The presence of messenger RNA for HLA class I in human platelets and its capability for protein biosynthesis

Abstract

In order to determine whether platelets contain specific messenger RNA encoding for HLA class I molecules, polymerase chain reaction (PCR) was performed with RNA from different platelet donors. Two amplified 300 bp and 279 bp cDNA fragments were obtained which encompassed sequences from 321 to 620 and from 795 to 1073. The 300 bp fragment encodes exon 2 and exon 3, the 279 bp encodes a portion of exon 4, exon 5, exon 6 and a portion of exon 7. A 300 bp nested PCR product from one donor, that encoded for the highly polymorphic region alpha 2, was cloned and sequenced. The resulting nucleotide sequences fitted to the expected sequence for HLA B*3801 of this donor. Sequence analysis of the 279 bp PCR product demonstrated the presence of exon 5 encoding for the 117 bp transmembrane domain. In addition, de novo protein biosynthesis was studied by radioimmunoprecipitation of HLA class I molecules from 35S-methionine metabolically labelled platelet lysates with a monoclonal antibody (mab) w6/32 specific for a monomorphic epitope on the heavy chain of HLA class I antigens. Analysis of the immunoprecipitates on SDS polyacrylamide gel electrophoresis showed a specific band with apparent molecular weight (M(r)) of 44 kD corresponding to integral membrane HLA protein. On the basis of these results, we conclude that platelets contain specific messenger RNA encoding for HLA class I molecules and have the capability to synthesize the integral HLA membrane protein.

Selective release of circRNAs in platelet‐derived extracellular vesicles

“…Platelets are peculiar in that they are, first, relatively short-lived (~7 days half-life); second, they are the smallest cells of blood, and third, although without a nucleus, they exhibit active RNA metabolism and are translationally active [2–5]. During thrombopoiesis, anucleated platelets are derived from megakaryocytes in the bone marrow and are released into the bloodstream.…”

Identification of serotonin transporter mRNA in rat platelets

“…Blood platelets, as cytoplasmic fragments of megakaryocytes, lack nucleus, but have been shown to contain RNA (Ault et al, 1992) and possess biosynthetic activity for the major platelet proteins (Kiefer et al, 1987). By the use of polymerase chain reaction (PCR), the presence of metabolically stable mRNA in human platelets was documented for some of the platelet proteins (Konkle et al, 1993;Matsuda et al, 1993;Mehta et al, 1995;Santoso et al, 1993), as well as the possibility of detecting changes in platelet mRNA levels in some pathologies (Matsuda et al, 1993). The existence of mRNA for platelet 5HT transporter was demonstrated in humans using Northern blot analysis and confirmed by reverse transcriptase-PCR (Lesch et al, 1993a).…”

MHC Class I–Associated Peptides Identified From Normal Platelets and From Individuals With Idiopathic Thrombocytopenic Purpura

“…It has been shown that platelets retain mRNA from megakaryocytes [41]. It has also been shown that platelets contain rough endoplasmic reticulum and polyribosomes, and de novo protein biosynthesis can occur in platelets (including translation of HLA) [42,43]. In addition, platelets contain the 20S proteasome [44,45].…”