Entrepreneurial ecosystem elements

There is a growing interest in ecosystems as an approach for understanding the context of entrepreneurship at the macro level of an organizational community. It consists of all the interdependent actors and factors that enable and constrain entrepreneurship within a particular territory. Although growing in popularity, the entrepreneurial ecosystem concept remains loosely defined and measured. This paper shows the value of taking a systems view of the context of entrepreneurship: understanding entrepreneurial economies from a systems perspective. We use a systems framework for studying entrepreneurial ecosystems, develop a measurement instrument of its elements, and use this to compose an entrepreneurial ecosystem index to examine the quality of entrepreneurial ecosystems in the Netherlands. We find that the prevalence of high-growth firms in a region is strongly related to the quality of its entrepreneurial ecosystem. Strong interrelationships among the ecosystem elements reveal their interdependence and need for a systems perspective

Bcl-2 proteins regulate ER membrane permeability to luminal proteins during ER stress-induced apoptosis

Endoplasmic reticulum (ER) stress-induced apoptosis may arise from multiple environmental and pharmacological causes, but the precise mechanism(s) involved are not completely known. Members of Bcl-2 protein family are important regulators of apoptosis. In this study, we report that in a process dependent on the proapoptotic Bcl-2 members Bax and Bak, exogenously expressed fluorescent protein localized to the ER lumen is released into the cytosol in cells undergoing ER stress. Upon ER stress induction, endogenous ER luminal proteins are also released into the cytosol in a similar manner accompanied by translocation and anchorage of Bax to the ER membrane. In addition, Bax and truncated-Bid (tBid) mediate a global increase in ER membrane permeability to ER luminal proteins in vitro. Importantly, antiapoptotic Bcl-XL antagonizes the effects of proapoptotic Bcl-2 proteins on ER membrane permeability. Consistent with Bax translocation to the ER membrane in whole apoptotic cells, there is also increased tight association of Bax with the ER membrane correlated with the increase in ER membrane permeability in vitro. Overall, these data suggest that the regulation of ER membrane permeability by Bcl-2 proteins could be an important molecular mechanism of ER stress-induced apoptosis