4-aminobutyrate aminotransferase (ABAT): genetic and pharmacological evidence for an involvement in gastro esophageal reflux disease

Role of 4‑aminobutyrate aminotransferase (ABAT) and the lncRNA co‑expression network in the development of myelodysplastic syndrome

IncRNAs play an important role in the regulation of gene expression. The present study profiled differentially expressed lncRNAs (DELs) and mRNAs (DEMs) in myelodysplastic syndrome (MDS) to construct a 4-aminobutyrate aminotransferase (ABAT)-DEL-DEM co-expression network in MDS development using the Agilent human BeadChips and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and network analyses. Compared with controls, there were 543 DELs and 2,705 DEMs in MDS patients, among which 285 (52.5%) DELs were downregulated and 258 (47.5%) DELs were upregulated, whereas 1,521 (56.2%) DEMs were downregulated and 1,184 (43.70%) DEMs were upregulated in MDS patients. The ABAT-DEL-DEM co-expression network contained six DELs that were co-expressed with ABAT in MDS. The GO analysis revealed that the co-expression network mainly participated in response to organic cyclic compound, cell proliferation, cell part morphogenesis, regulation of cell proliferation and enzyme-linked receptor protein signaling pathways, while the KEGG database showed that the co-expression network was involved in various pathways, such as phagosome and metabolic pathways. Furthermore, the expression of a selected DEL (lncENST00000444102) and ABAT was shown to be significantly downregulated in MDS patients, and in SKM-1 and THP-1 cells. The selected lncENST00000444102 was then overexpressed and ABAT expression was knocked down in the MDS cell lines using lentiviral transfection. In addition, lncENST00000444102 overexpression reduced the viability and increased the apoptosis of MDS cells, ABAT expression was upregulated by lncENST00000444102.

Integrative microRNA-mRNA Analysis of Muscle Tissues in Qianhua Mutton Merino and Small Tail Han Sheep Reveals Key Roles for oar-miR-655-3p and oar-miR-381-5p

The Qianhua Mutton Merino (QHMM) is a new variety of sheep (Ovis aries) with improved meat performance compared with the traditional Small Tail Han (STH) sheep variety. We recently reported the transcriptome profiling of longissimus muscle tissues between QHMM and STH sheep. In the present study, we aimed to evaluate key micro (mi)RNA-mRNA networks associated with sheep muscle growth and development. We used miRNA sequencing to obtain longissimus muscle miRNA profiles from QHMM and STH sheep. We identified a total of 153 known sheep miRNAs, of which 4 were differentially expressed (DE) between the 2 sheep varieties. We combined these results with mRNA library data to build an miRNA-mRNA network, including 26 target genes of the 4 DE miRNAs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that 26 target genes were significantly enriched in 86 biological processes, including muscle organogenesis, myoblast migration, cell proliferation, and adipose tissue development, and in 9 metabolic pathways, including carbohydrate, nucleotide, and amino acid metabolic pathways. oar-miR-655-3p and its target gene ACSM3 and oar-miR-381-5p and its target gene ABAT were selected for subsequent analysis based on GO and KEGG analyses. The binding sites of oar-miR-655-3p with ACSM3 and oar-miR-381-5p with ABAT were validated by a dual-luciferase reporter gene detection system. This represents the first integrative analysis of miRNA-mRNA networks in QHMM and STH muscles and suggests that DE miRNAs, especially oar-miR-655-3p and oar-miR-381-5p, play crucial roles in muscle growth and development.

High methylation of the 4-aminobutyrate aminotransferase gene predicts a poor prognosis in patients with myelodysplastic syndrome

In our previous study, the 4‑aminobutyrate aminotransferase (ABAT) gene was screened and selected as a target gene that may affect the prognosis of myelodysplastic syndrome (MDS). The present study aimed to determine the prognostic value of ABAT in 152 patients with MDS, 29 patients with acute myeloid leukemia (AML) and 40 controls, by detecting the expression and methylation levels of the ABAT gene. In patients with MDS, the expression levels of ABAT were significantly reduced compared with in the controls (P<0.0001), and the degree of DNA methylation was increased in MDS subjects (P<0.0001). Age, hemoglobin level, marrow blasts, International Prognostic Scoring System karyotype, and the expression and methylation levels of ABAT were associated with overall survival (OS), as determined by univariate analysis. Multivariate analysis revealed that older age, higher marrow blasts and higher methylation percentage were independent risk factors for OS. In addition, a functional study demonstrated that ABAT gene silencing increased cell apoptosis and blocked the G1/S phase in SKM‑1 and THP‑1 human leukemia cells. A γ‑aminobutyrate aminotransferase inhibitor also blocked the G1/S phase; however, it had no effect on cell apoptosis. In conclusion, the present study demonstrated that ABAT methylation served an essential role in the progression of MDS and therefore may be considered an indicator of poor prognosis for hematological malignancies.

Ornithine aminotransferase versus GABA aminotransferase: implications for the design of new anticancer drugs

Ornithine aminotransferase (OAT) and γ-aminobutyric acid aminotransferase (GABA-AT) are classified under the same evolutionary subgroup and share a large portion of structural, functional, and mechanistic features. Therefore, it is not surprising that many molecules that bind to GABA-AT also bind well to OAT. Unlike GABA-AT, OAT had not been viewed as a potential therapeutic target until recently; consequently, the number of therapeutically viable molecules that target OAT is very limited. In this review the two enzymes are compared with respect to their active-site structures, catalytic and inactivation mechanisms, and selective inhibitors. Insight is offered that could aid in the design and development of new selective inhibitors of OAT for the treatment of cancer.