Enzymatic activity of cGAS in the presence of three types of DNAs: limited cGAS stimulation by single-stranded HIV-1 SL2 DNA

Cyclic GMP-AMP (cGAMP) synthase (cGAS) is activated by binding to DNA. Activated cGAS produces 2'3'-cGAMP, which subsequently binds to the adaptor protein STING (stimulator of interferon genes). This interaction triggers the cGAS/STING signaling pathway, leading to the production of type I interferons. Three types of DNA, namely double-stranded DNA longer than 40 base pairs, a 70-nucleotide single-stranded HIV-1 DNA known as SL2, and Y-form DNA with unpaired guanosine trimers (G3 Y-form DNA), induce interferon production by activating cGAS/STING signaling. However, the extent of cGAS activation by each specific DNA type remains unclear. The comparison of cGAS stimulation by various DNAs is crucial for understanding the mechanisms underlying cGAS-mediated type I interferon production in the innate immune response. Here, we revealed that cGAS produces 2'3'-cGAMP at a significantly lower rate in the presence of single-stranded SL2 DNA than in the presence of double-stranded DNA or G3 Y-form DNA. Furthermore, the guanine-to-cytosine mutations and the deletion of unpaired guanosine trimers significantly reduced the 2'3'-cGAMP production rate and the binding of cGAS to Y-form DNA. These studies will provide new insights into the cGAS-mediated DNA-sensing in immune response.

New treatment of free-radical scavenger in adrenoleukodystrophy

WHAT IS KNOWN AND OBJECTIVE

Adrenoleukodystrophy (ALD) is an X-linked disorder and characterized by the accumulation of saturated very long-chain fatty acids. Treatment is still unsatisfactory. Our objective is to report on the effect of the free-radical scavenger, edaravone, in a patient with ALD.

CASE SUMMARY

The patient was given edaravone intravenously twice. D-ROM in cerebral spinal fluid decreased dramatically, and a shortening of neuronal transmission time as estimated on somatosensory evoked potential was observed. After terminating the treatment, his symptoms progressively reappeared.

WHAT IS NEW AND CONCLUSION

This is the first report of the use of edaravone in ALD. The drug is apparently effective in improving symptoms of ALD and should be evaluated more formally.

Sudden unexpected death associated with ileocecal duplication cyst and clinical review

Duplications of the alimentary tract are very rare. A one-month-old female presented with symptoms of anorexia, vomiting and continuous watery diarrhea. The plain abdominal radiograph showed thickened intestinal wall and signs of small bowel obstruction. The fevers, vomiting, and continuous wartery diarrhea persisted despite antibiotics, and worsened. The patient failed to respond to medical managements, 27 hours after admission, the patient died due to multiple organ failures. The autopsy was performed, small bowel obstruction due to an ileocecal duplication cyst (3 × 3 cm) was recognized. The ileocecal duplication cyst was attached to the ileum which was changed edematous and necrotic. This potential diagnosis should be borne in mind for a patient who complains of abdominal symptoms with an unknown cause, and duplication cyst should be recognized as a fatal cause in infant.