Heterotrimeric G proteins play critical roles in transducing extracellular signals generated by 7-transmembrane domain receptors. Somatic gain-of-function mutations in G protein α subunits are associated with a variety of diseases. Recently, we identified gain-of-function mutations in Gα11 in patients with autosomal-dominant hypocalcemia type 2 (ADH2), an inherited disorder of hypocalcemia, low parathyroid hormone (PTH), and hyperphosphatemia. We have generated knockin mice harboring the point mutation
Kelly L. Roszko, Ruiye Bi, Caroline M. Gorvin, Hans Bräuner-Osborne, Xiao-Feng Xiong, Asuka Inoue, Rajesh V. Thakker, Kristian Strømgaard, Thomas Gardella, Michael Mannstadt
Heterozygous germline gain-of-function mutations of G-protein subunit α11 (Gα11), a signaling partner for the calcium-sensing receptor (CaSR), result in autosomal dominant hypocalcemia type 2 (ADH2). ADH2 may cause symptomatic hypocalcemia with low circulating parathyroid hormone (PTH) concentrations. Effective therapies for ADH2 are currently not available, and a mouse model for ADH2 would help in assessment of potential therapies. We hypothesized that a previously reported dark skin mouse mutant (
Caroline M. Gorvin, Fadil M. Hannan, Sarah A. Howles, Valerie N. Babinsky, Sian E. Piret, Angela Rogers, Andrew J. Freidin, Michelle Stewart, Anju Paudyal, Tertius A. Hough, M. Andrew Nesbit, Sara Wells, Tonia L. Vincent, Stephen D.M. Brown, Roger D. Cox, Rajesh V. Thakker
Zachary Richards, Ken Batai, Rachael Farhat, Ebony Shah, Andrew Makowski, Peter H. Gann, Rick Kittles, Larisa Nonn
Loss of functional pancreatic β cells is a hallmark of both type 1 and 2 diabetes. Identifying the pathways that promote β cell proliferation and/or block β cell apoptosis is a potential strategy for diabetes therapy. The transcriptional coactivator Yes-associated protein (YAP), a major downstream effector of the Hippo signaling pathway, is a key regulator of organ size and tissue homeostasis by modulating cell proliferation and apoptosis. YAP is not expressed in mature primary human and mouse β cells. We aimed to identify whether reexpression of a constitutively active form of YAP promotes β cell proliferation/survival. Overexpression of YAP remarkably induced β cell proliferation in isolated human islets, while β cell function and functional identity genes were fully preserved. The transcription factor forkhead box M1 (FOXM1) was upregulated upon YAP overexpression and necessary for YAP-dependent β cell proliferation. YAP overexpression protected β cells from apoptosis triggered by multiple diabetic conditions. The small redox proteins thioredoxin-1 and thioredoxin-2 (Trx1/2) were upregulated by YAP; disruption of the Trx system revealed that Trx1/2 was required for the antiapoptotic action of YAP in insulin-producing β cells. Our data show the robust proproliferative and antiapoptotic function of YAP in pancreatic β cells. YAP reconstitution may represent a disease-modifying approach to restore a functional β cell mass in diabetes.
Ting Yuan, Sahar Rafizadeh, Zahra Azizi, Blaz Lupse, Kanaka Durga Devi Gorrepati, Sushil Awal, Jose Oberholzer, Kathrin Maedler, Amin Ardestani
The islet in type 2 diabetes (T2D) shares many features of the brain in protein misfolding diseases. There is a deficit of β cells with islet amyloid derived from islet amyloid polypeptide (IAPP), a protein coexpressed with insulin. Small intracellular membrane-permeant oligomers, the most toxic form of IAPP, are more frequent in β cells of patients with T2D and rodents expressing human IAPP. β Cells in T2D, and affected cells in neurodegenerative diseases, share a comparable pattern of molecular pathology, including endoplasmic reticulum stress, mitochondrial dysfunction, attenuation of autophagy, and calpain hyperactivation. While this adverse functional cascade in response to toxic oligomers is well described, the sequence of events and how best to intervene is unknown. We hypothesized that calpain hyperactivation is a proximal event and tested this in vivo by β cell–specific suppression of calpain hyperactivation with calpastatin overexpression in human IAPP transgenic mice. β Cell–specific calpastatin overexpression was remarkably protective against β cell dysfunction and loss and diabetes onset. The critical autophagy/lysosomal pathway for β cell viability was protected with calpain suppression, consistent with findings in models of neurodegenerative diseases. We conclude that suppression of calpain hyperactivation is a potentially beneficial disease-modifying strategy for protein misfolding diseases, including T2D.
Tatyana Gurlo, Safia Costes, Jonathan D. Hoang, Jacqueline F. Rivera, Alexandra E. Butler, Peter C. Butler
Obesity-related insulin resistance is associated with fatty liver, dyslipidemia, and low plasma adiponectin. Insulin resistance due to insulin receptor (INSR) dysfunction is associated with none of these, but when due to dysfunction of the downstream kinase AKT2 phenocopies obesity-related insulin resistance. We report 5 patients with SHORT syndrome and C-terminal mutations in
Isabel Huang-Doran, Patsy Tomlinson, Felicity Payne, Alexandra Gast, Alison Sleigh, William Bottomley, Julie Harris, Allan Daly, Nuno Rocha, Simon Rudge, Jonathan Clark, Albert Kwok, Stefano Romeo, Emma McCann, Barbara Müksch, Mehul Dattani, Stefano Zucchini, Michael Wakelam, Lazaros C. Foukas, David B. Savage, Rinki Murphy, Stephen O’Rahilly, Inês Barroso, Robert K. Semple
Primary pigmented nodular adrenocortical disease (PPNAD) is a rare cause of ACTH-independent hypercortisolism. The disease is primarily caused by germline mutations of the protein kinase A (PKA) regulatory subunit 1A (
Zakariae Bram, Estelle Louiset, Bruno Ragazzon, Sylvie Renouf, Julien Wils, Céline Duparc, Isabelle Boutelet, Marthe Rizk-Rabin, Rossella Libé, Jacques Young, Dennis Carson, Marie-Christine Vantyghem, Eva Szarek, Antoine Martinez, Constantine A. Stratakis, Jérôme Bertherat, Hervé Lefebvre
Despite identification of causal genes for various lipodystrophy syndromes, the molecular basis of some peculiar lipodystrophies remains obscure. In an African-American pedigree with a novel autosomal dominant, atypical familial partial lipodystrophy (FPLD), we performed linkage analysis for candidate regions and whole-exome sequencing to identify the disease-causing mutation. Affected adults reported marked loss of fat from the extremities, with excess fat in the face and neck at age 13–15 years, and developed metabolic complications later. A heterozygous g.112837956C>T mutation on chromosome 10 (c.202C>T, p.Leu68Phe) affecting a highly conserved residue in adrenoceptor α 2A (
Abhimanyu Garg, Shireesha Sankella, Chao Xing, Anil K. Agarwal
Although a close connection between uterine regeneration and successful pregnancy in both humans and mice has been consistently observed, its molecular basis remains unclear. We here established a mouse model of decellularized uterine matrix (DUM) transplantation. Resected mouse uteri were processed with SDS to make DUMs without any intact cells. DUMs were transplanted into the mouse uteri with artificially induced defects, and all the uterine layers were recovered at the DUM transplantation sites within a month. In the regenerated uteri, normal hormone responsiveness in early pregnancy was observed, suggesting the regeneration of functional uteri. Uterine epithelial cells rapidly migrated and formed a normal uterine epithelial layer within a week, indicating a robust epithelial-regenerating capacity. Stromal and myometrial regeneration occurred following epithelial regeneration. In ovariectomized mice, uterine regeneration of the DUM transplantation was similarly observed, suggesting that ovarian hormones are not essential for this regeneration process. Importantly, the regenerating epithelium around the DUM demonstrated heightened STAT3 phosphorylation and cell proliferation, which was suppressed in uteri of
Takehiro Hiraoka, Yasushi Hirota, Tomoko Saito-Fujita, Mitsunori Matsuo, Mahiro Egashira, Leona Matsumoto, Hirofumi Haraguchi, Sudhansu K. Dey, Katsuko S. Furukawa, Tomoyuki Fujii, Yutaka Osuga
Obesity is an increasing health problem worldwide, and nonsurgical strategies to treat obesity have remained rather inefficient. We here show that acute loss of TGF-β–activated kinase 1 (TAK1) in adipocytes results in an increased rate of apoptotic adipocyte death and increased numbers of M2 macrophages in white adipose tissue. Mice with adipocyte-specific TAK1 deficiency have reduced adipocyte numbers and are resistant to obesity induced by a high-fat diet or leptin deficiency. In addition, adipocyte-specific TAK1-deficient mice under a high-fat diet showed increased energy expenditure, which was accompanied by enhanced expression of the uncoupling protein UCP1. Interestingly, acute induction of adipocyte-specific TAK1 deficiency in mice already under a high-fat diet was able to stop further weight gain and improved glucose tolerance. Thus, loss of TAK1 in adipocytes reduces the total number of adipocytes, increases browning of white adipose tissue, and may be an attractive strategy to treat obesity, obesity-dependent diabetes, and other associated complications.
Antonia Sassmann-Schweda, Pratibha Singh, Cong Tang, Astrid Wietelmann, Nina Wettschureck, Stefan Offermanns
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