Min Li

Macroautophagy (hereafter called autophagy) is a highly conserved physiological process that degrades over-abundant or damaged organelles, large protein aggregates and invading pathogens via the lysosomal system (the vacuole in plants and yeast). Autophagy is generally induced by stress, such as oxygen-, energy-or amino acid-deprivation, irradiation, drugs, etc. In addition to non-selective bulk degradation, autophagy also occurs in a selective manner, recycling specific organelles, such as mitochondria, peroxisomes, ribosomes, endoplasmic reticulum (ER), lysosomes, nuclei, proteasomes and lipid droplets (LDs). This capability makes selective autophagy a major process in maintaining cellular homeostasis. The dysfunction of selective autophagy is implicated in neurodegenerative diseases (NDDs), tumorigenesis, metabolic disorders, heart failure, etc. Considering the importance of selective autophagy in cell biology, we systemically review the recent advances in our understanding of this process and its regulatory mechanisms. We emphasize the 'cargo-ligand-receptor' model in selective autophagy for specific organelles or cellular components in yeast and mammals, with a focus on mitophagy and ER-phagy, which are finely described as types of selective autophagy. Additionally, we highlight unanswered questions in the field, helping readers focus on the research blind spots that need to be broken.

The functional heterogeneity of potassium channels in eukaryotic cells arises not only from the multiple potassium channel genes and splice variants but also from the combinatorial mixing of different potassium channel polypeptides to form heteromultimeric channels with distinct properties. One structural element that determines the compatibility of different potassium channel polypeptides in subunit assembly has now been localized to the hydrophilic amino-terminal domain. A Drosophila Shaker B (ShB) potassium channel truncated polypeptide that contains only the hydrophilic amino-terminal domain can form a homomultimer; the minimal requirement for the homophilic interaction has been localized to a fragment of 114 amino acids. Substitution of the amino-terminal domain of a distantly related mammalian potassium channel polypeptide (DRK1) with that of ShB permits the chimeric DRK1 polypeptide to coassemble with ShB.

Tumor-associated macrophages (TAMs) have been implicated in the promotion of breast cancer growth and metastasis, and multiple TAM-secreted cytokines have been identified associating with poor clinical outcomes. However, the therapeutic targets existing in the loop between TAMs and cancer cells are still required for further investigation. Here in, cytokine array validated that C-X-C motif chemokine ligand 1 (CXCL1) is the most abundant chemokine secreted by TAMs, and CXCL1 can promote breast cancer migration and invasion ability, as well as epithelial-mesenchymal transition in both mouse and human breast cancer cells. QPCR screening further validated SOX4 as the highest responsive gene following CXCL1 administration. Mechanistic study revealed that CXCL1 binds to SOX4 promoter and activates its transcription via NF-κB pathway. In vivo breast cancer xenografts demonstrated that CXCL1 silencing in TAMs results in a significant reduction in breast cancer growth and metastatic burden. Bioinformatic analysis and clinical investigation finally suggested that high CXCL1 expression is significantly correlated with breast cancer lymph node metastasis, poor overall survival and basal-like subtype. Taken together, our results indicated that TAMs/CXCL1 promotes breast cancer metastasis via NF-κB/SOX4 activation, and CXCL1-based therapy might become a novel strategy for breast cancer metastasis prevention.