A genetic variant in the gene encoding the stress70 protein chaperone family member STCH is associated with gastric cancer in the Japanese population

HSPA13 modulates type I interferon antiviral pathway and NLRP3 inflammasome to restrict dengue virus infection in macrophages

Dengue virus (DENV) is a type of arthropod-borne Flavivirus, which leads to a series of serious diseases like dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). DENV has a devastating health and economic impact worldwide. However, there are no suitable drugs to combat the virus. Here we reported that HSPA13, also known as stress chaperone (STCH), is a member of the HSP70 family and is a key regulator of type I interferon (IFN-I) and pro-inflammatory responses during DENV infection. HSPA13 expression was increased in macrophages infected with DENV or other Flaviviruses like Zika virus (ZIKV), Yellow fever virus (YFV) and Japanese encephalitis virus (JEV). Further, HSPA13 suppressed the replication of DENV and other Flaviviruses (ZIKV, JEV, YFV), which exhibited broad-spectrum antiviral effects. On the one hand, HSPA13 promoted production of IFN-β and interferon-stimulated genes (ISGs, such as ISG15, OAS and IFIT3) by interacting with RIG-I and up-regulating RIG-I expression during DENV infection. On the other hand, HSPA13 enhanced NLRP3 inflammasome activation and IL-1β secretion by interacting with ASC in DENV infection. We identified HSPA13 as a potential anti-DENV target. Our results provide clues for the development of antiviral drugs against DENV based on HSPA13 and reveal novel drug target against Flaviviruses.

Heat shock protein Hspa13 regulates endoplasmic reticulum and cytosolic proteostasis through modulation of protein translocation

Most eukaryotic secretory proteins are cotranslationally translocated through Sec61 into the endoplasmic reticulum (ER). Because these proteins have evolved to fold in the ER, their mistargeting is associated with toxicity. Genetic experiments have implicated the ER heat shock protein 70 (Hsp70) Hspa13/STCH as involved in processing of nascent secretory proteins. Herein, we evaluate the role of Hspa13 in protein import and the maintenance of cellular proteostasis in human cells, primarily using the human embryonic kidney 293T cell line. We find that Hspa13 interacts primarily with the Sec61 translocon and its associated factors. Hspa13 overexpression inhibits translocation of the secreted protein transthyretin, leading to accumulation and aggregation of immature transthyretin in the cytosol. ATPase-inactive mutants of Hspa13 further inhibit translocation and maturation of secretory proteins. While Hspa13 overexpression inhibits cell growth and ER quality control, we demonstrate that HSPA13 knockout destabilizes proteostasis and increases sensitivity to ER disruption. Thus, we propose that Hspa13 regulates import through the translocon to maintain both ER and cytosolic protein homeostasis. The raw mass spectrometry data associated with this article have been deposited in the PRIDE archive and can be accessed at PXD033498.

Susceptibility to human cancer: From the perspective of a pathologist

The etiologies of human cancer can only be discerned when the genetic clustering of cancer occurs within a family or when cancer occurs endemically in a particular environment. The possible approaches to solving the nature/nurture problem, especially for human carcinogenesis, posit a fascinating challenge for pathologists. This perspective review presents some examples of how clues to human cancer etiologies and/or susceptibilities reside in the realm of pathology practice. These examples using various omics techniques including adductomics, which I would like to highlight in this article, show that the currently available concepts and methods in human pathology can open a path toward the brave new world of a post-genomic era of medicine for young pathologists, whether their original intention was toward the pursuit of diagnostic or investigative knowledge.

Chaperone stress 70 protein (STCH) binds and regulates two acid/base transporters NBCe1-B and NHE1

Regulation of intracellular pH is critical for the maintenance of cell homeostasis in response to stress. We used yeast two-hybrid screening to identify novel interacting partners of the pH-regulating transporter NBCe1-B. We identified Hsp70-like stress 70 protein chaperone (STCH) as interacting with NBCe1-B at the N-terminal (amino acids 96-440) region. Co-injection of STCH and NBCe1-B cRNA into Xenopus oocytes significantly increased surface expression of NBCe1-B and enhanced bicarbonate conductance compared with NBCe1-B cRNA alone. STCH siRNA decreased the rate of Na(+)-dependent pHi recovery from NH4(+) pulse-induced acidification in an HSG (human submandibular gland ductal) cell line. We observed that in addition to NBCe1-B, Na(+)/H(+) exchanger (NHE)-dependent pHi recovery was also impaired by STCH siRNA and further confirmed the interaction of STCH with NHE1 but not plasma membrane Ca(2+) ATPase. Both NBCe1-B and NHE1 interactions were dependent on a specific 45-amino acid region of STCH. In conclusion, we identify a novel role of STCH in the regulation of pHi through site-specific interactions with NBCe1-B and NHE1 and subsequent modulation of membrane transporter expression. We propose STCH may play a role in pHi regulation at times of cellular stress by enhancing the recovery from intracellular acidification.

Genetic factors associated with intestinal metaplasia in a high risk Singapore-Chinese population: a cohort study

Background

Intestinal metaplasia (IM) is an important precursor lesion in the development of gastric cancer (GC). The aim of this study was to investigate genetic factors previously linked to GC risk for their possible association with IM. A total of 18 polymorphisms in 14 candidate genes were evaluated in a Singapore-Chinese population at high risk of developing GC.

Methods

Genotype frequencies were compared between individuals presenting with (n = 128) or without (n = 246) IM by both univariate and multivariate analysis.

Results

Carriers of the NQO1 609 T allele showed an association with IM in individuals who were seropositive for Helicobacter pylori (HP+; OR = 2.61, 95%CI: 1.18-5.80, P = .018). The IL-10 819 C allele was also associated with IM in HP+ individuals (OR = 2.32, 95%CI: 1.21-4.43, P = 0.011), while the PTPN11 A allele was associated with IM in HP- individuals (OR = 2.51, 95%CI: 1.16-5.40, P = 0.019), but showed an inverse association in HP+ subjects (OR = 0.46, 95%CI: 0.21-0.99, P = 0.048).

Conclusion

Polymorphisms in NQO1, IL-10 and PTPN11, in combination with HP status, could be used to identify individuals who are more likely to develop IM and therefore GC.

Stomach cancer-derived del223V-226L mutation of the STCH gene causes loss of sensitization to TRAIL-mediated apoptosis

The stress 70 protein chaperone (STCH), a member of the heat shock protein 70 (HSP70) superfamily, is a microsomal protein that contains a N-terminal ATPase domain but lacks a C-terminal protein binding domain. Although cell-protective functions of HSP70 members are well characterized, the biological relevance of STCH remains unclear. We previously identified STCH as a candidate gene for susceptibility to stomach cancer by genetic analyses. In this study, we searched somatic mutations of STCH in human stomach cancer and identified the 668del12bp mutation in exon 4, resulting in a four amino acid deletion (del223V-226L) in the conserved ATP-binding domain. In vitro binding assays revealed that this mutant lacks ATP-binding activity. Overexpression of wild-type STCH sensitized cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced cell death, whereas del223V-226L mutant did not show any effect. These results suggest that STCH has a role in cell survival via modulation of the TRAIL-mediated cell death pathway.

TP53 and P21 polymorphisms: response to cisplatinum/paclitaxel-based chemotherapy in ovarian cancer

Ovarian cancer (OC) is the most lethal gynaecologic cancer and its standard treatment consists of platinum-based chemotherapy after cytoreductive surgery. The p53 protein plays a critical role on different cellular processes in response to DNA damage and it is responsible for transcriptional induction of the P21 gene. We have analysed 114 blood samples in order to investigate the effect of the TP53 codon 72 and the P21 3'UTR polymorphisms in response to cisplatinum/paclitaxel chemotherapy for OC treatment. The genotypes of the TP53 codon 72 and P21 3'UTR polymorphism were identified using AS-PCR and PCR-RFLP, respectively. Our results indicate that the TP53 P allele is associated with a worse prognosis (P=0.011) while P21 polymorphism genotypes did not reveal any statistically significant result (P>0.05). Furthermore, simultaneous carriers of the TP53 AA genotype and the P21 CC genotype demonstrate a longer progression-free interval (P=0.020). This study suggests that the characterisation of a genetic profile can contribute to the definition of a better chemotherapy treatment.