Molecular cloning and expression analysis of heat shock protein 20 (HSP20) from the pearl oyster Pinctada martensii.

Small heat shock proteins (HSPs) are molecular chaperones with ATP-independent properties. They are involved in a variety of physiological and stress processes. In this study, the full-length HSP 20 (HSP20) from Pinctada martensii, designated as PmHSP20, was obtained from hemocytes using rapid amplification of cDNA ends technology. The PmHSP20 cDNA was 952 bp in length, containing an open reading frame of 534 bp that encoded 177-amino acid residues, with an isoelectric point of 5.86 and molecular weight of 20.24 kDa. The sequence of this deduced polypeptide contained typical structure and function domains conserved in the HSP20 family, providing evidence that PmHSP20 belongs to the HSP20 family. The PmHSP20 mRNA expression levels were detected in various tissues of P. martensii and in hemocytes after challenges with the bacteria Vibrio harveyi and lipopolysaccharide (LPS) using quantitative real-time polymerase chain reaction amplification. The results indicated that PmHSP20 is constitutively expressed in all tissues tested and might be involved in the immune response. The upregulation of PmHSP20 after V. harveyi and LPS challenge suggests that PmHSP20 plays an important role in anti-bacterial immunity. Studies on PmHSP20 are a valuable resource to further explore the immune system in pearl oysters and might enhance our knowledge of molluscan innate immunity.

Isolation and characterization of white and brown adipocytes in Kunming mice.

White adipose tissue and brown adipose tissue play critical roles in controlling energy homeostasis and the development of obesity and diabetes. We isolated mouse white adipocytes from inguinal white fat tissues and brown adipocytes from interscapular brown fat tissues, and employed a variety of approaches, including immunofluorescent staining, quantitative real-time PCR, western blotting analysis, and differentiation assay, to characterize those adipocytes. Both white and brown adipocytes stained positively for CD44 and CD29, and lipid droplets were observed after the induction of adipogenesis. The Asc1 expression level in the white adipocytes was 2.5-fold higher than that in the brown adipocytes (P < 0.05), and the expression of Ucp1 in the white adipocytes was approximately 50% of that in the brown adipocytes (P < 0.05). The expression of α-tubulin in the brown adipocytes was approximately 70% of that in the white adipocytes. The brown adipocytes had a higher Cidea mRNA level (P < 0.05) and a lower Pparγ mRNA level (P < 0.05) than the white adipocytes. The results demonstrate that white and brown adipocytes have different gene expression signatures, and may represent two useful cell models to study the mechanisms involved in obesity.

Molecular cloning and expression analysis of a pearl oyster (Pinctada martensii) heat shock protein 90 (HSP90).

Heat shock protein 90 (HSP90) is an important molecular chaperone required for proper folding of cellular proteins, and thus, it plays an essential role in protecting cells from damage during stress. In this study, an HSP90 cDNA designated PmHSP90 was cloned from the mantle tissue of the pearl oyster Pinctada martensii using reverse transcription polymerase chain reaction (RT-PCR) coupled with the rapid amplification of cDNA ends (RACE) approach. PmHSP90 cDNA was 2584 bp in length, including an open reading frame of 2160 bp, which encodes a polypeptide of 719 amino acid residues, with predicted molecular mass and isoelectric point of 83.0 kDa and 4.87, respectively. Multiple-sequence alignment indicated that HSP90 is highly conserved among species, and PmHSP90 showed 89% sequence identity to Crassostrea gigas HSP90. Five conserved amino acid blocks defined as HSP90 protein family signatures were also observed in PmHSP90, indicating that PmHSP90 may be a cytosolic member of the HSP90 family. Expression levels of PmHSP90 were detected in various tissues of P. martensii and in hemocytes under three different stress conditions using quantitative real-time PCR (qPCR). The results demonstrate that PmHSP90 mRNA is constitutively expressed in all the tested tissues and may be involved in the immune response against thermal stress, lipopolysaccharide stimulation, and nucleus insertion operations. Studies on PmHSP90 are a valuable source to further explore the immune system in pearl oysters during the production of pearls, and may enhance our knowledge of molluscan innate immunity.

Sos recruitment system for the analysis of the interaction between sulfatase-modifying factor 2 subtypes and interleukin-13.

Interleukin (IL)-13 is a central mediator in allergic asthma. Our previous results have indicated that sulfatase-modifying factor 2 (SUMF2) interacts with IL-13 and inhibits its secretion. In this study, we investigated the interactions between SUMF2 subtypes and 2 types of IL-13. Wild type IL-13 (wh-IL-13) and its mutated counterpart (mh-IL-13) were analyzed and cloned into pSos yeast expression vectors. Protein was expressed in host cdc25H yeast strains. A quartet of agar growth plates was prepared for the yeast two-hybrid system, which was used to detect IL-13 and SUMF2 subtype interactions. Both yeast expression vectors, pSos/whIL-13 and pSos/whIL-13, and recombinant expression vectors for the 5 subtypes of SUMF2 (pMyr/SUMF2-Vx) were constructed. Our data showed that all of the SUMF2 subtypes bound to whIL-13 and mhIL-13 in the CytoTrap system. Five SUMF2 subtypes - SUMF2-V2, SUMF2-V3, SUMF2-V4, SUMF2-V5, and SUMF2-V7--interacted with whIL-13 and mhIL-13. These subtypes may contribute to allergic asthma by mediating IL-13 release.