Cellular senescence is a state of permanent proliferative arrest that occurs in response to DNA damage-inducing endogenous and exogenous stresses, and is often accompanied by dynamic molecular changes such as a senescence-associated secretory phenotype (SASP). Accumulating evidence indicates that age-associated increases in the upstream and downstream signals of regulated cell death, including apoptosis, necroptosis, pyroptosis, and ferroptosis, are closely related to the induction of cellular senescence and its phenotype. Furthermore, elevated levels of pro-inflammatory SASP factors with aging can be both a cause and consequence of several cell death modes, suggesting the reciprocal effects of cellular senescence and cells undergoing regulated cell death.
View Article and Find Full Text PDFFerroptosis is a form of regulated cell death characterized by iron-dependent phospholipid peroxidation and is closely related to various diseases. System Xc-, a cystine/glutamate antiporter, and glutathione peroxidase 4 (GPX4) are key molecules in ferroptosis. Erastin and RSL3, known as inhibitors of system Xc- and GPX4, respectively, are commonly used as ferroptosis inducers.
View Article and Find Full Text PDFGraefes Arch Clin Exp Ophthalmol
September 2024
Age-related macular degeneration (AMD) is the leading sight-threatening disease in developed countries. On the other hand, recent studies indicated an ethnic variation in the phenotype of AMD. For example, several reports demonstrated that the incidence of drusen in AMD patients is less in Asians compared to Caucasians though the reason has not been clarified yet.
View Article and Find Full Text PDFAquaporin-2 (AQP2) water channels are proteins that are recycled between intracellular vesicles and the apical plasma membrane in renal collecting ducts. Lipopolysaccharide-responsive beige-like anchor protein (LRBA) is a protein kinase A (PKA) anchoring protein that creates compartmentalized PKA signalling responsible for AQP2 phosphorylation. In response to increased plasma osmolality, vasopressin/cyclic adenosine monophosphate (cAMP)/PKA signalling phosphorylates AQP2, promoting AQP2 trafficking into the apical plasma membrane and increasing water reabsorption from urine.
View Article and Find Full Text PDFProtein ubiquitination, which is catalyzed by ubiquitin-activating enzymes, ubiquitin-conjugating enzymes, and ubiquitin ligases, is a crucial post-translational modification to regulate numerous cellular functions in a spatio-temporal-specific manner. The human genome encodes ~100 deubiquitinating enzymes (DUBs), which antagonistically regulate the ubiquitin system. OTUD1, an ovarian tumor protease (OTU) family DUB, has an N-terminal-disordered alanine-, proline-, glycine-rich region (APGR), a catalytic OTU domain, and a ubiquitin-interacting motif (UIM).
View Article and Find Full Text PDFIn neurodegenerative diseases such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS), the progressive accumulation of ubiquitin-positive cytoplasmic inclusions leads to proteinopathy and neurodegeneration. Along with the seven types of Lys-linked ubiquitin chains, the linear ubiquitin chain assembly complex (LUBAC)-mediated Met1-linked linear ubiquitin chain, which activates the canonical NF-κB pathway, is also involved in cytoplasmic inclusions of tau in AD and TAR DNA-binding protein 43 in ALS. Post-translational modifications, including heterologous ubiquitination, affect proteasomal and autophagic degradation, inflammatory responses, and neurodegeneration.
View Article and Find Full Text PDFActa Neuropathol Commun
December 2022
Spinocerebellar ataxia (SCA) type 17-digenic TBP/STUB1 disease (SCA17-DI) has been recently segregated from SCA17, caused by digenic inheritance of two gene mutations - intermediate polyglutamine-encoding CAG/CAA repeat expansions (polyQ) in TBP (TBP) and STUB1 heterozygosity - the former being associated with SCA17, and the latter with SCA48 and SCAR16 (autosomal recessive). In SCA17, most patients carry intermediate TBP alleles but show incomplete penetrance, and the missing heritability can be explained by a new entity whereby TBP requires the STUB1 variant to be symptomatic. The STUB1 gene encodes the chaperone-associated E3 ubiquitin ligase (CHIP) involved in ubiquitin-mediated proteasomal control of protein homeostasis.
View Article and Find Full Text PDFThe linear ubiquitin chain assembly complex (LUBAC), which is composed of RING finger protein 31 (RNF31), RANBP2-type and C3HC4-type zinc finger containing 1 and SHANK-associated RH domain interactor subunits, is the only ubiquitin ligase to generate Met1-linked linear ubiquitin chains. Linear ubiquitin chains regulate canonical NF-κB activation and cell death. Single nucleotide polymorphisms in RNF31, such as Q584H and Q622L, are known to cause the activated B cell-like subtype of diffuse large B cell lymphoma (ABC-DLBCL) because of enhanced LUBAC-mediated NF-κB activation.
View Article and Find Full Text PDFTAR DNA-binding protein 43 (TDP-43) is a predominant component of inclusions in the brains and spines of patients with amyotrophic lateral sclerosis (ALS). The progressive accumulation of inclusions leads to proteinopathy in neurons. We have previously shown that Met1(M1)-linked linear ubiquitin, which is specifically generated by the linear ubiquitin chain assembly complex (LUBAC), is colocalized with TDP-43 inclusions in neurons from -associated familial and sporadic ALS patients, and affects NF-κB activation and apoptosis.
View Article and Find Full Text PDFDeubiquitinating enzymes (DUBs) regulate numerous cellular functions by removing ubiquitin modifications. We examined the effects of 88 human DUBs on linear ubiquitin chain assembly complex (LUBAC)-induced NF-κB activation, and identified OTUD1 as a potent suppressor. OTUD1 regulates the canonical NF-κB pathway by hydrolyzing K63-linked ubiquitin chains from NF-κB signaling factors, including LUBAC.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
July 2022
Protein kinase A (PKA) directly phosphorylates aquaporin-2 (AQP2) water channels in renal collecting ducts to reabsorb water from urine for the maintenance of systemic water homeostasis. More than 50 functionally distinct PKA-anchoring proteins (AKAPs) respectively create compartmentalized PKA signaling to determine the substrate specificity of PKA. Identification of an AKAP responsible for AQP2 phosphorylation is an essential step toward elucidating the molecular mechanisms of urinary concentration.
View Article and Find Full Text PDFSaliva contributes to the innate immune system, which suggests that it can prevent SARS-CoV-2 entry. We studied the ability of healthy salivary proteins to bind to angiotensin-converting enzyme 2 (ACE2) using biolayer interferometry and pull-down assays. Their effects on binding between the receptor-binding domain of the SARS-CoV-2 spike protein S1 (S1) and ACE2 were determined using an enzyme-linked immunosorbent assay.
View Article and Find Full Text PDFPancreatic cancer is a highly challenging malignancy with extremely poor prognosis. Cytoglobin (CYGB), a hemeprotein involved in liver fibrosis and cancer development, is expressed in pericytes of all organs. Here, we examined the role of CYGB in the development of pancreatic cancer.
View Article and Find Full Text PDFBiochem Soc Trans
April 2022
Ubiquitin regulates numerous aspects of biology via a complex ubiquitin code. The linear ubiquitin chain is an atypical code that forms a unique structure, with the C-terminal tail of the distal ubiquitin linked to the N-terminal Met1 of the proximal ubiquitin. Thus far, LUBAC is the only known ubiquitin ligase complex that specifically generates linear ubiquitin chains.
View Article and Find Full Text PDFBackground & Aims: Hepatic stellate cells (HSCs) are the primary cell type in liver fibrosis, a significant global health care burden. Cytoglobin (CYGB), a globin family member expressed in HSCs, inhibits HSC activation and reduces collagen production. We studied the antifibrotic properties of globin family members hemoglobin (HB), myoglobin (MB), and neuroglobin (NGB) in comparison with CYGB.
View Article and Find Full Text PDFType I interferon (IFN) plays a crucial role in innate and adaptive immunity, and aberrant IFN responses are involved in systemic autoimmune diseases, such as systemic lupus erythematosus (SLE) and dermatomyositis (DM). Type I IFNs can be induced by transcribed retrotransposons. The regulation of retrotransposons and type I IFN and the downstream IFN pathways in SLE, DM, and autoimmune blistering disease (AIBD) were investigated.
View Article and Find Full Text PDFThe anti-apoptotic myeloid cell leukemia 1 (MCL1) protein belongs to the pro-survival BCL2 family and is frequently amplified or elevated in human cancers. MCL1 is highly unstable, with its stability being regulated by phosphorylation and ubiquitination. Here, we identify acetylation as another critical post-translational modification regulating MCL1 protein stability.
View Article and Find Full Text PDFNuclear dot protein 52 kDa (NDP52, also known as CALCOCO2) functions as a selective autophagy receptor. The linear ubiquitin chain assembly complex (LUBAC) specifically generates the N-terminal Met1-linked linear ubiquitin chain, and regulates innate immune responses, such as nuclear factor-κB (NF-κB), interferon (IFN) antiviral, and apoptotic pathways. Although NDP52 and LUBAC cooperatively regulate bacterial invasion-induced xenophagy, their functional crosstalk remains enigmatic.
View Article and Find Full Text PDFObjective: Histamine derived from mast cells and basophils plays important roles in inducing allergic symptoms. Although T cells also produce histamine, the involvement of the histamine produced from T cells has remained enigmatic. We sought to reveal the roles of T helper 2 (Th2) cell-derived histamine in nasal allergic disorders.
View Article and Find Full Text PDFObjective: To determine the frequency and effects of accidental ingestion of packaged processed foods, eating out, and over-the-counter sales in individuals with food allergies.
Methods: The participants were guardians of children hospitalized for an oral food challenge test during January and February 2016 at the Department of Pediatrics, Sagamihara National Hospital. We conducted a questionnaire survey on food allergies, accidental ingestion via packaged processed foods, eating out, and over-the-counter sales in the past 1 year, and the degree of understanding of the display of allergen-related information.
Histamine, which is mainly produced by mast cells and basophils, participates in various allergic symptoms, and some studies have reported that macrophages also produce histamine. Moreover, recent studies have revealed that macrophages, especially alternatively activated macrophages (M2) induced by T helper 2 (Th2) cytokines, such as interleukin (IL)-4 and IL-13, participate in the pathogenesis of allergic diseases. The major source of Th2 cytokines is antigen-specific Th2 cells.
View Article and Find Full Text PDFMind bomb 2 (MIB2) is an E3 ligase involved in Notch signalling and attenuates TNF-induced apoptosis through ubiquitylation of receptor-interacting protein kinase 1 (RIPK1) and cylindromatosis. Here we show that MIB2 bound and conjugated K48- and K63-linked polyubiquitin chains to a long-form of cellular FLICE-inhibitory protein (cFLIP), a catalytically inactive homologue of caspase 8. Deletion of MIB2 did not impair the TNF-induced complex I formation that mediates NF-κB activation but significantly enhanced formation of cytosolic death-inducing signalling complex II.
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