Extracellular calcium is essential for life and its concentration in the blood is maintained within a narrow range. This is achieved by a feedback loop that receives input from the calcium-sensing receptor (CASR), expressed on the surface of parathyroid cells. In response to low ionized calcium, the parathyroids increase secretion of parathyroid hormone (PTH) which increases serum calcium. The CASR is also highly expressed in the kidneys, where it regulates the reabsorption of calcium from the primary filtrate. Autosomal dominant hypocalcemia (ADH) type 1 is caused by heterozygous activating mutations in the CASR which increase the sensitivity of the CASR to extracellular ionized calcium. Consequently, PTH synthesis and secretion is suppressed at normal ionized calcium concentrations. Patients present with hypocalcemia, hyperphosphatemia, low magnesium levels, and low or low-normal levels of PTH. Urinary calcium excretion is typically increased due to the decrease in circulating PTH concentrations and by the activation of the renal tubular CASR. Therapeutic attempts using CASR antagonists (calcilytics) to treat ADH are currently under investigation. Recently, heterozygous mutations in the alpha subunit of the G protein G11 (GNA11) have been identified in patients with ADH, and this has been classified as ADH type 2. ADH2 mutations lead to a gain-of-function of Gα11, a key mediator of CASR signaling. Therefore, the mechanism of hypocalcemia appears similar to that of activating mutations in the CASR, namely an increase in the sensitivity of parathyroid cells to extracellular ionized calcium. Studies of activating mutations in the CASR and gain-of-function mutations in GNA11 can help define new drug targets and improve medical management of patients with ADH types 1 and 2.

Parathyroid‐hormone‐type 1 receptor (PTH1R) is extensively expressed in key regulatory organs for systemic mineral ion homeostasis, including kidney and bone. We investigated the bone‐specific functions of PTH1R in modulating mineral ion homeostasis by generating a novel mouse model in which PTH1R is ablated in the limb mesenchyme using Prx1Cre transgenic mice. Such ablation decreased FGF23 protein and serum levels by 50%, despite normal Fgf23 mRNA levels in long bones. Circulating calcium and PTH levels were unchanged, but inorganic phosphate and 1,25 (OH) ₂ D ₃ levels were significantly decreased and accompanied by elevated urinary calcium and phosphate wasting. Key renal genes for balancing mineral ion homeostasis, calbindinD _28k , Klotho, and Napi2a were suppressed by 30‐40%. Intermittent hPTH(1‐34) injections increased Fgf23 mRNA (7.3‐fold), Nurr1 mRNA (3.1‐fold), and serum intact‐FGF23 (1.6‐fold) in controls, but failed to induce Fgf23, Nurr1 mRNA, or intact FGF23 production in mutants. Moreover, a significant elevation in serum C‐terminal‐FGF23 levels (4‐fold) was detected in both genotypes. PTH markedly down‐regulated Galnt3 expression (2.7‐fold) in controls but not in mutants. These results demonstrate the pivotal role of PTH1R in long bones to regulate systemic mineral ion homeostasis and the direct induction of FGF23 by PTH1R signaling.—Fan, Y., Bi, R., Densmore, M. J., Sato, T., Kobayashi, T., Yuan, Q., Zhou, X., Erben, R. G., Lanske, B. Parathyroid hormone 1 receptor is essential to induce FGF23 production and maintain systemic mineral ion homeostasis. FASEB J. 30, 428‐440 (2016). www.fasebj.org

Neck dissection for oral squamous-cell carcinoma (OSCC) is a clinically controversial issue and has therefore been the subject of abundant research. However, no one has performed a bibliometric study on this topic to date. The aim of this study was to assess the development of research on neck dissection for OSCC in terms of the historical evolution, current hotspots and future directions, particularly including research trends and frontiers from 2010 to 2019. Literature records related to research on neck dissection for OSCC were retrieved from the Web of Science Core Collection (WoSCC). CiteSpace was used as a tool to perform a bibliometric analysis of this topic. The survey included 2 096 papers. “Otorhinolaryngology” was the most popular research area. The most active institutions and countries were Memorial Sloan Kettering Cancer Center and the USA, respectively. Shah J.P. was the most cited author. Among the six identified “core journals”,Head & Neckranked first. The top three trending keywords were ‘invasion’, ‘upper aerodigestive’ and ‘negative neck’. ‘D’Cruz AK (2015)’ was the most cited and the strongest burst reference in the last decade. The study evaluated the effect on survival of elective versus therapeutic neck dissection in patients with lateralized early-stage OSCC. The depth of invasion and the management of N0 OSCC were research frontiers in this field. The present study provides a comprehensive bibliometric analysis of research on neck dissection for OSCC, which will assist investigators in exploring potential research directions.

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 Gα ₁₁ 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 GNA11 c.C178T (p.Arg60Cys) identified in ADH2 patients. The mutant mice faithfully replicated human ADH2. They also exhibited low bone mineral density and increased skin pigmentation. Treatment with NPS 2143, a negative allosteric modulator of the calcium-sensing receptor (CASR), increased PTH and calcium concentrations in WT and mutant mice, suggesting that the gain-of-function effect of GNA11 ^R6OC is partly dependent on coupling to the CASR. Treatment with the Gα _11/q -specific inhibitor YM-254890 increased blood calcium in heterozygous but not in homozygous GNA11 ^R60C mice, consistent with published crystal structure data showing that Arg60 forms a critical contact with YM-254890. This animal model of ADH2 provides insights into molecular mechanism of this G protein–related disease and potential paths toward new lines of therapy.