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Protein aggregates are a common feature of diseased and aged cells. Membrane proteins comprise a quarter of the proteome, and yet, it is not well understood how aggregation of membrane proteins is regulated and what effects these aggregates can have on cellular health. We have determined in yeast that the derlin Dfm1 has a chaperone-like activity that influences misfolded membrane protein aggregation. We establish that this function of Dfm1 does not require recruitment of the ATPase Cdc48 and it is distinct from Dfm1's previously identified function in dislocating misfolded membrane proteins from the endoplasmic reticulum (ER) to the cytosol for degradation. Additionally, we assess the cellular impacts of misfolded membrane proteins in the absence of Dfm1 and determine that misfolded membrane proteins are toxic to cells in the absence of Dfm1 and cause disruptions to proteasomal and ubiquitin homeostasis.

To compare two types of lipid expression procedures to treat dry eye disease. Standardized treatment and evaluation methods were used in patients treated with either manual thermoelectric lipid expression (MiBoFlo) or automated lipid expression (Lipiflow) of the Meibomian glands. This was a contemporaneous, non-randomized study of both treatment methods. Treatment was per the manufacturers’ recommendation. The primary outcome included two types of dry eye questionnaires as well as objective analysis of ocular surface including tear break up time, Schirmer testing, Osmolarity, and fluorescein staining. Baseline characteristics analyzed included floppy lid, conjunctivochalasis and lagophthalmos. Statistical analysis was performed correcting for baseline factors such as age and co existing pathology using multivariable analysis. Both treatments improved the results of the OSDI and SPEED dry eye questionnaire results. Both treatments resulted in improvement of many objective findings including SPK, lissamine green staining and tear break up time with the MiBoFlo showing more improvement than Lipiflow. OSDI was more sensitive to improvement of symptoms than the SPEED questionnaire. Manual expression with MiBoFlo device resulted in statistically more improvement in questionnaire scores than did automated expression with Lipiflow. Negative prognostic factors for symptomatic improvement included blepharitis, autoimmune disease and ocular allergies. Thermal lid therapy along with mechanical expression of lipids from the meibomian glands successfully treats dry eye symptoms and signs. Manual therapy with MiBoFlo resulted in more subjective and objective improvement scores than automated therapy with the Lipiflow device. [ABSTRACT FROM AUTHOR]

Nearly one‐third of nascent proteins are initially targeted to the endoplasmic reticulum (ER), where they are correctly folded and assembled before being delivered to their final cellular destinations. To prevent the accumulation of misfolded membrane proteins, ER‐associated degradation (ERAD) removes these client proteins from the ER membrane to the cytosol in a process known as retrotranslocation. Our previous work demonstrated that rhomboid pseudoprotease Dfm1 is involved in the retrotranslocation of ubiquitinated membrane integral ERAD substrates. Herein, we found that Dfm1 associates with the SPOTS complex, which is composed of serine palmitoyltransferase (SPT) enzymes and accessory components that are critical for catalyzing the first rate‐limiting step of the sphingolipid biosynthesis pathway. Furthermore, Dfm1 employs an ERAD‐independent role for facilitating the ER export and endosome‐ and Golgi‐associated degradation (EGAD) of Orm2, which is a major antagonist of SPT activity. Given that the accumulation of human Orm2 homologs, ORMDLs, is associated with various pathologies, our study serves as a molecular foothold for understanding how dysregulation of sphingolipid metabolism leads to various diseases. Synopsis: Previously, yeast derlin Dfm1 was found to be critical for retrotranslocating integral membrane substrates targeted for ER‐associated degradation (ERAD). This study reveals an ERAD‐independent role for Dfm1 in regulating the degradation of the negative regulator of sphingolipid biosynthesis, Orm2. Dfm1 deletion leads to dysregulated levels of early precursors of the sphingolipid biosynthesis pathway.Derlin Dfm1 associates with rate‐limiting enzymes and regulators of the sphingolipid biosynthesis pathway.Dfm1 targets Ypk1‐dependent phosphorylated Orm2 for ER export and endosome‐ and Golgi‐associated degradation (EGAD).Dfm1's Cdc48‐recruitment function is not required for regulating Orm2 degradation. [ABSTRACT FROM AUTHOR]