Erythropoietin mediated bone formation is regulated by mTOR signaling

The role of erythropoietin (Epo) and Epo/Epo receptor (EpoR) signaling pathways for production of red blood cells are well established. However, little is known about Epo/EpoR signaling in non‐hematopoietic cells. Recently, we demonstrated that Epo activates JAK/STAT signaling in hematopoietic stem cells (HSCs), leading to the production of bone morphogenetic protein 2 (BMP2) and bone formation and that Epo also directly activates mesenchymal cells to form osteoblasts in vitro. In this study, we investigated the effects of mTOR signaling on Epo‐mediated osteoblastogenesis and osteoclastogenesis. We found that mTOR inhibition by rapamycin blocks Epo‐dependent and ‐independent osteoblastic phenotypes in human bone marrow stromal cells (hBMSCs) and ST2 cells, respectively. Furthermore, we found that rapamycin inhibits Epo‐dependent and ‐independent osteoclastogenesis in mouse bone marrow mononuclear cells and Raw264.7 cells. Finally, we demonstrated that Epo increases NFATc1 expression and decreases cathepsin K expression in an mTOR‐independent manner, resulting in an increase of osteoclast numbers and a decrease in resorption activity. Taken together, these results strongly indicate that mTOR signaling plays an important role in Epo‐mediated bone homeostasis. J. Cell. Biochem. 113: 220–228, 2012. © 2011 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89548/1/23347_ftp.pd

Location determinants of green technological entry: evidence from European regions

In this paper, we explore the spatial distribution and the location determinants of new green technology-based firms across European regions. Integrating insights from evolutionary economic geography and the literature on knowledge spillovers, we study the importance of new knowledge creation and the conditioning role played by regional technological relatedness in fostering combinatorial opportunities underlying the process of green technological entry. The analysis is based on a dataset covering over 900 NUTS3 regions for 15 European countries obtained merging economic data from ESPON-Eurostat and patent information from the PATSTAT-CRIOS database for the period 1996–2006. Our results show that the geographical distribution of green technological entry across European regions is not evenly distributed, offering evidence of spatial path dependence. In line with this, we find evidence of a significant role played by the characteristics of the regional innovation system. New green innovators are more likely to develop in regions defined by higher levels of technological activity underlying knowledge spillovers and more dynamism in technological entry. Moreover, our findings point to an inverted-U relationship between regional technological relatedness and green technological entry. Regions whose innovation activity is defined by cognitive proximity to environmental technologies support interactive learning and knowledge spillovers underlying entrepreneurship in this specific area. However, too much relatedness may cause technological lock-ins and reduce the set of combinatorial opportunities

Wealth, Tastes, and Entrepreneurial Choice

The nonpecuniary benefits of managing a small business are a first order consideration for many nascent entrepreneurs, yet the preference for business ownership is mostly ignored in models of entrepreneurship and occupational choice. In this paper, we study a population with varying entrepreneurial tastes and wealth in a simple general equilibrium model of occupational choice. This choice yields several important results: (1) entrepreneurship can be thought of as a normal good, generating wealth effects independent of any financing constraints; (2) nonpecuniary entrepreneurs select into small-scale firms; and (3) subsidies designed to stimulate more business entry can have regressive distributional effects. Despite abstracting from other important considerations such as risk, financing constraints, and innovation, we show that nonpecuniary compensation is particularly relevant in discussions of small businesses

Skill Variety, Innovation and New Business Formation

We extend Lazear's theory of skills variety and entrepreneurship in three directions. First, we provide a theoretical framework linking new business creation with an entrepreneur's skill variety. Second, in this model we allow for both generalists and specialists to possess skill variety. Third, we test our model empirically using data from Germany and the Netherlands. Individuals with more varied work experience seems indeed more likely to successfully start up a new business and that being a generalist does not seem to be important in this regard. Finally, we find that innovation positively moderates the relationship between having varied experiences, and being successful in starting up a new business. Our conclusion is that entrepreneurs with more varied work experience are more likely to introduce innovations that have not only technical, but also commercial value. Our findings support the notion that entrepreneurship can be learned

Unraveling the Shift to the Entrepreneurial Economy

A recent literature has emerged providing compelling evidence that a major shift in the organization of the developed economies has been taking place: away from what has been characterized as the managed economy towards the entrepreneurial economy. In particular, the empirical evidence provides consistent support that (1) the role of entrepreneurship has significantly increased, and (2) a positive relationship exists between entrepreneurial activity and economic performance. However, the factors underlying this observed shift have not been identified in a systematic manner. The purpose of this paper is to suggest some of the factors leading to this shift and implications for public policy. In particular, we find that a fundamental catalyst underlying the shift from the managed to the entrepreneurial economy involved the role of technological change. However, we also find that it was not just technological change but rather involved a number of supporting factors, ranging from the demise of the communist system, increased globalization, new competition for multinational firms and higher levels of prosperity. Recognition of the causes of the shift from the managed to the entrepreneurial economy suggests a rethinking of the public policy approach. Rather than the focus of directly and exclusively on promoting startups and SMEs, it may be that the current approach to entrepreneurship policy is misguided. The priority should not be on entrepreneurship policy but rather a more pervasive and encompassing approach, policy consistent with an entrepreneurial economy