OBJECTIVE: Picalm (phosphatidylinositol-binding clathrin assembly protein), a ubiquitously expressed clathrin-adapter protein, is a well-known susceptibility gene for Alzheimer\'s disease, but its role in white adipose tissue (WAT) function has not yet been studied. Transcriptome analysis revealed differential expression of Picalm in WAT of diabetes-prone and diabetes-resistant mice, hence we aimed to investigate the potential link between Picalm expression and glucose homeostasis, obesity-related metabolic phenotypes, and its specific role in insulin-regulated GLUT4 trafficking in adipocytes.
METHODS: Picalm expression and epigenetic regulation by microRNAs (miRNAs) and DNA methylation were analyzed in WAT of diabetes-resistant (DR) and diabetes-prone (DP) female New Zealand Obese (NZO) mice and in male NZO after time-restricted feeding (TRF) and alternate-day fasting (ADF). PICALM expression in human WAT was evaluated in a cross-sectional cohort and assessed before and after weight loss induced by bariatric surgery. siRNA-mediated knockdown of Picalm in 3T3-L1-cells was performed to elucidate functional outcomes on GLUT4-translocation as well as insulin signaling and adipogenesis.
RESULTS: Picalm expression in WAT was significantly lower in DR compared to DP female mice, as well as in insulin-sensitive vs. resistant NZO males, and was also reduced in NZO males following TRF and ADF. Four miRNAs (let-7c, miR-30c, miR-335, miR-344) were identified as potential mediators of diabetes susceptibility-related differences in Picalm expression, while 11 miRNAs (including miR-23a, miR-29b, and miR-101a) were implicated in TRF and ADF effects. Human PICALM expression in adipose tissue was lower in individuals without obesity vs. with obesity and associated with weight-loss outcomes post-bariatric surgery. siRNA-mediated knockdown of Picalm in mature 3T3-L1-adipocytes resulted in amplified insulin-stimulated translocation of the endogenous glucose transporter GLUT4 to the plasma membrane and increased phosphorylation of Akt and Tbc1d4. Moreover, depleting Picalm before and during 3T3-L1 differentiation significantly suppressed adipogenesis, suggesting that Picalm may have distinct roles in the biology of pre- and mature adipocytes.
CONCLUSIONS: Picalm is a novel regulator of GLUT4-translocation in WAT, with its expression modulated by both genetic predisposition to diabetes and dietary interventions. These findings suggest a potential role for Picalm in improving glucose homeostasis and highlight its relevance as a therapeutic target for metabolic disorders.

VEGFR2 (Vascular endothelial growth factor receptor 2) is a central regulator of placental angiogenesis. The study of the VEGFR2 proteome of chorionic villi at term revealed its partners MDMX (Double minute 4 protein) and PICALM (Phosphatidylinositol-binding clathrin assembly protein). Subsequently, the oxytocin receptor (OT-R) and vasopressin V1aR receptor were detected in MDMX and PICALM immunoprecipitations. Immunogold electron microscopy showed VEGFR2 on endothelial cell (EC) nuclei, mitochondria, and Hofbauer cells (HC), tissue-resident macrophages of the placenta. MDMX, PICALM, and V1aR were located on EC plasma membranes, nuclei, and HC nuclei. Unexpectedly, PICALM and OT-R were detected on EC projections into the fetal lumen and OT-R on 20-150 nm clusters therein, prompting the hypothesis that placental exosomes transport OT-R to the fetus and across the blood-brain barrier. Insights on gestational complications were gained by univariable and multivariable regression analyses associating preeclampsia with lower MDMX protein levels in membrane extracts of chorionic villi, and lower MDMX, PICALM, OT-R, and V1aR with spontaneous vaginal deliveries compared to cesarean deliveries before the onset of labor. We found select associations between higher MDMX, PICALM, OT-R protein levels and either gravidity, diabetes, BMI, maternal age, or neonatal weight, and correlations only between PICALM-OT-R (p < 2.7 × 10-8), PICALM-V1aR (p < 0.006), and OT-R-V1aR (p < 0.001). These results offer for exploration new partnerships in metabolic networks, tissue-resident immunity, and labor, notably for HC that predominantly express MDMX.

Endocytosis is a key cellular pathway required for the internalization of cellular nutrients, lipids and receptor-bound cargoes. It is also critical for the recycling of cellular components, cellular trafficking and membrane dynamics. The endocytic pathway has been consistently implicated in Alzheimer\'s disease (AD) through repeated genome-wide association studies and the existence of rare coding mutations in endocytic genes. BIN1 and PICALM are two of the most significant late-onset AD risk genes after APOE and are both key to clathrin-mediated endocytic biology. Pathological studies also demonstrate that endocytic dysfunction is an early characteristic of late-onset AD, being seen in the prodromal phase of the disease. Different cell types of the brain have specific requirements of the endocytic pathway. Neurons require efficient recycling of synaptic vesicles and microglia use the specialized form of endocytosis-phagocytosis-for their normal function. Therefore, disease-associated changes in endocytic genes will have varied impacts across different cell types, which remains to be fully explored. Given the genetic and pathological evidence for endocytic dysfunction in AD, understanding how such changes and the related cell type-specific vulnerabilities impact normal cellular function and contribute to disease is vital and could present novel therapeutic opportunities. This article is part of a discussion meeting issue \'Understanding the endo-lysosomal network in neurodegeneration\'.

Rs3851179, a variant of PICALM gene, and age are the risk factors of Alzheimer\'s disease (AD). AD is divided into early-onset AD (EOAD, < 65 years) and late-onset AD (LOAD, ≥ 65 years) by age. The purpose was to investigate the impact of different genotypes of PICALM rs3851179 on brain atrophy and cognitive decline across the AD continuum in different age groups. Four hundred seven cognitive normal (CN) controls, 362 mild cognitive impairment (MCI) patients, and 94 AD patients were enrolled to assess the interaction between AD continuum, age status, and PICALM on gray matter volume (GMV), global cognition, memory function, and executive function using full factorial ANCOVA (3 × 2 × 2). The interaction between AD continuum and PICALM significantly affected the GMV of the left putamen (PUT.L). rs3851179 A-allele carriers did not show a significant decrease in PUT.L GMV from CN to MCI to AD, while GG-allele carriers did. The interaction between AD continuum and age status was significant on GMV of the left angular gyrus (ANG.L) and right superior occipital gyrus (SOG.R). LOAD had higher GMV of ANG.L and SOG.R than EOAD. The interactive effects among AD continuum, age status, and PICALM were not significant on GMV but were significant on global cognition and executive function. The A-allele was found to have a protective effect on global cognition and executive function in EOAD, but not significantly so in LOAD. PICALM rs3851179 A-allele might alleviate the atrophy of PUT.L across the AD continuum than GG-allele. Age status did not affect the interaction between AD continuum and PICALM on brain atrophy. The ANG.L and SOG.R atrophied more severely in EOAD than in LOAD. Rs3851179 A-allele was protective for global cognition and executive function in EOAD.

PICALM (phosphatidylinositol-binding clathrin assembly protein) mutations have been linked to a number of human disorders, including leukemia, Alzheimer\'s disease, and Parkinson\'s disease. Nevertheless, the effect of PICALM on cancer, particularly on prognosis and immune infiltration in individuals with BRCA, is unknown. We obtained the data of breast cancer patients from The Cancer Genome Atlas (TCGA) database, and analyzed the expression of PICALM in breast cancer, its impact on survival\' and its role in tumor immune invasion. Finally, in vitro cellular experiments were performed to validate the results. Research has found that PICALM expression was shown to be downregulated in BRCA and to be substantially linked with clinical stage, histological type, PAM50, and age. PICALM downregulation was linked to a lower overall survival (OS) and disease-specific survival (DSS) in BRCA patients. A multivariate Cox analysis revealed that PICALM is an independent predictor of OS. The enriched pathways revealed by functional enrichment analysis included oxidative phosphorylation, angiogenesis, the TGF signaling pathway, and the IL-6/JAK/STAT3 signaling system. Furthermore, the amount of immune cell infiltration by B cells, eosinophils, mast cells, neutrophils, and T cells was positively linked with PICALM expression. Finally, we experimentally verified that low expression of PICALM can reduce proliferation, migration, and invasion in tumor cells. This evidence shows that PICALM expression impacts prognosis, immune infiltration, and pathway expression in breast cancer patients, and it might be a potential predictive biomarker for the disease.

OBJECTIVE: Mixed phenotype acute leukemia (MPAL) is a rare hematologic malignancy in which the leukemic cells cannot be assigned to any specific lineage. The lack of well-defined, pathogenetically relevant diagnostic criteria makes the clinical handling of MPAL patients challenging. We herein report the genetic findings in bone marrow cells from two pediatric MPAL patients.
METHODS: Bone marrow cells were examined using G-banding, array comparative genomic hybridization, RNA sequencing, reverse transcription polymerase chain reaction, Sanger sequencing, and fluorescence in situ hybridization.
RESULTS: In the first patient, the genetic analyses revealed structural aberrations of chromosomal bands 8p11, 10p11, 11q21, and 17p11, the chimeras MLLT10::PICALM and PICALM::MLLT10, and imbalances (gains/losses) on chromosomes 2, 4, 8, 13, and 21. A submicroscopic deletion in 21q was also found including the RUNX1 locus. In the second patient, there were structural aberrations of chromosome bands 1p32, 8p11, 12p13, 20p13, and 20q11, the chimeras ETV6::LEXM and NCOA6::ETV6, and imbalances on chromosomes 2, 8, 11, 12, 16, 19, X, and Y.
CONCLUSIONS: The leukemic cells from both MPAL patients carried chromosome aberrations resulting in fusion genes as well as genomic imbalances resulting in gain and losses of many gene loci. The detected fusion genes probably represent the main leukemogenic events, although the gains and losses are also likely to play a role in leukemogenesis.

APOE ɛ4 and PICALM are established genes associated with risk of late-onset Alzheimer\'s disease (AD). Previous study indicated interaction of PICALM with APOE ɛ4 in AD patients.
To explore whether PICALM variation could moderate the influences of APOE ɛ4 on AD pathology biomarkers and cognition in pre-dementia stage.
A total of 1,034 non-demented participants (mean age 74 years, 56% females, 40% APOE ɛ4 carriers) were genotyped for PICALM rs3851179 and APOE ɛ4 at baseline and were followed for influences on changes of cognition and cerebrospinal fluid (CSF) AD markers in six years. The interaction effects were examined via regression models adjusting for age, gender, education, and cognitive diagnosis.
The interaction term of rs3851179×APOE ɛ4 accounted for a significant amount of variance in baseline general cognition (p = 0.039) and memory function (p = 0.002). The relationships of APOE ɛ4 with trajectory of CSF Aβ42 (p = 0.007), CSF P-tau181 (p = 0.003), CSF T-tau (p = 0.001), and memory function (p = 0.017) were also moderated by rs3851179 variation.
APOE ɛ4 carriers experienced slower clinical and pathological progression when they had more protective A alleles of PICALM rs3851179. These findings firstly revealed the gene-gene interactive effects of PICALM with APOE ɛ4 in pre-dementia stage.

Membrane trafficking is a fundamental mechanism for protein and lipid transport in eukaryotic cells and exhibits marked diversity among eukaryotic lineages with distinctive body plans and lifestyles. Diversification of the membrane trafficking system is associated with the expansion and secondary loss of key machinery components, including RAB GTPases, soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and adaptor proteins, during plant evolution. The number of AP180 N-terminal homology (ANTH) proteins, an adaptor family that regulates vesicle formation and cargo sorting during clathrin-mediated endocytosis, increases during plant evolution. In the genome of Arabidopsis thaliana, 18 genes for ANTH proteins have been identified, a higher number than that in yeast and animals, suggesting a distinctive diversification of ANTH proteins. Conversely, the liverwort Marchantia polymorpha possesses a simpler repertoire; only two genes encoding canonical ANTH proteins have been identified in its genome. Intriguingly, a non-canonical ANTH protein is encoded in the genome of M. polymorpha, which also harbors a putative kinase domain. Similar proteins have been detected in sporadic lineages of plants, suggesting their ancient origin and multiple secondary losses during evolution. We named this unique ANTH group phosphatidylinositol-binding clathrin assembly protein-K (PICALM-K) and characterized it in M. polymorpha using genetic, cell biology-based and artificial intelligence (AI)-based approaches. Our results indicate a flagella-related function of MpPICALM-K in spermatozoids, which is distinct from that of canonical ANTH proteins. Therefore, ANTH proteins have undergone significant functional diversification during evolution, and PICALM-K represents a plant-unique ANTH protein that is delivered by neofunctionalization through exon shuffling.

Recently, the localization of amyloid precursor protein (APP) into reversible nanoscale supramolecular assembly or \"nanodomains\" has been highlighted as crucial towards understanding the onset of the molecular pathology of Alzheimer\'s disease (AD). Surface expression of APP is regulated by proteins interacting with it, controlling its retention and lateral trafficking on the synaptic membrane. Here, we evaluated the involvement of a key risk factor for AD, PICALM, as a critical regulator of nanoscale dynamics of APP. Although it was enriched in the postsynaptic density, PICALM was also localized to the presynaptic active zone and the endocytic zone. PICALM colocalized with APP and formed nanodomains with distinct morphological properties in different subsynaptic regions. Next, we evaluated if this localization to subsynaptic compartments was regulated by the C-terminal sequences of APP, namely, the \"Y682ENPTY687\" domain. Towards this, we found that deletion of C-terminal regions of APP with partial or complete deletion of Y682ENPTY687, namely, APP-Δ9 and APP-Δ14, affected the lateral diffusion and nanoscale segregation of APP. Lateral diffusion of APP mutant APP-Δ14 sequence mimicked that of a detrimental Swedish mutant of APP, namely, APP-SWE, while APP-Δ9 diffused similar to wild-type APP. Interestingly, elevated expression of PICALM differentially altered the lateral diffusion of the APP C-terminal deletion mutants. These observations confirm that the C-terminal sequence of APP regulates its lateral diffusion and the formation of reversible nanoscale domains. Thus, when combined with autosomal dominant mutations, it generates distinct molecular patterns leading to onset of Alzheimer\'s disease (AD).

Clathrin-mediated endocytosis (CME) controls the internalization and function of a wide range of cell surface proteins. CME occurs by the assembly of clathrin and many other proteins on the inner leaflet of the plasma membrane into clathrin-coated pits (CCPs). These structures recruit specific cargo destined for internalization, generate membrane curvature, and in many cases undergo scission from the plasma membrane to yield intracellular vesicles. The diversity of functions of cell surface proteins controlled via internalization by CME may suggest that regulation of CCP formation could be effective to allow cellular adaptation under different contexts. Of interest is how cues derived from cellular metabolism may regulate CME, given the reciprocal role of CME in controlling cellular metabolism. The modification of proteins with O-linked β-GlcNAc (O-GlcNAc) is sensitive to nutrient availability and may allow cellular adaptation to different metabolic conditions. Here, we examined how the modification of proteins with O-GlcNAc may control CCP formation and thus CME. We used perturbation of key enzymes responsible for protein O-GlcNAc modification, as well as specific mutants of the endocytic regulator AAK1 predicted to be impaired for O-GlcNAc modification. We identify that CCP initiation and the assembly of clathrin and other proteins within CCPs are controlled by O-GlcNAc protein modification. This reveals a new dimension of regulation of CME and highlights the important reciprocal regulation of cellular metabolism and endocytosis.