BioProject

Vitamin D deficiency poses a major global health challenge, shaped by environmental and genetic determinants. In this genetic context, the recently discovered rs11542462 nonsense variant in the short-chain dehydrogenase/reductase 42E1 (SDR42E1) gene emerges as a critical regulator, though its biological implications remain largely unexplored. Our comprehensive bioinformatic assessments revealed pronounced expression of SDR42E1 in skin keratinocytes and the analogous HaCat human keratinocyte cell lines, prompting us to select the latter as an experimental model. Employing CRISPR/Cas9 technology and an integrated multi-omics approach, combining transcriptomics and proteomics, we explored SDR42E1's functions, focusing on its localization, role in lipid and steroid biosynthesis, and the consequent effects on vitamin D biosynthesis. We highlighted the significant cytoplasmic presence of the SDR42E1 protein, essential for lipid and steroid production. Our whole transcriptomics analysis of the SDR42E1 depleted model showed a notable disruption in the steroid biosynthesis pathway by 1.6-fold (P = 0.03). This disruption was accompanied by considerable alterations in genes involved in vitamin D synthesis, a finding supported by our proteomics data. Notably, SERPINB2 (P = 2.17E−103), EBP (P = 2.46E−13), and DHCR7 (P = 8.03E−09) showed significant elevations by ~2-3 fold, while ALPP (P < 2.2E−308), SLC7A5 (P = 1.96E−215), and CYP26A1 (P = 1.06E−08) decreased by ~1.5-3 fold. These alterations led to an accumulation of 7-dehydrocholesterol, preventing its conversion to vitamin D3, as evidenced by our drug enrichment analysis (P = 4.39E−06). This investigation unveils SDR42E1's pivotal role in vitamin D homeostasis and its broader impact on metabolic pathways. Our findings provide a foundation for future research and highlight the potential of precision medicine in addressing vitamin D deficiency, offering significant insights into the genetic regulation of vitamin D biosynthesis. Overall design: To investiage global transcriptomic changes associated with SDR42E1, a suggested modulator of serum vitamin D levels, we performed bulk RNA sequencing on HaCat cell lines subjected to CRISPR/Cas9-induced SDR42E1 homozygous knockout, alongside wild-type HaCat cells serving as negative controls, all sampled simultaneously. Each sample in this study comprises three biological replicates.