LSR defines cell corners for tricellular tight junction formation in epithelial cells

J Cell Sci. 2011 Feb 15;124(Pt 4):548-55. Epub 2011 Jan 18.LSR defines cell corners for tricellular tight junction formation in epithelial cells.Masuda S, Oda Y, Sasaki H, Ikenouchi J, Higashi T, Akashi M, Nishi E, Furuse M.Source

Division of Cell Biology, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.Abstract

Epithelial cell contacts consist of not only bicellular contacts but also tricellular contacts, where the corners of three cells meet. At tricellular contacts, tight junctions (TJs) generate specialized structures termed tricellular TJs (tTJs) to seal the intercellular space. Tricellulin is the only known molecular component of tTJs and is involved in the formation of tTJs, as well as in the normal epithelial barrier function. However, the detailed molecular mechanism of how tTJs are formed and maintained remains elusive. Using a localization-based expression cloning method, we identified a novel tTJ-associated protein known as lipolysis-stimulated lipoprotein receptor (LSR). Upon LSR knockdown in epithelial cells, tTJ formation was affected and the epithelial barrier function was diminished. Tricellulin accumulation at the tricellular contacts was also diminished in these cells. By contrast, LSR still accumulated at the tricellular contacts upon tricellulin knockdown. Analyses of deletion mutants revealed that the cytoplasmic domain of LSR was responsible for the recruitment of tricellulin. On the basis of these observations, we propose that LSR defines tricellular contacts in epithelial cellular sheets by acting as a landmark to recruit tricellulin for tTJ formation.

treatments

Cell Sheets Therapy on Eye Disease - Vision Loss Treatment

Cell Sheets Therapy on eye/ocular disease in Japan

Eye (Ocular) disease, specifically corneal opacification of eye, could be treated with allograft transplantation. Recent progress in regenerative medicine makes a new alternative treatment to the patients not requiring immunosuppression by allograft transplantation, or to the patients who could not get transplantations.

Regenerative Medicine on Dilated Cardiomyopathy, or Myocardial Infarction

Recent technological advances in cell sheets engineering extended to the pre-clinical trial of the treatment of heart disease patients often in need for the heart transplant.

Cardiac myoblast, or embryonic heart muscle cell has been proposed for the alternative treatment of the patients with dilated cardiomyopathy replacing the heart transplant treatment. However, its post-transplantation inflammatory responses made it difficult for the clinical applications.

International Hospital Ranking

Cancer Adoptive Cell Immunotherapy in Japan

Cell based Immunotherapy (Autologous immune enhancement therapy) has been more frequently practised in Japan.Techniques to harvest the cells are extremely intricate and delicate processes. For the treatments to be rountinely available to the cancer patients apart from the clinical trials, advanced engineering cell reprocessing center must be available with good corroboration with the hospitals.

Since Japan made the Immuno-Cell Therapy to be a part of health care systems, the cell processing centers (CPCs) rapidly increased in the past decades. For the therapy of high complexity such as dendritic cell / autologous enhancement immunotherapy to be regularly practiced in the hospital, those CPCs were essential, and this explains why much of innovations in cell based cancer immunotherapy took place in Japan. 

Endoscopic Submucosal Dissection (ESD) \ Endoscopic Mucosal Resection (EMR) in Japan

Both EMR and ESD was originally developed in Japan. EMR / ESD (endoscopic biopsy or polyp resection procedure on gastrointestinal tract) is the area that Japanese surgeons are leading the research at forefront. It is the minimally invasive endoscopic procedure that conserves organs / tissues, and patients can be discharged from the hospital in the same day or a week after the operations. It is usually applicable to early stage cancer / tumor, and improves the post-surgical health conditions such as loss of appetite, fever, chills, pains and life-long medication.

Proton Beam Therapy

Currently there are about 31 proton (or carbon ion) therapy facilities in the world, 8 of which is built in Japan. Proton Beam Therapy is much less invasive than other radiotherapy treatments, and can treat the cancer without incision of the body, and with much less side effects than X-ray treatments. Japan has invested in Proton beam therapy (PBT) / Carbon Ion Therapy infrastructure for a long time, and clinical level studies are numerous and thus well experienced with all kinds of localized tumors.

Radiofrequency Ablation (RFA) on Liver cancer (Hepatocellular carcinoma)

Japan has been leading the RFA intervention technology for a long time, and the yearly number of RFA interventions in Japan currently exceeds that of United States and China. (See the Table below.) Survival rates for the patients undergoing the RFA are not different from those of surgery. But the surgery is harder to be operated multiple times, whereas the RFA is not restricted by the number of interventions or by the presence of Hepatitis.  For this reason, RFA becomes a standard treatment in Japan.

Yearly volume of RFA on Liver Cancer
Japan 34,000
US 14,000
China 9,500

Table: Yearly number of Radiofrequency ablation of Liver or hepatic tumors by country.

Regenerative Medicine on Dilated Cardiomyopathy, or Myocardial Infarction

Recent technological advances in cell sheets engineering extended to the pre-clinical trial of the treatment of heart disease patients often in need for the heart transplant.

Micro-Catheter treatments on varicose veins (including the veins below the knee)

In japan, complex operations towards varicose veins below the knee are established with safey and high response rates. Various catheter and micro-catheter devices are extensively used, and some of them are only available in Japan.

Cancer and Heart Disease Treatment in Japan  

Medical technology in Japan for cancer screening and gastrointestinal diseases are known to be very strong, supported by good clinical statistics, i.e., high five year survival rate after the surgery (or radiology / chemotherapy) among the colon, rectal, stomach, and esophageal cancer patients as well as liver, lung, and larynx cancer (See Table below). 

Since Japanese health agency is notoriously slow and counter-productive when it comes to the approval of new drugs, Japan's hospitals and patients suffered for so long by the technology lag from the rest of the world. Ironically, these regulatory problems lead physicians to the innovations in the fields other than drug discoveries, i.e., in the surgical / laparoscopic, endoscopic, micro-catheter procedures, cell based immunotherapy / vaccinations, radiation (carbon ion and proton beam), and regenerative medicine (iPS cells, cell sheets).

Since the Japanese physicians had less options in chemotherapy, they had more opportunities in experiencing difficult surgeries, and tried the new treatments due to the low availability of new drugs. Thus, many exotic and unique medical technologies emerged out of the isolations casued by the incompetence of Japanese health agency.

Site (Survival Rate:  %)

7 Cancer Registrates in Japan

US SEER Program Eurocare-3
Esophagus 25 14 10
Stomach 58 22 23
Colon 66 62 51
Rectum 63 63 48
Liver 17 7 7
Gallbladder 18 16 12
Pancreas 6 4 4
Larynx 77 65 62
Lung, bronchus 20 15 11