Endocrinology
Abstract
It is now recognized that patients and animal models expressing genetically-encoded misfolded mutant thyroglobulin (TG, the protein precursor for thyroid hormone synthesis) exhibit dramatic swelling of the endoplasmic reticulum (ER) with ER stress and cell death in thyrocytes — seen both in homozygotes (with severe hypothyroidism) and heterozygotes (with subclinical hypothyroidism). The thyrocyte death phenotype is exacerbated upon thyroidal stimulation (by thyrotropin, TSH), as cell death is inhibited upon treatment with exogenous thyroxine. TSH stimulation might contribute to cytotoxicity by promoting ER stress, or by an independent mechanism. Here we’ve engineered knockout mice completely lacking Tg expression. Like other animals/patients with mutant TG, these animals rapidly develop severe goitrous hypothyroidism; however, thyroidal ER stress is exceedingly low — lower even than that seen in wildtype mice. Nevertheless, mice lacking TG exhibit abundant thyroid cell death, which depends upon renegade thyroidal iodination — it is completely suppressed in a genetic model lacking effective iodination, or in Tg-KO mice treated with propylthiouracil (iodination inhibitor), or iodide deficiency. Thyrocytes in culture are killed not in the presence of H2O2 alone, but rather upon peroxidase-mediated iodination, with cell death blocked by propylthiouracil. Thus, in the thyroid gland bearing Tg mutation(s), TSH-stimulated iodination activity triggers thyroid cell death.
Authors
Crystal Young, Xiaohan Zhang, Xiaofan Wang, Aaron P. Kellogg, Kevin Pena, August Z. Cumming, Xiao-Hui Liao, Dennis Larkin, Hao Zhang, Emma Mastroianni, Helmut Grasberger, Samuel Refetoff, Peter Arvan
Abstract
Impaired glucose-stimulated insulin secretion (GSIS) is a hallmark of β-cell dysfunction in diabetes. Epigenetic mechanisms govern cellular glucose sensing and GSIS by β-cells, but they remain incompletely defined. Here, we found that BAF60a functions as a chromatin regulator that sustains biphasic GSIS and preserves β-cell function under metabolic stress conditions. BAF60a was downregulated in β-cells from obese and diabetic mice, monkeys, and humans. β-cell-specific inactivation of BAF60a in adult mice impaired GSIS, leading to hyperglycemia and glucose intolerance. Conversely, restoring BAF60a expression improved β-cell function and systemic glucose homeostasis. Mechanistically, BAF60a physically interacted with Nkx6.1 to selectively modulate chromatin accessibility and transcriptional activity of target genes critical for GSIS coupling in islet β-cells. A BAF60a V278M mutation associated with decreased β-cell GSIS function was identified in human subjects. Mice carrying this mutation, which disrupted the interaction between BAF60a and Nkx6.1, displayed β-cell dysfunction and impaired glucose homeostasis. In addition, GLP-1R and GIPR expression was significantly reduced in BAF60a-deficient islets, attenuating the insulinotropic effect of GLP-1R agonists. Together, these findings support a role for BAF60a as a component of the epigenetic machinery that shapes the chromatin landscape in β-cells critical for glucose sensing and insulin secretion.
Authors
Xinyuan Qiu, Ruo-Ran Wang, Qing-Qian Wu, Hongxing Fu, Shuaishuai Zhu, Wei Chen, Wen Wang, Haide Chen, Xiuyu Ji, Wenjing Zhang, Dandan Yan, Jing Yan, Li Jin, Rong Zhang, Mengjie Shi, Ping Luo, Yingqing Yang, Qintao Wang, Ziyin Zhang, Wei Ding, Xiaowen Pan, Chengbin Li, Bin Liang, Guoji Guo, Hai-long Piao, Min Zheng, Yan Sheng, Lingyun Zhu, Cheng Hu, Zhuo-Xian Meng
Abstract
Teplizumab, a humanized anti-CD3 monoclonal antibody, represents a breakthrough in autoimmune type 1 diabetes (T1D) treatment, by delaying clinical onset in stage 2 and slowing progression in early stage 3. However, therapeutic responses are heterogeneous. To better understand this variability, we applied single-cell transcriptomics to paired peripheral blood and pancreas samples from anti-mouse CD3-treated non-obese diabetic (NOD) mice and identified distinct gene signatures associated with therapy outcome, with consistent patterns across compartments. Success-associated signatures were enriched in NK/CD8⁺ T cells and other immune cell types, whereas resistance signatures were predominantly expressed by neutrophils. The immune communities underlying these response signatures were confirmed in human whole-blood sequencing data from the AbATE study at 6 months, which assessed teplizumab therapy in stage 3 T1D. Furthermore, baseline expression profiling in the human TN10 (stage 2) and AbATE (stage 3) cohorts identified immune signatures predictive of therapy response, T cell-enriched signatures in responders and neutrophil-enriched signatures in non-responders, highlighting the roles of both adaptive and innate immunity in determining teplizumab outcome. Using an elastic-net logistic regression model, we developed a 26-gene blood-based signature predicting teplizumab response (AUC = 0.97). These findings demonstrate the predictive potential of immune gene signatures and the value of transcriptomic profiling in guiding individualized treatment strategies with teplizumab in T1D.
Authors
Gabriele Sassi, Pierre Lemaitre, Laia Fernández Calvo, Francesca Lodi, Álvaro Cortés Calabuig, Samal Bissenova, Amber Wouters, Laure Degroote, Marijke Viaene, Niels Vandamme, Lauren Higdon, Peter S. Linsley, S. Alice Long, Chantal Mathieu, Conny Gysemans
Abstract
Type 1 diabetes (T1D) is characterized by the autoimmune destruction of most insulin-producing β-cells, along with dysregulated glucagon secretion from pancreatic α-cells. We conducted an integrated analysis that combines electrophysiological and transcriptomic profiling, along with machine learning, of islet cells from T1D donors. The few surviving β-cells exhibit altered electrophysiological properties and transcriptomic signatures indicative of increased antigen presentation, metabolic reprogramming, and impaired protein translation. In α-cells, we observed hyper-responsiveness and increased exocytosis, which are associated with upregulated immune signaling, disrupted transcription factor localization and lysosome homeostasis, as well as dysregulation of mTORC1 complex signaling. Notably, key genetic risk signals for T1D were enriched in transcripts related to α-cell dysfunction, including MHC class I, which were closely linked with α-cell dysfunction. Our data provide what we believe are novel insights into the molecular underpinnings of islet cell dysfunction in T1D, highlighting pathways that may be leveraged to preserve residual β-cell function and modulate α-cell activity. These findings underscore the complex interplay between immune signaling, metabolic stress, and cellular identity in shaping islet cell phenotypes in T1D.
Authors
Theodore dos Santos, Xiao-Qing Dai, Robert C. Jones, Aliya F. Spigelman, Hannah M. Mummey, Jessica D. Ewald, Cara E. Ellis, James G. Lyon, Nancy Smith, Austin Bautista, Jocelyn E. Manning Fox, Norma F. Neff, Angela M. Detweiler, Michelle Tan, Rafael Arrojo e Drigo, Jianguo Xia, Joan Camunas-Soler, Kyle J. Gaulton, Stephen R. Quake, Patrick E. MacDonald
Abstract
Type 2 diabetes affects more than 38 million people in the US, and a major complication is kidney disease. During the analysis of lipotoxicity in diabetic kidney disease, global fatty acid transport protein-2 (FATP2) gene deletion was noted to markedly reduce plasma glucose in db/db mice due to sustained insulin secretion. To identify the mechanism, we observed that islet FATP2 expression was restricted to α-cells, and α-cell FATP2 was functional. Basal glucagon and alanine-stimulated gluconeogenesis were reduced in FATP2KO db/db compared to db/db mice. Direct evidence of FATP2KO-induced α-cell-mediated glucagon-like peptide-1 (GLP-1) secretion included increased GLP-1-positive α-cell mass in FATP2KO db/db mice, small molecule FATP2 inhibitor enhancement of GLP-1 secretion in αTC1-6 cells and human islets, and exendin[9-39]-inhibitable insulin secretion in FATP2 inhibitor-treated human islets. FATP2-dependent enteroendocrine GLP-1 secretion was excluded by demonstration of similar glucose tolerance and plasma GLP-1 concentrations in db/db FATP2KO mice following oral versus intraperitoneal glucose loading, non-overlapping FATP2 and preproglucagon mRNA expression, and lack of FATP2/GLP-1 co-immunolocalization in intestine. We conclude that FATP2 deletion or inhibition exerts glucose-lowering effects through α-cell-mediated GLP-1 secretion and paracrine ß-cell insulin release.
Authors
Shenaz Khan, Robert J. Gaivin, Zhiyu Liu, Vincent Li, Ivy Samuels, Jinsook Son, Patrick Osei-Owusu, Jeffrey L. Garvin, Domenico Accili, Jeffrey R. Schelling
Abstract
Understanding the genetic causes of diseases affecting pancreatic β cells and neurons can give insights into pathways essential for both cell types. Microcephaly, epilepsy and diabetes syndrome (MEDS) is a congenital disorder with two known aetiological genes, IER3IP1 and YIPF5. Both genes encode proteins involved in endoplasmic reticulum (ER) to Golgi trafficking. We used genome sequencing to identify 6 individuals with MEDS caused by biallelic variants in the novel disease gene, TMEM167A. All had neonatal diabetes (diagnosed <6 months) and severe microcephaly, five also had epilepsy. TMEM167A is highly expressed in developing and adult human pancreas and brain. To gain insights into the mechanisms leading to diabetes, we silenced TMEM167A in EndoC-βH1 cells and knocked-in one patient’s variant, p.Val59Glu, in induced pluripotent stem cells (iPSCs). Both TMEM167A depletion in EndoC-βH1 cells and the p.Val59Glu variant in iPSC-derived β cells sensitized β cells to ER stress. The p.Val59Glu variant impaired proinsulin trafficking to the Golgi and induced iPSC-β cell dysfunction. The discovery of TMEM167A variants as a new genetic cause of MEDS highlights a critical role of TMEM167A in the ER to Golgi pathway in β cells and neurons.
Authors
Enrico Virgilio, Sylvia Tielens, Georgia Bonfield, Fang-Shin Nian, Toshiaki Sawatani, Chiara Vinci, Molly Govier, Hossam Montaser, Romane Lartigue, Anoop Arunagiri, Alexandrine Liboz, Flavia Natividade da Silva, Maria Lytrivi, Theodora Papadopoulou, Matthew N. Wakeling, James Russ-Silsby, Pamela Bowman, Matthew B. Johnson, Thomas W. Laver, Anthony Piron, Xiaoyan Yi, Federica Fantuzzi, Sirine Hendrickx, Mariana Igoillo-Esteve, Bruno J. Santacreu, Jananie Suntharesan, Radha Ghildiyal, Darshan G. Hegde, Nikhil Avnish Shah, Sezer Acar, Beyhan Özkaya Dönmez, Behzat Özkan, Fauzia Mohsin, Iman M. Talaat, Mohamed Tarek Abbas, Omar Saied Abbas, Hamed Ali Alghamdi, Nurgun Kandemir, Sarah E. Flanagan, Raphael Scharfmann, Peter Arvan, Matthieu Raoux, Laurent Nguyen, Andrew T. Hattersley, Miriam Cnop, Elisa De Franco
Abstract
The incretin receptor agonists semaglutide and tirzepatide have transformed the medical management of obesity. The neural mechanisms by which incretin analogs regulate appetite remain incompletely understood, and dissecting this process is critical for the development of next-generation anti-obesity drugs that are more targeted and tolerable. Moreover, the physiologic functions of incretins in appetite regulation and gut-brain communication have remained elusive. Using in vivo fiber photometry, we discovered distinct pharmacologic and physiologic roles for the incretin hormones glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1). We showed that GIP, but not GLP-1, was required for normal nutrient-mediated inhibition of hunger-promoting AgRP neurons. By contrast, both GIP and GLP-1 analogs at pharmacologic doses were sufficient to inhibit AgRP neurons. The magnitude of neural inhibition was proportional to the effect of each incretin on food intake, and dual GIP and GLP-1 receptor agonism more potently inhibited AgRP neurons and suppressed food intake than either agonist alone. Our results have revealed a role for endogenous GIP in gut-brain appetite regulation and indicate that incretin analogs act in part via AgRP neurons to mediate their anorectic effects.
Authors
Hayley E. McMorrow, Andrew B. Cohen, Carolyn M. Lorch, Nikolas W. Hayes, Stefan W. Fleps, Joshua A. Frydman, Jessica L. Xia, Ricardo J. Samms, Lisa R. Beutler
Abstract
Cancer cells present neoantigens dominantly through MHC class I (MHCI) to drive tumor rejection through cytotoxic CD8+ T-cells. There is growing recognition that a subset of tumors express MHC class II (MHCII), causing recognition of antigens by TCRs of CD4+ T-cells that contribute to the anti-tumor response. We find that mouse BrafV600E-driven anaplastic thyroid cancers (ATC) respond markedly to the RAF + MEK inhibitors dabrafenib and trametinib (dab/tram) and that this is associated with upregulation of MhcII in cancer cells and increased CD4+ T-cell infiltration. A subset of recurrent tumors lose MhcII expression due to silencing of Ciita, the master transcriptional regulator of MhcII, despite preserved interferon gamma signal transduction, which can be rescued by EZH2 inhibition. Orthotopically-implanted Ciita–/– and H2-Ab1–/– ATC cells into immune competent mice become unresponsive to the MAPK inhibitors. Moreover, depletion of CD4+, but not CD8+ T-cells, also abrogates response to dab/tram. These findings implicate MHCII-driven CD4+ T cell activation as a key determinant of the response of Braf-mutant ATCs to MAPK inhibition.
Authors
Vera Tiedje, Jillian Greenberg, Tianyue Qin, Soo-Yeon Im, Gnana P. Krishnamoorthy, Laura Boucai, Bin Xu, Jena D. French, Eric J. Sherman, Alan L. Ho, Elisa de Stanchina, Nicholas D. Socci, Jian Jin, Ronald A. Ghossein, Jeffrey A. Knauf, Richard P. Koche, James A. Fagin
Abstract
Selective and controlled expansion of endogenous β-cells has been pursued as a potential therapy for diabetes. Ideally, such therapies would preserve feedback control of β-cell proliferation to avoid excessive β-cell expansion. Here, we identified a regulator of β-cell proliferation whose inactivation results in controlled β-cell expansion: the protein deacetylase Sirtuin 2 (SIRT2). Sirt2 deletion in β-cells of mice increased β-cell proliferation during hyperglycemia with little effect in homeostatic conditions, indicating preservation of feedback control of β-cell mass. SIRT2 restrains proliferation of human islet β-cells, demonstrating conserved SIRT2 function. Analysis of acetylated proteins in islets treated with a SIRT2 inhibitor revealed that SIRT2 deacetylates enzymes involved in oxidative phosphorylation, dampening the adaptive increase in oxygen consumption during hyperglycemia. At the transcriptomic level, Sirt2 inactivation has context-dependent effects on β-cells, with Sirt2 controlling how β-cells interpret hyperglycemia as a stress. Finally, we provide proof-of-principle that systemic administration of a GLP1-coupled Sirt2-targeting antisense oligonucleotide achieves β-cell Sirt2 inactivation and stimulates β-cell proliferation during hyperglycemia. Overall, these studies identify a therapeutic strategy for increasing β-cell mass in diabetes without circumventing feedback control of β-cell proliferation. Future work should test the extent that these findings translate to human β-cells from individuals with and without diabetes.
Authors
Matthew Wortham, Bastian Ramms, Chun Zeng, Jacqueline R. Benthuysen, Somesh Sai, Dennis P. Pollow, Fenfen Liu, Michael Schlichting, Austin R. Harrington, Bradley Liu, Thazha P. Prakash, Elaine C. Pirie, Han Zhu, Siyouneh Baghdasarian, Sean T. Lee, Victor A. Ruthig, Kristen L. Wells, Johan Auwerx, Orian S. Shirihai, Maike Sander
Abstract
There is growing evidence for direct actions of follicle–stimulating hormone (FSH) on tissues other than the ovaries and testes. Blocking FSH action, either genetically or pharmacologically, protects against bone loss, fat gain, and memory loss in mice. We thus developed a humanized FSH–blocking antibody––MS-Hu6––as a lead therapeutic for three diseases of public health magnitude––osteoporosis, obesity and Alzheimer’s disease (AD) that track together in post–menopausal women. Here, we report the crystal structure of MS-Hu6 and its interaction with FSH in atomistic detail. Using our Good–Laboratory–Practice–Compliant platform (21CFR58), we formulated MS-Hu6 and the murine equivalent Hf2 at an ultra–high concentration; both formulated antibodies displayed enhanced thermal and colloidal stability. A single injection of 89Zr–labelled MS-Hu6 revealed a beta–phase t½ of 89 and 131 hours for female and male mice, respectively, with retention in regions of interest. Female mice injected subcutaneously with Hf2 displayed a dose–dependent reduction in body weight and body fat. Hf2 also rescued recognition memory and spatial learning loss in a context– and time–dependent manner in AD–prone 3xTg and APP/PS1 mice. MS-Hu6 injected into African green monkeys (8 mg/kg) intravenously, and then subcutaneously at monthly intervals, was safe, and without effects on vitals, blood chemistries or blood counts. There was a notable ~4% weight loss in all four monkeys after the first injection, which continued in two of four monkeys. We thus provide IND–enabling data towards an upcoming first–in–human study.
Authors
Anusha R. Pallapati, Funda Korkmaz, Satish Rojekar, Steven Sims, Anurag Misra, Judit Gimenez–Roig, Aishwarya Gangadhar, Victoria Laurencin, Anissa Gumerova, Uliana Cheliadinova, Farhath Sultana, Darya Vasilyeva, Liam Cullen, Jonathan Schuermann, Jazz Munitz, Hasni Kannangara, Surabhi Parte, Georgii Pevnev, Guzel Burganova, Zehra Tumoglu, Ronit Witztum, Soleil Wizman, Natan Kramskiy, Liah Igel, Fazilet Sen, Anna Ranzenigo, Anne Macdonald, Susan Hutchison, Abraham J.P. Teunissen, Heather Burkart, Mansi Saxena, Yelena Ginzburg, Ki Goosens, Weibin Zhou, Vitaly Ryu, Ofer Moldavski, Orly Barak, Michael Pazianas, John Caminis, Shalender Bhasin, Richard Fitzgerald, Se-Min Kim, Matthew Quinn, Shozeb Haider, Susan Appt, Tal Frolinger, Clifford J. Rosen, Daria Lizneva, Yogesh K. Gupta, Tony Yuen, Mone Zaidi
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)