Hhatl Reduces Apoptosis of Müller Cells in Diabetic Retinopathy by Relieving Endoplasmic Reticulum Stress.

BACKGROUND

Diabetic retinopathy (DR), a microvascular disease, also involves retinal neurodegeneration. Müller cells exert an important role in the retina, and their destabilization and reduction affect the physiological function of the retina. To investigate the effect and mechanism of hedgehog acyltransferase-like (Hhatl) on Müller cells in DR.

METHODS

The differentially expressed genes (DEGs) in Müller cells of DR rats were first analyzed by single-cell transcriptomics techniques (scRNA-seq). Regulating Hhatl expression, cell viability was detected using cell counting kit-8 (CCK-8) assay; apoptosis was detected by terminal deoxynucleotidyl transferase nick-end labeling (TUNEL); the expression of B-cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax), activating transcription factor 6 (ATF6), C/EBP homologous protein (CHOP), and glucose-regulated protein 78 (GRP78) was assessed by immunofluorescence; and Ca2+ concentration was determined by fluorescence quantification to observe the effect and mechanism of Hhatl on Müller cells of the high glucose (HG)-treated rats. Finally, the results of the cell assays were verified in male 6-week-old Zucker (fa/fa) diabetic fatty (ZDF) rats. Viral vectors expressing Hhatl were injected into the vitreous of ZDF rats, and apoptosis and endoplasmic reticulum stress (ERS)-related indices in rat retinal cells were detected using immunofluorescence.

RESULTS

scRNA-seq analysis revealed that Hhatl was low-expressed in Müller cells of DR rats. In vitro assays confirmed that upregulation of Hhatl could increase rMC-1 Bcl2 expression, decrease Bax expression, and reduce apoptosis in HG environments. In addition, Hhatl did downregulate ATF6 expression, decrease CHOP and GRP78 levels, and reduce Ca2+ concentration. Animal assays showed that Hhatl overexpression in the vitreous of ZDF rats did elevate Bcl2 level, decrease Bax expression, and reduce ATF6, CHOP, and GRP78 levels, which alleviated ERS in the retina of ZDF rats.

CONCLUSION

Hhatl reduces apoptosis of Müller cells in DR by alleviating ATF6-related ERS signaling.