bims-ecemfi 2024-03-17 papers

bims-ecemfi

Biomed News

on ECM and fibroblasts

Issue of 2024–03–17
fourteen papers selected by
Badri Narayanan Narasimhan, University of California, San Diego

"Patchiness" in mechanical stiffness across a tumor as an early-stage marker for malignancy.
Multicellular Tumoroids for Investigating Cancer Stem-Like Cells in the Heterogeneous Tumor Microenvironment.
Generation of Cancer Stem Cells by Co-Culture Methods.
In Vitro Tumorigenic Assay: A Tumor Sphere Assay for Cancer Stem Cells.
Spontaneous Fusion with Transformed Mesenchymal Stromal Cells Results in Complete Heterogeneity in Prostate Cancer Cells.
Intercellular crosstalk between cancer cells and cancer-associated fibroblasts via exosomes in gastrointestinal tumors.
Retrograde tracing of breast cancer-associated sensory neurons.
Matrix Resistance Toward Proteolytic Cleavage Controls Contractility-Dependent Migration Modes During Angiogenic Sprouting.
MiR-200c reprograms fibroblasts to recapitulate the phenotype of CAFs in breast cancer progression.
A Micro-scale Humanized Ventilator-on-a-Chip to Examine the Injurious Effects of Mechanical Ventilation.
The cellular composition of the tumor microenvironment is an important marker for predicting therapeutic efficacy in breast cancer.
Cancer cell response to extrinsic and intrinsic mechanical cue: opportunities for tumor apoptosis strategies.
Ferroptosis and EMT resistance in cancer: a comprehensive review of the interplay.
Cortical cell assemblies and their underlying connectivity: An in silico study.

BMC Ecol Evol. 2024 Mar 14. 24(1): 33

"Patchiness" in mechanical stiffness across a tumor as an early-stage marker for malignancy.

Zibah Mirzakhel, Gudur Ashrith Reddy, Jennifer Boman, Brianna Manns, Savannah Ter Veer, Parag Katira.

  Mechanical phenotyping of tumors, either at an individual cell level or tumor cell population level is gaining traction as a diagnostic tool. However, the extent of diagnostic and prognostic information that can be gained through these measurements is still unclear. In this work, we focus on the heterogeneity in mechanical properties of cells obtained from a single source such as a tissue or tumor as a potential novel biomarker. We believe that this heterogeneity is a conventionally overlooked source of information in mechanical phenotyping data. We use mechanics-based in-silico models of cell-cell interactions and cell population dynamics within 3D environments to probe how heterogeneity in cell mechanics drives tissue and tumor dynamics. Our simulations show that the initial heterogeneity in the mechanical properties of individual cells and the arrangement of these heterogenous sub-populations within the environment can dictate overall cell population dynamics and cause a shift towards the growth of malignant cell phenotypes within healthy tissue environments. The overall heterogeneity in the cellular mechanotype and their spatial distributions is quantified by a "patchiness" index, which is the ratio of the global to local heterogeneity in cell populations. We observe that there exists a threshold value of the patchiness index beyond which an overall healthy population of cells will show a steady shift towards a more malignant phenotype. Based on these results, we propose that the "patchiness" of a tumor or tissue sample, can be an early indicator for malignant transformation and cancer occurrence in benign tumors or healthy tissues. Additionally, we suggest that tissue patchiness, measured either by biochemical or biophysical markers, can become an important metric in predicting tissue health and disease likelihood just as landscape patchiness is an important metric in ecology.

Keywords:  Cancer ecology; Cell mechanics; Early markers; Landscape ecology; Physics of cancer; Tumor heterogeneity; Tumor malignancy

DOI:  https://doi.org/10.1186/s12862-024-02221-6
Methods Mol Biol. 2024 ;2777 99-122

Multicellular Tumoroids for Investigating Cancer Stem-Like Cells in the Heterogeneous Tumor Microenvironment.

Kathleen M Burkhard, Geeta Mehta.

  Cancer stem-like cells (CSC) are a major contributing factor to chemoresistance, tumor recurrence, and poor survival outcomes in patients across cancer types. Signaling from non-tumor cells in the tumor microenvironment (TME) enriches for and supports CSC. This complex cell-cell signaling in the heterogeneous TME presents a challenge for patient survival; however, it also presents an opportunity to develop new targeted therapies that can inhibit survival of CSC. In this chapter, we report a multicellular tumoroid model which can be used to investigate the interactions between cancer cells and non-tumor cells in the TME to better understand the contribution of various cell types to cancer cell phenotypes, as well as the underlying mechanisms involved. The following methods allow for each cell type to be distinguished using FACS and studied individually. Gene expression can be analyzed for cancer cells, as well as the other non-tumor cells using qPCR following sorting. The response to chemotherapeutic agents and expression of stem markers can be determined for cancer cells using flow cytometry, excluding the other cell types to get an accurate view of the cancer cells. Furthermore, the viability of non-tumor cells can be analyzed as well to determine if there are cytotoxic effects of the drugs on non-tumor cells. Thus, the multicellular tumoroid model will reveal the interactions between the CSC and non-tumor cells in the heterogenous TME, resulting in discoveries in the fields of cancer biology, novel targeted therapies, and personalized drug screening for precision medicine.

Keywords:  Alternately activated macrophages, AAM; Cancer stem-like cells, CSC; Carcinoma associated mesenchymal stem cells, CA-MSC; Carcinoma-associated fibroblasts, CAF; Heterogeneity; Immune microenvironment; Macrophages; Mesenchymal stem cells, MSC; Organoids; Spheroids; Tumor cells; Tumor microenvironment; Tumoroids

DOI:  https://doi.org/10.1007/978-1-0716-3730-2_8
Methods Mol Biol. 2024 ;2777 219-230

Generation of Cancer Stem Cells by Co-Culture Methods.

Biswajit Das, Chanakya Nath Kundu.

  Cancer stem cells (CSCs) exhibit intricate regulatory dynamics within the tumor microenvironment, involving interactions with various components like mesenchymal stem cells (MSCs), adipocytes, cancer-associated fibroblasts (CAFs), endothelial cells, tumor-associated macrophages (TAMs), and other immune cells. These interactions occur through complex networks of cytokines, inflammatory factors, and several growth factors. Diverse techniques are employed to generate CSCs, including serum-free sphere culture, chemotherapy, and radiation therapy. A novel approach to generate CSCs involves co-culturing, wherein recent research highlights the role of secreted factors such as inflammatory cytokines from MSCs, CAFs, and TAMs in inducing CSC-like characteristics in cancer cells. While the co-culture method shows promise in generating CSCs, further investigations are needed to comprehensively establish this process. This chapter focuses on establishing a co-culture-based technique for generating CSCs by combining cancer cells with TAMs and CAFs, elucidating the intricate mechanisms underlying this phenomenon.

Keywords:  Cancer associated fibroblasts; Cancer cells; Cancer stem cells; Co-culture; Tumor associated macrophages

DOI:  https://doi.org/10.1007/978-1-0716-3730-2_16
Methods Mol Biol. 2024 ;2777 91-98

In Vitro Tumorigenic Assay: A Tumor Sphere Assay for Cancer Stem Cells.

Amani Yehya, Hisham Bahmad, Wassim Abou-Kheir.

  Cancer stem cells (CSCs) represent a subpopulation of tumor cells that are thought to be responsible for therapy resistance, recurrence, and metastasis through their capacity to self-renew and differentiate into heterogeneous downstream lineages of cancer cells. Understanding the features of CSCs is crucial for managing cancer disease and establishing potential targeted therapeutics. Tumor sphere formation assay is a widely used in vitro method that selects and enriches the CSC subpopulation from the total population of cancer cells, based on their inherent ability to grow and clonally expand in serum-free and nonadherent culture conditions. Here we provide a detailed methodology to generate and propagate spheres from isolated cell suspensions of tumor tissues and cell lines using a semisolid MatrigelTM-based three-dimensional (3D) culture system.

Keywords:  Cancer stem cells; Differentiation; MatrigelTM; Self-renewal; Tumor sphere assay

DOI:  https://doi.org/10.1007/978-1-0716-3730-2_7
Cancers (Basel). 2024 Feb 27. pii: 951. [Epub ahead of print]16(5):

Spontaneous Fusion with Transformed Mesenchymal Stromal Cells Results in Complete Heterogeneity in Prostate Cancer Cells.

Ruoxiang Wang, Peizhen Hu, Fubo Wang, Ji Lyu, Yan Ou, Mouad Edderkaoui, Yi Zhang, Michael S Lewis, Stephen J Pandol, Haiyen E Zhau, Leland W K Chung.

  Tumor cells gain advantages in growth and survival by acquiring genotypic and phenotypic heterogeneity. Interactions with bystander cells in the tumor microenvironment contribute to the progression of heterogeneity. We have shown that fusion between tumor and bystander cells is one form of interaction, and that tumor-bystander cell fusion has contrasting effects. By trapping fusion hybrids in the heterokaryon or synkaryon state, tumor-bystander cell fusion prevents the progression of heterogeneity. However, if trapping fails, fusion hybrids will resume replication to form derivative clones with diverse genomic makeups and behavioral phenotypes. To determine the characteristics of bystander cells that influence the fate of fusion hybrids, we co-cultured prostate mesenchymal stromal cell lines and their spontaneously transformed sublines with LNCaP as well as HPE-15 prostate cancer cells. Subclones derived from cancer-stromal fusion hybrids were examined for genotypic and phenotypic diversifications. Both stromal cell lines were capable of fusing with cancer cells, but only fusion hybrids with the transformed stromal subline generated large numbers of derivative subclones. Each subclone had distinct cell morphologies and growth behaviors and was detected with complete genomic hybridization. The health conditions of the bystander cell compartment play a crucial role in the progression of tumor cell heterogeneity.

Keywords:  bystander cells; cancer–stromal hybridization; cell fusion; heterogeneity progression; stromal cell transformation; tumor cells

DOI:  https://doi.org/10.3390/cancers16050951
Front Oncol. 2024 ;14 1374742

Intercellular crosstalk between cancer cells and cancer-associated fibroblasts via exosomes in gastrointestinal tumors.

Longyang Cao, Hong Ouyang.

  Gastrointestinal (GI) tumors are a significant global health threat, with high rates of morbidity and mortality. Exosomes contain various biologically active molecules like nucleic acids, proteins, and lipids and can serve as messengers for intercellular communication. They play critical roles in the exchange of information between tumor cells and the tumor microenvironment (TME). The TME consists of mesenchymal cells and components of the extracellular matrix (ECM), with fibroblasts being the most abundant cell type in the tumor mesenchyme. Cancer-associated fibroblasts (CAFs) are derived from normal fibroblasts and mesenchymal stem cells that are activated in the TME. CAFs can secrete exosomes to modulate cell proliferation, invasion, migration, drug resistance, and other biological processes in tumors. Additionally, tumor cells can manipulate the function and behavior of fibroblasts through direct cell-cell interactions. This review provides a summary of the intercellular crosstalk between GI tumor cells and CAFs through exosomes, along with potential underlying mechanisms.

Keywords:  cancer-associated fibroblasts (CAFs); exosomes; gastrointestinal (GI) tumors; review; tumor microenvironment (TME)

DOI:  https://doi.org/10.3389/fonc.2024.1374742
bioRxiv. 2024 Mar 01. pii: 2024.02.26.582088. [Epub ahead of print]

Retrograde tracing of breast cancer-associated sensory neurons.

Svetllana Kallogjerovic, Inés Velázquez-Quesada, Rutva Hadap, Bojana Gligorijevic.

Breast cancer is one of the leading causes of mortality among women. The tumor microenvironment, consisting of host cells and extracellular matrix, has been increasingly studied for its interplay with cancer cells, and the resulting effect on tumor progression. While the breast is one of the most innervated organs in the body, the role of neurons, and specifically sensory neurons, has been understudied, mostly for technical reasons. One of the reasons is the anatomy of sensory neurons: sensory neuron somas are located in the spine, and their axons can extend longer than a meter across the body to provide innervation in the breast. Next, neurons are challenging to culture, and there are no cell lines adequately representing the diversity of sensory neurons. Finally, sensory neurons are responsible for transporting several different types of signals to the brain, and there are many different subtypes of sensory neurons. The subtypes of sensory neurons which innervate and interact with breast tumors are unknown. To establish the tools for labeling and subtyping neurons that interact with breast cancer cells, we utilized two retrograde tracer's standards in neuroscience, wheat-germ agglutinin (WGA) and cholera toxin subunit B (CTB). In vitro , we employed primary sensory neurons isolated from mouse dorsal root ganglia, cultured in a custom-built microfluidic device DACIT, that mimics the anatomical compartmentalization of the sensory neuron's soma and axons. In vivo , we utilized both syngeneic and transgenic mouse models of mammary carcinoma. We show that CTB and WGA trace different but overlapping sensory neuronal subpopulations: while WGA is more efficient in labeling CGRP+ neurons, CTB is superior in labeling the NF200+ neurons. Surprisingly, both tracers are also taken up by a significant population of breast cancer cells, both in vitro and in vivo . In summary, we have established methodologies for retrograde tracing of sensory neurons interacting with breast cancer cells. Our tools will be useful for future studies of breast tumor innervation, and development of therapies targeting breast cancer-associated neuron subpopulations of sensory neurons.

DOI: https://doi.org/10.1101/2024.02.26.582088
Adv Sci (Weinh). 2024 Mar 13. e2305947

Matrix Resistance Toward Proteolytic Cleavage Controls Contractility-Dependent Migration Modes During Angiogenic Sprouting.

Martin S Weiß, Giuseppe Trapani, Hongyan Long, Britta Trappmann.

  Tissue homeostasis and disease states rely on the formation of new blood vessels through angiogenic sprouting, which is tightly regulated by the properties of the surrounding extracellular matrix. While physical cues, such as matrix stiffness or degradability, have evolved as major regulators of cell function in tissue microenvironments, it remains unknown whether and how physical cues regulate endothelial cell migration during angiogenesis. To investigate this, a biomimetic model of angiogenic sprouting inside a tunable synthetic hydrogel is created. It is shown that endothelial cells sense the resistance of the surrounding matrix toward proteolytic cleavage and respond by adjusting their migration phenotype. The resistance cells encounter is impacted by the number of covalent matrix crosslinks, crosslink degradability, and the proteolytic activity of cells. When matrix resistance is high, cells switch from a collective to an actomyosin contractility-dependent single cellular migration mode. This switch in collectivity is accompanied by a major reorganization of the actin cytoskeleton, where stress fibers are no longer visible, and F-actin aggregates in large punctate clusters. Matrix resistance is identified as a previously unknown regulator of angiogenic sprouting and, thus, provides a mechanism by which the physical properties of the matrix impact cell migration modes through cytoskeletal remodeling.

Keywords:  angiogenesis; cell migration; cell-ECM interactions; organ-on-chip; synthetic hydrogels

DOI:  https://doi.org/10.1002/advs.202305947
Cell Stress. 2024 ;8 1-20

MiR-200c reprograms fibroblasts to recapitulate the phenotype of CAFs in breast cancer progression.

Zhao Lin, Megan E Roche, Víctor Díaz-Barros, Marina Domingo-Vidal, Diana Whitaker-Menezes, Madalina Tuluc, Guldeep Uppal, Jaime Caro, Joseph M Curry, Ubaldo Martinez-Outschoorn.

  Mesenchymal-epithelial plasticity driving cancer progression in cancer-associated fibroblasts (CAFs) is undetermined. This work identifies a subgroup of CAFs in human breast cancer exhibiting mesenchymal-to-epithelial transition (MET) or epithelial-like profile with high miR-200c expression. MiR-200c overexpression in fibroblasts is sufficient to drive breast cancer aggressiveness. Oxidative stress in the tumor microenvironment induces miR-200c by DNA demethylation. Proteomics, RNA-seq and functional analyses reveal that miR-200c is a novel positive regulator of NFκB-HIF signaling via COMMD1 downregulation and stimulates pro-tumorigenic inflammation and glycolysis. Reprogramming fibroblasts toward MET via miR-200c reduces stemness and induces a senescent phenotype. This pro-tumorigenic profile in CAFs fosters carcinoma cell resistance to apoptosis, proliferation and immunosuppression, leading to primary tumor growth, metastases, and resistance to immuno-chemotherapy. Conversely, miR-200c inhibition in fibroblasts restrains tumor growth with abated oxidative stress and an anti-tumorigenic immune environment. This work determines the mechanisms by which MET in CAFs via miR-200c transcriptional enrichment with DNA demethylation triggered by oxidative stress promotes cancer progression. CAFs undergoing MET trans-differentiation and senescence coordinate heterotypic signaling that may be targeted as an anti-cancer strategy.

Keywords:  NFκB-HIF signaling; cancer immunology and immunotherapy; chromatin modification; miR-200c; oxidative stress; senescence

DOI:  https://doi.org/10.15698/cst2024.03.293
bioRxiv. 2024 Mar 01. pii: 2024.02.26.582200. [Epub ahead of print]

A Micro-scale Humanized Ventilator-on-a-Chip to Examine the Injurious Effects of Mechanical Ventilation.

Basia Gabela-Zuniga, Vasudha C Shukla, Christopher Bobba, Natalia Higuita-Castro, Heather M Powell, Joshua A Englert, Samir N Ghadiali.

Patients with compromised respiratory function frequently require mechanical ventilation to survive. Unfortunately, non-uniform ventilation of injured lungs generates complex mechanical forces that lead to ventilator induced lung injury (VILI). Although investigators have developed lung-on-a-chip systems to simulate normal respiration, modeling the complex mechanics of VILI as well as the subsequent recovery phase is a challenge. Here we present a novel humanized in vitro ventilator-on-a-chip (VOC) model of the lung microenvironment that simulates the different types of injurious forces generated in the lung during mechanical ventilation. We used transepithelial/endothelial electrical resistance (TEER) measurements to investigate how individual and simultaneous application of the different mechanical forces alters real-time changes in barrier integrity during and after injury. We find that compressive stress (i.e. barotrauma) does not significantly alter barrier integrity while over-distention (20% cyclic radial strain, volutrauma) results in decreased barrier integrity that quickly recovers upon removal of mechanical stress. Conversely, surface tension forces generated during airway reopening (atelectrauma), result in a rapid loss of barrier integrity with a delayed recovery relative to volutrauma. Simultaneous application of cyclic stretching (volutrauma) and airway reopening (atelectrauma), indicate that the surface tension forces associated with reopening fluid-occluded lung regions is the primary driver of barrier disruption. Thus, our novel VOC system can monitor the effects of different types of injurious forces on barrier disruption and recovery in real-time and can be used to identify the biomechanical mechanisms of VILI.

DOI: https://doi.org/10.1101/2024.02.26.582200
Front Immunol. 2024 ;15 1368687

The cellular composition of the tumor microenvironment is an important marker for predicting therapeutic efficacy in breast cancer.

Tingyao Dou, Jing Li, Yaochen Zhang, Wanru Pei, Binyue Zhang, Bin Wang, Yanhong Wang, Hongyan Jia.

  At present, the incidence rate of breast cancer ranks first among new-onset malignant tumors in women. The tumor microenvironment is a hot topic in tumor research. There are abundant cells in the tumor microenvironment that play a protumor or antitumor role in breast cancer. During the treatment of breast cancer, different cells have different influences on the therapeutic response. And after treatment, the cellular composition in the tumor microenvironment will change too. In this review, we summarize the interactions between different cell compositions (such as immune cells, fibroblasts, endothelial cells, and adipocytes) in the tumor microenvironment and the treatment mechanism of breast cancer. We believe that detecting the cellular composition of the tumor microenvironment is able to predict the therapeutic efficacy of treatments for breast cancer and benefit to combination administration of breast cancer.

Keywords:  breast cancer; combination administration; immune cell; treatment mechanism; tumor microenvironment

DOI:  https://doi.org/10.3389/fimmu.2024.1368687
Regen Biomater. 2024 ;11 rbae016

Cancer cell response to extrinsic and intrinsic mechanical cue: opportunities for tumor apoptosis strategies.

Jun Shu, Huan Deng, Yu Zhang, Fang Wu, Jing He.

  Increasing studies have revealed the importance of mechanical cues in tumor progression, invasiveness and drug resistance. During malignant transformation, changes manifest in either the mechanical properties of the tissue or the cellular ability to sense and respond to mechanical signals. The major focus of the review is the subtle correlation between mechanical cues and apoptosis in tumor cells from a mechanobiology perspective. To begin, we focus on the intracellular force, examining the mechanical properties of the cell interior, and outlining the role that the cytoskeleton and intracellular organelle-mediated intracellular forces play in tumor cell apoptosis. This article also elucidates the mechanisms by which extracellular forces guide tumor cell mechanosensing, ultimately triggering the activation of the mechanotransduction pathway and impacting tumor cell apoptosis. Finally, a comprehensive examination of the present status of the design and development of anti-cancer materials targeting mechanotransduction is presented, emphasizing the underlying design principles. Furthermore, the article underscores the need to address several unresolved inquiries to enhance our comprehension of cancer therapeutics that target mechanotransduction.

Keywords:  anticancer materials; apoptosis; cancer cell; mechanical stimulation; mechanotransduction

DOI:  https://doi.org/10.1093/rb/rbae016
Front Oncol. 2024 ;14 1344290

Ferroptosis and EMT resistance in cancer: a comprehensive review of the interplay.

Huiming Zhang, Naifeng Chen, Chenglong Ding, Huinan Zhang, Dejiang Liu, Shuang Liu.

  Ferroptosis differs from traditional cell death mechanisms like apoptosis, necrosis, and autophagy, primarily due to its reliance on iron metabolism and the loss of glutathione peroxidase activity, leading to lipid peroxidation and cell death. The dysregulation of iron metabolism is a hallmark of various cancers, contributing to tumor progression, metastasis, and notably, drug resistance. The acquisition of mesenchymal characteristics by epithelial cells is known as Epithelial-Mesenchymal Transition (EMT), a biological process intricately linked to cancer development, promoting traits such as invasiveness, metastasis, and resistance to therapeutic interventions. EMT plays a pivotal role in cancer progression and contributes significantly to the complex dynamics of carcinogenesis. Research findings indicate that mesenchymal cancer cells exhibit greater susceptibility to ferroptosis compared to their epithelial counterparts. The induction of ferroptosis becomes more effective in eliminating drug-resistant cancer cells during the process of EMT. The interplay between ferroptosis and EMT, a process where epithelial cells transform into mobile mesenchymal cells, is crucial in understanding cancer progression. EMT is associated with increased cancer metastasis and drug resistance. The review delves into how ferroptosis and EMT influence each other, highlighting the role of key proteins like GPX4, which protects against lipid peroxidation, and its inhibition can induce ferroptosis. Conversely, increased GPX4 expression is linked to heightened resistance to ferroptosis in cancer cells. Moreover, the review discusses the implications of EMT-induced transcription factors such as Snail, Zeb1, and Twist in modulating the sensitivity of tumor cells to ferroptosis, thereby affecting drug resistance and cancer treatment outcomes. Targeting the ferroptosis pathway offers a promising therapeutic strategy, particularly for tumors resistant to conventional treatments. The induction of ferroptosis in these cells could potentially overcome drug resistance. However, translating these findings into clinical practice presents challenges, including understanding the precise mechanisms of ferroptosis induction, identifying predictive biomarkers, and optimizing combination therapies. The review underscores the need for further research to unravel the complex interactions between ferroptosis, EMT, and drug resistance in cancer. This could lead to the development of more effective, targeted cancer treatments, particularly for drug-resistant tumors, offering new hope in cancer therapeutics.

Keywords:  cancer therapeutics; drug resistance; ferroptosis; metastasis; tumorigenesis

DOI:  https://doi.org/10.3389/fonc.2024.1344290
PLoS Comput Biol. 2024 Mar;20(3): e1011891

Cortical cell assemblies and their underlying connectivity: An in silico study.

András Ecker, Daniela Egas Santander, Sirio Bolaños-Puchet, James B Isbister, Michael W Reimann.

Recent developments in experimental techniques have enabled simultaneous recordings from thousands of neurons, enabling the study of functional cell assemblies. However, determining the patterns of synaptic connectivity giving rise to these assemblies remains challenging. To address this, we developed a complementary, simulation-based approach, using a detailed, large-scale cortical network model. Using a combination of established methods we detected functional cell assemblies from the stimulus-evoked spiking activity of 186,665 neurons. We studied how the structure of synaptic connectivity underlies assembly composition, quantifying the effects of thalamic innervation, recurrent connectivity, and the spatial arrangement of synapses on dendrites. We determined that these features reduce up to 30%, 22%, and 10% of the uncertainty of a neuron belonging to an assembly. The detected assemblies were activated in a stimulus-specific sequence and were grouped based on their position in the sequence. We found that the different groups were affected to different degrees by the structural features we considered. Additionally, connectivity was more predictive of assembly membership if its direction aligned with the temporal order of assembly activation, if it originated from strongly interconnected populations, and if synapses clustered on dendritic branches. In summary, reversing Hebb's postulate, we showed how cells that are wired together, fire together, quantifying how connectivity patterns interact to shape the emergence of assemblies. This includes a qualitative aspect of connectivity: not just the amount, but also the local structure matters; from the subcellular level in the form of dendritic clustering to the presence of specific network motifs.

DOI: https://doi.org/10.1371/journal.pcbi.1011891