Abstract
Loricrin is the major protein component of the cornified cell envelope of terminally differentiated mammalian epidermal (stratum corneum) cells. Using a specific human cDNA clone, we have isolated and characterized the human loricrin gene. We show that it has a very simple structure of a single intron of 1188 base pairs (bp) in the 5'-untranslated region; there are no introns in coding sequences. By use of rodent-human somatic cell hybrids, followed by in situ hybridization with a biotin-labeled genomic DNA clone, the single-copy gene maps to chromosome location 1q21. Polymerase chain reaction analyses of genomic DNAs from different individuals show that human loricrin consists of two allelic size variants, due to sequence variations in its second glycine loop domain, and these variants segregate in the human population by normal Mendelian mechanisms. Furthermore, there are multiple sequence variants within these two size class alleles due to various deletions of 12 bp (4 amino acids) in the major loop of this glycine loop domain. By use of a specific loricrin antibody, we show by immunogold electron microscopy that loricrin initially appears in the granular layer of human epidermis and forms composite keratohyalin granules with profilaggrin, but localizes to the cell periphery (cell envelope) of fully differentiated stratum corneum cells.
Highlights
From the $Laboratoryof Skin Biology, National Institute of Arthritis and Musculoskeletal and S k i n Diseases and the BLaboratory of Biochemistry and
Polymerase chain reaction analyses of genomic DNAs from different individuals show that human loricrin consists of two allelic size variants,due to sequence variations in its second glycine loop domain, and these variants segregate in the human population by normal Mendelian mechanisms
By use of a specific loricrin antibody, we show by immunogold electron microscopy that loricrin initially appears in the granular layer of human epidermis and forms composite keratohyalin granules withprofilaggrin, but localizes to the cell periphery of fully differentiated stratum corneum cells
Summary
PCR was usedto amplify certain of the glycine loop sequences sion, structure, and function of the CE in normal as well as of loricrins using thevery highstringency conditionsdescribed earlier [25,26] and the Stoffel fragment of the Taqpolymerase [27].Routine diseased epidermis, it is necessary to further study the genes conditions used were: denaturation temperature of 95 "C, annealing for the CE structural protein components. We and elongation temperatures of 72-80 "C, and 33 cycles These methcharacterize the human loricrin gene, describe sequence pol- ods were standardized to the control genomic clone ofXHL-2 to ymorphisms in it that will be useful for future genetic linkage routinely yield a single amplified band.The lengths and sequences of analysis studies, and define its chromosomal location. Total human genomic DNA samples were obtained from mul- was elicited in goats against a synthetic peptideof the sequence His-
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