of RA macrophages are not fully understood. Here, global transcriptome profiling of RA macrophages revealed that the osmoprotective transcription factor nuclear factor of activated T cells 5 (NFAT5) critically regulates diverse pathologic processes in synovial macrophages including the cell cycle, apoptosis, and proliferation. Transcriptomic analysis of NFAT5-deficient macrophages revealed the molecular networks defining cell survival and proliferation. Proinflammatory M1-polarizing stimuli and hypoxic conditions were responsible for enhanced NFAT5 expression in RA macrophages. An in vitro functional study demonstrated that NFAT5-deficient macrophages were more susceptible to apoptotic death. Specifically, CCL2 secretion in an NFAT5-dependent fashion bestowed apoptotic resistance to RA macrophages in vitro. Injection of recombinant CCL2 into one of the affected joints of
Susanna Choi, Sungyong You, Donghyun Kim, Soo Youn Choi, H. Moo Kwon, Hyun-Sook Kim, Daehee Hwang, Yune-Jung Park, Chul-Soo Cho, Wan-Uk Kim
Tissue inflammation is a key component of obesity-induced insulin resistance, with a variety of immune cell types accumulating in adipose tissue. Here, we have demonstrated increased numbers of B2 lymphocytes in obese adipose tissue and have shown that high-fat diet–induced (HFD-induced) insulin resistance is mitigated in B cell-deficient (Bnull) mice. Adoptive transfer of adipose tissue B2 cells (ATB2) from wild-type HFD donor mice into HFD Bnull recipients completely restored the effect of HFD to induce insulin resistance. Recruitment and activation of ATB2 cells was mediated by signaling through the chemokine leukotriene B4 (LTB4) and its receptor LTB4R1. Furthermore, the adverse effects of ATB2 cells on glucose homeostasis were partially dependent upon T cells and macrophages. These results demonstrate the importance of ATB2 cells in obesity-induced insulin resistance and suggest that inhibition of the LTB4/LTB4R1 axis might be a useful approach for developing insulin-sensitizing therapeutics.
Wei Ying, Joshua Wollam, Jachelle M. Ofrecio, Gautam Bandyopadhyay, Dalila El Ouarrat, Yun Sok Lee, Da Young Oh, Pingping Li, Olivia Osborn, Jerrold M. Olefsky
The most frequent focal alterations in human retinoblastoma are mutations in the tumor-suppressor gene retinoblastoma (
Nan Wu, Deshui Jia, Breanna Bates, Ryan Basom, Charles G. Eberhart, David MacPherson
The mechanisms underlying the neurodevelopmental deficits associated with CHARGE syndrome, which include cerebellar hypoplasia, developmental delay, coordination problems, and autistic features, have not been identified. CHARGE syndrome has been associated with mutations in the gene encoding the ATP-dependent chromatin remodeler CHD7. CHD7 is expressed in neural stem and progenitor cells, but its role in neurogenesis during brain development remains unknown. Here we have shown that deletion of
Danielle E. Whittaker, Kimberley L.H. Riegman, Sahrunizam Kasah, Conor Mohan, Tian Yu, Blanca Pijuan Sala, Husam Hebaishi, Angela Caruso, Ana Claudia Marques, Caterina Michetti, María Eugenia Sanz Smachetti, Apar Shah, Mara Sabbioni, Omer Kulhanci, Wee-Wei Tee, Danny Reinberg, Maria Luisa Scattoni, Holger Volk, Imelda McGonnell, Fiona C. Wardle, Cathy Fernandes, M. Albert Basson
Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in
Svjetlana Lovric, Sara Goncalves, Heon Yung Gee, Babak Oskouian, Honnappa Srinivas, Won-Il Choi, Shirlee Shril, Shazia Ashraf, Weizhen Tan, Jia Rao, Merlin Airik, David Schapiro, Daniela A. Braun, Carolin E. Sadowski, Eugen Widmeier, Tilman Jobst-Schwan, Johanna Magdalena Schmidt, Vladimir Girik, Guido Capitani, Jung H. Suh, Noëlle Lachaussée, Christelle Arrondel, Julie Patat, Olivier Gribouval, Monica Furlano, Olivia Boyer, Alain Schmitt, Vincent Vuiblet, Seema Hashmi, Rainer Wilcken, Francois P. Bernier, A. Micheil Innes, Jillian S. Parboosingh, Ryan E. Lamont, Julian P. Midgley, Nicola Wright, Jacek Majewski, Martin Zenker, Franz Schaefer, Navina Kuss, Johann Greil, Thomas Giese, Klaus Schwarz, Vilain Catheline, Denny Schanze, Ingolf Franke, Yves Sznajer, Anne S. Truant, Brigitte Adams, Julie Désir, Ronald Biemann, York Pei, Elisabet Ars, Nuria Lloberas, Alvaro Madrid, Vikas R. Dharnidharka, Anne M. Connolly, Marcia C. Willing, Megan A. Cooper, Richard P. Lifton, Matias Simons, Howard Riezman, Corinne Antignac, Julie D. Saba, Friedhelm Hildebrandt
Chimeric antigen receptor (CAR) T cells have been highly successful in treating hematological malignancies, including acute and chronic lymphoblastic leukemia. However, treatment of solid tumors using CAR T cells has been largely unsuccessful to date, partly because of tumor-induced immunosuppressive mechanisms, including adenosine production. Previous studies have shown that adenosine generated by tumor cells potently inhibits endogenous antitumor T cell responses through activation of adenosine 2A receptors (A2ARs). Herein, we have observed that CAR activation resulted in increased A2AR expression and suppression of both murine and human CAR T cells. This was reversible using either A2AR antagonists or genetic targeting of A2AR using shRNA. In 2 syngeneic HER2+ self-antigen tumor models, we found that either genetic or pharmacological targeting of the A2AR profoundly increased CAR T cell efficacy, particularly when combined with PD-1 blockade. Mechanistically, this was associated with increased cytokine production of CD8+ CAR T cells and increased activation of both CD8+ and CD4+ CAR T cells. Given the known clinical relevance of the CD73/adenosine pathway in several solid tumor types, and the initiation of phase I trials for A2AR antagonists in oncology, this approach has high translational potential to enhance CAR T cell efficacy in several cancer types.
Paul A. Beavis, Melissa A. Henderson, Lauren Giuffrida, Jane K. Mills, Kevin Sek, Ryan S. Cross, Alexander J. Davenport, Liza B. John, Sherly Mardiana, Clare Y. Slaney, Ricky W. Johnstone, Joseph A. Trapani, John Stagg, Sherene Loi, Lev Kats, David Gyorki, Michael H. Kershaw, Phillip K. Darcy
Ischemic heart disease resulting from myocardial infarction (MI) is the most prevalent form of heart disease in the United States. Post-MI cardiac remodeling is a multifaceted process that includes activation of fibroblasts and a complex immune response. T-regulatory cells (Tregs), a subset of CD4+ T cells, have been shown to suppress the innate and adaptive immune response and limit deleterious remodeling following myocardial injury. However, the mechanisms by which injured myocardium recruits suppressive immune cells remain largely unknown. Here, we have shown a role for Hippo signaling in the epicardium in suppressing the post-infarct inflammatory response through recruitment of Tregs. Mice deficient in epicardial YAP and TAZ, two core Hippo pathway effectors, developed profound post-MI pericardial inflammation and myocardial fibrosis, resulting in cardiomyopathy and death. Mutant mice exhibited fewer suppressive Tregs in the injured myocardium and decreased expression of the gene encoding IFN-γ, a known Treg inducer. Furthermore, controlled local delivery of IFN-γ following MI rescued Treg infiltration into the injured myocardium of YAP/TAZ mutants and decreased fibrosis. Collectively, these results suggest that epicardial Hippo signaling plays a key role in adaptive immune regulation during the post-MI recovery phase.
Vimal Ramjee, Deqiang Li, Lauren J. Manderfield, Feiyan Liu, Kurt A. Engleka, Haig Aghajanian, Christopher B. Rodell, Wen Lu, Vivienne Ho, Tao Wang, Li Li, Anamika Singh, Dasan M. Cibi, Jason A. Burdick, Manvendra K. Singh, Rajan Jain, Jonathan A. Epstein
Primary adrenal insufficiency is life threatening and can present alone or in combination with other comorbidities. Here, we have described a primary adrenal insufficiency syndrome and steroid-resistant nephrotic syndrome caused by loss-of-function mutations in sphingosine-1-phosphate lyase (SGPL1). SGPL1 executes the final decisive step of the sphingolipid breakdown pathway, mediating the irreversible cleavage of the lipid-signaling molecule sphingosine-1-phosphate (S1P). Mutations in other upstream components of the pathway lead to harmful accumulation of lysosomal sphingolipid species, which are associated with a series of conditions known as the sphingolipidoses. In this work, we have identified 4 different homozygous mutations, c.665G>A (p.R222Q), c.1633_1635delTTC (p.F545del), c.261+1G>A (p.S65Rfs*6), and c.7dupA (p.S3Kfs*11), in 5 families with the condition. In total, 8 patients were investigated, some of whom also manifested other features, including ichthyosis, primary hypothyroidism, neurological symptoms, and cryptorchidism.
Rathi Prasad, Irene Hadjidemetriou, Avinaash Maharaj, Eirini Meimaridou, Federica Buonocore, Moin Saleem, Jenny Hurcombe, Agnieszka Bierzynska, Eliana Barbagelata, Ignacio Bergadá, Hamilton Cassinelli, Urmi Das, GOSgene, Ruth Krone, Bulent Hacihamdioglu, Erkan Sari, Ediz Yesilkaya, Helen L. Storr, Maria Clemente, Monica Fernandez-Cancio, Nuria Camats, Nanik Ram, John C. Achermann, Paul P. Van Veldhoven, Leonardo Guasti, Debora Braslavsky, Tulay Guran, Louise A. Metherell
Platelets are anuclear cells that are essential for blood clotting. They are produced by large polyploid precursor cells called megakaryocytes. Previous genome-wide association studies in nearly 70,000 individuals indicated that single nucleotide variants (SNVs) in the gene encoding the actin cytoskeletal regulator tropomyosin 4 (TPM4) exert an effect on the count and volume of platelets. Platelet number and volume are independent risk factors for heart attack and stroke. Here, we have identified 2 unrelated families in the BRIDGE Bleeding and Platelet Disorders (BPD) collection who carry a
Irina Pleines, Joanne Woods, Stephane Chappaz, Verity Kew, Nicola Foad, José Ballester-Beltrán, Katja Aurbach, Chiara Lincetto, Rachael M. Lane, Galina Schevzov, Warren S. Alexander, Douglas J. Hilton, William J. Astle, Kate Downes, Paquita Nurden, Sarah K. Westbury, Andrew D. Mumford, Samya G. Obaji, Peter W. Collins, NIHR BioResource, Fabien Delerue, Lars M. Ittner, Nicole S. Bryce, Mira Holliday, Christine A. Lucas, Edna C. Hardeman, Willem H. Ouwehand, Peter W. Gunning, Ernest Turro, Marloes R. Tijssen, Benjamin T. Kile
Elevated expression of the chemokine receptor CCR4 in tumors is associated with poor prognosis in several cancers. Here, we have determined that CCR4 was highly expressed in human renal cell carcinoma (RCC) biopsies and observed abnormal levels of CCR4 ligands in RCC patient plasma. An antagonistic anti-CCR4 antibody had antitumor activity in the RENCA mouse model of RCC. CCR4 inhibition did not reduce the proportion of infiltrating leukocytes in the tumor microenvironment but altered the phenotype of myeloid cells, increased NK cell and Th1 cytokine levels, and reduced immature myeloid cell infiltrate and blood chemokine levels. In spite of prominent changes in the myeloid compartment, the anti-CCR4 antibody did not affect RENCA tumors in T cell–deficient mice, and treatment with an anti–class II MHC antibody abrogated its antitumor activity. We concluded that the effects of the anti-CCR4 antibody required the adaptive immune system and CD4+ T cells. Moreover, CCL17-induced IFN-γ production was reduced when Th1-polarized normal CD4+ T cells were exposed to the CCR4 ligand, evidencing the involvement of CCR4 in Th1/Th2 regulation. The anti-CCR4 antibody, alone or in combination with other immune modulators, is a potential treatment approach to human solid cancers with high levels of CCR4-expressing tumor-infiltrating leukocytes and abnormal plasma CCR4 ligand levels.
Chiara Berlato, Moddasar N. Khan, Tiziana Schioppa, Richard Thompson, Eleni Maniati, Anne Montfort, Maryam Jangani, Monica Canosa, Hagen Kulbe, Urs B. Hagemann, Alexander R. Duncan, Laura Fletcher, Robert W. Wilkinson, Thomas Powles, Sergio A. Quezada, Frances R. Balkwill
Disruption of the retinoblastoma (RB) tumor suppressor pathway, either through genetic mutation of upstream regulatory components or mutation of
Lindsey N. Kent, Sooin Bae, Shih-Yin Tsai, Xing Tang, Arunima Srivastava, Christopher Koivisto, Chelsea K. Martin, Elisa Ridolfi, Grace C. Miller, Sarah M. Zorko, Emilia Plevris, Yannis Hadjiyannis, Miguel Perez, Eric Nolan, Raleigh Kladney, Bart Westendorp, Alain de Bruin, Soledad Fernandez, Thomas J. Rosol, Kamal S. Pohar, James M. Pipas, Gustavo Leone
Long-acting anti-HIV products can substantively change the standard of care for patients with HIV/AIDS. To this end, hydrophobic antiretroviral drugs (ARVs) were recently developed for parenteral administration at monthly or longer intervals. While shorter-acting hydrophilic drugs can be made into nanocarrier-encased prodrugs, the nanocarrier encasement must be boosted to establish long-acting ARV depots. The mixed-lineage kinase 3 (MLK-3) inhibitor URMC-099 provides this function by affecting autophagy. Here, we have shown that URMC-099 facilitates ARV sequestration and its antiretroviral responses by promoting the nuclear translocation of the transcription factor EB (TFEB). In monocyte-derived macrophages, URMC-099 induction of autophagy led to retention of nanoparticles containing the antiretroviral protease inhibitor atazanavir. These nanoparticles were localized within macrophage autophagosomes, leading to a 4-fold enhancement of mitochondrial and cell vitality. In rodents, URMC-099 activation of autophagy led to 50-fold increases in the plasma drug concentration of the viral integrase inhibitor dolutegravir. These data paralleled URMC-099–mediated induction of autophagy and the previously reported antiretroviral responses in HIV-1–infected humanized mice. We conclude that pharmacologic induction of autophagy provides a means to extend the action of a long-acting, slow, effective release of antiretroviral therapy.
Divya Prakash Gnanadhas, Prasanta K. Dash, Brady Sillman, Aditya N. Bade, Zhiyi Lin, Diana L. Palandri, Nagsen Gautam, Yazen Alnouti, Harris A. Gelbard, JoEllyn McMillan, R. Lee Mosley, Benson Edagwa, Howard E. Gendelman, Santhi Gorantla
Type I IFNs promote cellular responses to viruses, and IFN receptor (IFNAR) signaling regulates the responses of endothelial cells of the blood-brain barrier (BBB) during neurotropic viral infection. However, the role of astrocytes in innate immune responses of the BBB during viral infection of the CNS remains to be fully elucidated. Here, we have demonstrated that type I IFNAR signaling in astrocytes regulates BBB permeability and protects the cerebellum from infection and immunopathology. Mice with astrocyte-specific loss of IFNAR signaling showed decreased survival after West Nile virus infection. Accelerated mortality was not due to expanded viral tropism or increased replication. Rather, viral entry increased specifically in the hindbrain of IFNAR-deficient mice, suggesting that IFNAR signaling critically regulates BBB permeability in this brain region. Pattern recognition receptors and IFN-stimulated genes had higher basal and IFN-induced expression in human and mouse cerebellar astrocytes than did cerebral cortical astrocytes, suggesting that IFNAR signaling has brain region–specific roles in CNS immune responses. Taken together, our data identify cerebellar astrocytes as key responders to viral infection and highlight the existence of distinct innate immune programs in astrocytes from evolutionarily disparate regions of the CNS.
Brian P. Daniels, Harsha Jujjavarapu, Douglas M. Durrant, Jessica L. Williams, Richard R. Green, James P. White, Helen M. Lazear, Michael Gale Jr., Michael S. Diamond, Robyn S. Klein
The mechanism by which leptin reverses diabetic ketoacidosis (DKA) is unknown. We examined the acute insulin-independent effects of leptin replacement therapy in a streptozotocin-induced rat model of DKA. Leptin infusion reduced rates of lipolysis, hepatic glucose production (HGP), and hepatic ketogenesis by 50% within 6 hours and were independent of any changes in plasma glucagon concentrations; these effects were abrogated by coinfusion of corticosterone. Treating leptin- and corticosterone-infused rats with an adipose triglyceride lipase inhibitor blocked corticosterone-induced increases in plasma glucose concentrations and rates of HGP and ketogenesis. Similarly, adrenalectomized type 1 diabetic (T1D) rats exhibited decreased rates of lipolysis, HGP, and ketogenesis; these effects were reversed by corticosterone infusion. Leptin-induced decreases in lipolysis, HGP, and ketogenesis in DKA were also nullified by relatively small increases (15 to 70 pM) in plasma insulin concentrations. In contrast, the chronic glucose-lowering effect of leptin in a STZ-induced mouse model of poorly controlled T1D was associated with decreased food intake, reduced plasma glucagon and corticosterone concentrations, and decreased ectopic lipid (triacylglycerol/diacylglycerol) content in liver and muscle. Collectively, these studies demonstrate marked differences in the acute insulin-independent effects by which leptin reverses fasting hyperglycemia and ketoacidosis in a rodent model of DKA versus the chronic pleotropic effects by which leptin reverses hyperglycemia in a non-DKA rodent model of T1D.
Rachel J. Perry, Liang Peng, Abudukadier Abulizi, Lynn Kennedy, Gary W. Cline, Gerald I. Shulman
Olfactory dysfunction is broadly associated with neurodevelopmental and neurodegenerative diseases and predicts increased mortality rates in healthy individuals. Conventional measurements of olfactory health assess odor processing pathways within the brain and provide a limited understanding of primary odor detection. Quantification of the olfactory sensory neurons (OSNs), which detect odors within the nasal cavity, would provide insight into the etiology of olfactory dysfunction associated with disease and mortality. Notably, OSNs are continually replenished by adult neurogenesis in mammals, including humans, so OSN measurements are primed to provide specialized insights into neurological disease. Here, we have evaluated a PET radiotracer, [11C]GV1-57, that specifically binds mature OSNs and quantifies the mature OSN population in vivo. [11C]GV1-57 monitored native OSN population dynamics in rodents, detecting OSN generation during postnatal development and aging-associated neurodegeneration. [11C]GV1-57 additionally measured rates of neuron regeneration after acute injury and early-stage OSN deficits in a rodent tauopathy model of neurodegenerative disease. Preliminary assessment in nonhuman primates suggested maintained uptake and saturable binding of [18F]GV1-57 in primate nasal epithelium, supporting its translational potential. Future applications for GV1-57 include monitoring additional diseases or conditions associated with olfactory dysregulation, including cognitive decline, as well as monitoring effects of neuroregenerative or neuroprotective therapeutics.
Genevieve C. Van de Bittner, Misha M. Riley, Luxiang Cao, Janina Ehses, Scott P. Herrick, Emily L. Ricq, Hsiao-Ying Wey, Michael J. O’Neill, Zeshan Ahmed, Tracey K. Murray, Jaclyn E. Smith, Changning Wang, Frederick A. Schroeder, Mark W. Albers, Jacob M. Hooker
We recently demonstrated that selective expression of the Rho GTPase-activating protein ARHGAP42 in smooth muscle cells (SMCs) controls blood pressure by inhibiting RhoA-dependent contractility, providing a mechanism for the blood pressure–associated locus within the
Xue Bai, Kevin D. Mangum, Rachel A. Dee, George A. Stouffer, Craig R. Lee, Akinyemi Oni-Orisan, Cam Patterson, Jonathan C. Schisler, Anthony J. Viera, Joan M. Taylor, Christopher P. Mack
Parkinson’s disease (PD) patients experience loss of normal motor function (hypokinesia), but can develop uncontrollable movements known as dyskinesia upon treatment with L-DOPA. Poverty or excess of movement in PD has been attributed to overactivity of striatal projection neurons forming either the indirect (iSPNs) or the direct (dSPNs) pathway, respectively. Here, we investigated the two pathways’ contribution to different motor features using SPN type–specific chemogenetic stimulation in rodent models of PD (PD mice) and L-DOPA–induced dyskinesia (LID mice). Using the activatory Gq-coupled human M3 muscarinic receptor (hM3Dq), we found that chemogenetic stimulation of dSPNs mimicked, while stimulation of iSPNs abolished the therapeutic action of L-DOPA in PD mice. In LID mice, hM3Dq stimulation of dSPNs exacerbated dyskinetic responses to L-DOPA, while stimulation of iSPNs inhibited these responses. In the absence of L-DOPA, only chemogenetic stimulation of dSPNs mediated through the Gs-coupled modified rat muscarinic M3 receptor (rM3Ds) induced appreciable dyskinesia in PD mice. Combining D2 receptor agonist treatment with rM3Ds-dSPN stimulation reproduced all symptoms of LID. These results demonstrate that dSPNs and iSPNs oppositely modulate both therapeutic and dyskinetic responses to dopamine replacement therapy in PD. We also show that chemogenetic stimulation of different signaling pathways in dSPNs leads to markedly different motor outcomes. Our findings have important implications for the design of effective antiparkinsonian and antidyskinetic drug therapies.
Cristina Alcacer, Laura Andreoli, Irene Sebastianutto, Johan Jakobsson, Tim Fieblinger, Maria Angela Cenci