A Glance into the Destiny of Transcriptomic Activity, Embodied by the HOX Genes, in Neonatal and Aging Dermal Cells.

Skin is an organ having a crucial role in the protection of muscle, bone, and internal organs and undergoing continuous self-renewal and aged. The growing interest in the prevention of skin aging and rejuvenation has sparked a surge of industrial and research studies focusing on the biological and transcriptional changes that occur during skin development and aging. In this study, the aim is to identify transcriptional differences between two main types of human skin cells: the human dermal fibroblasts (HDFs) and the human epidermis keratinocytes (HEKs) isolated from 30 neonatal and 30 adults (old) skin. Through differentially expressed gene (DEG) profiling using DEseq2, 604 up-, and 769 down-regulated genes are identified in the old group. A functional analysis using Metascape Gene Ontology and Reactome pathways revealed systematic transcriptomic shifts in key skin formation and maintenance markers, alongside a distinct difference in HOX gene families crucial for embryonic development and diverse biological processes. Among the 39 human HOX gene family, ten posterior HOX genes (HOXA10, 11, 13, HOXB13, HOXC11, and HOXD9-13) are significantly downregulated, and anterior 25 genes (HOXA2-7, HOXB1-9, HOXC4-6 and 8-9, and HOXD1,3,4 and 8) are upregulated, especially in the old HDFs. The study successfully demonstrates the correlation between HOX genes and the skin aging process, providing strong evidence that HOX genes are proposed as a new marker for skin aging assessment.

Dermatobacter hominis gen. nov., sp. nov., a new member of the family Iamiaceae, revealed the potential utilisation of skin-derived metabolites.

A non-motile, novel actinobacterial strain, Kera-3T, which is a gram-positive, aerobic, rod-shaped bacterium, was isolated from human keratinocytes on 1/10 diluted R2A agar. Whole-cell hydrolysis of amino acids revealed the presence of meso-DAP, alanine, and glutamic acid. The predominant menaquinone was MK-9 (H8), whereas the primary fatty acids were C16:0 and C18:1 ω9c. The major phospholipids included diphosphatidylglycerol and aminophospholipids, along with an unidentified phosphoglycolipid and an aminophosphoglycolipid. The G+C content of the genomic DNA was 73.2%, based on the complete genome sequence. Phylogenetic analyses of the 16S rRNA gene sequence and phylogenomic analysis of 91 core genes showed that strain Kera-3T formed a new lineage in the family Iamiaceae, with the closest neighbour Rhabdothermincola sediminis SYSU G02662T having 91.19% 16S rRNA gene sequence identity. A comparative genomic study of the predicted general metabolism and carbohydrate-active enzymes supported the phylogenetic and phylogenomic data. Based on the analysis of physiological, biochemical, and genomic characteristics, strain Kera-3T can be distinguished from known genera in the family Iamiaceae and represents a novel genus and species. Therefore, the name Dermatobacter hominis gen. nov., sp. nov. was proposed, with the type strain Kera-3T (= KACC 22415T = LMG 32493T).