Two major 5'-untranslated regions for type XVII collagen mRNA.
BACKGROUND
Type XVII collagen is an important structural component of keratinocyte hemidesmosomes and its functional loss in genetic or autoimmune disease results in blistering of the skin. In neoplastic tissue aberrant expression is seen dependent on the stage of the tumor. While the sequence of the type XVII collagen encoding gene -COL17A1 - is now completely elucidated, the sequence of the 5'-untranslated region (UTR) of the mRNA is still unknown. Since UTRs can modulate translation efficiency, the determination of the UTR sequence is indispensable for understanding the regulation of translation of type XVII collagen mRNA.


OBJECTIVE
To resolve the sequence of the 5'UTR of type XVII collagen mRNA and to analyse the promoter region for transcription motifs.


METHODS
5' Rapid amplification of cDNA ends (RACE) followed by sequence analysis and ribonuclease protection assays (RPA) were performed.


RESULTS
RACE and sequence analysis revealed the presence of six different 5'UTRs for the type XVII collagen mRNA. The start points of these six transcripts differ but no alternative exons are used. The longest 5'UTR starts 220 nucleotides before the open reading frame, whereas the shortest UTR is only 89 nucleotides in length. RPA confirmed the RACE results and furthermore demonstrated that the 5'UTRs with lengths of 102 and 220 nucleotides are the two major transcripts. Transcription motif analysis of the 5' region of the COL17A gene demonstrated several binding sites for transcription factors including the Sp1 and activating protein-1 (AP-1) families.


CONCLUSIONS
Type XVII collagen mRNA is alternatively transcribed, which may result in complex regulation of type XVII collagen.
van Zalen
Sebastiaan
S
Department of Dermatology, Center for Blistering Diseases, University Medical Center Groningen, University of Groningen, Hanzeplein 1, NL-9713 GZ Groningen, The Netherlands.
Nijenhuis
Miranda
M
Jonkman
Marcel F
MF
Pas
Hendri H
HH
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D017398:Alternative Splicing; D001324:Autoantigens / Q000235:genetics*; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000235:genetics; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D024041:Non-Fibrillar Collagens / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics*; D012334:RNA, Neoplasm / Q000235:genetics; D000097805:Collagen Type XVII
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D001324:Autoantigens; D017931:DNA Primers; D024041:Non-Fibrillar Collagens; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D000097805:Collagen Type XVII