Signal transduction abnormalities in melancholic depression

Abstract

Intracellular signal transduction cascades, particularly those linked to protein kinases A (PKA) and C (PKC), have been implicated in mood disorders. This study examined the activity of PKA and PKC, as well as levels of PKA regulatory (R) and catalytic (C) subunit proteins, in fibroblasts cultured from skin biopsies from patients with major depression, melancholic subtype, in contrast to non-melancholic depressives and controls (n = 12 each group). PKA activity was determined as a function of the transfer of 32P to a target polypeptide, Kemptide. R and C subunit expression was assayed in the melancholic depressed and normal control groups by Western blots. In a separate experiment, the degree of phosphorylation of the endogenous substrate cAMP response element-binding protein (CREB) was estimated in samples from melancholic and non-melancholic patients and normal controls (n = 8 each) after incubation with isoproterenol or phorbol ester, which activate PKA and PKC respectively. Melancholics had significantly reduced phosphorylation of Kemptide in contrast to non-melancholics and controls. This was associated with lower levels of PKA RII alpha, C alpha, and C beta subunit isoform proteins, but not RI alpha, RI beta, or RII beta. Furthermore, activation of both PKA and PKC was associated with reduced CREB-P in melancholics relative to normal controls. Finally, PKA activity was found to correlate positively with Hamilton depression scores after 16 weeks of treatment with serotonin reuptake inhibitor antidepressants. These data further implicate signal transduction abnormalities in melancholic major depression, particularly PKA and PKC. This suggests an abnormality of factors controlling the expression or degradation of these enzymes.

An oxysterol biomarker for 7-dehydrocholesterol oxidation in cell/mouse models for Smith-Lemli-Opitz syndrome

“…Fibroblasts derived from human skin are used as cellular models to study the pathophysiology of a variety of disorders (28)(29)(30)(31), especially those involved in lipid metabolism (32)(33)(34). For example, fi broblasts from SLOS patients contain elevated levels of 7-DHC and these cells have been used to establish methods for 7-DHC analysis and to determine the biological effects of this lipid ( 32,33 ).…”

Pharmacogenetics of antidepressant response

“…251 Moreover, paroxetine and nefazodone may exert their antidepressant effects through regulation of 5-HT 2A receptors, 249,[252][253][254] although controversial findings can also be found. 255 Finally, 5-HT 2A receptors have been reported to mediate some of the antidepressant effects seen in experimental animal models of depression. 256 Three variations within the coding region of 5-HT 2A have been implicated in antidepressant response: 102T>C (rs 6313) 176 and 1438G>A (rs6311) 190,257 and 1420C>T, 153 although results were not unequivocal and some findings not replicated.…”

Consensus paper of the WFSBP Task Force on Biological Markers: Biological Markers in Depression

“…These data further implicate signal transduction abnormalities in melancholic major depression, particularly PKA and PKC. This suggests an abnormality of factors controlling the expression or degradation of these enzymes (Akin et al 2005). …”