The monomer-binding protein profilin 1 (PFN1) plays a crucial role in actin polymerization. However, mutations in PFN1 are also linked to hereditary amyotrophic lateral sclerosis, resulting in a broad range of cellular pathologies which cannot be explained by its primary function as a cytosolic actin assembly factor. This implies that there are important, undiscovered roles for PFN1 in cellular physiology. Here we screened knockout cells for novel phenotypes associated with PFN1 loss of function and discovered that mitophagy was significantly upregulated. Indeed, despite successful autophagosome formation, fusion with the lysosome, and activation of additional mitochondrial quality control pathways, PFN1 knockout cells accumulate depolarized, dysmorphic mitochondria with altered metabolic properties. Surprisingly, we also discovered that PFN1 is present inside mitochondria and provide evidence that mitochondrial defects associated with PFN1 loss are not caused by reduced actin polymerization in the cytosol. These findings suggest a previously unrecognized role for PFN1 in maintaining mitochondrial integrity and highlight new pathogenic mechanisms that can result from PFN1 dysregulation.

Multiple myeloma (MM) is an incurable hematological malignancy with poor survival. Accumulating evidence reveals that lactylation modification plays a vital role in tumorigenesis. However, research on lactylation-related genes (LRGs) in predicting the prognosis of MM remains limited. Differentially expressed LRGs (DELRGs) between MM and normal samples were investigated from the Gene Expression Omnibus database. Univariate Cox regression and LASSO Cox regression analysis were applied to construct gene signature associated with overall survival. The signature was validated in two external datasets. A nomogram was further constructed and evaluated. Additionally, Enrichment analysis, immune analysis, and drug chemosensitivity analysis between the two groups were investigated. qPCR and immunofluorescence staining were performed to validate the expression and localization of PFN1. CCK-8 and flow cytometry were performed to validate biological function. A total of 9 LRGs (TRIM28, PPIA, SOD1, RRP1B, IARS2, RB1, PFN1, PRCC, and FABP5) were selected to establish the prognostic signature. Kaplan-Meier survival curves showed that high-risk group patients had a remarkably worse prognosis in the training and validation cohorts. A nomogram was constructed based on LRGs signature and clinical characteristics, and showed excellent predictive power by calibration curve and C-index. Moreover, biological pathways, immunologic status, as well as sensitivity to chemotherapy drugs were different between high- and low-risk groups. Additionally, the hub gene PFN1 is highly expressed in MM, knocking down PFN1 induces cell cycle arrest, suppresses cell proliferation and promotes cell apoptosis. In conclusion, our study revealed that LRGs signature is a promising biomarker for MM that can effectively early distinguish high-risk patients and predict prognosis.

Art v4.01 is a well-known profilin protein belonging to the pan-allergens group and is commonly involved in triggering allergic asthma, polyallergy, and cross-sensitization. It is also referred to as Wormwood due to its origin. Crude wormwood extracts are applied for allergen-specific immunotherapy (AIT). Whether the recombinant Art v4.01 (rArt v4.01) can produce in vivo immunological tolerance by subcutaneous immunotherapy (SCIT) remains elusive. In this study, to investigate the in vivo immunological response of rArt v4.01, Th2, Th1, Treg, Th17 type-related cytokines and phenotypes of immune cells were tested, facilitating the exploration of the underlying mechanisms. The expression and purification of Art v4.01 were carried out using recombinant techniques. Allergic asthma female BALB/c mice were induced by subcutaneous sensitization of wormwood pollen extract and intranasal challenges. SCIT without adjuvant was performed using the rArt v4.01 and wormwood pollen extract for 2 weeks. Following exposure to challenges, the levels of immunoglobulin E (IgE), cytokines, and inflammatory cells were assessed through enzyme-linked immunosorbent assay (ELISA) and histological examination of sera, bronchoalveolar lavage fluid (BALF), and lung tissue. These parameters were subsequently compared between treatment groups receiving rArt v4.01 and wormwood pollen extract. The rArt v4.01 protein was expressed, which had a high purity (>90%) and an allergenic potency. Compared with the pollen extract, rArt v4.01 was superior in terms of reducing the number of white blood cells (WBCs), total nucleated cells (TNCs), and monocytes (MNs) in BALF and the degree of lung inflammation (1.77±0.99 vs. 2.31±0.80, P > 0.05). Compared with the model group, only rArt v4.01 reduced serum IgE level (1.19±0.25 vs. 1.61±0.17 μg/ml, P = 0.062), as well as the levels of Th2 type-related cytokines (interleukin-4 (IL-4) (107.18±16.17 vs. 132.47±20.85 pg/ml, P < 0.05) and IL-2 (19.52±1.19 vs. 24.02±2.14 pg/ml, P < 0.05)). The study suggested that rArt v4.01 was superior to pollen extract in reducing the number of inflammatory cells in BALF, pneumonitis, levels of pro-inflammatory cytokines, and serum IgE level. These findings confirmed that Art v4.01 could be a potential candidate protein for allergen-specific immunotherapy.

Pollen from Salsola kali, i.e., saltwort, Russian thistle, is a major allergen source in the coastal regions of southern Europe, in Turkey, Central Asia, and Iran. S. kali-allergic patients mainly suffer from hay-fever (i.e., rhinitis and conjunctivitis), asthma, and allergic skin symptoms. The aim of this study was to investigate the importance of individual S. kali allergen molecules. Sal k 1, Sal k 2, Sal k 3, Sal k 4, Sal k 5, and Sal k 6 were expressed in Escherichia coli as recombinant proteins containing a C-terminal hexahistidine tag and purified by nickel affinity chromatography. The purity of the recombinant allergens was analyzed by SDS-PAGE. Their molecular weight was determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and their fold and secondary structure were studied by circular dichroism (CD) spectroscopy. Sera from clinically well-characterized S. kali-allergic patients were used for IgE reactivity and basophil activation experiments. S. kali allergen-specific IgE levels and IgE levels specific for the highly IgE cross-reactive profilin and the calcium-binding allergen from timothy grass pollen, Phl p 12 and Phl p 7, respectively, were measured by ImmunoCAP. The allergenic activity of natural S. kali pollen allergens was studied in basophil activation experiments. Recombinant S. kali allergens were folded when studied by CD analysis. The sum of recombinant allergen-specific IgE levels and allergen-extract-specific IgE levels was highly correlated. Sal k 1 and profilin, reactive with IgE from 64% and 49% of patients, respectively, were the most important allergens, whereas the other S. kali allergens were less frequently recognized. Specific IgE levels were highest for profilin. Of note, 37% of patients who were negative for Sal k 1 showed IgE reactivity to Phl p 12, emphasizing the importance of the ubiquitous cytoskeletal actin-binding protein, profilin, for the diagnosis of IgE sensitization in S. kali-allergic patients. rPhl p 12 and rSal k 4 showed equivalent IgE reactivity, and the clinical importance of profilin was underlined by the fact that profilin-monosensitized patients suffered from symptoms of respiratory allergy to saltwort. Accordingly, profilin should be included in the panel of allergen molecules for diagnosis and in molecular allergy vaccines for the treatment and prevention of S. kali allergy.

Schizophrenia is a severe psychological disorder. The current diagnosis mainly relies on clinical symptoms and lacks laboratory evidence, which makes it very difficult to make an accurate diagnosis especially at an early stage. Plasma protein profiles of schizophrenia patients were obtained and compared with healthy controls using 4D-DIA proteomics technology. Furthermore, 79 DEPs were identified between schizophrenia and healthy controls. GO functional analysis indicated that DEPs were predominantly associated with responses to toxic substances and platelet aggregation, suggesting the presence of metabolic and immune dysregulation in patients with schizophrenia. KEGG pathway enrichment analysis revealed that DEPs were primarily enriched in the chemokine signaling pathway and cytokine receptor interactions. A diagnostic model was ultimately established, comprising three proteins, namely, PFN1, GAPDH and ACTBL2. This model demonstrated an AUC value of 0.972, indicating its effectiveness in accurately identifying schizophrenia. PFN1, GAPDH and ACTBL2 exhibit potential as biomarkers for the early detection of schizophrenia. The findings of our studies provide novel insights into the laboratory-based diagnosis of schizophrenia.

Humans express 15 formins that play crucial roles in actin-based processes, including cytokinesis, cell motility and mechanotransduction1,2. However, the lack of structures bound to the actin filament (F-actin) has been a major impediment to understanding formin function. Whereas formins are known for their ability to nucleate and elongate F-actin3-7, some formins can additionally depolymerize, sever or bundle F-actin. Two mammalian formins, inverted formin 2 (INF2) and diaphanous 1 (DIA1, encoded by DIAPH1), exemplify this diversity. INF2 shows potent severing activity but elongates weakly8-11 whereas DIA1 has potent elongation activity but does not sever4,8. Using cryo-electron microscopy (cryo-EM) we show five structural states of INF2 and two of DIA1 bound to the middle and barbed end of F-actin. INF2 and DIA1 bind differently to these sites, consistent with their distinct activities. The formin-homology 2 and Wiskott-Aldrich syndrome protein-homology 2 (FH2 and WH2, respectively) domains of INF2 are positioned to sever F-actin, whereas DIA1 appears unsuited for severing. These structures also show how profilin-actin is delivered to the fast-growing barbed end, and how this is followed by a transition of the incoming monomer into the F-actin conformation and the release of profilin. Combined, the seven structures presented here provide step-by-step visualization of the mechanisms of F-actin severing and elongation by formins.

Profilin binds microtubules in vitro. However, a new study by Vitriol and colleagues (https://doi.org/10.1083/jcb.202309097) now suggests that effects of profilin on microtubule dynamics in cells are indirect and result from its impact on actin dynamics rather than its direct binding to microtubules.

In addition to its well-established role in actin assembly, profilin 1 (PFN1) has been shown to bind to tubulin and alter microtubule growth. However, whether PFN1\'s predominant control over microtubules in cells occurs through direct regulation of tubulin or indirectly through the polymerization of actin has yet to be determined. Here, we manipulated PFN1 expression, actin filament assembly, and actomyosin contractility and showed that reducing any of these parameters for extended periods of time caused an adaptive response in the microtubule cytoskeleton, with the effect being significantly more pronounced in neuronal processes. All the observed changes to microtubules were reversible if actomyosin was restored, arguing that PFN1\'s regulation of microtubules occurs principally through actin. Moreover, the cytoskeletal modifications resulting from PFN1 depletion in neuronal processes affected microtubule-based transport and mimicked phenotypes that are linked to neurodegenerative disease. This demonstrates how defects in actin can cause compensatory responses in other cytoskeleton components, which in turn significantly alter cellular function.

BACKGROUND: Bladder cancer is the most common malignancy of the urinary system, and the search for new and reliable biomarkers has important clinical significance for the personalized treatment of bladder cancer. This study aims to explore the correlation between nuclear proliferation antigen (Ki-67) or Profilin-1 (PFN1) levels, clinicopathological characteristics, and postoperative prognosis in patients with bladder cancer.
METHODS: Patients with bladder cancer who underwent transurethral resection of bladder cancer tumor in The Fourth Affiliated Hospital of Soochow University, hospital from January 2019 to January 2021 were selected as the study group (n = 60), and patients with benign lesions of bladder cancer during the same period were selected as the control group (n = 60). The expression of Ki-67 and PFN1 in tumor and bladder tissues of the two groups was analyzed. Ki-67 recorded the patient\'s pathological parameters and calculated the patient\'s postoperative prognosis. The correlation between Ki-67 and PFN1 expression levels, pathological parameters, and postoperative prognosis was analyzed.
RESULTS: The positive expression rates of Ki-67 and PFN1 in the study group were 63.33% and 73.33%, respectively, which were significantly higher than the positive expression rates in the control group (χ2 = 14.803, 17.757, p < 0.001). The positive expression rates of Ki-67 and PFN1 were related to histological grade, clinical stage, infiltration, and lymph node metastasis, and the differences were statistically significant (p < 0.05). Bladder cancer patients with non muscle-invasive bladder cancer (NMIBC), high-grade histological grade, Ta~T1 clinical stage, invasive, and lymph node metastasis have a higher Ki-67 positive expression rate than bladder cancer patients with muscle-invasive bladder cancer (MIBC), low-grade histological grade, T2~T4, non-invasive, and no lymph node metastasis. The high expression level of Ki-67 has little relationship with gender, age, tumor diameter, and vascular invasion (p > 0.05). The survival time and three-year survival rate of the Ki-67 positive expression group were significantly lower than those of the Ki-67 negative expression group (p < 0.05). The survival time and three-year survival rate of the PFN1 positive expression group were significantly lower than those of the PFN1 negative expression group (p < 0.05).
CONCLUSIONS: The positive expression rates of Ki-67 and PFN1 in bladder tumor tissue are significantly higher than those in bladder tissue, and pathological pattern, histological grade, clinical stage, infiltration, and lymph node metastasis are related to the positive expression rates of Ki-67 and PFN1, and different genders, ages, tumors diameter and vascular invasion are not related to the positive expression rates of Ki-67 and PFN1. The survival time and three-year survival rates of bladder cancer patients with Ki-67 positive and PFN1 positive expression are shorter.

OBJECTIVE: Analyze phylogenetic relationships and molecular mimicry of Cit s 2 and other plant profilins.
METHODS: Online bioinformatics tools including Basic Local Alignment Search Tool (BLASTP), PRALINE and MEGA were used for multiple alignments and phylogenetic analysis. A 3D-homology model of Cit s 2 was predicted. Models were calculated with MODELLER. The best model was selected with the model scoring option of MAESTRO. Conserved regions between Cit s 2 and other profilins were located on the 3D model and antigenic regions were predicted by ElliPro server (3-5).
RESULTS: Cit s 2 amino acid sequence (Uniprot code:P84177) was compared with other 30 profilins from different allergenic sources. The identity between Cit s 2 and other profilins ranged between 82 and 99%. The highest identity was observed with Cucumis melo (99%) followed by Prunus persica (98%) and Malus domestica (92%). High conserved antigenic regions were observed on the 3D predicted model. Seven lineal and six discontinuous epitopes were found in Cit s 2.
CONCLUSIONS: High conserved antigenic regions were observed on the 3D predicted model of Cit s 2, which might involve potential cross-reactivity between Cit s 2 and other profilins. Future studies are needed to further analyze these results.
OBJECTIVE: Analizar las relaciones filogenéticas y el mimetismo molecular de Cit s 2 y otras profilinas vegetales.
UNASSIGNED: Se utilizaron herramientas bioinformáticas en línea, incluida la de búsqueda de alineación local básica (BLASTP), PRALINE y MEGA, para alineamientos múltiples y análisis filogenético. Se predijo un modelo de homología 3D de Cit s 2. Los modelos se calcularon con MODELLER. El mejor modelo fue seleccionado con la opción de puntuación de modelo de Maestro. Las regiones conservadas entre Cit s 2 y otras profilinas se ubicaron en el modelo 3D y las regiones antigénicas fueron predichas por el servidor ElliPro (3-5).
RESULTS: La secuencia de aminoácidos de Cit s 2 (código Uniprot: P84177), se comparó con otras 30 profilinas de diferentes fuentes alergénicas. La mayor identidad se observó con Cucumis melo (99%) seguida de Prunus persica (98%) y Malus domestica (92%). Se observaron regiones antigénicas altamente conservadas en el modelo predicho en 3D. Se encontraron siete epítopes lineales, y seis epítopes discontinuos en Cit s 2.
UNASSIGNED: Se observaron regiones antigénicas altamente conservadas en el modelo 3D predicho de Cit s 2, lo que podría implicar una posible reactividad cruzada entre Cit s 2 y otras profilinas. Se necesitan estudios futuros para analizar más a fondo estos resultados.