FAS apoptotic inhibitory molecule 2 is a stress-induced intrinsic neuroprotective factor in the retina

Pawar, Mercy; Busov, Boris; Chandrasekhar, Aaruran; Yao, Jingyu; Zacks, David N.; Besirli, Cagri G.

doi:10.1038/cdd.2017.109

Cited by 16 publications

(18 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cells were cultured as described previously and treated with DMSO or LY294002 (Cell Signaling Technology; Denver, MA, USA, Cat# 9901, 150µM, 5mL) in glucose-free DMEM (Thermo Fisher Scientific; Cat # 11966025) supplemented with 5.5mM Glucose for 1.5 hours prior to fractionation. 24 Whole cell lysates were also collected to verify loss of p-AKT after 1.5 hours of LY294002 treatment.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Hexokinase 2 is dispensable for photoreceptor development but is required for survival during aging and outer retinal stress

Weh

Lutrzykowska

Smith

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

Max 300 words 1 1Photoreceptor death is the ultimate cause of vision loss in many retinal degenerative 1 2 conditions. Identifying novel therapeutic avenues for prolonging photoreceptor health and 1 3 function has the potential to improve vision and quality of life for patients suffering from 1 4 degenerative retinal disorders. Photoreceptors are metabolically unique among other neurons in 1 5 that they process the majority of their glucose via aerobic glycolysis. One of the main regulators 1 6 of aerobic glycolysis is hexokinase 2 (HK2). Beyond its enzymatic function of phosphorylating 1 7 glucose to glucose-6-phosphate, HK2 has additional non-enzymatic roles, including the 1 8 regulation of apoptotic signaling via AKT signaling. Determining the role of HK2 in photoreceptor 1 9 homeostasis may identify novel signaling pathways that can be targeted with neuroprotective 2 0 agents to boost photoreceptor survival during metabolic stress. Here we show that following 2 1 experimental retinal detachment, p-AKT is upregulated and HK2 translocates to mitochondria. 2Inhibition of AKT phosphorylation in 661W photoreceptor-like cells results in translocation of 2 3 mitochondrial HK2 to the cytoplasm, increased caspase activity, and decreased cell viability. 4Rod-photoreceptors lacking HK2 upregulate HK1 and appear to develop normally. Interestingly, 2 5we found that HK2-deficient photoreceptors are more susceptible to acute nutrient deprivation in 2 6the experimental retinal detachment model. Additionally, HK2 appears to be important for 2 7 preserving photoreceptors during aging. We show that retinal glucose metabolism is largely 2 8 unchanged after HK2 deletion, suggesting that the non-enzymatic role of HK2 is important for 2 9 maintaining photoreceptor health. These results suggest that HK2 expression is critical for 3 0 preserving photoreceptors during acute nutrient stress and aging. More specifically, p-AKT 3 1

show abstract

Section: Methodsmentioning

confidence: 99%

“…Counts were normalized to the total number of nuclei in the outer nuclear layer in the detached region, counted manually or with an automated cell counting macro using ImageJ. 7,24…”

Section: Methodsmentioning

confidence: 99%

Hexokinase 2 is dispensable for photoreceptor development but is required for survival during aging and outer retinal stress

Weh

Lutrzykowska

Smith

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…The remaining steps were identical. Cells were cultured as described previously and treated with DMSO or LY294002 (Cell Signaling Technology; Denver, MA, USA, Cat# 9901, 50 µM, 5 mL) in glucose-free DMEM (Thermo Fisher Scientific; Cat # 11966025) supplemented with 5.5 mM Glucose for 1.5 h prior to fractionation 56 . Wholecell lysates were also collected to verify loss of p-AKT after 1.5 h of LY294002 treatment.…”

Section: Sub-cellular Fractionationmentioning

confidence: 99%

“…TUNEL positive cells were manually counted across the detached portion of the retina. Counts were normalized to the total number of nuclei in the outer nuclear layer in the detached region, counted manually or with an automated cell counting macro using ImageJ 7,56 .…”

Section: Functional Assessmentmentioning

confidence: 99%

Hexokinase 2 is dispensable for photoreceptor development but is required for survival during aging and outer retinal stress

et al. 2020

Self Cite

View full text Add to dashboard Cite

Photoreceptor death is the ultimate cause of vision loss in many retinal degenerative conditions. Identifying novel therapeutic avenues for prolonging photoreceptor health and function has the potential to improve vision and quality of life for patients suffering from degenerative retinal disorders. Photoreceptors are metabolically unique among other neurons in that they process the majority of their glucose via aerobic glycolysis. One of the main regulators of aerobic glycolysis is hexokinase 2 (HK2). Beyond its enzymatic function of phosphorylating glucose to glucose-6-phosphate, HK2 has additional non-enzymatic roles, including the regulation of apoptotic signaling via AKT signaling. Determining the role of HK2 in photoreceptor homeostasis may identify novel signaling pathways that can be targeted with neuroprotective agents to boost photoreceptor survival during metabolic stress. Here we show that following experimental retinal detachment, p-AKT is upregulated and HK2 translocates to mitochondria. Inhibition of AKT phosphorylation in 661W photoreceptor-like cells results in translocation of mitochondrial HK2 to the cytoplasm, increased caspase activity, and decreased cell viability. Rod-photoreceptors lacking HK2 upregulate HK1 and appear to develop normally. Interestingly, we found that HK2-deficient photoreceptors are more susceptible to acute nutrient deprivation in the experimental retinal detachment model. Additionally, HK2 appears to be important for preserving photoreceptors during aging. We show that retinal glucose metabolism is largely unchanged after HK2 deletion, suggesting that the non-enzymatic role of HK2 is important for maintaining photoreceptor health. These results suggest that HK2 expression is critical for preserving photoreceptors during acute nutrient stress and aging. More specifically, p-AKT mediated translocation of HK2 to the mitochondrial surface may be critical for protecting photoreceptors from acute and chronic stress.

show abstract

“…FAIM2 carrying mutations in SWAYV, the predicted LIR motif within the N-terminal region, failed to interact F I G U R E 6 FAIM2 interacts with the lipidated form of LC3 via its N-terminal LIR motif. 40,41 The only transmembrane protein in the core ATG machinery is the multi-spanning membrane protein ATG9. Immunoblotted with MAP1LC3B and FLAG.…”

Section: Discussionmentioning

confidence: 99%

Fas‐apoptotic inhibitory molecule 2 localizes to the lysosome and facilitates autophagosome‐lysosome fusion through the LC3 interaction region motif–dependent interaction with LC3

et al. 2019

View full text Add to dashboard Cite

Abbreviations: BafA1, bafilomycin A1; BI-1, bax inhibitor-1; CASP, caspase; ER, endoplasmic reticulum; FAIM2, Fas-apoptotic inhibitory molecule 2; GABARAP, GABA type A receptor-associated protein; IDPR, intrinsically disordered protein region; LIR, LC3-interacting region; MAP1LC3B, microtubuleassociated protein 1 light chain 3 beta; MTOR, mammalian target of rapamycin; shRNA, small hairpin RNA; STX17, syntaxin 17; TMBIM, transmembrane BAX inhibitor motif containing. AbstractFas-apoptotic inhibitory molecule 2 (FAIM2) is a member of the transmembrane BAX inhibitor motif-containing (TMBIM) family. TMBIM family is comprised of six anti-apoptotic proteins that suppress cell death by regulating endoplasmic reticulum Ca 2+ homeostasis. Recent studies have implicated two TMBIM proteins, GRINA and BAX Inhibitor-1, in mediating cytoprotection via autophagy. However, whether FAIM2 plays a role in autophagy has been unknown. Here we show that FAIM2 localizes to the lysosomes at basal state and facilitates autophagy through interaction with microtubule-associated protein 1 light chain 3 proteins in human neuroblastoma SH-SY5Y cells. FAIM2 overexpression increased autophagy flux, while autophagy flux was impaired in shRNA-mediated knockdown (shFAIM2) cells, and the impairment was more evident in the presence of rapamycin. In shFAIM2 cells, autophagosome maturation through fusion with lysosomes was impaired, leading to accumulation of autophagosomes. A functional LC3-interacting region motif within FAIM2 was essential for the interaction with LC3 and rescue of autophagy flux in shFAIM2 cells while LC3-binding property of FAIM2 was dispensable for the antiapoptotic function in response to Fas receptor-mediated apoptosis. Suppression of autophagosome maturation was also observed in a null mutant of Caenorhabditis elegans lacking xbx-6, the ortholog of FAIM2. Our study suggests that FAIM2 is a novel regulator of autophagy mediating autophagosome maturation through the interaction with LC3.

show abstract

FAS apoptotic inhibitory molecule 2 is a stress-induced intrinsic neuroprotective factor in the retina

Cited by 16 publications

References 33 publications

Hexokinase 2 is dispensable for photoreceptor development but is required for survival during aging and outer retinal stress

Hexokinase 2 is dispensable for photoreceptor development but is required for survival during aging and outer retinal stress

Hexokinase 2 is dispensable for photoreceptor development but is required for survival during aging and outer retinal stress

Fas‐apoptotic inhibitory molecule 2 localizes to the lysosome and facilitates autophagosome‐lysosome fusion through the LC3 interaction region motif–dependent interaction with LC3

Contact Info

Product

Resources

About