Adiponectin is an adipokine playing an important role in regulating energy homeostasis and insulin sensitivity. However, the effect of adiponectin on bone metabolism shows contradictory results according to different research studies. In this study femurs were isolated from genetically doublelabeled mBSP9.0Luc/-ACT-EGFP transgenic mice and were transplanted into adiponectin knock-out mice or wild type mice to investigate the effect of temporary exposure to adiponectin deficiency on bone growth and metabolism. We found that the growth of bone explants in adiponectin knock-out mice was significantly retarded. Histological analysis, microcomputed tomography analysis, and tartrate-resistant acid phosphatase staining revealed reduced trabecular bone volume, decreased cortical bone, and increased osteoclast number in bone explants in adiponectin knock-out mice. We then found that adiponectin inhibits RANKL-induced osteoclastogenesis from RAW264.7 cells and down-regulates RANKL-enhanced expressions of osteoclastogenic regulators including NFAT2, TRAF6, cathepsin K, and tartrate-resistant acid phosphatase. Adiponectin also increases osteoclast apoptosis and decreases survival/proliferation of osteoclast precursor cells. Using siRNA specifically targeting APPL1, the first identified adaptor protein of adiponectin signaling, we found that the inhibitory effect of adiponectin on osteoclasts was induced by APPL1-mediated down-regulation of Akt1 activity. In addition, overexpression of Akt1 successfully reversed adiponectin-induced inhibition in RANKL-stimulated osteoclast differentiation. In conclusion, adiponectin is important in maintaining the balance of energy metabolism, inflammatory responses, and bone formation.Adipose tissue is not just an inert organ for energy storage. It also secretes proinflammatory cytokines and synthesizes a wide range of biologically active molecules known as adipokines (1, 2). Adiponectin, a 30-kDa protein containing a collagen-repeat domain at the N terminus and a globular domain at the C terminus, is among these adipokines (3). It has been reported that adiponectin plays an important role in regulating energy homeostasis and insulin sensitivity, and plasma adiponectin levels correlate positively with insulin sensitivity (4, 5). APPL1 (adaptor protein containing pleckstrin homology domain, phosphotyrosine domain, and leucine zipper motif), is the first identified protein interacting with adiponectin receptors and is suggested to be an adaptor protein responsible for the mediation of adiponectin signal transduction (6). Knockdown of APPL1 expression resulted in a significant reduction in insulin-stimulated Akt phosphorylation (6). In addition to its insulin-sensitizing effect, adiponectin has also been reported to have potent antiinflammatory properties by suppressing the expressions of inflammatory cytokines while inducing production of anti-inflammatory cytokines (7-9). However, unlike other adipose tissue-derived molecules, adiponectin mRNA and plasma protein levels were shown to decreas...
The cyanobacterium Fremyella diplosiphon can alternate its light-harvesting pigments, a process called comple-mentary chromatic adaptation (CCA), allowing it to photosynthesize in green light (GL) and in fluctuating light conditions. Nevertheless, F. diplosiphon requires chlorophylls for photosynthesis under all light conditions. Two alternative enzymes catalyze the penultimate step of chlorophyll synthesis, light-dependent protochlorophyllide oxidoreductase (LPOR) and dark-operative protochlo-rophyllide oxidoreductase (DPOR). DPOR enzymatic activity is light independent, while LPOR requires light. Therefore, we hypothesize that F. diplosiphon up-regulates DPOR gene expression in GL, so that DPOR is more abundant when LPOR is less functional. We cloned the genes encoding the three subunits of DPOR, chlL, chlN and chlB, and the LPOR gene, por, to determine the abundance of the transcripts under red light (RL), GL and dark conditions. We found that F. diplosiphon chlL and chlN genes are transcribed as parts of a single operon, a gene structure that is conserved within cyanobacteria. Tran-scripts levels of all DPOR genes are up-regulated approximately 2-fold in GL relative to levels in RL, whereas LPOR transcript levels are reduced in GL. Moreover, mutations in CCA regulators, RcaE and CpeR, modify DPOR and LPOR transcript levels under specific light conditions. Finally, both DPOR and LPOR transcripts are down-regulated 2- to 5-fold in the dark. These results provide the first evidence that light quality and CCA affect the genetic regulation of chlorophyll biosynthesis in freshwater cyanobacteria, ecologically important photosynthetic organisms.
No abstract
The field of Communication Studies has traditionally dismissed the gender question as trivial, or incorporated it through a view of the 'sexless audience.' The integration of feminist questions remains for many a non-issue in media studies. Unfortunately, this is true for both the more traditional sectors of our scholastic community and for those committed to teaching communication within a critical perspective. It is interesting, for example, that a recent issue of Media, Culture and Society, devoted to the subject "Critical Comunications Research in North America," does not include one piece on the gender issue and its place within a critical perspective. The special issue of the Journal of Communication entitled, "Ferment In The Field," was comprised of thirty-five original essays which the editors argued were 'representative1 of the 'critical issues' and 'research tasks' facing our discipline today. Again, the gender issues does not appear on the agenda. If the question of social and economic power is central to any critical perspective, and I would argue that it is, then the failure of such work to come to terms with sex-based power differentials and their role in cultural production and reproduction is sympotmatic of serious flaws in our theoretical traditions.My intention in this article is not, however, to demonstrate how the gender issue can and should be made a key element of mainstream communication curriculum although I consider this task a crucial step in the development of a critical tradition in communication theory. Rather, I intend to demonstrate how a critical perspective can inform the construction of a course in media studies centered around the gender i ssue . CRITICAL TEACHINGA beginning point in this exercise is to clarify one's objective in teaching a critical perspective. What can one hope to contribute in providing a critical frame of reference to the students? Perhaps the best we can do is to enable them to make sense of their own experience. In the words of C. W. Mills:What they need, and what they feel they need, is a quality of mind that will help them to use information and to develop reason in order to achieve lucid summations of what is going on in the world and of what may be happening within themselves ( 1959, 5).These words have particular significance when applied to the subject of media and gender. Most students, and indeed most consumers of popular culture, have a loosely-defined understanding of 'sexism' in the media. When asked to articulate that understanding, the common response runs the gamut from "busty blondes in skimpy outfits who are always rescued by handsome male heroes" to "fat women with their heads in their ovens"! Underlying assumptions about the sources of media sexism, the mechanisms by which it is re-created and transmitted, the cultural context in which gender is constructed or even the contradictory levels of meaning regarding femininity, are seldom questioned. Therefore one of the major tasks in a course of this type is to teach students h w to ask thes...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.