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SYM-A3 : Post-Translational Modifications for Signal Transduction

오거나이저: 박강식(경희대학교)

이민재(서울대학교) / 양원호(연세대학교) / Hsin-Yi Chang(National Defense Medical Center)



이민재
Speaker
이민재   CV
Affiliation
서울대학교
Title
Dynamics of Mammalian Proteasomes Under Various Stress Conditions
Abstract

The 26S proteasome is a self-compartmentalized protease complex, one of whose crucial functions is protein quality control. Multiple layers of regulatory systems elaborately modulate proteasomal activity, i.e., hydrolysis of polyubiquitinated proteins. However, the mechanism of destruction of mammalian proteasomes is poorly understood. We found that inactive 26S proteasomes are concentrated into an insoluble aggresome via HDAC6-mediated retrograde transport. These proteasomes were colocalized with autophagic receptor SQSTM1 in a large perinuclear inclusion body and were cleared through selective macroautophagy, linking aggresomal segregation to proteaphagic degradation. This pathway might be counterbalanced with recovery of proteasomal activity and critical for reducing cellular proteasomal stress. Structural alteration, changes in associated proteins, and polyubiquitination on inactive proteasomes participated in the targeting mechanism to the aggresome and autophagosome. The CHIP E3 Ub ligase polyubiquitinated purified human proteasomes in vitro mainly with Lys63-linked polyubiquitin chains. CHIP silencing significantly delayed aggresome formation by inactive proteasomes. Thus, aggresomal sequestration and autophagic degradation are crucial for proteasome quality control and overall mammalian protein homeostasis.

 

양원호
Speaker
양원호   CV
Affiliation
연세대학교
Title
Neu3 neuraminidase induction triggers intestinal inflammation and colitis in a model of recurrent human food-poisoning
Abstract

Intestinal inflammation is the underlying basis of colitis and the inflammatory bowel diseases. These syndromes originate from genetic and environmental factors that remain to be fully identified. Infections are possible disease triggers, including recurrent human food-poisoning by the common foodborne pathogen Salmonella enterica Typhimurium (ST), which in laboratory mice causes progressive intestinal inflammation leading to an enduring colitis. In this colitis model, disease onset has been linked to Toll-like receptor-4–dependent induction of intestinal neuraminidase activity, leading to the desialylation, reduced half-life, and acquired deficiency of anti-inflammatory intestinal alkaline phosphatase (IAP). Neuraminidase (Neu) inhibition protected against disease onset; however, the source and identity of the Neu enzyme(s) responsible remained unknown. Herein, we report that the mammalian Neu3 neuraminidase is responsible for intestinal IAP desialylation and deficiency. Absence of Neu3 thereby prevented the accumulation of lipopolysaccharide-phosphate and inflammatory cytokine expression in providing protection against the development of severe colitis.

 

Prof. Hsin-Yi Chang
Speaker
Prof. Hsin-Yi Chang   CV
Affiliation
National Defense Medical Center
Title
Nutritional Control of Protein modifications Defines the Cell Fate in Adipogenesis