Knockdown of SAR1B suppresses proliferation and induces apoptosis of RKO colorectal cancer cells

Sar1 Interacts with Sec23/Sec24 and Sec13/Sec31 Complexes: Insight into Its Involvement in the Assembly of Coat Protein Complex II in the Microsporidian Nosema bombycis

Microsporidia, as unicellular eukaryotes, also have an endomembrane system for transporting proteins, which is essentially similar to those of other eukaryotes. In eukaryotes, coat protein complex II (COPII) consists of Sar1, Sec23, Sec24, Sec13, and Sec31 and mediates protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus. Sar1 is the central player in the regulation of coat protein complex II vesicle formation in the endoplasmic reticulum. In this study, we successfully cloned the NbSar1, NbSec23-1, NbSec23-2, NbSec24-1, NbSec24-2, NbSec13, NbSec31-1, and NbSec31-2 genes and prepared NbSar1 polyclonal antibody. We found that NbSar1 was localized mainly in the perinuclear cytoplasm of Nosema bombycis by immunofluorescence analysis (IFA). Yeast two-hybrid assays demonstrated that NbSar1 interacts with NbSec23-2, NbSec23-2 interacts with NbSec24-1 or NbSec24-2, NbSec23-1 interacts with NbSec31, and NbSec31 interacts with NbSec13. Moreover, the silencing of NbSar1 by RNA interference resulted in the aberrant expression of NbSar1, NbSec23-1, NbSec24-1, NbSec24-2, NbSec13, NbSec31-1, and NbSec31-2 and significantly inhibited the proliferation of N. bombycis. Altogether, these findings indicated that the subunits of coat protein complex II work together to perform functions in the proliferation of N. bombycis and that NbSar1 may play a crucial role in coat protein complex II vesicle formation. IMPORTANCE As eukaryotes, microsporidia have retained the endomembrane system for transporting and sorting proteins throughout their evolution. Whether the microsporidia form coat protein complex II (COPII) vesicles to transport cargo proteins and whether they play other roles besides cargo transport are not fully explained at present. Our results showed that NbSar1, NbSec23-1/NbSec23-2, NbSec24-1/NbSec24-2, NbSec13, and NbSec31 might be assembled to form COPII in the ER of N. bombycis, and the functions of COPII are also closely related to the proliferation of N. bombycis, this may be a new target for the prevention of pébrine disease of the silkworm.

Over-expression of SRD5A3 and its prognostic significance in breast cancer

Objective

The study aimed to compare the Steroid 5 alpha-reductase 3 (SRD5A3) expression levels in breast cancer (BC) and normal tissues, to investigate the prognostic value of SRD5A3 mRNA expression in BC patients and to identify the SRD5A3-related signaling pathways using bioinformatics approaches.

Methods

We evaluated the expression levels of SRD5A3 and survival data in BC patients using different bioinformatic databases. Further, Cox regression analysis was conducted to predict the independent prognostic factors for BC. Moreover, the association of SRD5A3 with clinicopathological factors was measured through LinkedOmics database. And the potential role of SRD5A3 was determined by Gene Ontology and KEGG pathway enrichment analysis. Finally, protein network of SRD5A3 was constructed and genetic alterations were analyzed.

Results

Bioinformatic data indicated that both mRNA and protein expression levels of SRD5A3 were higher in BC group than those in the normal group (P < 0.05). Besides, BC patients with higher SRD5A3 mRNA expression levels had a lower overall survival (all P < 0.05). Cox regression analysis further demonstrated the independent prognostic value of SRD5A3 in BC (P = 0.015). SRD5A3 mRNA expression was significantly associated with N stage (P < 0.001), age (P < 0.05), and histologic subtype (P < 0.001) but had no significant relationship with other clinical characteristics (all P > 0.05). Moreover, the functional enrichment analysis revealed that the SRD5A3 was involved in metabolism-related pathways (all P < 0.05).

Conclusions

SRD5A3 was highly expressed in BC tissues and high SRD5A3 expression was related to poorer prognosis. SRD5A3 serves as an oncogene and might function as a potential biomarker for prognosis and a therapeutic target for BC.

Roles of a small GTPase Sar1 in ecdysteroid signaling and immune response of red swamp crayfish Procambarus clarkii

Secretion-associated and ras-related protein 1 (Sar1) is a small GTPase that plays an important role in the transport of protein coated with coat protein complex II vesicles. However, its alternative roles in the biological processes of Procambarus clarkii remain unclear. Here, a sar1 gene (named as Pc-sar1) with an open reading frame of 582 bp from P. clarkii was identified. Pc-sar1 was expressed in all examined tissues with highest expression levels in muscle, which was determined by real-time PCR and western blotting. After the induction of lipopolysaccharide (LPS) and polycytidylic acid (Poly I: C), the transcriptional levels of Pc-sar1 differed in hepatopancreas, gill, muscle and intestine. In contrast, the expression of Pc-sar1 was upregulated by 20-hydroxyecdysone in these four tissues. In addition, the RNA interference of Pc-sar1 significantly affected the expression levels of immune and hormone-related genes. These results indicate that Pc-sar1 is involved in the innate immune response and ecdysteroid signaling pathway.