Protein phosphorylation systems in postmortem human brain

Abstract

Protein phosphorylation systems regulated by cyclic adenosine 3',5'-monophosphate (cyclic AMP), or calcium in conjunction with calmodulin or phospholipid/diacylglycerol, have been studied by phosphorylation in vitro of particulate and soluble fractions from human postmortem brain samples. One-dimensional or two-dimensional gel electrophoretic protein separations were used for analysis. Protein phosphorylation catalyzed by cyclic AMP-dependent protein kinase was found to be highly active in both particulate and soluble preparations throughout the human CNS, with groups of both widely distributed and region-specific substrates being observed in different brain nuclei. Dopamine-innervated parts of the basal ganglia and cerebral cortex contained the phosphoproteins previously observed in rodent basal ganglia. In contrast, calcium/phospholipid-dependent and calcium/calmodulin-dependent protein phosphorylation systems were less prominent in human postmortem brain than in rodent brain, and only a few widely distributed substrates for these protein kinases were found. Protein staining indicated that postmortem proteolysis, particularly of high-molecular-mass proteins, was prominent in deeply located, subcortical regions in the human brain. Our results indicate that it is feasible to use human postmortem brain samples, when obtained under carefully controlled conditions, for qualitative studies on brain protein phosphorylation. Such studies should be of value in studies on human neurological and/or psychiatric disorders.

Anesthesia and post‐mortem interval profoundly influence the regulatory serine phosphorylation of glycogen synthase kinase‐3 in mouse brain

“…The two main findings of the present investigation have a direct impact on this field as further in vivo regulators of GSK3 are investigated because both post-mortem interval and anesthesia were found to cause very large changes in the regulatory serine phosphorylation of both isoforms of GSK3. It is well known that phosphorylated proteins are subject to variable rates of dephosphorylation during the post-mortem interval (Conway and Routtenberg 1979;Tsuyama et al 1987;Walaas et al 1989;Jope et al 1991;Matsuo et al 1994). The present results reveal an especially rapid post-mortem serine dephosphorylation of GSK3.…”

“…It is well known that phosphorylated proteins are subject to variable rates of dephosphorylation during the post‐mortem interval (Conway and Routtenberg 1979; Tsuyama et al . 1987; Walaas et al . 1989; Jope et al .…”

Phospholipase C Beta 1 Expression in the Dorsolateral Prefrontal Cortex from Patients with Schizophrenia at Different Stages of Illness

“…The use of post-mortem tissue poses further restrictions, one of which is that phosphorylated proteins are often rapidly dephosphorylated [50,51]. Thus, we may not be measuring an accurate representation of levels of proteins at the time of death.…”