The F220C and F45L rhodopsin mutations identified in retinitis pigmentosa patients do not cause pathology in mice.

Retinitis pigmentosa is a retinal degenerative disease that leads to blindness through photoreceptor loss. Rhodopsin is the most frequently mutated protein in this disease. While many rhodopsin mutations have well-understood consequences that lead to cell death, the disease association of several rhodopsin mutations identified in retinitis pigmentosa patients, including F220C and F45L, has been disputed. In this study, we generated two knockin mouse lines bearing each of these mutations. We did not observe any photoreceptor degeneration in either heterozygous or homozygous animals of either line. F220C mice exhibited minor disruptions of photoreceptor outer segment dimensions without any mislocalization of outer segment proteins, whereas photoreceptors of F45L mice were normal. Suction electrode recordings from individual photoreceptors of both mutant lines showed normal flash sensitivity and photoresponse kinetics. Taken together, these data suggest that neither the F220C nor F45L mutation has pathological consequences in mice and, therefore, may not be causative of retinitis pigmentosa in humans

Photoreceptor disc membranes are formed through an Arp2/3-dependent lamellipodium-like mechanism

The light-sensitive outer segment of the vertebrate photoreceptor is a highly modified primary cilium filled with disc-shaped membranes that provide a vast surface for efficient photon capture. The formation of each disc is initiated by a ciliary membrane evagination driven by an unknown molecular mechanism reportedly requiring actin polymerization. Since a distinct F-actin network resides precisely at the site of disc morphogenesis, we employed a unique proteomic approach to identify components of this network potentially driving disc morphogenesis. The only identified actin nucleator was the Arp2/3 complex, which induces the polymerization of branched actin networks. To investigate the potential involvement of Arp2/3 in the formation of new discs, we generated a conditional knockout mouse lacking its essential ArpC3 subunit in rod photoreceptors. This knockout resulted in the complete loss of the F-actin network specifically at the site of disc morphogenesis, with the time course of ArpC3 depletion correlating with the time course of F-actin loss. Without the actin network at this site, the initiation of new disc formation is completely halted, forcing all newly synthesized membrane material to be delivered to the several nascent discs whose morphogenesis had already been in progress. As a result, these discs undergo uncontrolled expansion instead of normal enclosure, which leads to formation of unusual, large membrane whorls. These data suggest a model of photoreceptor disc morphogenesis in which Arp2/3 initiates disc formation in a "lamellipodium-like" mechanism

TMEM67, TMEM237, and Embigin in Complex With Monocarboxylate Transporter MCT1 Are Unique Components of the Photoreceptor Outer Segment Plasma Membrane.

The outer segment (OS) organelle of vertebrate photoreceptors is a highly specialized cilium evolved to capture light and initiate light response. The plasma membrane which envelopes the OS plays vital and diverse roles in supporting photoreceptor function and health. However, little is known about the identity of its protein constituents, as this membrane cannot be purified to homogeneity. In this study, we used the technique of protein correlation profiling to identify unique OS plasma membrane proteins. To achieve this, we used label-free quantitative MS to compare relative protein abundances in an enriched preparation of the OS plasma membrane with a preparation of total OS membranes. We have found that only five proteins were enriched at the same level as previously validated OS plasma membrane markers. Two of these proteins, TMEM67 and TMEM237, had not been previously assigned to this membrane, and one, embigin, had not been identified in photoreceptors. We further showed that embigin associates with monocarboxylate transporter MCT1 in the OS plasma membrane, facilitating lactate transport through this cellular compartment

Comprehensive identification of mRNA isoforms reveals the diversity of neural cell-surface molecules with roles in retinal development and disease

Here the authors present an approach that can reveal the full complement of mRNA isoforms encoded by individual genes, and they identify a major isoform of the retinal degeneration gene CRB1 which functions at the cell-cell junctions of the outer limiting membrane to promote photoreceptor survival

Massachusetts Justice Community Opioid Innovation Network (MassJCOIN)

A major driver of the U.S. opioid crisis is limited access to effective medications for opioid use disorder (MOUD) that reduce overdose risks. Traditionally, jails and prisons in the U.S. have not initiated or maintained MOUD for incarcerated individuals with OUD prior to their return to the community, which places them at high risk for fatal overdose. A 2018 law (Chapter 208) made Massachusetts (MA) the first state to mandate that five county jails deliver all FDA-approved MOUDs (naltrexone [NTX], buprenorphine [BUP], and methadone). Chapter 208 established a 4-year pilot program to expand access to all FDA-approved forms of MOUD at five jails, with two more MA jails voluntarily joining this initiative. The law stipulates that MOUD be continued for individuals receiving it prior to detention and be initiated prior to release among sentenced individuals where appropriate. The jails must also facilitate continuation of MOUD in the community on release. The Massachusetts Justice Community Opioid Innovation Network (MassJCOIN) partnered with these seven diverse jails, the MA Department of Public Health, and community treatment providers to conduct a Type 1 hybrid effectiveness-implementation study of Chapter 208. We will: (1) Perform a longitudinal treatment outcome study among incarcerated individuals with OUD who receive NTX, BUP, methadone, or no MOUD in jail to examine postrelease MOUD initiation, engagement, and retention, as well as fatal and nonfatal opioid overdose and recidivism; (2) Conduct an implementation study to understand systemic and contextual factors that facilitate and impede delivery of MOUDs in jail and community care coordination, and strategies that optimize MOUD delivery in jail and for coordinating care with community partners; (3) Calculate the cost to the correctional system of implementing MOUD in jail, and conduct an economic evaluation from state policy-maker and societal perspectives to compare the value of MOUD prior to release from jail to no MOUD among matched controls. MassJCOIN made significant progress during its first six months until the COVID-19 pandemic began in March 2020. Participating jail sites restricted access for nonessential personnel, established other COVID-19 mitigation policies, and modified MOUD programming. MassJCOIN adapted research activities to this new reality in an effort to document and account for the impacts of COVID-19 in relation to each aim. The goal remains to produce findings with direct implications for policy and practice for OUD in criminal justice settings. •Seven Massachusetts jails are mandated to provide medications for opioid use disorder (OUD) during incarceration and post-release.•The Massachusetts Justice Community Opioid Innovation Network (MassJCOIN) is conducting an effectiveness-implementation study of the program.•MassJCOIN adapted research activities in response to the COVID-19 pandemic.•MassJCOIN will produce findings with direct implications for policy and practice for OUD in criminal justice settings

Meningioma DNA methylation groups identify biological drivers and therapeutic vulnerabilities

Meningiomas are the most common primary intracranial tumors. There are no effective medical therapies for meningioma patients, and new treatments have been encumbered by limited understanding of meningioma biology. Here, we use DNA methylation profiling on 565 meningiomas integrated with genetic, transcriptomic, biochemical, proteomic and single-cell approaches to show meningiomas are composed of three DNA methylation groups with distinct clinical outcomes, biological drivers and therapeutic vulnerabilities. Merlin-intact meningiomas (34%) have the best outcomes and are distinguished by NF2/Merlin regulation of susceptibility to cytotoxic therapy. Immune-enriched meningiomas (38%) have intermediate outcomes and are distinguished by immune infiltration, HLA expression and lymphatic vessels. Hypermitotic meningiomas (28%) have the worst outcomes and are distinguished by convergent genetic and epigenetic mechanisms driving the cell cycle and resistance to cytotoxic therapy. To translate these findings into clinical practice, we show cytostatic cell cycle inhibitors attenuate meningioma growth in cell culture, organoids, xenografts and patients