Comprehensive royal jelly (RJ) proteomics using one- and two-dimensional proteomics platforms reveals novel RJ proteins and potential phospho/glycoproteins

Molecular and biochemical characterization of the major royal jelly protein in bumblebees suggest a non-nutritive function

Honeybee queens are generated on purpose by extensive feeding with a glandular secretion termed royal jelly. Major royal jelly proteins (MRJPs) are the dominant proteinaceous component of royal jelly. One of them, MRJP1, was found to play a central role in honeybee queen development. Genes encoding MRJPs were reported to originate from a single originator, and several of them have evolved nutritive function. Phylogenetic analysis provides evidence that the same originator has multiplied independently in Nasonia and ant lineages. Here we show that bumblebees represent a transition species preserving a single-copy pre-multiplication stage of MRJP evolution. By exploring the single-copy BtRJPL gene, we found striking similarities with MRJPs of the honeybee such as gene structure and expression regulation. At the same time it turned out that BtRJPL does not fulfill criteria for functioning as a nutritive protein. Instead we found evidence that BtRJPL is involved in food digestion or modification, which appears to be the original MRJP function, at least in this lineage. Thus, the evolutionary pattern of MRJPs in hymenopterans constitutes an excellent example of a functional diversification combined with the origin of new properties followed by intensive gene duplication events.

Growth stimulating effect on queen bee larvae of histone deacetylase inhibitors

Royal jelly (RJ) is a widely used natural food. It is also a major source of nutrition for queen bees and plays a key role in their development. RJ is secreted from the hypopharyngeal and mandibular glands of young adult worker bees. The regulation of gene expression in these two glands may influence the development of queen bees by affecting the content of RJ. This study investigated the epigenetic effects in these two glands in young adult worker bees treated with histone deacetylase inhibitors (HDACis), a U.S. Food and Drug Administration-approved drug, suberoylanilide hydroxamic acid (SAHA), and NBM-HD-1, a novel compound synthesized in this laboratory. Western blot analyses indicated that the levels of acetyl-histone 3 and p21 protein expression in MCF-7 cells increased markedly after treatment with NBM-HD-1. The data proved that NBM-HD-1 was a novel and potent HDACi. Furthermore, a method of affecting epigenetic regulation of the mrjp family gene in the hypopharyngeal and mandibular glands of young adult worker bees was developed by feeding young adult worker bees HDACi. Epigenetic regulation produced several important biological effects. A marked change in the protein composition of the RJ secreted from these treated bees was found. Only the ratio of specific major royal jelly protein 3 (MRJP3) was significantly altered in the treated bees versus the untreated controls. Other MRJP family proteins did not change. This alteration in the ratio of royal jelly proteins resulted in a significant increase in the body size of queen bee larvae. The data seem to suggest that HDACis may play an important role in the epigenetic regulation of the hypopharyngeal and mandibular glands of young adult worker bees. They appear to change mrjp3 gene expression and alter the ratio of MRJP3 protein in RJ. This study presents the first evidence that HDACis are capable of regulating the ratio of MRJP3 proteins in RJ, which has the potential to change the body size of queen bees during their development.

Towards posttranslational modification proteome of royal jelly

Royal jelly (RJ) is a secretory protein from the hypopharyngeal glands of nurse honeybee workers, which contains a variety of proteins of which major royal jelly proteins (MRJPs) are some of the most important. It plays important roles both for honeybee and human. Each family of MRJP 1-5 displays a string of modified protein spots in the RJ proteome profile, which may be caused by posttranslational modifications (PTMs) of MRJPs. However, information on the RJ PTMs is still limited. Therefore, the PTM status of RJ was identified by using complementary proteome strategies of two-dimensional gel electrophoresis (2-DE), shotgun analysis in combination with high performance liquid chromatography-chip/electrospray ionization quadrupole time-of-flight/tandem mass spectrometry and bioinformatics. Phosphorylation was characterized in MRJP 1, MRJP 2 and apolipophorin-III-like protein for the first time and a new site was localized in venom protein 2 precursor. Methylation and deamidation were also identified in most of the MRJPs. The results indicate that methylation is the most important PTM of MRJPs that triggers the polymorphism of MRJP 1-5 in the RJ proteome. Our data provide a comprehensive catalog of several important PTMs in RJ and add valuable information towards assessing both the biological roles of these PTMs and deciphering the mechanisms underlying the beneficial effects of RJ for human health.

Worker honeybee brain proteome

A large-scale mapping of the worker honeybee brain proteome was achieved by MudPIT. We identified 2742 proteins from forager and nurse honeybee brain samples; 17% of the total proteins were found to be differentially expressed by spectral count sampling statistics and a G-test. Sequences were compared with the EuKaryotic Orthologous Groups (KOG) catalog set using BLASTX and then categorized into the major KOG categories of most similar sequences. According to this categorization, nurse brain showed increased expression of proteins implicated in translation, ribosomal structure, and biogenesis (14.5%) compared with forager (1.8%). Experienced foragers overexpressed proteins involved in energy production and conversion, showing an extensive difference in this set of proteins (17%) in relation to the nurse subcaste (0.6%). Examples of proteins selectively expressed in each subcaste were analyzed. A comparison between these MudPIT experiments and previous 2-DE experiments revealed nine coincident proteins differentially expressed in both methodologies.

Novel royal jelly proteins identified by gel-based and gel-free proteomics

Royal jelly (RJ) plays an important role in caste determination of the honeybee; the genetically same female egg develops into either a queen or worker bee depending on the time and amount of RJ fed to the larvae. RJ also has numerous health-promoting properties for humans. Gel-based and gel-free proteomics approaches and high-performance liquid chromatography-chip quadruple time-of-flight tandem mass spectrometry were applied to comprehensively investigate the protein components of RJ. Overall, 37 and 22 nonredundant proteins were identified by one-dimensional gel electrophoresis and gel-free analysis, respectively, and 19 new proteins were found by these two proteomics approaches. Major royal jelly proteins (MRJPs) were identified as the principal protein components of RJ, and proteins related to carbohydrate metabolism such as glucose oxidase, α-glucosidase precursor, and glucose dehydrogenase were also successfully identified. Importantly, the 19 newly identified proteins were mainly classified into three functional categories: oxidation-reduction (ergic53 CG6822-PA isoform A isoform 1, Sec61 CG9539-PA, and ADP/ATP translocase), protein binding (regucalcin and translationally controlled tumor protein CG4800-PA isoform 1), and lipid transport (apolipophorin-III-like protein). These new findings not only significantly increase the RJ proteome coverage but also help to provide new knowledge of RJ for honeybee biology and potential use for human health promotion.

Molecular characteristics and physiological functions of major royal jelly protein 1 oligomer

Royal jelly contains numerous components, including proteins. Major royal jelly protein (MRJP) 1 is the most abundant protein among the soluble royal jelly proteins. In its physiological state, MRJP 1 exists as a monomer and/or oligomer. This study focuses the molecular characteristics and functions of MRJP 1 oligomer. MRJP 1 oligomer purified using HPLC techniques was subjected to the following analyses. The molecular weight of MRJP 1 oligomer was found to be 290 kDa using blue native-PAGE. MRJP 1 oligomer was separated into 55 and 5 kDa spots on 2-D blue native/SDS-PAGE. The 55 kDa protein was identified as MRJP 1 monomer by proteome analysis, whereas the 5 kDa protein was identified as Apisimin by N-terminal amino acid sequencing, and this protein may function as a subunit-joining protein within MRJP 1 oligomer. We also found that the oligomeric form included noncovalent bonds and was stable under heat treatment at 56 degrees C. Furthermore, MRJP 1 oligomer dose dependently enhanced and sustained cell proliferation in the human lymphoid cell line Jurkat. In conclusion, MRJP 1 oligomer is a heat-resistant protein comprising MRJP 1 monomer and Apisimin, and has cell proliferation activity. These findings will contribute to further studies analyzing the effects of MRJP 1 in humans.

Identification of major royal jelly proteins in the brain of the honeybee Apis mellifera

The consumption of royal jelly (RJ) determines the differences between castes and behavioral development in the honeybee Apis mellifera. However, it is not known whether the proteins of RJ are related to these differences, or which proteins are responsible for the changes. To understand the functions of RJ proteins that are present in other tissues of the bee, in addition to hypopharyngeal gland, we used a polyclonal antibody anti-MRJP1 to investigate the presence of this protein in nervous system of honeybee. This study showed the presence of three polypeptides (p57, p70 and p128) in specific tissues of bee brain. Mushroom body, optic lobe and antennal lobe neuropils all contained proteins recognized by anti-MRJP1. Proteomic analysis showed that the three polypeptides are correlated with proteins of the MRJP family. p57 is correlated with MRJP1, p70 with MRJP3, while p128 may be an oligomeric form or a new polypeptide. Immunostaining of the brain and hypopharyngeal gland revealed differential expression of MRJPs in various brain regions and in different honeybee castes and subcastes. The identification and localization of these MRJPs contribute to the elucidation of the biological roles of this protein family.

Electrospray ionization mass spectrometry as a critical tool for revealing new properties of snake venom phospholipase A2

Results from high-performance liquid chromatography/nano-electrospray ionization tandem mass spectrometry (HPLC/nESI-MS/MS) coupled to two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2D SDS-PAGE) indicated that the monomer and dimer of phospholipase A(2) (PLA(2)) coexisted in crude Chinese Agkistrodon blomhoffii Ussurensis snake venom (ABUSV). Then, an acidic PLA(2) with the accurate molecular mass of 13979.6 Da was purified from ABUSV (mo-ABUSV-aPLA(2)). MS/MS-derived peptides from ABUSV-aPLA(2) were compared with other homologous snake venom PLA(2)s, which in turn showed that ABUSV-aPLA(2) is a novel snake venom PLA(2). Meanwhile, the ABUSV-aPLA(2) dimer (di-ABUSV-aPLA(2)) was also obtained. MS/MS analysis identified the same peptides from di-ABUSV-aPLA(2) as from mo-ABUSV-aPLA(2), which indicates that di-ABUSV-aPLA(2) is a homodimer. One Ca(2+) ion is contained per ABUSV-aPLA(2). The Ca(2+) ion is critical for both the hydrolytic activity and the structure of ABUSV-aPLA(2). Pro-Q Emerald and Pro-Q Diamond specific glycoprotein and phosphoprotein staining combined with MS/MS analysis indicated that the ABUSV-aPLA(2) is both a glycoprotein and a phosphoprotein, which to our knowledge is the first such report for a snake venom PLA(2) and thus provides new threads for the study of the functions and structures of snake venom PLA(2)s. One phosphorylation site and the size of the glycan chain are determined by using HPLC/nESI-MS/MS and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS. The delicate utilization of ESI-MS can exert tremendous impact on protein sciences.

Applications of proteomics in the study of inflammatory bowel diseases: Current status and future directions with available technologies

Inflammatory bowel diseases (IBD) are chronic, heterogeneous, and multifactorial intestinal inflammatory disorders. Major challenges in IBD research include identification of major pathogenic alterations of genes/proteins as well as effective biomarkers for early diagnosis, prognosis, and prediction of therapeutic response. Since proteins govern cellular structure and biological function, a wide selection of proteomic approaches enables effective characterization of IBD pathogenesis by investigating the dynamic nature of protein expression, cellular and subcellular distribution, posttranslational modifications, and interactions at both the cellular and subcellular levels. The aims of this review are to 1) highlight the current status of proteomic studies of IBD, and 2) introduce the available and emerging proteomic technologies that have potential applications in the study of IBD. These technologies include various mass spectrometry technologies, quantitative proteomics (2D-PAGE, ICAT, SILAC, iTRAQ), protein/antibody arrays, and multi-epitope-ligand cartography. This review also presents information and methodologies, from sample selection and enrichment to protein identification, that are not only essential but also particularly relevant to IBD research. The potential future application of these technologies is expected to have a significant impact on the discovery of novel biomarkers and key pathogenic factors for IBD.