Biology subjects

Yang, C. D.

Publications and source records attributed to Yang, C. D..

4 recordsLinked to original sources

bioRxiv2023

Pulsed ultrasound modulates the cytotoxic effect of cisplatin and doxorubicin on cultured human retinal pigment epithelium cells (ARPE-19)

ObjectivePulsed ultrasound has been proposed as a tool to enhance ocular drug delivery, but its effects on drug potency are not well understood. Doxorubicin-HCl and cisplatin are two drugs commonly used to treat ocular melanoma. We report the effects of pulsed ultrasound on the cytotoxicity of doxorubicin-HCl and cisplatin in vitro. MethodsCultured human retinal pigment epithelium cells (ARPE-19) cells were treated with doxorubicin-HCl or cisplatin in the presence or absence of ultrasound. MTT and Trypan blue assays were performed at 24 and 48 hours post-treatment to assess cell metabolism and death. ResultsCells treated with ultrasound plus doxorubicin-HCl demonstrated a significant decrease in metabolism compared to cells treated with doxorubicin-HCl alone. In contrast, cells treated with ultrasound plus cisplatin exhibited a significant increase in metabolism compared to cells treated with cisplatin alone at 48-hours. Cells treated with cisplatin pre-treated with ultrasound (US-Cis) exhibited a significant decrease in metabolism. Cell death was similar in doxorubicin- and cisplatin-treated cells with and without ultrasound. ConclusionPulsed ultrasound enhances the cytotoxicity of doxorubicin-HCl at 24- and 48-hours post-treatment but abrogates cisplatin toxicity 48-hours post-treatment. This suggests ultrasound modulates cell-drug interactions in a drug-specific manner. These findings may influence the future development of ultrasound-assisted ocular drug delivery systems.

cell biology↗

bioRxiv2023

MFGE8 inhibits insulin signaling through PTP1B

The role of integrins in regulating insulin signaling is incompletely understood. We have previously shown that binding of the integrin ligand milk fat globule epidermal growth factor like 8 (MFGE8) to the v{beta}5 integrin promotes termination of insulin receptor signaling in mice. Upon ligation of MFGE8, {beta}5 complexes with the insulin receptor beta (IR{beta}) in skeletal muscle resulting in dephosphorylation of IR{beta} and reduction of insulin-stimulated glucose uptake. Here we investigate the mechanism by which the interaction between {beta}5 and IR{beta} impacts IR{beta} phosphorylation status. We show that {beta}5 blockade inhibits and MFGE8 promotes PTP1B binding to and dephosphorylation of IR{beta} resulting in reduced or increased insulin-stimulated myotube glucose uptake respectively. The {beta}5-PTP1B complex is recruited by MFGE8 to IR{beta} leading to termination of canonical insulin signaling. {beta}5 blockade enhances insulin-stimulated glucose uptake in wild type but not Ptp1b KO mice indicating that PTP1B functions downstream of MFGE8 in modulating insulin receptor signaling. Furthermore, in a human cohort, we report serum MFGE8 levels correlate with indices of insulin resistance. These data provide mechanistic insights into the role of MFGE8 and {beta}5 in regulating insulin signaling.

physiology↗

bioRxiv2023

Genome-wide screens identify SEL1L as an intracellular rheostat controlling collagen turnover

Accumulating evidence has implicated impaired extracellular matrix (ECM) clearance as a key factor in fibrotic disease. Despite decades of research elucidating the effectors of ECM clearance, relatively little is understood regarding the upstream regulation of this process. Collagen is the most abundant constituent of normal and fibrotic ECM in mammalian tissues. Its catabolism occurs through extracellular proteolysis and cell-mediated uptake of collagen fragments for intracellular degradation. Given the paucity of information regarding the regulation of this latter process, we executed unbiased genome-wide screens to understand the molecular underpinnings of cell-mediated collagen clearance. Using this approach, we discovered a previously unappreciated mechanism through which collagen biosynthesis is sensed by cells internally and directly regulates clearance of extracellular collagen. The sensing mechanism is dependent on endoplasmic reticulum-resident protein SEL1L and occurs via a noncanonical function of SEL1L. This pathway functions as a homeostatic negative feedback loop that limits collagen accumulation in tissues. In human fibrotic lung disease, the induction of this collagen clearance pathway by collagen synthesis is impaired, thereby contributing to the pathological accumulation of collagen in lung tissue. Thus cell-autonomous, rheostatic collagen clearance is a previously unidentified pathway of tissue homeostasis.

cell biology↗

bioRxiv2022

MFGE8 links absorption of dietary fatty acids with catabolism of enterocyte lipid stores through HNF4 γ- dependent transcription of CES enzymes

Enterocytes modulate the extent of postprandial lipemia, a potent risk factor for developing atherosclerotic disease, by storing dietary fats in cytoplasmic lipid droplets (cLDs). We have previously demonstrated that the integrin ligand MFGE8 links absorption of dietary fats with activation of triglyceride (TG) hydrolases that catabolize cLDs for chylomicron production. The hydrolase(s) responsible for mobilization of TG from diet-derived cLDs is unknown though recent evidence indicates that this process is independent of the canonical pathway of TG hydrolysis mediated by ATGL. Here we identify CES1D as the key hydrolase downstream of the MFGE8-v{beta}5 integrin pathway that regulates catabolism of diet-drive cLDs. Mfge8 KO enterocytes have reduced CES1D transcript and protein levels and reduced protein levels of the transcription factor HNF4{gamma}. Mice KO for Ces1d or Hnf4{gamma} have decreased enterocyte TG hydrolase activity coupled with retention of TG in cLDs. Mechanistically, MFGE8-dependent fatty acid uptake through CD36 leads to stabilization of HNF4{gamma} protein levels; HNF4{gamma} then increases Ces1d transcription. Our work identifies a regulatory network by which MFGE8 and v{beta}5 regulate the severity of postprandial lipemia by linking dietary fat absorption with protein stabilization of a transcription factor that increases expression of enterocyte TG hydrolases that catabolize diet-derived cLDs.

physiology↗