A New DARS2 Mutation Discovered in an Adult Patient

High expression of DARS2 indicates poor prognosis in lung adenocarcinoma

Background

DARS2 was overexpressed in multiple tumor types, but the biological role of DARS2 in lung adenocarcinoma (LUAD) have not been elucidated.

Methods

Firstly, the DARS2 expression in LUAD was explored using The Cancer Genome Atlas (TCGA). Then, qRT‐PCR and Western blot were performed to confirm DARS2 expression in LUAD. Next, Cox regression and Kaplan–Meier methods were utilized to evaluate whether DARS2 expression can affect the overall survival. The relationships between DARS2 expression and clinicopathological characteristics were investigated by TCGA database. Moreover, we utilized Gene Set Enrichment Analysis (GSEA) to detect DARS2‐related signaling pathways in LUAD. Finally, the special function of DARS2 in cell proliferation, invasion and apoptosis was assessed in vitro.

Results

The higher expression of DARS2 was found in LUAD compared to para‐carcinoma tissues and significantly related to tumor stage, T stage, and M stage. The survival analysis indicated that DARS2 overexpression was related to poor prognosis in LUAD. Multivariate analysis suggested that DARS2 expression was a prognostic indicator. GSEA revealed that DARS2 was primarily involved in cell cycle‐related pathways. In addition, upregulation of DARS2 facilitated LUAD cell proliferation, migration, invasion and inhabited apoptosis, DARS2 knockdown showed an opposite result.

Conclusion

DARS2 modulates the proliferation, invasion and apoptosis of LUAD cells, and sever as a promising therapeutic target for LUAD.

The Leukodystrophies HBSL and LBSL-Correlates and Distinctions

Aminoacyl-tRNA synthetases (ARSs) accurately charge tRNAs with their respective amino acids. As such, they are vital for the initiation of cytosolic and mitochondrial protein translation. These enzymes have become increasingly scrutinized in recent years for their role in neurodegenerative disorders caused by the mutations of ARS-encoding genes. This review focuses on two such genes-DARS1 and DARS2-which encode cytosolic and mitochondrial aspartyl-tRNA synthetases, and the clinical conditions associated with mutations of these genes. We also describe attempts made at modeling these conditions in mice, which have both yielded important mechanistic insights. Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is a disease caused by a range of mutations in the DARS2 gene, initially identified in 2003. Ten years later, hypomyelination with brainstem and spinal cord involvement and leg spasticity (HBSL), caused by mutations of cytosolic DARS1, was discovered. Multiple parallels have been drawn between the two conditions. The Magnetic Resonance Imaging (MRI) patterns are strikingly similar, but still set these two conditions apart from other leukodystrophies. Clinically, both conditions are characterized by lower limb spasticity, often associated with other pyramidal signs. However, perhaps due to earlier detection, a wider range of symptoms, including peripheral neuropathy, as well as visual and hearing changes have been described in LBSL patients. Both HBSL and LBSL are spectrum disorders lacking genotype to phenotype correlation. While the fatal phenotype of Dars1 or Dars2 single gene deletion mouse mutants revealed that the two enzymes lack functional redundancy, further pursuit of disease modeling are required to shed light onto the underlying disease mechanism, and enable examination of experimental treatments, including gene therapies.