Motoki Hiroyoshi

Stoichiometric interaction of smg p21 with its GDPGTP exchange protein and its novel action to regulate the translocation of smg p21 between membrane and cytoplasm

We have previously purified a GDP/GTP exchange protein for smg p21A and -B, members of a ras p21/ras p21-like small GTP-binding protein superfamily. This regulatory protein, named smg p21 GDP dissociation stimulator (GDS), stimulates the dissociation of both GDP and GTP from and the subsequent binding of both GDP and GTP to smg p21s. We show here that smg p21 GDS forms a complex with both the GDP- and GTP-bound forms of smg p21B at a molar ratio of about 1:1. Both the GDP- and GTP-bound forms of smg p21B bound to membranes. smg p21 GDS inhibited this binding and moreover induced the dissociation of the prebound smg p21B from the membranes. These results indicate that smg p21 GDS stoichiometrically interacts with smg p21B and thereby regulates its GDP/GTP exchange reaction and its translocation between membranes and cytoplasm.

Possible involvement of Rab11 p24, a Ras-like small GTP-binding protein, in intracellular vesicular transport of isolated pancreatic acini

Rab11 p24 is a Ras-like small guanosine triphosphate (GTP)-binding protein, and specific antibodies against it were newly developed to explore its function. Using the antibody, Rab11 p24 was shown to be abundant in rat pancreas as well as in most rat tissues. To explore the involvement of Rab11 p24 into the exocytotic process, the subcellular distribution of Rab11 p24 in rat pancreatic acini was evaluated also by use of the antibody. When the isolated acini were incubated with 1×10−10 M cholecystokinin octapeptide (CCK-8) that induced the maximal stimulation, the amount of Rab11 p24 increased in the fractions of plasma membrane and zymogen granules, but decreased in the cytosol fraction. This redistribution was time-dependent and occurred within 1 min after the CCK-8 stimulation and reached a maximal level within 2 min after the stimulation. Moreover, a light microscopic immunolabeling technique on the isolated rat pancreatic acini also revealed that higher immunoreactivity with Rab11 p24 was observed over the zymogen granule membrane under CCK-8 stimulation. The present results indicate that Rab11 p24 is translocated from cytosol to the membrane fraction during stimulation with CCK-8 and suggest that Rab11 p24 is involved in the intracellular vesicular transport of isolated pancreatic acini.

A Case of Small Bowel Strangulation Ileus Squeezed by Appendiceal Band

はじめに 絞扼性イレウスは,臨床の現場ではしばしば遭遇す る疾患であるが,虫垂自体が絞扼帯になることは稀で あり,また粘液嚢腫を背景にしないものはさらに稀で ある.今回われわれは虫垂先端の癒着により,虫垂自 体が絞扼帯となり発症した絞扼性イレウスの 1 例を経 験したので,若干の文献的考察を加えて報告する. 症 例 患者:75歳,男性. 主訴:腹痛,摂食困難. 家族歴:特記すべきことなし. 既往歴:62歳:直腸癌に対し低位前方切除術施行. 65歳:糖尿病性腎不全に対し血液透析開始. 74歳:肝細胞癌に対しラジオ波焼却術施行. 現病歴:2014年11月, 3 日前より腹痛・摂食困難が 出現し,症状増悪を認めたため当院を救急受診.腹部 X線検査・CT検査にてニボー像を認めイレウスと診 断され,同日入院となった. 入院時現症:体温36.8°C,血圧109/62mmHg,脈拍 75回/分.腹部はやや膨満するも軟,右下腹部に軽度 圧痛を認めるも反跳痛・筋性防御は認めなかった.下 腹部正中に手術痕を認めた. 血液検査所見:白血球数は4,900(好中球72.5%)/ μlと正常範囲であったがCRP 5.4mg/dLと軽度の炎 症反応上昇を認めた. 腹部単純X線検査(Fig. 1):立位像で腹部全体に ニボー像を認め,胃の拡張も認めた. 腹部単純CT検査:胃,小腸は拡張し液面形成を認 めた.回腸末端部で径の変化を認め,同部位でのイレウ