Progress and Challenges in the Use of MAP1LC3 as a Legitimate Marker for Measuring Dynamic Autophagy In Vivo

Abstract

Tremendous efforts have been made these last decades to increase our knowledge of intracellular degradative systems, especially in the field of autophagy. The role of autophagy in the maintenance of cell homeostasis is well documented and the existence of defects in the autophagic machinery has been largely described in diseases and aging. Determining the alterations occurring in the many forms of autophagy that coexist in cells and tissues remains complicated, as this cellular process is highly dynamic in nature and can vary from organ to organ in the same individual. Although autophagy is extensively studied, its functioning in different tissues and its links with other biological processes is still poorly understood. Several assays have been developed to monitor autophagy activity in vitro, ex vivo, and in vivo, based on different markers, the use of various inhibitors and activators, and distinct techniques. This review emphasizes the methods applied to measure (macro-)autophagy in tissue samples and in vivo via a protein, which centrally intervenes in the autophagy pathway, the microtubule-associated protein 1A/1B-light chain 3 (MAP1LC3), which is the most widely used marker and the first identified to associate with autophagosomal structures. These approaches are presented and discussed in terms of pros and cons. Some recommendations are provided to improve the reliability of the interpretation of results.

Autophagy in spinal ligament fibroblasts: evidence and possible implications for ossification of the posterior longitudinal ligament

“…However, LC3 expression was not significantly correlated with osteogenic differentiation makers. A possible explanation for this is that LC3 mRNA level is not a very reliable measurement for changes in autophagy [25].…”

Autophagy in spinal ligament fibroblasts: evidence and possible implications for ossification of the posterior longitudinal ligament

“…However, LC3 expression was not signi cantly correlated with osteogenic differentiation makers. A possible explanation for this is that LC3 mRNA level is not a very reliable measurement for changes in autophagy [25].…”

Targeting Autophagy in Breast Cancer

“…The main ATGs complexes, such as the Unc-51 like autophagy activating kinase (ULK1) complex, the Beclin-ATG4-1-VPS34 class III phosphoinositide 3-kinase (PI3K) complex, the ATG5-ATG12-ATG16 complex, and ATG8/LC3 complex, involved in this process, have been extensively reported in other review [9][10][11]. An overview of the autophagy process [12], its induction [13,14] and regulation [15] have been reported in Figure 1. The Unc-51 like autophagy activating kinase (ULK1) serine threonine kinase complex, involving ULK1, FIP200, and ATG13, acts in the initiation process, phosphorylating multiple downstream factors.…”

“…The main ATGs complexes, such as the Unc-51 like autophagy activating kinase (ULK1) complex, the Beclin–ATG4-1-VPS34 class III phosphoinositide 3-kinase (PI3K) complex, the ATG5-ATG12-ATG16 complex, and ATG8/LC3 complex, involved in this process, have been extensively reported in other review [ 9 , 10 , 11 ]. An overview of the autophagy process [ 12 ], its induction [ 13 , 14 ] and regulation [ 15 ] have been reported in Figure 1 .…”