Gécz J, Hillman M A, Gedeon A K, Cox T C, Baker E, Mulley J C
Centre for Medical Genetics, Women's and Children's Hospital, Adelaide, South Australia, 5006, Australia.
Genomics. 2000 Oct 15;69(2):242-51. doi: 10.1006/geno.2000.6326.
Spondyloepiphyseal dysplasia tarda (SEDL) is an X-linked recessive disorder of endochondral bone formation caused by mutations in the SEDL gene. Here we present the structural analysis and subcellular localization of human SEDL. The SEDL gene is composed of six exons and spans a genomic region of approximately 20 kb in Xp22. It contains four Alu sequences in its 3' UTR and an alternatively spliced MER20 sequence in its 5' UTR (exon 2). Complex alternative splicing was detected for exon 4. Altogether seven SEDL pseudogenes were detected in the human genome: SEDLP1, a transcribed retropseudogene (or retro-xaptonuon) on chromosome 19q13.4 with potential to encode a protein identical to that of the SEDL gene; SEDLP2, another retropseudogene (not transcribed) on chromosome 8; and five truncated pseudogenes, SEDLP3-SEDLP7, on chromosome Yq11.23. Based on the knowledge of the yeast SEDL ortholog we speculated that the SEDL protein may participate along the ER-to-Golgi transport compartments. To test this hypothesis we performed transient transfection studies with tagged recombinant mammalian SEDL proteins in Cos-7 cells. The tagged SEDL proteins localized to perinuclear structures that partly overlapped with the intermediate ER-Golgi compartment (ERGIC; or vesicular tubular complex, VTC). Two human SEDL mutations (157-158delAT and C271T(STOP)) introduced into SEDL FLAG and GFP constructs led to the misplacement of the SEDL protein primarily to the cell nucleus and partially to the cytoplasm. Based on these experiments we suggest that the COOH end of the SEDL protein might be responsible for proper targeting of SEDL along the ER-Golgi membrane compartments (including Golgi and ERGIC/VTC).
迟发性脊椎骨骺发育不良（SEDL）是一种X连锁隐性疾病，由SEDL基因突变导致软骨内骨形成异常。在此，我们展示了人类SEDL的结构分析和亚细胞定位。SEDL基因由六个外显子组成，跨越Xp22约20 kb的基因组区域。其3'UTR包含四个Alu序列，5'UTR（外显子2）含有一个可变剪接的MER20序列。外显子4存在复杂的可变剪接。在人类基因组中总共检测到七个SEDL假基因：SEDLP1，位于19号染色体q13.4上的一个转录反转录假基因（或反转录xaptonuon），有潜力编码与SEDL基因相同的蛋白质；SEDLP2，位于8号染色体上的另一个反转录假基因（不转录）；以及位于Y染色体q11.23上的五个截短假基因，SEDLP3 - SEDLP7。基于对酵母SEDL直系同源物的了解，我们推测SEDL蛋白可能参与内质网到高尔基体的运输过程。为了验证这一假设，我们在Cos - 7细胞中对标记的重组哺乳动物SEDL蛋白进行了瞬时转染研究。标记的SEDL蛋白定位于核周结构，部分与内质网 - 高尔基体中间区室（ERGIC；或囊泡管状复合体，VTC）重叠。引入SEDL FLAG和GFP构建体的两个人类SEDL突变（157 - 158delAT和C271T(STOP)）导致SEDL蛋白错位，主要定位于细胞核，部分定位于细胞质。基于这些实验，我们认为SEDL蛋白的COOH末端可能负责SEDL在内质网 - 高尔基体膜区室（包括高尔基体和ERGIC/VTC）的正确靶向定位。
