Biomedical subjects

Libin Liu

Publications and source records attributed to Libin Liu.

3 recordsLinked to original sources

PubMed2006

Role of insulin-dependent cortical fodrin/spectrin remodeling in glucose transporter 4 translocation in rat adipocytes.

Fodrin or nonerythroid spectrin is an abundant component of the cortical cytoskeletal network in rat adipocytes. Fodrin has a highly punctate distribution in resting cells, and insulin causes a dramatic remodeling of fodrin to a more diffuse pattern. Insulin-mediated remodeling of actin occurs to a lesser extent than does that of fodrin. We show that fodrin interacts with the t-soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) syntaxin 4, and this interaction is increased by insulin stimulation and decreased by prior latrunculin A treatment. Latrunculin A disrupts all actin filaments, inhibits glucose transporter 4 (GLUT4) translocation, and causes fodrin to partially redistribute from the plasma membrane to the cytosol. In contrast, cytochalasin D disrupts only the short actin filament signal, and cytochalasin D neither inhibits GLUT4 translocation nor fodrin redistribution in adipocytes. Together, our data suggest that insulin induces remodeling of the fodrin-actin network, which is required for the fusion of GLUT4 storage vesicles with the plasma membrane by permitting their access to the t-SNARE syntaxin 4.

Actins↗

PubMed2006

Clustering DNA sequences by feature vectors.

We represent all DNA sequences as points in twelve-dimensional space in such a way that homologous DNA sequences are clustered together, from which a new genomic space is created for global DNA sequences comparison of millions of genes simultaneously. More specifically, basing on the contents of four nucleotides, their distances from the origin and their distribution along the sequences, a twelve-dimensional vector is given to any DNA sequence. The applicability of this analysis on global comparison of gene structures was tested on myoglobin, beta-globin, histone-4, lysozyme, and rhodopsin families. Members from each family exhibit smaller vector distances relative to the distances of members from different families. The vector distance also distinguishes random sequences generated based on same bases composition. Sequence comparisons showed consistency with the BLAST method. Once the new gene is discovered, we can compute the location of this new gene in our genomic space. It is natural to predict that the properties of this new gene are similar to the properties of known genes that are locating near by. Biologists can do various experiments to test these properties.

DNA↗

PubMed2002

Clinical and gene mutation studies on a Chinese pedigree with glucocorticoid-remediable aldosteronism.

OBJECTIVE: To report the clinical characteristics, biochemical profiles, diagnosis and treatment of one Chinese pedigree with glucocorticoid-remediable aldosteronism (GRA) and to study its molecular mechanism. METHODS: Plasma and urinary aldosterone, cortisol and plasma renin activities were dynamically tested and diagnostic therapy with dexamethasone was undergone in 3 affected subjects. Long-distance PCR as well as DNA sequencing were applied to detect the fusion gene in this pedigree. RESULTS: In this GRA pedigree, there were 4 affected subjects who had hypertension, hypokalemia and low basic and provoked renin activity. Three patients were given dexamethasone treatment, and had a significant decrease in plasma aldosterone concentrations (PACs) (from 192 +/- 9 ng/L to 87 +/- 7ng/L, P < 0.05) after 5 days. Among them, one patient (II -3) responded quite satisfactorily to the therapy, with serum K(+) rising from baseline value of 2.5 to 2.9, 3.8 and 4.15 mEq/L on the 10th, 28th and 35th days after treatment respectively. Three weeks later, his blood pressure decreased from its original level of 146.3 +/- 1 0.7/94.6 +/- 5.3 mm Hg to 138.3 +/- 3.1/87.3 +/- 6.1 mm Hg (P < 0.05). The other 2 members (III -2 and III -4) showed modest improvement although their PACs decreased significantly. Using long-distance PCR, we found a 3.9 kb band in all 4 affected individuals, which was absent in 5 unaffected members from this pedigree or 8 patients with aldosterone-producing adenoma (APA) or idiopathic hyperaldosteronism (IHA). By DNA sequence analysis, we found that the breakpoint of "unequal crossing-over" is both within intron 2 of the 11beta-hydroxylase gene (CYP11B1) and the aldosterone synthase gene (CYP11B2). CONCLUSIONS: The excess of mineralocorticoid in patients with GRA can be inhibited by exogenous glucocorticoids. The fusion gene resulting from unequal crossing-over between the 11beta-hydroxylase gene and the aldosterone synthase gene is the pathogenesis of this Chinese GRA pedigree.

Adrenocorticotropic Hormone↗