Biochemistry and Cell Biology最新文献

Lactoferrin (Lf), we have previously shown, has therapeutic potential in the field of skeletal regenerative medicine demonstrating its potent stimulating effects on bone growth. Recently, we have identified bovine lactoferrin (bLf) as a factor that also enhances antibiotic killing of Staphylococcus aureus (S. aureus). Biofilms are associated with around 65% of all infections and 80% of chronic infections. One feature of biofilm infection is tolerance to antibiotics due to the survival of a subpopulation of biofilm bacteria, where laboratory tests on planktonic cells indicate susceptibility. Tolerance is seen in bone infections of osteomyelitis and prosthetic joints, where methicillin-susceptible S. aureus (MSSA) strains predominate, but where treatments with the frontline penicillinase-resistant antibiotic cefazolin (CEF) can be ineffective. In vitro-grown biofilms of MSSA are 1000-fold more tolerant to CEF but can be eradicated by CEF at 10x minimal inhibitory concentration in the presence of bLf. Bone infection can impede blood circulation within the bone, leading to bone death. Lf as a potent stimulator of bone growth adds to its appeal as a treatment for bone infections.

Surface receptors in Gram-negative bacteria that bind and extract iron from the host glycoproteins transferrin (Tf) or lactoferrin (Lf) was discovered 35 years ago in pathogenic Neisseria species and subsequently was discovered in other pathogens of humans and food production animals. These bacterial species reside exclusively on the mucosal surfaces of the respiratory or genitourinary tract of their mammalian host and rely on their host specific Tf and Lf receptors to acquire iron for survival. Since the specificity of the bacterial Tf receptors was shown to be due to selective pressures on the host Tf, their presence in bacteria that reside in both mammals and birds indicates that they arose over 320 million years ago. Once Lf arose in mammals due to a gene duplication event, Lf receptors subsequently arose from Tf receptors. The focus on pathogens for discovery of these receptors has led to a limited understanding of how prevalent the Tf and Lf receptors are in commensal species and raises the question whether they are present in additional bacterial lineages. Since the Lf receptor provides a secondary iron acquisition system plus can provide protection from cationic peptides its presence varies in bacterial lineages.

Epicardial adipose tissue (EAT) is a rich source of EAT-derived stromal cells (EATDS), which possess regenerative potential. CRSP2, HSP27, IL8, HSP90, and Cofilin 1 were detected in the secretome of left ventricular stromal cells under ischemia challenge. However, the association of these genes in the EAT and EATDS remain understudied. We aim to assess the status of cofilin 1, CRSP2, HSP27, IL8, and HSP90 in the EAT of myocardial infarction (MI) and coronary artery bypass graft (CABG) swine models and in vitro stimulated ischemic EATDS. Expression status of these proteins in EAT were assessed by immunostaining, and in EATDS using qRT-PCR, immunostaining, and Western blot. EATDS phenotyping was performed using sc-RNAseq analysis. Cofilin 1 was increased while the other four genes were decreased in the CABG. IL8 and HSP90 were increased, while CRSP2, HSP27, and cofilin 1 were decreased in the MI group. Similar trend was displayed in the expression of these genes in EATDS. Additionally, EATDS displayed versatile phenotypes at single cell resolution based on the differential expression of various gene signatures. The findings revealed novel insights into EAT/EATDS biology and further understanding regarding the EATDS sub-phenotypes would open novel avenues in translational cardiology.

Osteoarthritis (OA) is a degenerative joint disorder characterized by chondrocyte dysfunction and progressive cartilage destruction, with ferroptosis emerging as a key contributor to disease pathogenesis. This study investigates the therapeutic potential of Aucubin, a natural iridoid glycoside, in OA treatment through modulation of the Keap1/NRF2 pathway and ferroptosis inhibition. Using an in vitro OA model established by IL-1β treatment of immortalized human chondrocytes, we demonstrate that Aucubin significantly improves cell viability, colony formation capacity, and migratory potential while promoting cell cycle progression. Aucubin also reduces ferroptosis-associated oxidative damage by decreasing MDA, GSSG, Fe²⁺, and ROS levels while increasing GSH content. Ferrostatin-1(Fer-1) ferroptosis inhibitor further supports this result. Molecularly, qPCR and Western blot analyses reveal that Aucubin upregulates NRF2 expression while suppressing Keap1 and modulating the levels of ferroptotic markers. These findings are further corroborated in a surgically induced OA rat model, where Aucubin administration attenuates cartilage degradation, restores Keap1/NRF2 expression, and normalizes ferroptosis-related protein expression. Our preliminary findings suggest that aucubin exerts its chondroprotective effects by inhibiting ferroptosis, at least partially through activation of the Keap1/NRF2 pathway, and may represent a potential therapeutic agent for osteoarthritis.

Our purpose was to explore the role and regulatory mechanisms of kringle containing transmembrane protein 2 (KREMEN2) in the development and progression of non-small cell lung cancer (NSCLC). KREMEN2 expression levels were higher in NSCLC tissues and cells than in normal tissues and cells. Down-regulation of KREMEN2 by siRNAs suppressed proliferation, migration, invasion, and epithelial mesenchymal transition (EMT), and accelerated apoptosis in NSCLC cells. Furthermore, KREMEN2 knockdown repressed PI3K/AKT/mTOR signaling, and KREMEN2 overexpression activated PI3K/AKT/mTOR signaling. Additionally, PI3K activator (740Y-P) treatment or PI3K overexpression reversed the inhibitory function of KREMEN2 knockdown on proliferation and metastasis, as well as the strengthened function of KREMEN2 knockdown on the apoptosis of NSCLC cells. Moreover, KREMEN2 suppressed tumor growth by inhibiting PI3K/AKT/mTOR signaling in mice. The pharmacologic inhibitor of KREMEN2 (genistein) was also demonstrated to suppress tumor growth in mice. In conclusion, our study suggested that KREMEN2 knockdown could repress the proliferative, migratory, and invasive capacity, as well as EMT, while accelerating the apoptotic capacity of NSCLC cells by inhibiting PI3K/AKT/mTOR signaling.

Estrogen receptor alpha (ERα) is an established biomarker for breast tumors, the loss of which is associated with poor cancer progression. Over 70% of breast cancers express ERα and targeting this protein has helped stem the progress of breast cancer. Therefore, it is paradoxical that only a small fraction of patients with ovarian and uterine cancers, which express ERα, are insensitive to antiestrogenic therapies. We propose the hypothesis that ERα association with different cofactors dictates the susceptibility of these cancers to therapies. To support this hypothesis, we analyzed data from cBioportal patient samples and showed that a strong positive correlation exists between ERα and its cofactors GATA3 and FOXA1 in breast cancer, but not in ovarian and uterine cancers. We further show that ERα genomic localization differs in the three cancer types, using available ChIP-seq datasets. Together, our analyses suggest that both localization and the nature of co-factors might be relevant for driving ERα-dependent cancer progression in different cell environments. We further discuss potential mechanisms for these differences in this commentary.

Increasing evidence has indicated that transforming growth factor beta 1 (TGFB1) is engaged in tumorigenesis and progression. Nevertheless, the underlying role and mechanism of TGFB1 in stomach adenocarcinoma (STAD) chemotherapy remains unknown. TGFB1 levels in various types of cancers were first analyzed by the TCGA database. Next, the degree of cellular damage, apoptosis and autophagy were detected by lactate dehydrogenase kit, flow cytometry, autophagy fluorescence analysis, and Western blot assay. The gene highly correlated with TGFB1 expression was searched by LinkedOmics and KEGG. We disclosed TGFB1 was enhanced in STAD. Besides, TGFB1 was remarkably higher in STAD patients in oxaliplatin (OXA) chemoresistant group than sensitive group. Additionally, the half maximal inhibitory concentration (IC50) values of OXA-resistant cells were markedly elevated. Furthermore, TGFB1 reduced AGS-OXA and HGC27-OXA cell injury, inhibited apoptosis and induced cellular autophagy. The addition of the autophagy inhibitor 3-methyladenine hindered this phenomenon. Further studies revealed that muscle RAS oncogene homolog (MRAS) is a downstream target gene of TGFB1. TGFB1 accelerated MRAS level in OXA cells, and MRAS knockdown reversed the effects of TGFB1 on OXA cell function. TGFB1 induces cellular autophagy via MRAS, thereby promoting STAD OXA resistance.

Myelination is essential for the proper conduction of impulses across neuronal networks. Mature, myelinating glia differentiate from progenitor cells through distinct stages that correspond to oligodendrocyte-specific gene expression markers. Reverse transcription quantiatative PCR (RT-qPCR) is a common technique used to quantify gene expression across cell development; however, a lack of standardization and transparency in methodology may lead to irreproducible data. Here, we have designed and validated RT-qPCR assays for oligodendrocyte genes and reference genes in the developing C57BL6/J mouse brain that align with the MIQE guidelines, including quality controls for primer specificity, temperature dependence, and efficiency. A panel of eight commonly used reference genes was ranked using a series of reference gene stability methods that consistently identified Gapdh, Sdha, Hmbs, Hprt1, and Pgk1 as the top candidates for normalization across brain regions. In the cerebrum, myelin genes peaked in expression at postnatal day 21, which corresponds to the peak of developmental myelination. The gene expression patterns from the brain homogenate were in agreement with previously reported RNA-seq and microarray profiles from oligodendrocyte lineage cells. The validated RT-qPCR assays begin to build a framework for future investigation into the molecular mechanisms that regulate myelination in mouse models of brain development, aging, and disease.

The field of RNA research has provided profound insights into the basic mechanisms modulating the function and adaption of biological systems. RNA has also been at the center stage in the development of transformative biotechnological and medical applications, perhaps most notably was the advent of mRNA vaccines that were critical in helping humanity through the Covid-19 pandemic. Unbeknownst to many, Canada boasts a diverse community of RNA scientists, spanning multiple disciplines and locations, whose cutting-edge research has established a rich track record of contributions across various aspects of RNA science over many decades. Through this position paper, we seek to highlight key contributions made by Canadian investigators to the RNA field, via both thematic and historical viewpoints. We also discuss initiatives underway to organize and enhance the impact of the Canadian RNA research community, particularly focusing on the creation of the not-for-profit organization RNA Canada ARN. Considering the strategic importance of RNA research in biology and medicine, and its considerable potential to help address major challenges facing humanity, sustained support of this sector will be critical to help Canadian scientists play key roles in the ongoing RNA revolution and the many benefits this could bring about to Canada.

Over the past four decades, prion diseases have received considerable research attention owing to their potential to be transmitted within and across species as well as their consequences for human and animal health. The unprecedented nature of prions has led to the discovery of a paradigm of templated protein misfolding that underlies a diverse range of both disease-related and normal biological processes. Indeed, the "prion-like" misfolding and propagation of protein aggregates is now recognized as a common underlying disease mechanism in human neurodegenerative disorders such as Alzheimer's and Parkinson's disease, and the prion principle has led to the development of novel diagnostic and therapeutic strategies for these illnesses. Despite these advances, research into the fundamental biology of prion diseases has declined, likely due to their rarity and the absence of an acute human health crisis. Given the past translational influence, continued research on the etiology, pathogenesis, and transmission of prion disease should remain a priority. In this review, we highlight several important "unsolved mysteries" in the prion disease research field and how solving them may be crucial for the development of effective therapeutics, preventing future outbreaks of prion disease, and understanding the pathobiology of more common human neurodegenerative disorders.