[
Nature,
1999]
Animal evolution is commonly viewed as producing diverse, environmentally adapted bodies to propagate the germ line. The evolutionary theory of ageing suggests that genetic limits to lifespan may be inadvertent consequences of evolutionary selection for maximizing that propagation. In other words, trade-offs occur that favour reproductive success over post-reproductive longevity; lifespan should be inversely correlated with fecundity when progeny production diverts resources from the maintenance of somatic (non-reproductive) cells. The germ line contains all the genetic information to specify the soma. But it is also possible that there are other, environmentally modulated instructions for life history that the germ line conveys to the soma to maximize reproduction.
[
Genetics,
2014]
Ca(2+)/calmodulin-dependent Kinase II (CaMKII) is a calcium-regulated serine threonine kinase whose functions include regulation of synaptic activity (Coultrap and Bayer 2012). A postsynaptic role for CaMKII in triggering long-lasting changes in synaptic activity at some synapses has been established, although the relevant downstream targets remain to be defined (Nicoll and Roche 2013). A presynaptic role for CaMKII in regulating synaptic activity is less clear with evidence for CaMKII either increasing or decreasing release of neurotransmitter from synaptic vesicles (SVs) (Wang 2008). In this issue Hoover et al. (2014) further expand upon the role of CaMKII in presynaptic cells by demonstrating a role in regulating another form of neuronal signaling, that of dense core vesicles (DCVs), whose contents can include neuropeptides and insulin-related peptides, as well as other neuromodulators such as serotonin and dopamine (Michael et al. 2006). Intriguingly, Hoover et al. (2014) demonstrate that active CaMKII is required cell autonomously to prevent premature release of DCVs after they bud from the Golgi in the soma and before they are trafficked to their release sites in the axon. This role of CaMKII requires it to have kinase activity as well as an activating calcium signal released from internal ER stores via the ryanodine receptor. Not only does this represent a novel function for CaMKII but also it offers new insights into how DCVs are regulated. Compared to SVs we know much less about how DCVs are trafficked, docked, and primed for release. This is despite the fact that neuropeptides are major regulators of human brain function, including mood, anxiety, and social interactions (Garrison et al. 2012; Kormos and Gaszner 2013; Walker and Mcglone 2013). This is supported by studies showing mutations in genes for DCV regulators or cargoes are associated with human mental disorders (Sadakata and Furuichi 2009; Alldredge 2010; Quinn 2013; Quinn et al. 2013). We lack even a basic understanding of DCV function, such as, are there defined DCV docking sites and, if so, how are DCVs delivered to these release sites? These results from Hoover et al. (2014) promise to be a starting point in answering some of these questions.