Endocrinology
Abstract
The androgen receptor (AR) is a master transcription factor that regulates prostate cancer (PC) development and progression. Inhibition of AR signaling by androgen deprivation is the first-line therapy with initial efficacy for advanced and recurrent PC. Paradoxically, supraphysiological levels of testosterone (SPT) also inhibit PC progression. However, as with any therapy, not all patients show a therapeutic benefit, and responses differ widely in magnitude and duration. In this study, we evaluated whether differences in the AR cistrome before treatment can distinguish between SPT-responding (R) and -nonresponding (NR) tumors. We provide the first preclinical evidence to our knowledge that SPT-R tumors exhibit a distinct AR cistrome when compared with SPT-NR tumors, indicating a differential biological role of the AR. We applied an integrated analysis of ChIP-Seq and RNA-Seq to the pretreatment tumors and identified an SPT-R signature that distinguishes R and NR tumors. Because transcriptomes of SPT-treated clinical specimens are not available, we interrogated available castration-resistant PC (CRPC) transcriptomes and showed that the SPT-R signature is associated with improved survival and has the potential to identify patients who would respond to SPT. These findings provide an opportunity to identify the subset of patients with CRPC who would benefit from SPT therapy.
Authors
Xintao Qiu, Lisha G. Brown, Jennifer L. Conner, Holly M. Nguyen, Nadia Boufaied, Sarah Abou Alaiwi, Ji-Heui Seo, Talal El Zarif, Connor Bell, Edward O’Connor, Brian Hanratty, Mark Pomerantz, Matthew L. Freedman, Myles Brown, Michael C. Haffner, Peter S. Nelson, Felix Y. Feng, David P. Labbé, Henry W. Long, Eva Corey
Abstract
Insulin secretion from pancreatic β cells is essential for glucose homeostasis. An insufficient response to the demand for insulin results in diabetes. We previously showed that β cell–specific deletion of Zfp148 (β-Zfp148KO) improves glucose tolerance and insulin secretion in mice. Here, we performed Ca2+ imaging of islets from β‑Zfp148KO and control mice fed both a chow and a Western-style diet. β-Zfp148KO islets demonstrated improved sensitivity and sustained Ca2+ oscillations in response to elevated glucose levels. β-Zfp148KO islets also exhibited elevated sensitivity to amino acid–induced Ca2+ influx under low glucose conditions, suggesting enhanced mitochondrial phosphoenolpyruvate-dependent (PEP-dependent), ATP-sensitive K+ channel closure, independent of glycolysis. RNA-Seq and proteomics of β-Zfp148KO islets revealed altered levels of enzymes involved in amino acid metabolism (specifically, SLC3A2, SLC7A8, GLS, GLS2, PSPH, PHGDH, and PSAT1) and intermediary metabolism (namely, GOT1 and PCK2), consistent with altered PEP cycling. In agreement with this, β-Zfp148KO islets displayed enhanced insulin secretion in response to l-glutamine and activation of glutamate dehydrogenase. Understanding pathways controlled by ZFP148 may provide promising strategies for improving β cell function that are robust to the metabolic challenge imposed by a Western diet.
Authors
Christopher H. Emfinger, Eleonora de Klerk, Kathryn L. Schueler, Mary E. Rabaglia, Donnie S. Stapleton, Shane P. Simonett, Kelly A. Mitok, Ziyue Wang, Xinyue Liu, Joao A. Paulo, Qinq Yu, Rebecca L. Cardone, Hannah R. Foster, Sophie L. Lewandowski, José C. Perales, Christina M. Kendziorski, Steven P. Gygi, Richard G. Kibbey, Mark P. Keller, Matthias Hebrok, Matthew J. Merrins, Alan D. Attie
Abstract
Greater than 25% of all men develop an inguinal hernia in their lifetime, and more than 20 million inguinal hernia repair surgeries are performed worldwide each year. The mechanisms causing abdominal muscle weakness, the formation of inguinal hernias, or their recurrence are largely unknown. We previously reported that excessively produced estrogen in the lower abdominal muscles (LAM) triggers extensive LAM fibrosis, leading to hernia formation in a transgenic male mouse model expressing the human aromatase gene (Aromhum). To understand the cellular basis of estrogen-driven muscle fibrosis, we performed single-cell RNA-sequencing on LAM tissue from Aromhum and wild-type littermates. We found a fibroblast-like cell group comprised of six clusters, two of which were validated for their enrichment in Aromhum LAM tissue. One of the novel hernia-associated fibroblast clusters in Aromhum was enriched for the estrogen receptor-α gene (Esr1Hi). Esr1Hi fibroblasts maximally expressed estrogen target genes and seemed to serve as the progenitors of another cluster expressing ECM-altering enzymes (Mmp3Hi) and upregulate expression of pro-inflammatory, pro-fibrotic genes. The discovery of these two novel and unique hernia-associated fibroblasts may lead to the development of novel treatments that can non-surgically prevent or reverse inguinal hernias.
Authors
Tanvi Potluri, Matthew J. Taylor, Jonah J. Stulberg, Richard L. Lieber, Hong Zhao, Serdar E. Bulun
Abstract
While critical for neurotransmitter synthesis, 14-3-3 proteins are often assumed to have redundant functions due to their ubiquitous expression, but despite this assumption, various 14-3-3 isoforms have been implicated in regulating metabolism. We previously reported contributions of 14-3-3ζ in β-cell function, but these studies were performed in tumor-derived MIN6 cells and systemic knockout mice. To further characterize the regulatory roles of 14-3-3ζ in β-cell function, we generated β-cell-specific 14-3-3ζ knockout mice. Although no effects on beta-cell mass were detected, potentiated glucose-stimulated insulin secretion (GSIS), mitochondrial function, and ATP synthesis were observed. 14-3-3ζ deletion also altered the β-cell transcriptome, as genes associated with mitochondrial respiration and oxidative phosphorylation were upregulated. Acute 14-3-3 protein inhibition in mouse and human islets recapitulated the enhancements in GSIS and mitochondrial function, suggesting that 14-3-3ζ is the critical isoform in β-cells. In dysfunctional db/db islets and human islets from type 2 diabetic donors, expression of Ywhaz/YWHAZ, the gene encoding 14-3-3ζ, was inversely associated with insulin secretion, and pan-14-3-3 protein inhibition led to enhanced GSIS and mitochondrial function. Taken together, this study demonstrates important regulatory functions of 14-3-3ζ in the regulation of β-cell function and provides a deeper understanding of how insulin secretion is controlled in β-cells.
Authors
Yves Mugabo, Cheng Zhao, Ju Jing Tan, Anindya Ghosh, Scott A. Campbell, Evgenia Fadzeyeva, Frédéric Paré, Siew Siew Pan, Maria Galipeau, Julia Ast, Johannes Broichhagen, David J. Hodson, Erin E. Mulvihill, Sophie Petropoulos, Gareth E. Lim
Abstract
Altered islet architecture is associated with β cell dysfunction and Type 2 Diabetes (T2D) progression, but molecular effectors of islet spatial organization remain mostly unknown. Although Notch signaling is known to regulate pancreatic development, we observed “re-activated” β cell Notch activity in obese mouse models. To test the repercussions and reversibility of Notch effects, we generated doxycycline-dependent, β cell-specific Notch gain-of-function mice. As predicted, we found that Notch activation in post-natal β cells impaired glucose stimulated insulin secretion (GSIS) and glucose intolerance, but we observed a surprising remnant glucose intolerance after doxycycline withdrawal and cessation of Notch activity, associated with a marked disruption of normal islet architecture. Transcriptomic screening of Notch-active islets revealed increased Ephrin signaling. Commensurately, exposure to Ephrin ligands increased β cell repulsion, and impaired murine and human pseudo-islet formation. Consistent with our mouse data, Notch and Ephrin signaling are increased in metabolically-inflexible β cells in patients with T2D. These studies suggest than islet architecture can be permanently altered by β cell Notch/Ephrin signaling during a morphogenetic window in early life.
Authors
Alberto Bartolomé, Nina Suda, Junjie Yu, Changyu Zhu, Jinsook Son, Hongxu Ding, Andrea Califano, Domenico Accili, Utpal B. Pajvani
Abstract
BACKGROUND. Pathophysiology of type 1 diabetes (T1D) is illustrated by pancreatic islet infiltration of inflammatory lymphocytes, including CD8+ T-cells; however, the molecular factors mediating their recruitment remain unknown. We hypothesized that single-cell RNA-sequencing (scRNA-Seq) analysis of immune cell populations isolated from islets of non-obese diabetic (NOD) mice captured gene expression dynamics providing critical insight into autoimmune diabetes pathogenesis. METHODS. Pancreatic sections from human donors were investigated, including T1D subjects, auto-antibody-positive (aAb+), and non-diabetic controls. Immunohistochemistry was performed to assess islet hormones, and both novel and canonical immune-cell markers that were identified from state-of-the-art workflows after reanalyzing murine scRNA-seq datasets. RESULTS. Computational workflows identified Cadm1-mediated binding among the most significant intercellular interactions among all cell clusters as well as Cadm1 enrichment in macrophages and dendritic cells from pancreata of NOD mice. Immunostaining of human pancreata revealed an increased number of CADM1+GCG+ cells adjacent to CD8+ T-cells in sections from T1D and aAb+ donors compared to non-diabetic subjects. Numbers of CADM1+CD68+ peri-islet myeloid cells adjacent to CD8+ T-cells were also increased in pancreatic sections from both T1D and aAb+ donors compared to non-diabetic subjects. CONCLUSION. Increased detection of CADM1+ cells adjacent to CD8+ T-cells in pancreatic sections of T1D and aAb+ human subjects validated workflows, and indicates CADM1-mediated intercellular contact may facilitate islet infiltration of cytotoxic T lymphocytes and serve as a potential therapeutic target for preventing T1D pathogenesis. FUNDING. The Johns Hopkins All Children’s Foundation IRG Program, NSFC (82071326) and DFG (431549029–SFB 1451, EXC 2030–390661388, and 411422114-GRK 2550).
Authors
Chandan Sona, Yu-Te Yeh, Andreas Patsalos, Laszlo Halasz, Xin Yan, Natalia L. Kononenko, Laszlo Nagy, Matthew N. Poy
Abstract
Diabetic nephropathy (DN) arises from systemic and local changes in glucose metabolism and hemodynamics. We have reported that many glycolytic and mitochondrial enzymes, such as pyruvate kinase M2 (PKM2), were elevated in renal glomeruli of DN-protected type 1 and type 2 diabetic patients. Here, mice with PKM2-specific overexpression in podocytes (PPKM2Tg) were generated to uncover its renal protective function as potential therapeutic target, which prevented elevated albumin-creatinine ratio (ACR), mesangial expansion, basement membrane thickness and podocyte foot process effacement after 7-months of STZ-induced diabetes. Further, diabetes-induced impairment of glycolytic rate and mitochondrial function were normalized in diabetic PPKM2Tg glomeruli, in concordance with elevated Ppargc1a and Vegf expressions. Restored VEGF expression improved glomerular maximal mitochondrial function in diabetic PPKM2Tg and WT mice. Elevated VEGF levels were observed in the glomeruli of DN-protected patients with chronic type 1 diabetes, and clinically correlated with estimated GFR, but not glycemic control. Mechanistically, the preservations of mitochondrial function and VEGF expression were dependent on tetrameric structure and enzymatic activities of PKM2 in podocyte. These findings demonstrated that PKM2 structure and enzymatic activation in podocytes can preserve entire glomerular mitochondrial function against toxicity of hyperglycemia via paracrine factors such as VEGF and prevent DN progression.
Authors
Jialin Fu, Takanori Shinjo, Qian Li, Ronald St-Louis, Kyoungmin Park, Marc G. Yu, Hisashi Yokomizo, Fabricio Simao, Qian Huang, I-Hsien Wu, George L. King
Pathogenic variants in the human m6A reader YTHDC2 are associated with primary ovarian insufficiency
Abstract
Primary ovarian insufficiency (POI) affects 1% of women and carries significant medical and psychosocial sequelae. Approximately 10% of POI has a defined genetic cause, with most implicated genes relating to biological processes involved in early fetal ovary development and function. Recently, Ythdc2, an RNA helicase and N6-methyladenosine (m6a) reader, has emerged as a novel regulator of meiosis in mice. Here, we describe homozygous pathogenic variants in YTHDC2 in three women with early-onset POI from two families: c. 2567C>G, p.P856R in the helicase-associated (HA2) domain; and c.1129G>T, p.E377*. We demonstrate that YTHDC2 is expressed in the developing human fetal ovary and is upregulated in meiotic germ cells, together with related meiosis-associated factors. The p.P856R variant results in a less flexible protein that likely disrupts downstream conformational kinetics of the HA2 domain, whereas the p.E377* variant truncates the helicase core. Taken together, our results reveal that YTHDC2 is a key new regulator of meiosis in humans and pathogenic variants within this gene are associated with POI.
Authors
Sinead M. McGlacken-Byrne, Ignacio del Valle, Polona Le Quesne Stabej, Laura Bellutti, Luz Garcia-Alonso, Louise A. Ocaka, Miho Ishida, Jenifer P. Suntharalingham, Andrey Gagunashvili, Olumide K. Ogunbiyi, Talisa Mistry, Federica Buonocore, GOSgene, Berta Crespo, Nadjeda Moreno, Paola Niola, Tony Brooks, Caroline E. Brain, Mehul T. Dattani, Daniel Kelberman, Roser Vento-Tormo, Carlos F. Lagos, Gabriel Livera, Gerard S. Conway, John C. Achermann
Abstract
Currently, the most effective strategy for dealing with Alzheimer’s disease (AD) is delaying the onset of dementia. Severe hypoglycemia is strongly associated with dementia; however, the effects of recurrent moderate hypoglycemia (RH) on progression of cognitive deficits in diabetic patients with genetic susceptibility to AD remain unclear. Here, we report that insulin-controlled hyperglycemia only slightly aggravated AD-type pathologies and cognitive impairment; however, RH significantly increased neuronal hyperactivity and accelerated the progression of cognitive deficits in streptozotocin(STZ)-induced diabetic APP/PS1 mice. GLUT3-mediated neuronal glucose uptake was not significantly altered under hyperglycemia, but was markedly reduced by RH, which induced excessive mitochondrial fission in the hippocampus. Overexpression of GLUT3 specifically in DG area of hippocampus enhanced mitochondrial function and improved cognitive deficits induced by RH. Activation of TRPC6 increased GLUT3-mediated glucose uptake in brain and alleviated RH-induced cognitive deficits, and inactivation of Ca2+/AMPK pathway was responsible for TRPC6-induced GLUT3 inhibition. Taken together, RH impairs brain GLUT3-mediated glucose uptake and further provokes neuronal mitochondrial dysfunction by inhibiting TRPC6 expression, which then accelerates the progression of cognitive deficits in diabetic APP/PS1 mice. Avoiding RH is essential for glycemic control in diabetic patients, and TRPC6/GLUT3 represent potent targets for delaying the onset of dementia in diabetic patients.
Authors
Chengkang He, Qiang Li, Yuanting Cui, Peng Gao, WenTao Shu, Qing Zhou, Lijuan Wang, Li Li, Zongshi Lu, Yu Zhao, Huan Ma, Xiaowei Chen, Hongbo Jia, Hongting Zheng, Gangyi Yang, Daoyan Liu, Martin Tepel, Zhiming Zhu
Abstract
Type 1 diabetes is an autoimmune disease characterized by insulin-producing beta-cell destruction. While islet transplantation restores euglycemia and improves patient outcomes, an ideal transplant site remains elusive. Brown adipose tissue (BAT) is a highly vascularized and anti-inflammatory microenvironment. As these tissue features can promote islet graft survival, we hypothesize that islets transplanted into BAT will maintain islet graft and BAT function, while delaying immune-mediated rejection. We performed syngeneic and allogeneic islet transplants into BAT or under the kidney capsule of streptozotocin (STZ)-induced diabetic NOD.Rag and NOD mice to investigate islet graft function, BAT function, metabolism, and immune-mediated rejection. Islet grafts within BAT restored euglycemia similarly to kidney capsule controls. Islets transplanted in BAT maintained expression of islet hormones, transcription factors, and were vascularized. Compared to kidney capsule and euglycemic mock surgery controls, no differences in glucose or insulin tolerance, thermogenic regulation, or energy expenditure were observed with islet grafts in BAT. Immune profiling of BAT revealed enriched anti-inflammatory macrophages and T cells. Compared to kidney capsule, islets transplanted in BAT demonstrated significant delays in autoimmune and allograft rejection, possibly due to increased anti-inflammatory immune populations. Our data support BAT as an alternative islet transplantation site that may improve graft survival.
Authors
Jessica D. Kepple, Jessie M. Barra, Martin E. Young, Chad S. Hunter, Hubert M. Tse
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