Heterologous regulation of CXCR4 lysosomal trafficking.

G protein-coupled receptor (GPCR) signaling is regulated by members of the protein kinase C (PKC) and GPCR kinase (GRK) families, although the relative contribution of each to GPCR function varies among specific GPCRs. The CXC motif receptor 4 (CXCR4) is a member of the GPCR superfamily that binds the CXC motif chemokine ligand 12 (CXCL12), initiating signaling that is subsequently terminated in part by internalization and lysosomal degradation of CXCR4. The purpose of this study is to define the relative contribution of PKC and GRK to CXCR4 signaling attenuation by studying their effects on CXCR4 lysosomal trafficking and degradation. Our results demonstrate that direct activation of PKC via the phorbol ester phorbol 12-myristate 13-acetate (PMA) mimics CXCL12-mediated desensitization, internalization, ubiquitination, and lysosomal trafficking of CXCR4. In agreement, heterologous activation of PKC by stimulating the chemokine receptor CXCR5 with its ligand, CXCL13, also mimics CXCL12-mediated desensitization, internalization, ubiquitination, and lysosomal degradation of CXCR4. Similar to CXCL12, PMA promotes PKC-dependent phosphorylation of serine residues within CXCR4 C-tail that are required for binding and ubiquitination by the E3 ubiquitin ligase AIP4 (atrophin-interacting protein 4). However, inhibition of PKC activity does not alter CXCL12-mediated ubiquitination and degradation of CXCR4, suggesting that other kinases are also required. Accordingly, siRNA-mediated depletion of GRK6 results in decreased degradation and ubiquitination of CXCR4. Overall, these results suggest that PKC and GRK6 contribute to unique aspects of CXCR4 phosphorylation and lysosomal degradation to ensure proper signal propagation and termination.

A rare case of severe bilateral Graves' orbitopathy involving an anophthalmic socket.

Summary: This is a report of a rare case of Graves' hyperthyroidism associated with severe bilateral Graves' orbitopathy, in a patient with an anophthalmic eye socket. On clinical review her prosthetic eye (left eye) was tilting upwards, along with worsening of Graves' orbitopathy (GO) in the only seeing eye. As she refused IV glucocorticoids, she was offered rituximab which only caused a transient improvement in the clinical activity score of the eye. She had persistent right upper lid retraction of 6 mm, associated with lagophthalmos. To protect her seeing eye from corneal ulceration, the patient received a botulinum toxin injection to the right upper eyelid to induce blepharoptosis as an interim measure prior to right upper eyelid blepharotomy in April 2021. This patient remains biochemically euthyroid on block and replace therapy and her TRAb level is falling over time. Treatment for active GO is ongoing and the patient required a redo blepharotomy for painful corneal exposure in the right eye. Learning points: Graves' orbitopathy (GO) does not actually primarily affect the eyeball itself but the orbital contents as well. Patients with severe GO in an only seeing-eyed patient should be referred early to a multidisciplinary Joint Thyroid Eye clinic for expert review and management. Patient outcomes including sight loss are likely to be improved by the extended range of medical and surgical treatment modalities available at specialist clinics treating GO, including the use of immunomodulatory drugs like rituximab or teprotumumab.

Sequencing during Times of Change: Evaluating SARS-CoV-2 Clinical Samples during the Transition from the Delta to Omicron Wave.

The pandemic of SARS-CoV-2 is characterized by the emergence of new variants of concern (VOCs) that supplant previous waves of infection. Here, we describe our investigation of the lineages and host-specific mutations identified in a particularly vulnerable population of predominantly older and immunosuppressed SARS-CoV-2-infected patients seen at our medical center in Chicago during the transition from the Delta to Omicron wave. We compare two primer schemes, ArticV4.1 and VarSkip2, used for short read amplicon sequencing, and describe our strategy for bioinformatics analysis that facilitates identifying lineage-associated mutations and host-specific mutations that arise during infection. This study illustrates the ongoing evolution of SARS-CoV-2 VOCs in our community and documents novel constellations of mutations that arise in individual patients. The ongoing evaluation of the evolution of SARS-CoV-2 during this pandemic is important for informing our public health strategies.