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ST3Gal1 is a key sialyltransferase which adds α2,3‐linked sialic acid to substrates and generates core 1 O‐glycan structure. Upregulation of ST3Gal1 has been associated with worse prognosis of breast cancer patients. However, the protein substrates of ST3Gal1 implicated in tumor progression remain elusive. In our study, we demonstrated that ST3GAL1‐silencing significantly reduced tumor growth along with a notable decrease in vascularity of MCF7 xenograft tumors. We identified vasorin (VASN) which was shown to bind TGF‐β1, as a potential candidate that links ST3Gal1 to angiogenesis. LC‐MS/MS analysis of VASN secreted from MCF7, revealed that more than 80% of its O‐glycans are sialyl‐3T and disialyl‐T. ST3GAL1‐silencing or desialylation of VASN by neuraminidase enhanced its binding to TGF‐β1 by 2‐ to 3‐fold and thereby dampening TGF‐β1 signaling and angiogenesis, as indicated by impaired tube formation of HUVECs, suppressed angiogenesis gene expression and reduced activation of Smad2 and Smad3 in HUVEC cells. Examination of 114 fresh primary breast cancer and their adjacent normal tissues showed that the expression levels of ST3Gal1 and TGFB1 were high in tumor part and the expression of two genes was positively correlated. Kaplan Meier survival analysis showed a significantly shorter relapse‐free survival for those with lower expression VASN, notably, the combination of low VASN with high ST3GAL1 yielded even higher risk of recurrence (p = 0.025, HR = 2.967, 95% CI = 1.14–7.67). Since TGF‐β1 is known to transcriptionally activate ST3Gal1, our findings illustrated a feedback regulatory loop in which TGF‐β1 upregulates ST3Gal1 to circumvent the negative impact of VASN., What's new? The addition of sialic acid to glycoproteins is dysregulated in many cancers, and enhanced expression of one key enzyme, the sialyltransferase ST3Gal1, is associated with poor prognosis. Here, the authors identified the membrane protein vasorin as a new ST3Gal1 substrate and connect it with TGF‐β1‐induced signaling and angiogenesis in breast cancer. As silencing of ST3Gal1 dampened TGF‐β1 signaling and suppressed angiogenesis, development of ST3Gal1 inhibitors might be clinically useful to improve the prognosis of breast cancer patients.

At its simplest level, obesity is a disorder of energy balance, where energy intake exceeds energy expenditure; as a consequence, the excess energy is stored in the form of fat in adipocytes. The primary onset mechanisms are dietary and/or genetic (Kopelman 2000). Of those known genetic factors involved in determining adiposity in animals, many are regulatory and exert their effect directly on adipocyte differentiation and development (Rosen et al. 2000; Flier 2004). These factors include CCAAT/enhancer-binding proteins (C/EBPs), SREBP, and PPARγ, whose concerted action during adipogenesis leads to the development of fat-laden mature adipocytes (Rosen et al. 2000). The C/EBP family consists of five members, of which C/EBPα, C/EBPβ, and C/EBPδ have a profound impact on fat cell differentiation (Yeh et al. 1995). During adipogenesis, C/EBP family functions in a transcriptional cascade, in which the early and transiently expressed C/EBPβ and C/EBPδ activate transcription of PPARγ. PPARγ is then responsible for the expression of C/EBPα (Wu et al. 1996; Rosen et al. 1999). Subsequently, PPARγ and C/EBPα, together with SREBP, work synergistically to transactivate expression of most or all of the genes encoding for factors, such as fatty-acid synthase and adipocyte-specific fatty acid-binding protein aP2, which characterize the fat cell phenotype (Speigelman et al. 1993). In this study, we used previously manipulated gene knock-in mice, known as β/β mice, in which the C/EBPα gene has been replaced by the C/EBPβ gene (referred here as β/β allele) to study their function in tissues (Chen et al. 2000). β/β mice are lean, and despite markedly reduced fat storage in their fat cells, they do not develop hyperlipidemia or fatty liver, commonly found in the forced leaness that typically causes the liver to take up and store fatty acids when their circulating levels are elevated (Moitra et al. 1998; Shimomura et al. 1998; Chen et al. 2000). We monitored closely the physiology and lifespan of the lean β/β mice and undertook mechanistic studies to understand the effect of β/β allele in energy metabolism. We found that the β/β allele caused an increase in mitochondrial biogenesis only in fat cells of white adipose tissues (WAT), and this WAT specifically enhanced mitochondrial biogenesis was possibly elicited by the markedly elevated expression of G protein α stimulatory subunit (Gαs).

H5N1 influenza virus is a highly pathogenic virus, posing a pandemic threat. Previously, we showed that phenyl analogs of α-galactosylceramide (α-GalCer) displayed greater NKT stimulation than α-GalCer. Here, we examined the adjuvant effects of one of the most potent analogs, C34, on consensus hemagglutinin based DNA vaccine (pCHA5) for H5N1 virus. Upon intramuscular electroporation of mice with pCHA5 with/without various α-GalCer analogs, C34-adjuvanted group developed the highest titer against consensus H5 and more HA-specific IFN-γ secreting CD8 cells (203±13.5) than pCHA5 alone (152.6±13.7, p0.05). Upon lethal challenge of NIBRG-14 virus, C34-adjuvanted group (84.6%) displayed higher survival rate than pCHA5 only group (46.1%). In the presence of C34 as adjuvant, the antisera displayed broader and greater neutralizing activities against virions pseudotyped with HA of clade 1, and 2.2 than pCHA5 only group. Moreover, to simulate an emergency response to a sudden H5N1 outbreak, we injected mice intramuscularly with single dose of a new consensus H5 (pCHA5-II) based on 1192 full-length H5 sequences, with C34 as adjuvant. The latter not only enhanced the humoral immune response and protection against virus challenge, but also broadened the spectrum of neutralization against pseudotyped HA viruses. Our vaccine strategy can be easily implemented for any H5N1 virus outbreak by single IM injection of a consensus H5 DNA vaccine based on updated HA sequences using C34 as an adjuvant.

Various therapeutic strategies have been developed to tolerize autoreactive T cells and prevent autoimmune pathology in type 1 diabetes. 4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is a costimulatory receptor primarily expressed on activated T cells. The administration of an agonistic anti-4-1BB antibody (2A) dramatically reduced the incidence and severity of experimental autoimmune encephalomyelitis (EAE). Treatment with the same antibody in Fas-deficient MRL/lpr mice blocked lymphadenopathy and lupus-like autoimmune processes. Paradoxically, transgenic non-obese diabetic (NOD) mice overexpressing membrane-bound agonistic single-chain anti-4-1BB Fv in pancreatic beta cells developed more severe diabetes than their non-transgenic littermates, with earlier onset, faster diabetic processes, and higher mortality. Forty percent of transgenic mice developed diabetes by 4 weeks of age, compared with their control littermates, which first exhibited diabetes at 14 weeks. The frequency of diabetes in female transgenics reached 70% by 8 weeks of age. Most female transgenic mice died around 12 weeks. Consistent with this, transgenic mice developed earlier and more severe insulitis and showed stronger GAD-specific T-cell responses, compared with age-matched control littermates. Our results indicate an adverse effect of transgenic anti-4-1BB scFv in NOD mice and suggest a potential risk of this anti-4-1BB-based immunotherapy for autoimmune diseases.