Biomedical subjects

Huihua Fu

Publications and source records attributed to Huihua Fu.

5 recordsLinked to original sources

PubMed2006

Gene expression profiling of bone marrow stromal cells from juvenile, adult, aged and osteoporotic rats: with an emphasis on osteoporosis.

PURPOSE: Osteoporosis is a multi-factorial, age-related disease with a complex etiology and mode of regulation involving a large numbers of genes. To better understand the possible relationships among genes, we fingerprinted genes in a rat model induced by ovariectomy to determine differences among osteoporotic, non-osteoporotic, aged and juvenile rats. METHODS: We applied genome wide cDNA microarray technology to analyze genes expressed in bone marrow mesenchymal stromal cells (BMSC) and compared non-osteoporotic adult vs. osteoporotic, non-osteoporotic adult vs. aged, and non-osteoporotic adult vs. juvenile. Rigorous statistical analysis of functional annotation (EASE program) identified over-represented biological and molecular functions with significant group wide changes (p< or =0.05). Some of the expressed genes were further confirmed by quantitative RT-PCR (reverse transcription-polymerase chain reaction). RESULTS: Differences in gene expression were observed by identifying transcripts selected by t-test that were consistently changed by a minimum of two-fold. There were 195 transcripts that showed an increased expression and 109 transcripts that showed decreased expression relative to the osteoporotic condition. Of these, 75% transcripts were unknown gene products or ESTs (expressed sequence tag). A number of genes found in the aged and juvenile groups were not present in the osteoporotic rats. Functional clustering of the genes using the EASE bioinformatics program revealed that transcripts in osteoporosis were associated with signal transduction, lipid metabolism, protein metabolism, ionic and protein transport, neuropeptide and G protein signaling pathways. Although some of the genes have previously been shown to play a key role in osteoporosis, several genes were uniquely identified in this study and likely play a role in developing aged related osteoporosis that could have compelling implications in the development of new diagnostic strategies and therapeutics for osteoporosis. CONCLUSIONS: These data suggest that osteoporosis is associated with changes of multiple novel gene expression and that numerous pathways could play important roles in osteoporosis pathogenesis.

Age Factors↗

PubMed2005

A calcium phosphate-based gene delivery system.

Although nonviral vectors have lower transfection efficiency than viral vectors, the excellent safety profile of nonviral vectors is appealing for gene therapy. An efficient, simple nonviral vector gene delivery system has been designed that includes plasmid DNA-calcium phosphate precipitates (pDNA-CaP) and porous collagen spheres (Cultispherestrade mark). The hypothesis for this study was the pDNA-CaP would achieve efficient plasmid DNA transfection and the porous collagen spheres would provide a suitable delivery carrier system for three-dimensional (3D) administration. To test the hypothesis, plasmid DNA including the LacZ reporter gene encoding beta-galactosidase was precipitated with CaP to form particles of compacted LacZ-CaP and delivered directly or by Cultispherestrade mark to cells in vitro. The transfection efficiency was determined by beta-galactosidase gene expression. Results indicated that pLacZ-CaP promoted 25-84% of transfection efficiency in a broad cell line spectrum and in flexible experimental conditions. Maximum transfection efficiency was achieved by having mostly nano-sized partles (50-200 nm in diameter) of pDNA-CaP precipitates. Seeding density of 0.7-4 x 10(4) cells/cm2 provided sufficient transfection efficiency, and storage of pDNA-CaP at 4 degrees C was most efficient to preserve transfection efficacy for up to 3 days. The pDNA-CaP worked well in the presence of serum and serum-free conditions and was less cytotoxic than the liposomes. Cultispherestrade mark carrying plasmid LacZ-CaP was an effective 3D system for gene delivery. The technique described here is a simple and safe procedure to deliver genes, and may have application to regenerate bone and other tissues.

Animals↗

PubMed2004

Jittery, a Mutator distant relative with a paradoxical mobile behavior: excision without reinsertion.

The unstable mutation bz-m039 arose in a maize (Zea mays) stock that originated from a plant infected with barley stripe mosaic virus. The instability of the mutation is caused by a 3.9-kb mobile element that has been named Jittery (Jit). Jit has terminal inverted repeats (TIRs) of 181 bp, causes a 9-bp direct duplication of the target site, and appears to excise autonomously. It is predicted to encode a single 709-amino acid protein, JITA, which is distantly related to the MURA transposase protein of the Mutator system but is more closely related to the MURA protein of Mutator-like elements (MULEs) from Arabidopsis thaliana and rice (Oryza sativa). Like MULEs, Jit resembles Mutator in the length of the element's TIRs, the size of the target site duplication, and in the makeup of its transposase but differs from the autonomous element Mutator-Don Robertson in that it encodes a single protein. Jit also differs from Mutator elements in the high frequency with which it excises to produce germinal revertants and in its copy number in the maize genome: Jit-like TIRs are present at low copy number in all maize lines and teosinte accessions examined, and JITA sequences occur in only a few maize inbreds. However, Jit cannot be considered a bona fide transposon in its present host line because it does not leave footprints upon excision and does not reinsert in the genome. These unusual mobile element properties are discussed in light of the structure and gene organization of Jit and related elements.

Amino Acid Sequence↗

PubMed2002

Intraspecific violation of genetic colinearity and its implications in maize.

Although allelic sequences can vary extensively, it is generally assumed that each gene in one individual will have an allelic counterpart in another individual of the same species. We report here that this assumption does not hold true in maize. We have sequenced over 100 kb from the bz genomic region of two different maize lines and have found dramatic differences between them. First, the retrotransposon clusters, which comprise most of the repetitive DNA in maize, differ markedly in make-up and location relative to the genes in the bz region. Second, and more importantly, the genes themselves differ between the two lines, demonstrating that genetic microcolinearity can be violated within the same species. Our finding has bearing on the underlying genetic basis of hybrid vigor in maize, and possibly other organisms, and on the measurement of genetic distances.

Alleles↗

PubMed2002

Recombination rates between adjacent genic and retrotransposon regions in maize vary by 2 orders of magnitude.

Genetic map length and gene number in eukaryotes vary considerably less than genome size, giving rise to the hypothesis that recombination is restricted to genes. The complex genome of maize contains a large fraction of repetitive DNA, composed principally of retrotransposons arranged in clusters. Here, we assess directly the contribution of retrotransposon clusters and genes to genetic length. We first measured recombination across adjacent homozygous genetic intervals on either side of the bronze (bz) locus. We then isolated and characterized two bacterial artificial chromosome clones containing those intervals. Recombination was almost 2 orders of magnitude higher in the distal side, which is gene-dense and lacks retrotransposons, than in the proximal side, which is gene-poor and contains a large cluster of methylated retrotransposons. We conclude that the repetitive retrotransposon DNA in maize, which constitutes the bulk of the genome, most likely contributes little if any to genetic length.

Chromosomes, Artificial, Bacterial↗