Biology subjects

Kessler, O.

Publications and source records attributed to Kessler, O..

2 recordsLinked to original sources

bioRxiv2021

CD72-semaphorin3A axis: a possible new player in immune regulation

Semaphorin3A (sema3A) inhibits the activity of B and T cells in autoimmune diseases such as Systemic Lupus Erythematosus (SLE). We have now found that CD72 functions as a novel sema3A binding and signal-transducing receptor. These functions of CD72 are independent of the known sema3A receptor neuropilin-1 (NRP-1). We find that sema3A induces the phosphorylation of CD72 on tyrosine residues and the association of CD72 with SHP-1 and SHP-2. In contrast, sema4D/CD100 inhibits these functions. sema3A signals mediated by CD72, inhibit the phosphorylation of STAT-4 and HDAC-1 and induce the phosphorylation of p38-MAPK and PKC-theta in B-cells derived B-lymphoblastoid (BLCL) cells lacking NRP-1 expression, and in primary B-cells isolated from either healthy donors or SLE (Systemic Lupus Erythematosus) patients. We have also generated a modified truncated sema3A (T-sema3A) which cannot signal via NRP-1 yet still activates inhibitory CD72 signaling. We propose that T-sema3A may have potential as a possible therapeutic for autoimmune diseases such as SLE. One Sentence SummaryCD72 found as a novel sema3A receptor transduces inhibitory signals in Bcells. A modified sema3A can be used to treat autoimmunity.

immunology↗

bioRxiv2021

Plexin-A2 Promotes The Proliferation And The Development Of Tumors From Glioblastoma Derived Cells

The semaphorin guidance factors receptor Plexin-A2 transduces sema6A and sema6B signals and when associated with neuropilins can also transduce sema3C signals. Inhibition of plexin-A2 expression in U87MG glioblastoma cells resulted in strong inhibition of cell proliferation and tumor forming ability. Knock-out of the plexin-A2 gene using CRISPR/Cas9 also inhibited cell proliferation which was rescued following re-expression of the plexin-A2 cDNA or expression of a truncated plexin-A2 lacking the extracellular domain. Inhibition of plexin-A2 expression resulted in cell cycle arrest at the G2/M stage, and was accompanied by changes in cytoskeletal organization, cell flattening, and by the expression of senescence associated {beta}-galactosidase. It was also associated with reduced AKT phosphorylation and enhanced phosphorylation of p38MAPK. We find that the pro-proliferative effects of plexin-A2 are mediated by FARP2 and FYN since mutations in the FARP2 binding domain of plexin-A2 or in the FYN phosphorylation sites of plexin-A2 compromised the rescue of the proliferative activity by the plexin-A2 intracellular domain. Our results suggest that plexin-A2 may represent a novel target for the development of anti-tumorigenic therapeutics.

cell biology↗