The gene encoding α_s1-casein is expressed in human mammary epithelial cells during lactation

Abstract

Summary -Reverse-phase high performance Iiquid chromatograhy lollowed by N-terminal microsequencing performed directly on each peak collected, has provided a comprehensive survey 01 six individual human milk protein Iractions. Sequencing 01 tryptic peptides arising lrom a putative Us1-casein Iraction identifies sequences showing some similarity with uS1-casein lrom other species. Ordering 01 these tryptic peptides and linally deciphering 01 the human uS1-casein amino acid sequence was achieved alter cloning and sequencing 01 the relevant cD NA, amplilied by reverse transcription-polyme rase chain reaction starting Irom mRNA extracted lrom mammary epithelial cells harvested lrom breast milk. Shorter th an its ruminant counterparts (170 vs 199 amino acid residues) the human uS1-casein displays very low similarities with us1-caseins known so lar, very Iikely owing to combinatory splicing processes, characteristic lor each species, as weil as to genomic rearrangements. It is elsewhere distinguishable by the presence 01 three cysteinyl residues. Multiple lorms 01 uS1-casein messengers were identified lrom each individual mRNA sample studied, strongly suggesting, therelore, a differential splicing lrom a single primary transcript. Finally, we provide delinite evidence lor the existence 01 a lunctional us1-Cas locus in the human genome, which is expressed in the mammary tissue during lactation. breast milk / RP-HPLC / human us1-casein 1 RT-PCR 1 cDNA 1 sequence Résumé -Le gène spécifiant la caséine Us1 est exprimé dans les cellules épithéliales mammaires humaines pendant la lactation.

Differential Splicing of Pre‐Messenger RNA Produces Multiple Forms of Mature Caprine αs1‐Casein

“…Total RNA was extracted from milk somatic cells according to the procedure of Chomczynsky and Sacchi (1987) with the modifica- tions described by Martin et al (1996). Goat genomic DNA was prepared from leukocytes isolated from plasma fraction of EDTA-anticoagulated peripheral blood samples, as described previously .…”

Potential uses of milk epithelial cells: a review

“…A simple procedure to isolate mRNA directly from milk cells has also been reported [38,41]. The existence of a s1 -casein polymorphism in humans, previously shown in goats and cows, was demonstrated by the reverse transcriptase polymerase chain reaction technique (RT-PCR) using RNA from human milk epithelial cells [41].…”

“…The existence of a s1 -casein polymorphism in humans, previously shown in goats and cows, was demonstrated by the reverse transcriptase polymerase chain reaction technique (RT-PCR) using RNA from human milk epithelial cells [41]. Similarly, b casein mRNA and its gene were studied in epithelial cells isolated from human milk [38] and from bovine colostrum [26].…”

A specific pattern of splicing for the horse ?S1-Casein mRNA and partial genomic characterization of the relevant locus

“…From another highly conserved region detected in the 3 -UTR after the alignment of known αS1-Cn cDNA sequences from various species, the BT56 reverse primer was defined, starting 13 to 15 nt upstream of the polyadenylation signal as previously described [18]. DNA fragments obtained after PCR on reversed transcribed mRNA under standard conditions using the αS1-Cn BT56/71 specific primer pair were cloned into pUC18 essentially as previously described [18]. These clones were screened by PCR using the same αS1-Cn primer pair, BT56/71.…”