The concept of micelles was first proposed in 1913 by McBain and has rationalized numerous experimental results of the self-aggregation of surfactants. It is generally agreed that the aggregation number (Nagg) for spherical micelles has no exact value and a certain distribution. However, our studies of calix[4]arene surfactants showed that they were monodisperse with a defined Nagg whose values are chosen from 6, 8, 12, 20, and 32. Interestingly, some of these numbers coincide with the face numbers of Platonic solids, thus we named them “Platonic micelles”. The preferred Nagg values were explained in relation to the mathematical Tammes problem: how to obtain the best coverage of a sphere surface with multiple identical circles. The coverage ratio D(N) can be calculated and produces maxima at N = 6, 12, 20, and 32, coinciding with the observed Nagg values. We presume that this “Platonic nature” may hold for any spherical micelles when Nagg is sufficiently small.

Although α-synuclein (αSyn) has been linked to Parkinson’s disease (PD), the mechanisms underlying the causative role in PD remain unclear. We previously proposed a model for a transportable microtubule (tMT), in which dynein is anchored to a short tMT by LIS1 followed by the kinesin-dependent anterograde transport; however the mechanisms that produce tMTs have not been determined. Our in vitro investigations of microtubule (MT) dynamics revealed that αSyn facilitates the formation of short MTs and preferentially binds to MTs carrying 14 protofilaments (pfs). Live-cell imaging showed that αSyn co-transported with dynein and mobile βIII-tubulin fragments in the anterograde transport. Furthermore, bi-directional axonal transports are severely affected in αSyn and γSyn depleted dorsal root ganglion neurons. SR-PALM analyses further revealed the fibrous co-localization of αSyn, dynein and βIII-tubulin in axons. More importantly, 14-pfs MTs have been found in rat femoral nerve tissue, and they increased approximately 19 fold the control in quantify upon nerve ligation, indicating the unconventional MTs are mobile. Our findings indicate that αSyn facilitates to form short, mobile tMTs that play an important role in the axonal transport. This unexpected and intriguing discovery related to axonal transport provides new insight on the pathogenesis of PD.

The regenerating gene/regenerating islet-derived (Reg) family is a group of small secretory proteins. Within this family, Reg type-III (Reg-III) consists of: Reg-IIIα, -β, -γ, and -δ. To elucidate the physiological relevance of Reg-III, we examined the localization and ontogeny of Reg-IIIβ and Reg-IIIγ in mice at different time points spanning from embryonic day 13.5 to 7 weeks old, using in situ hybridization and immunohistochemistry. Our results showed that Reg-IIIβ was expressed in specific subsets of primary sensory neurons and motor neurons, and that expression was transient during the embryonic and perinatal periods. Reg-IIIβ expression was also observed in absorptive epithelial cells of the intestine. In contrast, Reg-IIIγ expression was mainly observed in epithelial cells of the airways and intestine, but not in the nervous system, and expression levels showed a gradually increasing pattern along with development. In the airways Reg-IIIγ was expressed in goblet and Clara-like cells, whereas in the intestine Reg-IIIγ was expressed in the absorptive epithelial cells and Paneth cells, and was found to be expressed in development before these organs had been exposed to the outside world. The present findings imply that Reg-IIIβ and Reg-IIIγ expression is regulated along divergent pathways. Furthermore, we also suggest that expression of Reg-IIIγ in the airway and intestinal epithelia may occur to protect these organs from exposure to antigens or other factors (e.g., microbes) in the outer world, whereas the transient expression of Reg-IIIβ in the nervous system may be associated with the development of the peripheral nervous system including such processes as myelination.