Aims/hypothesis: Prolactin regulatory element binding (PREB) protein has been identified as a factor that regulates prolactin promoter activity in rat anterior pituitary. PREB is located not only in the anterior pituitary but also in pancreas; however its role in the pancreas is not known. We therefore examined the role of PREB in insulin gene expression. Materials and methods: To analyse the effects of PREB on insulin gene transcription, we employed the luciferase reporter gene assay and electrophoretic mobility shift assay (EMSA). In cells expressing or knocked down for PREB, insulin expression and secretion were determined. Results: PREB was located mainly in nuclei of rat pancreatic beta cells and its cell line, INS-1. A nuclear extract of INS-1 cells contained material that was recognised by PREB antiserum. This nuclear extract also showed insulin promoter binding activity that was super-shifted by PREB antiserum in EMSA studies. In the INS-1 cells, co-expression of PREB and the insulin promoter induced activity of the latter. The addition of glucose to the cells increased PREB expression. Deletional analysis of the insulin promoter showed that A3, a glucose-responsive cis-element in the insulin promoter, mediated the transcriptional effect of PREB. In addition, synthesised PREB bound the A3 element by EMSA, while a mutant of this motif in the insulin promoter abrogated the effect of PREB. Cells expressing or knocked down for PREB exhibited increased or decreased insulin expression, respectively. Conclusions/interpretation: These results demonstrate that PREB may contribute to the regulation of insulin gene transcription and insulin secretion in response to glucose stimulation.

A number of factors have been reported to affect insulin synthesis in β-cells. Although glucose is the most important regulator of insulin gene expression in pancreatic β-cells, the mechanisms whereby glucose stimulates insulin gene transcription in response to changes in glucose concentration have not been clarified yet. In this study, we examined the role of the Ca2+/calmodulin (CaM)-dependent protein kinase (CaM-K) cascade in transcriptional activation of insulin. RT-PCR, Western blotting, and immunohistochemical staining analysis revealed that CaM-K kinase-α (CaM-KKα) and CaM-KIV were localized in rat pancreatic β-cells and their cell line, INS-1. Exposure of INS-1 cells to 11.2 mmol/l glucose elicited an increase of insulin promoter activity as well as upregulation of CaM-KIV activity within 2 min after stimulation. We investigated the influence on insulin promoter activity of the constitutively active form (CaM-KIVc) or dominant-negative mutant (CaM-KIVdn) of CaM-KIV in transfected INS-1 cells. CaM-KIVc alone was sufficient, and the upstream kinase, CaM-KK, was enhanced to upregulate the insulin promoter activity in INS-1 cells. Furthermore, cotransfection of CaM-KIVdn suppressed to a significant degree the glucose-upregulated activity of the insulin promoter. Taken together, these results indicated that the CaM-KK/CaM-KIV cascade might play an important role in glucose-upregulated transcriptional activation of the insulin gene.

Dunnigan-type familial partial lipodystrophy (FPLD) is a rare monogenic adipose tissue disorder in which the affected subjects have increased predisposition to insulin resistance and related metabolic complications, such as glucose intolerance, diabetes, dyslipidemia, and hepatic steatosis. Our patient was a 35-year-old female who had been receiving insulin injection therapy for diabetes mellitus and was transferred to our hospital. She was diagnosed with FPLD on the basis of the following symptoms: increase in subcutaneous fat in the face, neck, and upper trunk; loss of subcutaneous fat in the lower limbs and the gluteal region. We found a heterozygous CGG to CAG transition in codon 482 of exon 8 in the gene encoding lamin A/C (LMNA), which leads to an arginine to glutamine substitution (R482Q). At the time of admission, her serum creatinine level was 8.4 mg/dl, and her blood urea nitrogen (BUN) level was 81 mg/dl. Her serum creatinine level was elevated and hemodialysis was performed twice every week. However, she died of cerebral hemorrhage 9 months after hemodialysis. Although it is uncommon for patients with FPLD to exhibit renal dysfunction and require hemodialysis, this case suggests the need for careful analysis of renal function in a patient with FPLD.

To obtain an extra high quality imaging system in electrical imaging, new important physical factors and physical characters are considered and partly tested in addition to traditional characteristics such as frequency characteristics, quantization errors and so on. We have discussed the problem systematically based on the Uniform Lightness-Chromaticness Scale System and Picture Quality which is derived from the discussion of psychophysics.

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