Atypical granulation in neutrophils of a domestic shorthair cat.

A 13-year-old male domestic short-hair cat presented for evaluation of labored breathing, hyporexia, and lethargy. Pertinent initial diagnostics yielded leukocytosis, characterized by neutrophilia and monocytosis. Numerous small, round, magenta granules were observed within all neutrophils in Wright-Giemsa-stained blood films on the day of presentation and the day thereafter. No other neutrophil morphologic abnormalities were present, making cytoplasmic toxicity highly unlikely. Hyperadrenocorticism was diagnosed based on the lack of suppression in a low-dose dexamethasone suppression test, and without other diagnostics, the cat was discharged on trilostane therapy. Neutrophil granules did not stain with Alcian blue pH 1.0, periodic acid-Schiff (PAS), PAS and Alcian blue pH 2.5, and toluidine blue. Electron microscopy identified no differences in the morphology of the secretory granules or other neutrophil features. Metabolic screening tests of the cat's urine did not identify a genetic metabolic disorder. However, serum α- and ß -hexosaminidase (HexA and HexB) activities were 4.3% and 0% of normal controls, respectively, which is supportive of GM2-gangliosidosis, that is, Sandhoff disorder. However, the historical, clinical, and electron microscopy findings did not provide evidence to confirm this genetic defect. To the author's knowledge, this is the first case of magenta-staining granules within neutrophils in a breed other than a Birman, Siamese, or Himalayan.

Stress granule-mediated RNA regulatory mechanism in Alzheimer's disease.

Living organisms experience a range of stresses. To cope effectively with these stresses, eukaryotic cells have evolved a sophisticated mechanism involving the formation of stress granules (SGs), which play a crucial role in protecting various types of RNA species under stress, such as mRNAs and long non-coding RNAs (lncRNAs). SGs are non-membranous cytoplasmic ribonucleoprotein (RNP) granules, and the RNAs they contain are translationally stalled. Importantly, SGs have been thought to contribute to the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD). SGs also contain multiple RNA-binding proteins (RBPs), several of which have been implicated in AD progression. SGs are transient structures that dissipate after stress relief. However, the chronic stresses associated with aging lead to the persistent formation of SGs and subsequently to solid-like pathological SGs, which could impair cellular RNA metabolism and also act as a nidus for the aberrant aggregation of AD-associated proteins. In this paper, we provide a comprehensive summary of the physical basis of SG-enriched RNAs and SG-resident RBPs. We then review the characteristics of AD-associated gene transcripts and their similarity to the SG-enriched RNAs. Furthermore, we summarize and discuss the functional implications of SGs in neuronal RNA metabolism and the aberrant aggregation of AD-associated proteins mediated by SG-resident RBPs in the context of AD pathogenesis. Geriatr Gerontol Int 2024; 24: 7-14.

Formation, function, and pathology of RNP granules.

Ribonucleoprotein (RNP) granules are diverse membrane-less organelles that form through multivalent RNA-RNA, RNA-protein, and protein-protein interactions between RNPs. RNP granules are implicated in many aspects of RNA physiology, but in most cases their functions are poorly understood. RNP granules can be described through four key principles. First, RNP granules often arise because of the large size, high localized concentrations, and multivalent interactions of RNPs. Second, cells regulate RNP granule formation by multiple mechanisms including posttranslational modifications, protein chaperones, and RNA chaperones. Third, RNP granules impact cell physiology in multiple manners. Finally, dysregulation of RNP granules contributes to human diseases. Outstanding issues in the field remain, including determining the scale and molecular mechanisms of RNP granule function and how granule dysfunction contributes to human disease.

Rare Pseudo-Chediak-Higashi Inclusions in Therapy-Related Acute Myeloid Leukemia with Myelodysplasia-Related Changes.

BACKGROUND: Defined as rare large azurophilic cytoplasmic inclusions, Pseudo-Chediak-Higashi granules mimic those in granulocytes cytoplasm of Chediak-Higashi syndrome. Rare cases of hematopoietic and lymphoid tissues tumors showed Pseudo-Chediak-Higashi inclusions in cytoplasm, some of which presented with unusual morphological characteristics. METHODS: Herein, we report the first case, in which rare pseudo-Chediak-Higashi inclusions were observed in therapy-related acute myeloid leukemia with myelodysplasia-related changes (t-AML-MRC). RESULTS: The rare pseudo-Chediak-Higashi inclusions may be positive for Sudan black, and some scholars think that these rare inclusions are a kind of dysgranulopoiesis. CONCLUSIONS: The case highlights the significance of an integrated diagnostic work-up, with an interesting effect for morphology.

Connecting the dots: Neuronal senescence, stress granules, and neurodegeneration.

Cellular senescence increases with aging. While senescence is associated with an exit of the cell cycle, there is ample evidence that post-mitotic cells including neurons can undergo senescence as the brain ages, and that senescence likely contributes significantly to the progression of neurodegenerative diseases (ND) such as Alzheimer's Disease (AD) and Amyotrophic Lateral Sclerosis (ALS). Stress granules (SGs) are stress-induced cytoplasmic biomolecular condensates of RNA and proteins, which have been linked to the development of AD and ALS. The SG seeding hypothesis of NDs proposes that chronic stress in aging neurons results in static SGs that progress into pathological aggregates Alterations in SG dynamics have also been linked to senescence, though studies that link SGs and senescence in the context of NDs and the aging brain have not yet been performed. In this Review, we summarize the literature on senescence, and explore the contribution of senescence to the aging brain. We describe senescence phenotypes in aging neurons and glia, and their links to neuroinflammation and the development of AD and ALS. We further examine the relationships of SGs to senescence and to ND. We propose a new hypothesis that neuronal senescence may contribute to the mechanism of SG seeding in ND by altering SG dynamics in aged cells, thereby providing additional aggregation opportunities within aged neurons.

Stress Granules in Cancer.

The capacity of cells to organize complex biochemical reactions in intracellular space is a fundamental organizational principle of life. Key to this organization is the compartmentalization of the cytoplasm into distinct organelles, which is frequently achieved through intracellular membranes. Recent evidence, however, has added a new layer of flexibility to cellular compartmentalization. As such, in response to specific stimuli, liquid-liquid phase separations can lead to the rapid rearrangements of the cytoplasm to form membraneless organelles. Stress granules (SGs) are one such type of organelle that form specifically when cells are faced with stress stimuli, to aid cells in coping with stress. Inherently, altered SG formation has been linked to the pathogenesis of diseases associated with stress and inflammatory conditions, including cancer. Exciting discoveries have indicated an intimate link between SGs and tumorigenesis. Several pro-tumorigenic signaling molecules including the RAS oncogene, mTOR, and histone deacetylase 6 (HDAC6) have been shown to upregulate SG formation. Based on these studies, SGs have emerged as structures that can integrate oncogenic signaling and tumor-associated stress stimuli to enhance cancer cell fitness. In addition, growing evidence over the past decade suggests that SGs function not only to regulate the switch between survival and cell death, but also contribute to cancer cell proliferation, invasion, metastasis, and drug resistance. Although much remains to be learned about the role of SGs in tumorigenesis, these studies highlight SGs as a key regulatory hub in cancer and a promising therapeutic target.

Stress Granule Homeostasis, Aberrant Phase Transition, and Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. In recent years, a large number of ALS-related mutations have been discovered to have a strong link to stress granules (SGs). SGs are cytoplasmic ribonucleoprotein condensates mediated by liquid-liquid phase separation (LLPS) of biomacromolecules. They help cells cope with stress. The normal physiological functions of SGs are dependent on three key aspects of SG "homeostasis": SG assembly, disassembly, and SG components. Any of these three aspects can be disrupted, resulting in abnormalities in the cellular stress response and leading to cytotoxicity. Several ALS-related pathogenic mutants have abnormal LLPS abilities that disrupt SG homeostasis, and some of them can even cause aberrant phase transitions. As a result, ALS-related mutants may disrupt various aspects of SG homeostasis by directly disturbing the intermolecular interactions or affecting core SG components, thus disrupting the phase equilibrium of the cytoplasm during stress. Considering that the importance of the "global view" of SG homeostasis in ALS pathogenesis has not received enough attention, we first systematically summarize the physiological regulatory mechanism of SG homeostasis based on LLPS and then examine ALS pathogenesis from the perspective of disrupted SG homeostasis and aberrant phase transition of biomacromolecules.

Molecular interaction of stress granules with Tau and autophagy in Alzheimer's disease.

Stress Granules (SGs) are RNA granules composed of untranslated mRNA and associated proteins, which are related to the cytoplasmic metabolism of mRNA in response to cellular stress and certain drug stimuli. Physiological SGs are dynamic structures that protect cells from the effects of stress, and continuous stress ripens the SGs into more stable complexes. Numerous studies have found that dysregulation of RNA metabolism in stress response led to misfolded protein aggregation in the pathophysiology of neurodegenerative diseases. For example, in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Alzheimer's disease (AD), and Parkinson's disease (PD), SGs aggregation is mainly due to up-regulation of SGs formation and down-regulation of SGs clearance. Recent studies have revealed the role of SGs in the pathogenesis and pathology of AD, especially the interaction of SGs and RNA-binding proteins with Tau and autophagy. Aggregation of SGs and increased RNA-binding proteins, especially TIA1, can facilitate Tau misfolding and propagation, and vice versa. Autophagy dysfunction disrupts the normal pathway of SGs clearance. In this review, we summarized the regulation of SGs and their relationship with Tau protein and autophagy, as well as the pathological mechanisms of AD such as RNA splicing, microglial cell proliferation and phagocytosis.

Eosinophil exocytosis in a poorly differentiated tubular gastric adenocarcinoma: case report.

A case of poorly differentiated tubular gastric adenocarcinoma with tumor-associated tissue eosinophilia (TATE) is studied by light and electron microscopy, focusing on membrane interactions between eosinophils and tumor cells. 29.2% of the eosinophils in contact with tumor cells showed intact granules, 28.3% exhibited piecemeal degranulation (PMD), 40% were characterized by coexistence of PMD and compound exocytosis in the same granulocyte, whereas classical exocytosis was found in 2.5% of the eosinophils with PMD. Eosinophil Sombrero Vesicles (EoSVs), important tubulovesicular carriers for delivery of cytotoxic proteins from the specific granules during PMD, were also studied at the ultrastructural level. In activated eosinophils, EoSVs and specific granules with ultrastructural signs of degranulation were polarized toward tumor cells. Ultrastructural changes in paraptosis-like cell death, such as mitochondrial swelling, dilation of the nuclear envelope, cytoplasmic vacuoles, and nuclear chromatin condensation, but without margination of the chromatin, were observed in these tumor cells. Our data support the notion that eosinophils may exert an antitumoral role in gastric cancer. Finally, the case reported provides, for the first time, ultrastructural evidence of classical and compound exocytosis of eosinophils in the tumor stroma of human adenocarcinoma.

Aberrant Stress Granule Dynamics and Aggrephagy in ALS Pathogenesis.

Stress granules are conserved cytosolic ribonucleoprotein (RNP) compartments that undergo dynamic assembly and disassembly by phase separation in response to stressful conditions. Gene mutations may lead to aberrant phase separation of stress granules eliciting irreversible protein aggregations. A selective autophagy pathway called aggrephagy may partially alleviate the cytotoxicity mediated by these protein aggregates. Cells must perceive when and where the stress granules are transformed into toxic protein aggregates to initiate autophagosomal engulfment for subsequent autolysosomal degradation, therefore, maintaining cellular homeostasis. Indeed, defective aggrephagy has been causally linked to various neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). In this review, we discuss stress granules at the intersection of autophagy and ALS pathogenesis.

The Emerging Role of Stress Granules in Hepatocellular Carcinoma.

Stress granules (SGs) are small membrane-free cytosolic liquid-phase ordered entities in which mRNAs are protected and translationally silenced during cellular adaptation to harmful conditions (e.g., hypoxia, oxidative stress). This function is achieved by structural and functional SG components such as scaffold proteins and RNA-binding proteins controlling the fate of mRNAs. Increasing evidence indicates that the capacity of cells to assemble/disassemble functional SGs may significantly impact the onset and the development of metabolic and inflammatory diseases, as well as cancers. In the liver, the abnormal expression of SG components and formation of SG occur with chronic liver diseases, hepatocellular carcinoma (HCC), and selective hepatic resistance to anti-cancer drugs. Although, the role of SG in these diseases is still debated, the modulation of SG assembly/disassembly or targeting the expression/activity of specific SG components may represent appealing strategies to treat hepatic disorders and potentially cancer. In this review, we discuss our current knowledge about pathophysiological functions of SGs in HCC as well as available molecular tools and drugs capable of modulating SG formation and functions for therapeutic purposes.

Predictive value of cytoplasmic granulation patterns during in vitro fertilization in metaphase II oocytes: part II, donor oocyte cycles.

OBJECTIVE: To determine whether the ooplasm granulation patterns of donor oocytes, like those of oocytes from poor-prognosis patients, are predictive of in vitro fertilization (IVF) outcomes. DESIGN: Retrospective cohort study. SETTING: Academically affiliated private clinical infertility and research center. PATIENT(S): 770 fresh and 381 vitrified-thawed metaphase II oocytes from young donors (aged 21.0-34.6 years) used for IVF during 2017-2020. INTERVENTION(S): Determination of granulation patterns in every oocyte during intracytoplasmic sperm injection as fine, central, uneven, dispersed, and peripheral (thawed only). MAIN OUTCOME MEASURE(S): Fertilization, pregnancy, and live birth rates in fresh and thawed donor oocytes. Both overall and known-outcome analyses were performed for pregnancy and live birth. RESULT(S): In fresh donor oocytes, 2 pronuclei rates trended down from 96.1% to 90.2%, 88.9%, and 69.7% from fine to central, uneven, and dispersed granulations; overall pregnancy rates trended down from 50.4% to 29.0%, 17.7%, and 6.9%, as well as live birth rates (43.4%, 21.6%, 12.5%, and 6.4%), from fine to uneven, central, and dispersed granulations. Known pregnancy and known-live birth analyses showed similar findings. Thawed donor oocytes demonstrated similar trends in differences in fertilization, pregnancy, and live birth analyses with relatively worse outcomes. Peripheral granulation, unique to vitrification and thawing, always demonstrated the worst IVF outcomes. Moreover, granulation patterns were relatively disassociated from embryo morphological grades in fresh and largely disassociated in thawed donor oocytes. CONCLUSION(S): Predictive values of oocyte granulation patterns for fertilization, pregnancy, and live birth in IVF cycles are even more pronounced in young donors than results in older poor-prognosis patients, further supporting integration of oocyte granulation patterns into embryo selection.

Huntington's disease mice and human brain tissue exhibit increased G3BP1 granules and TDP43 mislocalization.

Chronic cellular stress associated with neurodegenerative disease can result in the persistence of stress granule (SG) structures, membraneless organelles that form in response to cellular stress. In Huntington's disease (HD), chronic expression of mutant huntingtin generates various forms of cellular stress, including activation of the unfolded protein response and oxidative stress. However, it has yet to be determined whether SGs are a feature of HD neuropathology. We examined the miRNA composition of extracellular vesicles (EVs) present in the cerebrospinal fluid (CSF) of patients with HD and show that a subset of their target mRNAs were differentially expressed in the prefrontal cortex. Of these targets, SG components were enriched, including the SG-nucleating Ras GTPase-activating protein-binding protein 1 (G3BP1). We investigated localization and levels of G3BP1 and found a significant increase in the density of G3BP1-positive granules in the cortex and hippocampus of R6/2 transgenic mice and in the superior frontal cortex of the brains of patients with HD. Intriguingly, we also observed that the SG-associated TAR DNA-binding protein 43 (TDP43), a nuclear RNA/DNA binding protein, was mislocalized to the cytoplasm of G3BP1 granule-positive HD cortical neurons. These findings suggest that G3BP1 SG dynamics may play a role in the pathophysiology of HD.

Reduced Granule Cell Proliferation and Molecular Dysregulation in the Cerebellum of Lysosomal Acid Phosphatase 2 (ACP2) Mutant Mice.

Lysosomal acid phosphatase 2 (Acp2) mutant mice (naked-ataxia, nax) have a severe cerebellar cortex defect with a striking reduction in the number of granule cells. Using a combination of in vivo and in vitro immunohistochemistry, Western blotting, BrdU assays, and RT-qPCR, we show downregulation of MYCN and dysregulation of the SHH signaling pathway in the nax cerebellum. MYCN protein expression is significantly reduced at P10, but not at the peak of proliferation at around P6 when the number of granule cells is strikingly reduced in the nax cerebellum. Despite the significant role of the SHH-MycN pathway in granule cell proliferation, our study suggests that a broader molecular pathway and additional mechanisms regulating granule cell development during the clonal expansion period are impaired in the nax cerebellum. In particular, our results indicate that downregulation of the protein synthesis machinery may contribute to the reduced number of granule cells in the nax cerebellum.

Lin28, a major translation reprogramming factor, gains access to YB-1-packaged mRNA through its cold-shock domain.

The RNA-binding protein Lin28 (Lin28a) is an important pluripotency factor that reprograms translation and promotes cancer progression. Although Lin28 blocks let-7 microRNA maturation, Lin28 also binds to a large set of cytoplasmic mRNAs directly. However, how Lin28 regulates the processing of many mRNAs to reprogram global translation remains unknown. We show here, using a structural and cellular approach, a mixing of Lin28 with YB-1 (YBX1) in the presence of mRNA owing to their cold-shock domain, a conserved ß-barrel structure that binds to ssRNA cooperatively. In contrast, the other RNA binding-proteins without cold-shock domains tested, HuR, G3BP-1, FUS and LARP-6, did not mix with YB-1. Given that YB-1 is the core component of dormant mRNPs, a model in which Lin28 gains access to mRNPs through its co-association with YB-1 to mRNA may provide a means for Lin28 to reprogram translation. We anticipate that the translational plasticity provided by mRNPs may contribute to Lin28 functions in development and adaptation of cancer cells to an adverse environment.