Pannexin 1 (Panx1) is a channel-forming glycoprotein important in paracrine signaling and cellular development. In this study, we discovered that mice globally lacking Panx1 (KO) have significantly ...greater total fat mass and reduced lean mass compared to wild type (WT) mice under a normal diet. Despite having higher fat content, Panx1 KO mice on a high fat diet exhibited no differences in weight gain and blood markers of obesity as compared to WT controls, except for an increase in glucose and insulin levels. However, metabolic cage data revealed that these Panx1 KO mice display significantly increased activity levels, higher ambulatory activity, and reduced sleep duration relative to their WT littermates on a high-fat diet. To uncover the cellular mechanism responsible for the increased fat content in the KO, we isolated primary cultures of adipose-derived stromal cells (ASCs) from WT and KO fat pads. In WT ASCs we observed that Panx1 protein levels increase upon induction into an adipogenic lineage. ASCs isolated from Panx1 KO mice proliferate less but demonstrate enhanced adipogenic differentiation with increased intracellular lipid accumulation, glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity, and adipokine secretion, as compared to WT ASCs. This was consistent with the increased adipocyte size and decreased adipocyte numbers observed in subcutaneous fat of the Panx1 KO mice compared to WT. We concluded that Panx1 plays a key role in adipose stromal cells during the early stages of adipogenic proliferation and differentiation, regulating fat accumulation in vivo.
There is great interest in the application of advanced proteomic techniques to characterize decellularized tissues in order to develop a deeper understanding of the effects of the complex ...extracellular matrix (ECM) composition on the cellular response to these pro-regenerative bioscaffolds. However, the identification of proteins in ECM-derived bioscaffolds is hindered by the high abundance of collagen in the samples, which can interfere with the detection of lower-abundance constituents that may be important regulators of cell function. To address this limitation, we developed a novel multi-enzyme digestion approach using treatment with a highly-purified collagenase derived from Clostridium Histolyticum to selectively deplete collagen from ECM-derived protein extracts, reducing its relative abundance from up to 90% to below 10%. Moreover, we applied this new method to characterize the proteome of human decellularized adipose tissue (DAT), human decellularized cancellous bone (DCB), and commercially-available bovine tendon collagen (BTC). We successfully demonstrated with all three sources that collagenase treatment increased the depth of detection and enabled the identification of a variety of signaling proteins that were masked by collagen in standard digestion protocols with trypsin/LysC, increasing the number of proteins identified in the DAT by ∼2.2 fold, the DCB by ∼1.3 fold, and the BTC by ∼1.6 fold. In addition, quantitative proteomics using label-free quantification demonstrated that the DAT and DCB extracts were compositionally distinct, and identified a number of adipogenic and osteogenic proteins that were consistently more highly expressed in the DAT and DCB respectively. Overall, we have developed a new processing method that may be applied in advanced mass spectrometry studies to improve the high-throughput proteomic characterization of bioscaffolds derived from mammalian tissues. Further, our study provides new insight into the complex ECM composition of two human decellularized tissues of interest as cell-instructive platforms for regenerative medicine.
An injectable composite scaffold incorporating decellularized adipose tissue (DAT) as a bioactive matrix within a hydrogel phase capable of in situ polymerization would be advantageous for ...adipose-derived stem cell (ASC) delivery in the filling of small or irregular soft tissue defects. Building on previous work, the current study investigates DAT milling methods and the effects of DAT particle size and cell seeding density on the response of human ASCs encapsulated in photo-cross-linkable methacrylated chondroitin sulphate (MCS)-DAT composite hydrogels. DAT particles were generated by milling lyophilized DAT and the particle size was controlled through the processing conditions with the goal of developing composite scaffolds with a tissue-specific 3D microenvironment tuned to enhance adipogenesis. ASC proliferation and adipogenic differentiation were assessed in vitro in scaffolds incorporating small (average diameter of 38 ± 6 μm) or large (average diameter of 278 ± 3 μm) DAT particles in comparison to MCS controls over a period of up to 21 d. Adipogenic differentiation was enhanced in the composites incorporating the smaller DAT particles and seeded at the higher density of 5 × 10(5) ASCs/scaffold, as measured by glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity, semi-quantitative analysis of perilipin expression and oil red O staining of intracellular lipid accumulation. Overall, this study demonstrates that decellularized tissue particle size can impact stem cell differentiation through cell-cell and cell-matrix interactions, providing relevant insight towards the rational design of composite biomaterial scaffolds for adipose tissue engineering.
Cell function is mediated by interactions with the extracellular matrix (ECM), which has complex tissue-specific composition and architecture. The focus of this article is on the methods for ...fabricating ECM-derived porous foams and microcarriers for use as biologically-relevant substrates in advanced 3D in vitro cell culture models or as pro-regenerative scaffolds and cell delivery systems for tissue engineering and regenerative medicine. Using decellularized tissues or purified insoluble collagen as a starting material, the techniques can be applied to synthesize a broad array of tissue-specific bioscaffolds with customizable geometries. The approach involves mechanical processing and mild enzymatic digestion to yield an ECM suspension that is used to fabricate the three-dimensional foams or microcarriers through controlled freezing and lyophilization procedures. These pure ECM-derived scaffolds are highly porous, yet stable without the need for chemical crosslinking agents or other additives that may negatively impact cell function. The scaffold properties can be tuned to some extent by varying factors such as the ECM suspension concentration, mechanical processing methods, or synthesis conditions. In general, the scaffolds are robust and easy to handle, and can be processed as tissues for most standard biological assays, providing a versatile and user-friendly 3D cell culture platform that mimics the native ECM composition. Overall, these straightforward methods for fabricating customized ECM-derived foams and microcarriers may be of interest to both biologists and biomedical engineers as tissue-specific cell-instructive platforms for in vitro and in vivo applications.
Pannexins (Panx) are channel‐forming glycoproteins important in paracrine signaling and cellular development. Panx1 and Panx3 are expressed in adipocytes and adipose stromal cells. We discovered that ...mice globally lacking Panx1 (KO) have significantly greater total fat mass and reduced lean mass compared to wild type (WT) mice under a normal diet, while Panx3 KO mice have reduced total fat mass and weigh less than WT controls. Despite having higher fat content, Panx1 KO mice on a high fat diet exhibited no differences in weight gain but showed an increase in glucose and insulin levels compared to WT. However, metabolic cage data revealed that these Panx1 KO mice display significantly increased activity levels, higher ambulatory activity, and reduced sleep duration relative to their WT littermates on a high‐fat diet. To uncover the cellular mechanism responsible for the increased fat content in the Panx1 KO, we isolated primary cultures of adipose‐derived stromal cells (ASCs) from WT and KO fat pads. In WT ASCs we observed that Panx1 protein levels increase upon induction into an adipogenic lineage. ASCs isolated from Panx1 KO mice proliferate less but demonstrate enhanced adipogenic differentiation with increased intracellular lipid accumulation, glycerol‐3‐phosphate dehydrogenase (GPDH) enzyme activity, and adipokine secretion, as compared to WT ASCs. This was consistent with the increased adipocyte size (hypertrophy) and decreased adipocyte numbers observed in subcutaneous fat of the Panx1 KO mice compared to WT. Panx3 is also expressed in adipose stromal cells and Panx3 protein levels significantly increase in differentiated adipocytes. However, the effect of the Panx3 KO seems to be the opposite of the Panx1 KO, with decreased weight under a high fat diet and lower fat mass (even under a normal chow diet). We propose that Panx1 and Panx3 may play opposing roles in adipose stromal cells during the early stages of adipogenic proliferation and differentiation, regulating fat accumulation in vivo.
Support or Funding Information
Funded by the Canadian Institutes of Health Research (CIHR) grants to SP and LF
This is from the Experimental Biology 2019 Meeting. There is no full text article associated with this published in The FASEB Journal.
During July 2021, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.617.2 variant infections, including vaccine breakthrough infections, occurred after large public gatherings in ...Provincetown, Massachusetts, USA, prompting a multistate investigation. Public health departments identified primary and secondary cases by using coronavirus disease surveillance data, case investigations, and contact tracing. A primary case was defined as SARS-CoV-2 detected <14 days after travel to or residence in Provincetown during July 3-17. A secondary case was defined as SARS-CoV-2 detected <14 days after close contact with a person who had a primary case but without travel to or residence in Provincetown during July 3-August 10. We identified 1,098 primary cases and 30 secondary cases associated with 26 primary cases among fully and non-fully vaccinated persons. Large gatherings can have widespread effects on SARS-CoV-2 transmission, and fully vaccinated persons should take precautions, such as masking, to prevent SARS-CoV-2 transmission, particularly during substantial or high transmission.
Basement membranes are defining features of the cellular microenvironment; however, little is known regarding their assembly outside cells. We report that extracellular Cl(-) ions signal the assembly ...of collagen IV networks outside cells by triggering a conformational switch within collagen IV noncollagenous 1 (NC1) domains. Depletion of Cl(-) in cell culture perturbed collagen IV networks, disrupted matrix architecture, and repositioned basement membrane proteins. Phylogenetic evidence indicates this conformational switch is a fundamental mechanism of collagen IV network assembly throughout Metazoa. Using recombinant triple helical protomers, we prove that NC1 domains direct both protomer and network assembly and show in Drosophila that NC1 architecture is critical for incorporation into basement membranes. These discoveries provide an atomic-level understanding of the dynamic interactions between extracellular Cl(-) and collagen IV assembly outside cells, a critical step in the assembly and organization of basement membranes that enable tissue architecture and function. Moreover, this provides a mechanistic framework for understanding the molecular pathobiology of NC1 domains.
Proton craniospinal irradiation (p-CSI) has been proposed to reduce side effects associated with CSI. We evaluated acute toxicities and preliminary clinical outcomes in a series of adults treated ...with p-CSI.
We reviewed medical records for 50 patients (aged 16-63 y) with malignancies of varying histologies treated consecutively with vertebral body-sparing p-CSI at MD Anderson Cancer Center from 2007 to 2011. Median CSI and total boost doses were 30.6 and 54 Gy. Forty patients received chemotherapy, varying by histology. Median follow-up was 20.1 months (range, 0.3-59).
Median doses to the thyroid gland, pituitary gland, hypothalamus, and cochleae were 0.003 Gy-relative biological effectiveness (RBE; range, 0.001-8.5), 36.1 Gy-RBE (22.5-53.0), 37.1 Gy-RBE (22.3-54.4), and 33.9 Gy-RBE (22.2-52.4), respectively. Median percent weight loss during CSI was 1.6% (range, 10% weight loss to 14% weight gain). Mild nausea/vomiting was common (grade 1 = 46%, grade 2 = 20%); however, only 5 patients experienced grade ≥2 anorexia (weight loss >5% baseline weight). Median percent baseline white blood cells, hemoglobin, and platelets at nadir were 52% (range, 13%-100%), 97% (65%-112%), and 61% (10%-270%), respectively. Four patients developed grade ≥3 cytopenias. Overall and progression-free survival rates were 96% and 82%, respectively, at 2 years and 84% and 68% at 5 years.
This large series of patients treated with p-CSI confirms low rates of acute toxicity, consistent with dosimetric models. Vertebral body-sparing p-CSI is feasible and should be considered as a way to reduce acute gastrointestinal and hematologic toxicity in adults requiring CSI.
Holocene climate reconstructions are useful for understanding the diverse
features and spatial heterogeneity of past and future climate change. Here
we present a database of western North American ...Holocene paleoclimate
records. The database gathers paleoclimate time series from 184 terrestrial
and marine sites, including 381 individual proxy records. The records span
at least 4000 of the last 12 000 years (median duration of 10 725 years)
and have been screened for resolution, chronologic control, and climate
sensitivity. Records were included that reflect temperature, hydroclimate,
or circulation features. The database is shared in the machine readable
Linked Paleo Data (LiPD) format and includes geochronologic data for
generating site-level time-uncertain ensembles. This publicly accessible and
curated collection of proxy paleoclimate records will have wide research
applications, including, for example, investigations of the primary features
of ocean–atmospheric circulation along the eastern margin of the North
Pacific and the latitudinal response of climate to orbital changes. The
database is available for download at https://doi.org/10.6084/m9.figshare.12863843.v1 (Routson and McKay, 2020).
Men who have sex with men (MSM) and transgender women (TGW) are highly affected by HIV and need novel prevention strategies. Using HIV self-testing (HIVST) kits to screen sexual partners may ...represent a viable risk-reduction alternative; however, more research is needed on effective strategies for broaching HIVST with partners. In the ISUM study, 136 MSM and TGW were given ten HIVST kits for self- and partner-testing. After 3 months, they returned for a follow-up assessment; thirty participants were also selected for in-depth interviews about their experiences initiating HIVST with partners. Most found proposing HIVST to a diverse array of partners relatively easy. They employed strategies such as joint testing and integrating HIVST into larger discussions about protection and sexual health, with moderate success. Nonetheless, real or anticipated negative partner reactions were a significant barrier. Future research can inform best practices for safely and successfully broaching HIVST with sexual partners.
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