PMID- 35625601 OWN - NLM STAT- MEDLINE DCOM- 20220531 LR - 20220716 IS - 2218-273X (Electronic) IS - 2218-273X (Linking) VI - 12 IP - 5 DP - 2022 May 6 TI - Loricrin at the Boundary between Inside and Outside. LID - 10.3390/biom12050673 [doi] LID - 673 AB - Cornification is a specialized mode of the cell-death program exclusively allowed for terrestrial amniotes. Recent investigations suggest that loricrin (LOR) is an important cornification effector. As the connotation of its name ("lorica" meaning an armor in Latin) suggests, the keratin-associated protein LOR promotes the maturation of the epidermal structure through organizing covalent cross-linkages, endowing the epidermis with the protection against oxidative injuries. By reviewing cornification mechanisms, we seek to classify ichthyosiform dermatoses based on their function, rather than clinical manifestations. We also reviewed recent mechanistic insights into the Kelch-like erythroid cell-derived protein with the cap "n" collar homology-associated protein 1/nuclear factor erythroid 2-related factor 2 (NRF2) signaling pathway in skin health and diseases, as LOR and NRF2 coordinate the epidermis-intrinsic xenobiotic metabolism. Finally, we refine the theoretical framework of cross-talking between keratinocytes and epidermal resident leukocytes, dissecting an LOR immunomodulatory function. FAU - Ishitsuka, Yosuke AU - Ishitsuka Y AUID- ORCID: 0000-0002-1733-5427 AD - Department of Dermatology Integrated Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita 565-0871, Osaka, Japan. FAU - Roop, Dennis R AU - Roop DR AD - Department of Dermatology and Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA. LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't PT - Review DEP - 20220506 PL - Switzerland TA - Biomolecules JT - Biomolecules JID - 101596414 RN - 0 (Membrane Proteins) RN - 0 (NF-E2-Related Factor 2) RN - 0 (loricrin) SB - IM MH - Epidermis/metabolism MH - Keratinocytes/metabolism MH - *Membrane Proteins/metabolism MH - *NF-E2-Related Factor 2/metabolism PMC - PMC9138667 OTO - NOTNLM OT - Langerhans cell OT - TGF-beta OT - ichthyosis OT - loricrin OT - oxidation OT - reduction COIS- The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. EDAT- 2022/05/29 06:00 MHDA- 2022/06/01 06:00 PMCR- 2022/05/06 CRDT- 2022/05/28 01:06 PHST- 2022/04/13 00:00 [received] PHST- 2022/04/30 00:00 [revised] PHST- 2022/05/04 00:00 [accepted] PHST- 2022/05/28 01:06 [entrez] PHST- 2022/05/29 06:00 [pubmed] PHST- 2022/06/01 06:00 [medline] PHST- 2022/05/06 00:00 [pmc-release] AID - biom12050673 [pii] AID - biomolecules-12-00673 [pii] AID - 10.3390/biom12050673 [doi] PST - epublish SO - Biomolecules. 2022 May 6;12(5):673. doi: 10.3390/biom12050673.