Konoki Keiichi, Okada Kayo, Kohama Mami, Matsuura Hiroki, Saito Kaori, Cho Yuko, Nishitani Goh, Miyamoto Tomofumi, Fukuzawa Seketsu, Tachibana Kazuo, Yotsu-Yamashita Mari
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
Toxicon. 2015 Dec 15;108:38-45. doi: 10.1016/j.toxicon.2015.09.026. Epub 2015 Sep 28.
Okadaic acid (OA) and OA binding protein 2 (OABP2) were previously isolated from the marine sponge Halichondria okadai. Because the amino acid sequence of OABP2 is completely different from that of protein phosphatase 2A, a well-known target of OA, we have been investigating the production and function of OABP2. In the present study, we hypothesized that OABP2 plays a role in the detoxification of OA in H. okadai and that the OA concentrations are in proportional to the OABP2 concentrations in the sponge specimens. Based on the OA concentrations and the OABP2 concentrations in the sponge specimens collected in various places and in different seasons, however, we could not determine a positive correlation between OA and OABP2. We then attempted to determine distribution of OA and OABP2 in the sponge specimen. When the mixture of dissociated sponge cells and symbiotic species were separated with various pore-sized nylon meshes, most of the OA and OABP2 was detected from the same 0-10 μm fraction. Next, when sponge cell clusters were prepared from a mixture of dissociated sponge cells and symbiotic species in the presence of penicillin and streptomycin, we identified the 18S rDNA of H. okadai and the gene of OABP2 in the analysis of genomic DNA but could not detect OA by LC-MS/MS. We thus concluded that the sponge cells express OABP2, and that OA was not apparently present in the sponge cells but could be colocalized with OABP2 in the sponge cells at a concentration less than the limit of detection.
冈田酸（OA）和OA结合蛋白2（OABP2）先前是从海洋海绵冈村氏软海绵中分离出来的。由于OABP2的氨基酸序列与蛋白磷酸酶2A（一种众所周知的OA靶点）的氨基酸序列完全不同，我们一直在研究OABP2的产生和功能。在本研究中，我们假设OABP2在冈村氏软海绵中OA的解毒过程中发挥作用，并且OA浓度与海绵标本中的OABP2浓度成正比。然而，根据在不同地点和不同季节采集的海绵标本中的OA浓度和OABP2浓度，我们无法确定OA和OABP2之间存在正相关关系。然后，我们试图确定OA和OABP2在海绵标本中的分布。当用各种孔径的尼龙网分离解离的海绵细胞和共生物种的混合物时，大部分OA和OABP2是从相同的0 - 10μm组分中检测到的。接下来，当在青霉素和链霉素存在的情况下，从解离的海绵细胞和共生物种的混合物中制备海绵细胞团时，我们在基因组DNA分析中鉴定出了冈村氏软海绵的18S rDNA和OABP2基因，但通过LC-MS/MS未检测到OA。因此，我们得出结论，海绵细胞表达OABP2，并且OA显然不存在于海绵细胞中，但可能以低于检测限的浓度与OABP2在海绵细胞中共定位。
