LAMP-1/ESGp appears on the cell surface of single celled mouse embryos subsequent to fertilization.
LAMP-1/ESGp appears on the cell surface of single celled mouse embryos subsequent to fertilization.
复制标题
LAMP-1/ESGp 出现在受精后的单细胞小鼠胚胎的细胞表面。
DOI：
10.1007/s11626-998-0013-1
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Bonventre,EJ
中科院分区：
文献类型：
--
作者：
McCormick,PJ;Finneran,A;Bonventre,EJ
Dear Editor: The mouse t-complex is associated with, among other traits, a series of recessive embryonic t-lethal mutations which map to the centromeric portion of chromosome 17 (8). Evidence has been presented suggesting that the t-lethal alleles somehow specify surface antigens, each of which is expressed on t-bearing embryos and tes-ticular cells and for which the immunodominant determinant is a simple carbohydrate (8). An antigen associated with the earliest acting t-mutation, ie, t12 [which in the homozygous state blocks embryonic compaction (8)] had previously been identified by Cheng et al.(2). We have recently reported that this molecule (which we refer to as ESGp for embryonic surface glycoprotein) is expressed on the surface of early stage embryos and carries substantially more galactose, the immunodominant sugar for the" t12 associated antigen"(2), than do wild type or other t-lethal allele cells (1, 5). We also reported that biochemical, molecular, and immunological analyses indicate that this glycoprotein is highly homologous to mouse lysosomal associated protein (mLAMP-1). LAMP-1s are members of a family of conserved proteins found on the lumenal side of vertebrate lysosomal membranes (3). Because they are highly resistant to digestion by the molecular contents of the lysosome, one of the presumed functions of these proteins is to maintain lysosomal membrane integrity (3). Comparison of ESGp and mLAMP-1 indicates that they have similar N-terminal amino acid sequences and a shared internal peptide; have similar precursor, core, and mature protein sizes; are both sulfated but not phosphorylated; are extremely resistant to proteolytic digestion; and are distributed in a perinuclear cap of intracellular vesicles. Northern analysis with cDNA probes against both 5'and 3'regions and the full length LAMP-1 message reveal only a single murine transcript of 2.7 kb (5). However, there are some apparent differences between ESGp and mLAMP-1. The amino acid se-quences of the N-terminal and internal peptides differ at key residues (1). Southern analyses demonstrate that there are at least two separate mLAMP-1 loci (5) and immunological analyses indicate that the polyclonal anti-ESGp antiserum recognizes LAMP-1 type molecules not recognized by either mouse or human monoclonal anti-LAMP-1 antibodies (1). In particular, the polyclonal anti-ESGp antiserum recognizes cell surface-expressed molecules on early embryos, testicular cells, and embryonal carcinoma (EC) cells that are not recognized by mouse monoclonal anti-mLAMP-1 antibodies (1, 7). Curiously, the only cells on which we have detected surface expression using the mouse monoclonals have been the blastomeres of two cell-stage embryos. By the four-cell stage, mLAMP-1 surface expression can no longer be detected with the monoclonal antibody although it persists, at least through the morula stage, as evidenced by recognition with the anti-ESGp-antiserum (1, 7). In these earlier studies (1, 7), we did not examine embryos prior to the two-cell stage, and it is possible, therefore, that ESGp/LAMP-1 is present on the surface at earlier stages, such as the unfertilized oocyte or the fertilized egg. Such surface expressed molecules might then play a role in the process of fertilization. Therefore, we have now examined both fertilized and unfertilized single cell stage eggs via indirect immunofluorescence for reaction with the mouse anti-LAMP-i mab and the anti-ESGp antiserum.CF-1 female mice (Charles River) were injected with hormones for superovulation as previously described (1, 6) and caged alone or with fertile CF-1 male mice. Females caged with males were …
