Pyk2 is essential for astrocytes mobility following brain lesion

Abstract

Proline-rich tyrosine kinase 2 (Pyk2) is a calcium-dependent, non-receptor protein-tyrosine kinase of the focal adhesion kinase (FAK) family. Pyk2 is enriched in the brain, especially the forebrain. Pyk2 is highly expressed in neurons but is also present in astrocytes, where its role is not known. We used Pyk2 knockout mice (Pyk2(-/-) ) developed in our laboratory to investigate the function of Pyk2 in astrocytes. Morphology and basic properties of astrocytes in vivo and in culture were not altered in the absence of Pyk2. However, following stab lesions in the motor cortex, astrocytes-mediated wound filling was slower in Pyk2(-/-) than in wild-type littermates. In an in vitro wound healing model, Pyk2(-/-) astrocytes migrated slower than Pyk2(+/+) astrocytes. The role of Pyk2 in actin dynamics was investigated by treating astrocytic cultures with the actin-depolymerizing drug latrunculin B. Actin filaments re-polymerization after latrunculin B treatment was delayed in Pyk2(-/-) astrocytes as compared with wild-type astrocytes. We mimicked wound-induced activation by treating astrocytes in culture with tumor-necrosis factor alpha (TNFα), which increased Pyk2 phosphorylation at Tyr402. TNFα increased PKC activity, and Rac1 phosphorylation at Ser71 similarly in wild-type and Pyk2-deficient astrocytes. Conversely, we found that gelsolin, an actin-capping protein known to interact with Pyk2 in other cell types, was less enriched at the leading edge of migrating Pyk2(-/-) astrocytes, suggesting that its lack of recruitment mediated in part the effects of the mutation. This work shows the critical role of Pyk2 in astrocytes migration during wound healing.

Pyk2 modulates hippocampal excitatory synapses and contributes to cognitive deficits in a Huntington’s disease model

“…No N-terminal truncated fragment was detected in the knockout mice (Supplementary Fig. 2a), showing that deletion of exons 15–18 in the Pyk2 gene20 destabilized the resulting mRNA and/or protein. There was no compensatory alteration of the related focal adhesion kinase (FAK, Fig.…”

“…To study the role of Pyk2 in the brain, we used a knockout mouse line20 that we recently generated. As previously observed for a similar line18, these mice bred normally and there were no differences between Pyk2 +/+ , Pyk2 +/− and Pyk2 −/− mice in body weight, muscular strength, general locomotor activity or anxiety levels evaluated in the elevated plus-maze (Supplementary Fig.…”

“…For Pyk2 deletion, Pyk2 f/f C57Bl/6 mice were generated in which the PTK2B exons 15b-18 were flanked with LoxP sequences (Gen-O-way, Lyon, France) leading to a deletion that disrupts the protein kinase domain when crossed with a expressing Cre line20. Pyk2 −/− mice and Pyk2 f/f mice were genotyped from a tail biopsy (Charles River, Saint-Germain-Nuelles, France) using for DNA amplification of floxed PTK2B as forward primer 5′-GAGAGTGCTGGGTACTCCAGACTCAGATAG-3′ and as reverse primer 5′-TTCAGGAACACCAGAGAACTAGGGTGG-3′ and previously reported primers20 for Pyk2 −/− mice.…”

“…Pyk2 −/− mice and Pyk2 f/f mice were genotyped from a tail biopsy (Charles River, Saint-Germain-Nuelles, France) using for DNA amplification of floxed PTK2B as forward primer 5′-GAGAGTGCTGGGTACTCCAGACTCAGATAG-3′ and as reverse primer 5′-TTCAGGAACACCAGAGAACTAGGGTGG-3′ and previously reported primers20 for Pyk2 −/− mice. Heterozygous mice were crossed to generate +/+, +/− and −/− mice.…”

Astrocyte Structural and Molecular Response to Elevated Intraocular Pressure Occurs Rapidly and Precedes Axonal Tubulin Rearrangement within the Optic Nerve Head in a Rat Model

“…Integrin receptor activity leads to direct activation of a number of intracellular kinases, including the focal adhesion kinase (FAK) and Src kinase family members [32]. Active FAK and Src kinase family members have been shown to be important regulators of cellular responses to injury in cultured astrocytes [33, 34]. …”