Assignment of the vascular smooth muscle actin gene ACTSA to human chromosome 10

Mossy fiber expression of αSMA in human hippocampus and its relevance to brain evolution and neuronal development

α-Smooth muscle actin (αSMA) is best characterized as the building block of thin filaments in smooth muscle cells. We observed a clear αSMA immunolabeling in adult human hippocampal mossy fibers (MF), prompting us to explore this novel pattern in phylogenic and ontogenic perspectives in the present study. αSMA immunolabeling occurred distinctively at the hippocampal MF terminals in humans from infancy to elderly. Hippocampal MF αSMA immunolabeling was not observed in mice and rats, visible in CA3 in guinea pigs and cats, and prominent in CA3 and dentate hilus in Rhesus monkeys. MF αSMA immunolabeling in human hippocampus emerged and refined from the last gestational trimester to early infancy. A transient overall neuronal labeling of ɑSMA was observed in prenatal human brains. ɑSMA expression was detected in human and rat primary neuronal cultures. The specificity of ɑSMA antibodies was confirmed by ACTA2 small interfering RNA (siRNA) silencing in SH-SY5Y cells. With this validation, we detected a higher αSMA protein level in dentate gyrus lysates relative to other human brain areas. Taken together, αSMA is distinctly expressed in human hippocampal mossy fibers. This pattern is related to hippocampal evolution among mammals and involves a refinement of neuronal αSMA expression during brain development.

Arsenic trioxide and curcumin attenuate cisplatin-induced renal fibrosis in rats through targeting Hedgehog signaling

Renal fibrosis is a progressive process resulting from a sustained injury that may ultimately cause renal failure. Cisplatin is an antitumor drug that induces renal injury and nephrotoxicity and is widely employed as a model for acute and chronic renal injury. Several signaling pathways are implicated in fibrogenic cell activation among which is Hedgehog (Hh) signaling. We here investigated the effects of arsenic trioxide (Ars) and curcumin in ameliorating cisplatin-induced kidney fibrosis via regulating Hh signaling. Cisplatin (4.5 mg/kg) was administered in Sprague-Dawley rats for two consecutive days and renal fibrosis was induced after 21 days. Once renal fibrosis was confirmed, Ars (3.5 mg/kg/day, orally) and curcumin (200 mg/kg/day, orally) were administered daily for another 21 days. Ars and curcumin corrected kidney function markers as creatinine clearance and urea nitrogen. Both agents ameliorated fibrosis as shown by lowered TGF-β1 mRNA levels, α-SMA protein levels, and hydroxylproline content. Cisplatin-activated Hh signaling which was blocked by both Ars and curcumin as demonstrated by decreased mRNA levels of Shh, Smo, and Ptch and suppressed renal Gli1 and Gli2 protein levels. Our results indicate new therapeutic roles for Ars and curcumin and suggest that blocking Hh signaling may be a promising approach for alleviating renal fibrosis. Symbols indicate α-SMA, alpha-smooth muscle actin; TGF-β, transforming growth factor-beta; Ptch, patched; Smo, smoothened; Shh, sonic hedgehog; Ihh, Indian hedgehog; Dhh, desert hedgehog; and SUFU, suppressor of fused.

Expanding the Distinctive Neuroimaging Phenotype of ACTA2 Mutations

BACKGROUND AND PURPOSE

Arg179His mutations in ACTA2 are associated with a distinctive neurovascular phenotype characterized by a straight course of intracranial arteries, absent basal Moyamoya collaterals, dilation of the proximal internal carotid arteries, and occlusive disease of the terminal internal carotid arteries. We now add to the distinctive neuroimaging features in these patients by describing their unique constellation of brain malformative findings that could flag the diagnosis in cases in which targeted cerebrovascular imaging has not been performed.

MATERIALS AND METHODS

Neuroimaging studies from 13 patients with heterozygous Arg179His mutations in ACTA2 and 1 patient with pathognomonic clinicoradiologic findings for ACTA2 mutation were retrospectively reviewed. The presence and localization of brain malformations and other abnormal brain MR imaging findings are reported.

RESULTS

Characteristics bending and hypoplasia of the anterior corpus callosum, apparent absence of the anterior gyrus cinguli, and radial frontal gyration were present in 100% of the patients; flattening of the pons on the midline and multiple indentations in the lateral surface of the pons were demonstrated in 93% of the patients; and apparent "squeezing" of the cerebral peduncles in 85% of the patients.

CONCLUSIONS

Because α-actin is not expressed in the brain parenchyma, only in vascular tissue, we speculate that rather than a true malformative process, these findings represent a deformation of the brain during development related to the mechanical interaction with rigid arteries during the embryogenesis.

In-Depth Proteomic Analysis of the Hippocampus in a Rat Model after Cerebral Ischaemic Injury and Repair by Danhong Injection (DHI)

Stroke is the second most common cause of death worldwide. A systematic description and characterization of the strokes and the effects induced in the hippocampus have not been performed so far. Here, we analysed the protein expression in the hippocampus 24 h after cerebral ischaemic injury and repair. Drug intervention using Danhong injection (DHI), which has been reported to have good therapeutic effects in a clinical setting, was selected for our study of cerebral ischaemia repair in rat models. A larger proteome dataset and total 4091 unique proteins were confidently identified in three biological replicates by combining tissue extraction for rat hippocampus and LC-MS/MS analysis. A label-free approach was then used to quantify the differences among the four experimental groups (Naive, Sham, middle cerebral artery occlusion (MCAO) and MCAO + DHI groups) and showed that about 2500 proteins on average were quantified in each of the experiment group. Bioinformatics analysis revealed that in total 280 unique proteins identified above were differentially expressed (P < 0.05). By combining the subcellular localization, hierarchical clustering and pathway information with the results from injury and repair phase, 12 significant expressed proteins were chosen and verified with respect to their potential as candidates for cerebral ischaemic injury by Western blot. The primary three signalling pathways of the candidates related may be involved in molecular mechanisms related to cerebral ischaemic injury. In addition, a glycogen synthase kinase-3β (Gsk-3β) inhibitor of the candidates with the best corresponding expression trends between western blotting (WB) and label-free quantitative results were chosen for further validation. The results of Western blot analysis of protein expression and 2,3,5- chloride three phenyl tetrazole (TTC) staining of rat brains showed that DHI treatment and Gsk-3β inhibitor are both able to confer protection against ischaemic injury in rat MCAO model. The observations of the present study provide a novel understanding regarding the regulatory mechanism of cerebral ischaemic injury.

The apple polyphenol phloretin inhibits breast cancer cell migration and proliferation via inhibition of signals by type 2 glucose transporter

Human triple-negative breast cancer (TNBC) is the most aggressive and poorly understood subclass of breast cancer. Glucose transporters (GLUTs) are required for glucose uptake in malignant cancer cells and are ideal targets for cancer therapy. To determine whether the inhibition of GLUTs could be used in TNBC cell therapy, the apple polyphenol phloretin (Ph) was used as a specific antagonist of GLUT2 protein function in human TNBC cells. Interestingly, we found that Ph (10–150 μM, for 24 h) inhibited cell growth and arrested the cell cycle in MDA-MB-231 cells in a p53 mutant-dependent manner, which was confirmed by pre-treatment of the cells with a p53-specific dominant-negative expression vector. We also found that Ph treatment (10–150 μM, for 24 h) significantly decreased the migratory activity of the MDA-MB-231 cells through the inhibition of paxillin/FAK, Src, and alpha smooth muscle actin (α-sMA) and through the activation of E-cadherin. Furthermore, the anti-tumorigenic effect of Ph (10, 50 mg/kg or DMSO twice a week for six weeks) was demonstrated in vivo using BALB/c nude mice bearing MDA-MB-231 tumor xenografts. A decrease in N-cadherin, vimentin and an increase in p53, p21 and E-cadherin were detected in the tumor tissues. In conclusion, inhibition of GLUT2 by the apple polyphenol Ph could potentially suppress TNBC tumor cell growth and metastasis.

Small molecules enhance CRISPR genome editing in pluripotent stem cells

The bacterial CRISPR-Cas9 system has emerged as an effective tool for sequence-specific gene knockout through non-homologous end joining (NHEJ), but it remains inefficient for precise editing of genome sequences. Here we develop a reporter-based screening approach for high-throughput identification of chemical compounds that can modulate precise genome editing through homology-directed repair (HDR). Using our screening method, we have identified small molecules that can enhance CRISPR-mediated HDR efficiency, 3-fold for large fragment insertions and 9-fold for point mutations. Interestingly, we have also observed that a small molecule that inhibits HDR can enhance frame shift insertion and deletion (indel) mutations mediated by NHEJ. The identified small molecules function robustly in diverse cell types with minimal toxicity. The use of small molecules provides a simple and effective strategy to enhance precise genome engineering applications and facilitates the study of DNA repair mechanisms in mammalian cells.

Gene mapping of familial autosomal dominant dilated cardiomyopathy to chromosome 10q21-23

Dilated cardiomyopathy (DCM) is the most common form of primary myocardial disorder, accounting for 60% of all cardiomyopathies. In 20-30% of cases, familial inheritance can be demonstrated; an autosomal dominant transmission is the usual type of inheritance pattern identified. Previously, genetic heterogeneity was demonstrated in familial autosomal dominant dilated cardiomyopathy (FDCM). Gene localization to chromosome 1 (1p1-1q1 and 1q32), chromosome 3 (3p25-3p22), and chromosome 9 (9q13-9q22) has recently been identified. We report one family with 26 members (12 affected) with familial autosomal dominant dilated cardiomyopathy in which linkage to chromosome 10 at the 10q21-q23 locus is identified. Using short tandem repeat polymorphism (STR) markers with heterozygosity > 70%, 169 markers (50% of the genome) were used before linkage was found to markers D10S605 and D10S201 with a pairwise LOD score = 3.91, theta = 0, penetrance = 100% for both markers. Linkage to 1p1-1q1, 1q32, 3p25-3p22, and 9q13-9q22 was excluded. We conclude that a new locus for pure autosomal dominant FDCM exists, and that this gene is localized to a 9 cM region of 10q21-10q23. The search for the disease causing gene and the responsible mutation(s) is ongoing.

Molecular analysis of bovine actin gene and pseudogene sequences: expression of nonmuscle and striated muscle isoforms in adult tissues

Most studies on the tissue distribution of actin isoform transcripts have been done in small mammals such as rat and mouse. We have begun a characterization of the actin gene family in a large mammal, the bovine. The alpha skeletal gene was isolated, and an isoform-specific probe to the 3' untranslated region of the transcript identified. This probe, in combination with isoform specific probes for alpha cardiac, beta nonmuscle, and gamma nonmuscle actins, was used to examine expression of nonmuscle and striated muscle actin gene transcription in different tissues. In contrast to other species so far examined, striated muscle isoforms were more strictly tissue specific, with virtually no alpha cardiac isoform transcripts detected in skeletal muscle and almost no alpha skeletal transcripts in cardiac tissue. The distribution of the beta and gamma nonmuscle actins was also unique in bovine compared to other species. A partial beta-actin pseudogene, and the chromosomal DNA flanking one end of it, were also cloned and sequenced. This chromosomal site was found to be homologous to a viral integration site previously identified in simian virus 40 (SV40)-transformed rat cells, suggesting that this region of the chromosome may be a preferred target for insertion events.

Chromosomal mapping of the human smooth muscle actin gene (enteric type, ACTA3) to 2p13.1 and molecular nature of the hindIII polymorphism

The human gene for smooth muscle actin (enteric type, ACTA3) has been isolated, and three overlapping clones, lambda HACTSG-17, -2, and -112, were used as probes for fluorescence in situ hybridization of human chromosomes. The gene was localized to chromosome 2p13.1. To clarify the molecular nature of the HindIII RFLP present in the first intron of the gene, the 1105-bp EcoRI-BamHI fragment contained in lambda HACTSG-17 was sequenced. PCR with primers designed from the determined sequence yielded either the 463- or the 439-bp product or both, using human DNA as template. The 463-bp product was cleavable with HindIII, but the 439-bp product was not. Comparison of their nucleotide sequences revealed that they differ in the presence/absence of a 24-bp sequence harboring a HindIII restriction site. Therefore, analysis of PCR products by size has been shown to be sufficient to detect the RFLP. The allelic frequency on 156 chromosomes was determined by PCR to be 45 (439 bp, corresponding to the formerly designated A1 allele):55 (463 bp, A2 allele) in the Japanese population.

Structure, chromosome location, and expression of the human smooth muscle (enteric type) gamma-actin gene: evolution of six human actin genes

Recombinant phages that carry the human smooth muscle (enteric type) gamma-actin gene were isolated from human genomic DNA libraries. The amino acid sequence deduced from the nucleotide sequence matches those of cDNAs but differs from the protein sequence previously reported at one amino acid position, codon 359. The gene containing one 5' untranslated exon and eight coding exons extends for 27 kb on human chromosome 2. The intron between codons 84 and 85 (site 3) is unique to the two smooth muscle actin genes. In the 5' flanking region, there are several CArG boxes and E boxes, which are regulatory elements in some muscle-specific genes. Hybridization with the 3' untranslated region, which is specific for the human smooth muscle gamma-actin gene, suggests the single gene in the human genome and specific expressions in enteric and aortic tissues. From characterized molecular structures of the six human actin isoform genes, we propose a hypothesis of evolutionary pathway of the actin gene family. A presumed ancestral actin gene had introns at least sites 1, 2, and 4 through 8. Cytoplasmic actin genes may have directly evolved from it through loss of introns at sites 5 and 6. However, through duplication of the ancestral actin gene with substitutions of many amino acids, a prototype of muscle actin genes had been created. Subsequently, striated muscle actin and smooth muscle actin genes may have evolved from this prototype by loss of an intron at site 4 and acquisition of a new intron at site 3, respectively.

Structure, chromosome location, and expression of the human smooth muscle (enteric type) gamma-actin gene: evolution of six human actin genes

Recombinant phages that carry the human smooth muscle (enteric type) gamma-actin gene were isolated from human genomic DNA libraries. The amino acid sequence deduced from the nucleotide sequence matches those of cDNAs but differs from the protein sequence previously reported at one amino acid position, codon 359. The gene containing one 5' untranslated exon and eight coding exons extends for 27 kb on human chromosome 2. The intron between codons 84 and 85 (site 3) is unique to the two smooth muscle actin genes. In the 5' flanking region, there are several CArG boxes and E boxes, which are regulatory elements in some muscle-specific genes. Hybridization with the 3' untranslated region, which is specific for the human smooth muscle gamma-actin gene, suggests the single gene in the human genome and specific expressions in enteric and aortic tissues. From characterized molecular structures of the six human actin isoform genes, we propose a hypothesis of evolutionary pathway of the actin gene family. A presumed ancestral actin gene had introns at least sites 1, 2, and 4 through 8. Cytoplasmic actin genes may have directly evolved from it through loss of introns at sites 5 and 6. However, through duplication of the ancestral actin gene with substitutions of many amino acids, a prototype of muscle actin genes had been created. Subsequently, striated muscle actin and smooth muscle actin genes may have evolved from this prototype by loss of an intron at site 4 and acquisition of a new intron at site 3, respectively.