Coordination between cell proliferation and cell death is essential to maintain homeostasis in multicellular organisms. In Drosophila, these two processes are regulated by a pathway involving the Ste20-like kinase Hippo (Hpo) and the NDR family kinase Warts (Wts; also called Lats). Hpo phosphorylates and activates Wts, which in turn, through unknown mechanisms, negatively regulates the transcription of cell-cycle and cell-death regulators such as cycE and diap1. Here we identify Yorkie (Yki), the Drosophila ortholog of the mammalian transcriptional coactivator yes-associated protein (YAP), as a missing link between Wts and transcriptional regulation. Yki is required for normal tissue growth and diap1 transcription and is phosphorylated and inactivated by Wts. Overexpression of yki phenocopies loss-of-function mutations of hpo or wts, including elevated transcription of cycE and diap1, increased proliferation, defective apoptosis, and tissue overgrowth. Thus, Yki is a critical target of the Wts/Lats protein kinase and a potential oncogene.

SUMMARY Centriole duplication occurs once per cell cycle, ensuring that each cell contains two centrosomes, each containing a mother-daughter pair of tightly engaged centrioles at mitotic entry. Loss of the tight engagement between mother and daughter centrioles appears to license the next round of centriole duplication. However, the molecular mechanisms regulating this process remain largely unknown. Mutations in CDK5RAP2, which encodes a centrosomal protein, cause autosomal recessive primary microcephaly (MCPH) in humans. Here we show that CDK5RAP2 loss of function in mice causes centriole amplification with a preponderance of single, unpaired centrioles and increased numbers of daughter-daughter centriole pairs. These results indicate that CDK5RAP2 is required to maintain centriole engagement and cohesion, thereby restricting centriole replication. Early in mitosis, amplified centrosomes assemble multipolar spindles in CDK5RAP2 mutant cells. Moreover, both mother and daughter centrioles are amplified, and the excess mother centrioles template multiple primary cilia in CDK5RAP2 mutant cells.

Elevations in C-reactive protein (CRP) are associated with an increased risk of insulin resistance. Whether CRP plays a causal role is unknown. Here we show that CRP transgenic mice and wild-type mice administered recombinant CRP are insulin resistant. Mice lacking the inhibitory Fcγ receptor IIB (FcγRIIB) are protected from CRP-induced insulin resistance, and immunohistochemistry reveals that FcγRIIB is expressed in skeletal muscle microvascular endothelium and is absent in skeletal muscle myocytes, adipocytes, and hepatocytes. The primary mechanism in glucose homeostasis disrupted by CRP is skeletal muscle glucose delivery, and CRP attenuates insulin-induced skeletal muscle blood flow. CRP does not impair skeletal muscle glucose delivery in FcγRIIB−/− mice or in endothelial nitric oxide synthase knock-in mice with phosphomimetic modification of Ser1176, which is normally phosphorylated by insulin signaling to stimulate nitric oxide–mediated skeletal muscle blood flow and glucose delivery and is dephosphorylated by CRP/FcγRIIB. Thus, CRP causes insulin resistance in mice through FcγRIIB-mediated inhibition of skeletal muscle glucose delivery.

gated estrogen prevent diet-induced obesity, hepatic steatosis, and type 2 diabetes in mice without impacting the reproductive tract. Am J Physiol Endocrinol Metab 307: E345-E354, 2014. First published June 17, 2014 doi:10.1152/ajpendo.00653.2013.-Despite the capacity of estrogens to favorably regulate body composition and glucose homeostasis, their use to combat obesity and type 2 diabetes is not feasible, because they promote sex steroid-responsive cancers. The novel selective estrogen receptor modulator (SERM) bazedoxifene acetate (BZA) uniquely antagonizes both breast cancer development and estrogen-related changes in the female reproductive tract. How BZA administered with conjugated estrogen (CE) or alone impacts metabolism is unknown. The effects of BZA or CE ϩ BZA on body composition and glucose homeostasis were determined in ovariectomized female mice fed a Western diet for 10 -12 wk. In contrast to vehicle, estradiol (E2), CE, BZA, and CE ϩ BZA equally prevented body weight gain by 50%. In parallel, all treatments caused equal attenuation of the increase in body fat mass invoked by the diet as well as the increases in subcutaneous and visceral white adipose tissue. Diet-induced hepatic steatosis was attenuated by E2 or CE, and BZA alone or with CE provided even greater steatosis prevention; all interventions improved pyruvate tolerance tests. Glucose tolerance tests and HOMA-IR were improved by E2, CE, and CE ϩ BZA. Whereas E2 or CE alone invoked a uterotrophic response, BZA alone or CE ϩ BZA had negligible impact on the uterus. Thus, CE ϩ BZA affords protection from diet-induced adiposity, hepatic steatosis, and insulin resistance with minimal impact on the female reproductive tract in mice. These combined agents may provide a valuable new means to favorably regulate body composition and glucose homeostasis and combat fatty liver. bazedoxifene; conjugated estrogen; hepatic steatosis; obesity; type 2 diabetes IN ADDITION TO THEIR ROLES in sexual development and reproduction, estrogens contribute to the regulation of body weight and body composition and to glucose homeostasis. Insulin sensitivity is greater in women prior to menopause vs. agematched men (16,42), in women the risk for weight gain and for the development of type 2 diabetes increases with the decline in the levels of estrogens that occurs at menopause, and menopause favors an increase in total body fat and visceral fat deposition (4). In addition, hormone replacement therapy with conjugated estrogen (CE) and medroxyprogesterone acetate (MPA) in postmenopausal women causes a 21-35% decrease in diabetes occurrence (29,35). Furthermore, in female rodents and primates, ovariectomy results in impaired insulin sensitivity and glucose homeostasis, and these effects are reversed by estradiol (E 2 ) (30, 54). Studies in mice have additionally demonstrated that E 2 provides potent protection against highfat diet-induced glucose intolerance and insulin resistance (46). The metabolic actions of estrogens are mediated primarily by estrogen receptor (E...

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Estrogens have the potential to afford atheroprotection, to prevent excess adiposity and its metabolic complications including insulin resistance, and to lessen hepatic steatosis. Cellular responses to estrogens occur through gene regulation by nuclear estrogen receptors (ERs), and through signal initiation by plasma membrane-associated ER. Leveraging the potentially favorable cardiometabolic actions of estrogens has been challenging, because their reproductive tract and cancer-promoting effects adversely impact the risk to benefit ratio of the therapy. In previous works, we discovered that an estrogen dendrimer conjugate (EDC) comprised of ethinyl-estradiol (E) molecules linked to a poly(amido)amine dendrimer selectively activates nonnuclear ER, and in mice, EDC does not invoke a uterotrophic response or support ER-positive breast cancer growth. In the present investigation, we employed EDC to determine how selective nonnuclear ER activation impacts atherosclerosis, adiposity, glucose homeostasis, and hepatic steatosis in female mice. In contrast to E, EDC did not blunt atherosclerosis in hypercholesterolemic apoE mice. Also in contrast to E, EDC did not prevent the increase in adiposity caused by Western diet feeding in wild-type mice, and it did not affect Western diet-induced glucose intolerance. However, E and EDC had comparable favorable effect on diet-induced hepatic steatosis, and this was related to down-regulation of fatty acid and triglyceride synthesis genes in the liver. Predictably, only E caused a uterotrophic response. Thus, although nonnuclear ER activation does not prevent atherosclerosis or diet-induced obesity or glucose intolerance, it may provide a potential new strategy to combat hepatic steatosis without impacting the female reproductive tract or increasing cancer risk.

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