Identification of genetic basis of human immune-mediated diseases

Human diseases are caused by many genetic or environmental factors. The identification of causal variants or a mechanistic understanding for how those variations are involved in the human diseases is crucial for establishing strategies for treating or preventing human diseases. Our group has investigated the causal genes for familial inflammatory, autoimmune or immunodeficient disorders by using recent genotyping and sequencing technologies. We have recently demonstrated that a mutation in one of immunoproteasomes subunit, PSMB8, causes an autoinflammatory syndromes characterized by periodic fever, nodular erythema and progressive lipodystrophy. The mutation disturbs the assembly of immunoproteasomes, which is responsible for the accumulation of ubiquutinated proteins. The accumulation of ubiquitinated protein activates p38 and hyperproduction of interleukin-6. The discovery of PSMB8 as a causal gene for the autoinflammatory syndrome provides new insight into the pathogenesis of human inflammatory responses as well as the particular autoinflammatory syndrome. Several projects are underway in our laboratory to identify the causal genes for the familial immune-mediated diseases in order to understand the essential molecular pathway to control human immune responses as well as how inflammatory responses are dysregulated in human diseases.




Nano-material technologies for novel semiconductor optical devices

Nano-material technology laboratory was established in 2006 as a branch of the Center for Frontier Research of Engineering of the Institute of Science and Technology by the contribution of Nichia Corporation. In the laboratory, novel semiconductor optical devices with nano-structures are developed based on advanced technologies for the fabrication. The research covers a molecular beam epitaxial growth of semiconductor quantum structures, novel processes for fabrication of nano-scale structures, and evaluation technologies of ultrafast properties of quantum structure materials and devices. We also study dynamics of the nonlinear optical responses of nano-structured semiconductors for novel optical devices.

Ultrafast all-optical switches with semiconductor multilayer cavity structure and quantum dots are one of the main researched targets. Ultrafast responses of the optical Kerr gate signals were obtained due to the enhanced optical fields in the cavity structure and large optical nonlinear response by the InAs quantum dots. We are also developing a wavelength conversion devices based on four-wave-mixing in the cavity structure.

A semiconductor terahertz light-emitting device is another main research target. We have proposed a novel device consisting of the coupled cavity structure by semiconductor multilayers which induces effective difference frequency generation between two cavity modes. From the coupled cavity structure, terahertz radiation has been observed under the femtosecond laser pulse irradiation.