Tryptophan 415 Is Critical for the Cholesterol Transport Functions of Scavenger Receptor BI

High density lipoproteins (HDL) are anti-atherogenic particles, primarily due to their role in the reverse cholesterol transport pathway whereby HDL delivers cholesteryl esters (CE) to the liver for excretion upon interaction with its receptor, scavenger receptor BI (SR-BI). We designed experiments to test the hypothesis that one or more of the eight highly conserved tryptophan (Trp; W) residues in SR-BI are critical for mediating function. We created a series of Trp-to-phenylalanine (Phe, F) mutant receptors, as well as Trp-less SR-BI (ΔW-SR-BI), and assessed their ability to mediate cholesterol transport. Wild-type (WT) or mutant SR-BI receptors were transiently expressed in COS-7 cells, and cell surface expression was confirmed. Next, we showed that Trp-less- and W415F-SR-BI had significantly decreased abilities to bind HDL and promote selective uptake of HDL-CE, albeit with higher selective uptake efficiency as compared to WT-SR-BI. Interestingly, only Trp-less-, but not W415F-SR-BI, showed an impaired ability to mediate efflux of free cholesterol (FC). Furthermore, both W415F- and Trp-less-SR-BI were unable to reorganize plasma membrane pools of FC based on lack of sensitivity to exogenous cholesterol oxidase. Restoration of Trp 415 into the Trp-less-SR-BI background was unable to rescue Trp-less-SR-BI’s impaired functions, suggesting that Trp 415 is critical, but not sufficient for full receptor function. Furthermore, with the exception of Trp 262, restoration of individual extracellular Trp residues, in combination with Trp 415, into the Trp-less-SR-BI background partially rescued SR-BI function, indicating that Trp 415 must be present in combination with other Trp residues for proper cholesterol transport functions

Effect of adiposity on tissue-specific adiponectin secretion - Fig 3

<p>A: Secretion levels of adiponectin from visceral adipose tissue (VAT) is negatively associated with BMI while there was no association with subcutaneous adipose tissue (SAT) (p < 0.05) B: Secretion levels of adiponectin from VAT is negatively associated with total fat mass while there was no association with SAT (p < 0.001) C: Secretion levels of adiponectin from VAT is negatively associated with visceral fat percentage while there was no association with SAT (p < 0.05).</p

Associations of adiposity measures with tissue specific adiponectin secretion.

<p>Associations of adiposity measures with tissue specific adiponectin secretion.</p

Visceral adipose tissue (VAT) (A) and subcutaneous adipose tissue (SAT) (B) tissue homogenates (50 μg protein) were separated by 15% SDS-PAGE and transferred to nitrocellulose membranes for immunoblot analyses.

<p>Adiponectin (ADPN) levels from paired SAT and VAT samples are shown for 7 different subjects. Beta-actin loading control and monomeric recombinant adiponectin (~30 kDa) are shown).</p

Correlations of BMI with metabolic characteristics.

<p>Correlations of BMI with metabolic characteristics.</p

Baseline demographic, anthropometric, and metabolic characteristics (mean ± SD).

<p>Baseline demographic, anthropometric, and metabolic characteristics (mean ± SD).</p

Secretion levels of adiponectin from both visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) at 4 hours and 24 hours were highly correlated with each other (p < 0.001).

<p>Secretion levels of adiponectin from both visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) at 4 hours and 24 hours were highly correlated with each other (p < 0.001).</p

Patients’ views and experiences on the supported self-management/patient-initiated follow up pathway for breast cancer

Purpose: To explore patients’ expectations and experience of Supportive Self-Management (SSM)/ Patient Initiated Follow Up (PIFU) following breast cancer treatments over a 12-month period. Methods: 32/110 (29%) patient participants in the PRAGMATIC (Patients’ experiences of a suppoRted self-manAGeMent pAThway In breast Cancer) study were interviewed at baseline, 3, 6, 9 and 12-months. Interviews in this sub-study used a mix-methods approach to explore understanding of the pathway, confidence in self-management, triggers to seek help and/or re-engage with the clinical breast team and impact of the COVID-19 pandemic. Responses to pre-assigned categories were summarised as counts/ percentages and collated in tabular or graphic format. Free responses were recorded verbatim and reviewed using framework analysis. Results: Participants regarded the SSM/PIFU pathway as a way to save time and money for them and the National Health Service (NHS) (14/32; 44%) and as a means of assuming responsibility for their own follow-up (18/32; 56%). Most maintained (very/somewhat) confidence in managing their BC follow-up care (baseline 31/32, 97%; 12-months 29/31, 93%). During the year 19% (5/26) stopped endocrine therapy altogether because of side effects. Qualitative analysis revealed general satisfaction with SSM/PIFU and described the breast care nurses as reassuring and empathic. However, there was a lingering anxiety about identifying signs and symptoms correctly, particularly for those with screen-detected cancers. There was also uncertainty about who to contact for psychological support. The COVID-19 pandemic discouraged some participants from contacting the helpline as they did not want to overburden the NHS. Conclusions: The results show that during the first year on the SSM/PIFU pathway, most patients felt confident managing their own care. Clinical teams should benefit from understanding patients’ expectations and experience and potentially modify the service for men with BC and/or those with screen detected breast cancers.</p