In order to understand the mechanism of the endocannabinoid (eCB) signal, which has so far been shown to work in oocyte genesis and maturation, it is critical to clarify detailed localization of the eCB synthesizing enzyme molecules as well as receptors for eCBs in oocytes in the ovary in situ. For this purpose, diacylglycerol lipase (DGL) α and β are involved in the synthesis of an eCB 2-arachidonoylglycerol (2-AG). DGLα/β and the cannabinoid receptor 1 (CB1) for 2-AG were shown to be localized to the primary oocytes of postnatal mice using immuno-light and electron microscopy. It was found that two types of localization existed: first, immunoreactivities for DGLα and β were weakly detected throughout the ooplasm in light microscopy for which the intracellular membranes of vesicles forming tiny scattered aggregates were responsible.Secondly, DGLβ-immunoreactivity was distinctly confined to the nuage of Balbiani bodies and small nuage-derivative structures; both amorphous materials and membranes of vesicles were responsible for their localization. On the other hand, the weak immunoreactivity for CB1 was localized in a pattern similar to the first one for DGLs, but not found in a pattern for the Balbiani nuage. Two routes of functional exertion of 2-AG synthesized by DGLs were suggested from the two types of localization: one was that the eCB synthesized at all the sites of DGLs is released from the oocytes and exerts paracrine or autocrine effects on adjacent intra-ovarian cells as well as the oocytes themselves. The other was that the eCB synthesized within the nuage was involved in the modulation of the posttranscriptional processing of oocytes. Owing to the failure in the detection of CB1 in the Balbiani nuage, however, the validity of the latter possibility remains to be elucidated.

The Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that affects the world’s population with chikungunya disease. Adaptation of the viral life cycle to their host cells’ environment is a key step for establishing their infection and pathogenesis. Recently, the accumulating evidence advocates a principal role of extracellular vesicles (EVs), including exosomes, in both the infection and pathogenesis of infectious diseases. However, the participation of exosomes in CHIKV infection and transmission is not well clarified. Here, we demonstrated that the CHIKV RNA and proteins were captured in exosomes, which were released by viral-infected epithelial cells. A viral genomic element in the isolated exosomes was infectious to naïve mammalian epithelial cells. The assay of particle size distribution and transmission electron microscopy (TEM) revealed CHIKV-derived exosomes with a size range from 50 to 250 nm. Treatments with RNase A, Triton X-100, and immunoglobulin G antibodies from CHIKV-positive patient plasma indicated that infectious viral elements are encompassed inside the exosomes. Interestingly, our viral plaque formation also exhibited that infectious viral elements might be securely transmitted to neighboring cells by a secreted exosomal pathway. Taken together, our recent findings emphasize the evidence for a complementary means of CHIKV infection and suggest the role of exosome-mediated CHIKV transmission.

The present immunohistochemical study was attempted to localize in the submandibular glands of mice at various postnatal stages a diacylglycerol kinase (DGK) isoform termed DGKζ which is characterized by a nuclear localization signal and a nuclear export signal. This attempt was based on following facts: the continuous postnatal differentiation of glandular cells in the rodent submandibular gland, the regulatory role of DGK in the activity of protein kinase C (PKC) through attenuation of diacylglycerol (DAG), and the possible involvement of PKC in various cellular activities including the saliva secretion as well as the cell differentiation. As a result, a selective localization of immunoreactivity for DGKζ was detected in terminal tubule (TT) cells which comprise a majority of the newborn acinar structure and differentiate into the intercalated duct cells and/or the acinar cells. The immunoreactivity was deposited in portions of the cytoplasm lateral and basal to the nucleus, but not in the nuclei themselves. Although the immunoreactive TT cells remained until later stages in female specimen than in male, they eventually disappeared in both sexes by young adult stages. The present finding suggests that the regulatory involvement of DGKζ in PKC functions via control of DAG is exerted in the differentiation of the TT cells. In addition, another possible involvement of DGKζ in the regulation of secretion of the TT cells as well as its functional significance of its nuclear localization in the submandibular ganglion cells was also discussed.

No abstract

No abstract