KCTD: A new gene family involved in neurodevelopmental and neuropsychiatric disorders.

The underlying molecular basis for neurodevelopmental or neuropsychiatric disorders is not known. In contrast, mechanistic understanding of other brain disorders including neurodegeneration has advanced considerably. Yet, these do not approach the knowledge accrued for many cancers with precision therapeutics acting on well-characterized targets.

Multiple functions of BCL-2 family proteins.

BCL-2 family proteins are the regulators of apoptosis, but also have other functions. This family of interacting partners includes inhibitors and inducers of cell death. Together they regulate and mediate the process by which mitochondria contribute to cell death known as the intrinsic apoptosis pathway.

The N-terminal helix of Bcl-xL targets mitochondria.

Anti- and pro-apoptotic Bcl-2 family members regulate the mitochondrial phase of apoptotic cell death. The mitochondrial targeting mechanisms of Bcl-2 family proteins are tightly regulated. Known outer mitochondrial membrane targeting sequences include the C-terminal tail and central helical hairpin.

A new view of the lethal apoptotic pore.

Cell death by apoptosis is indispensable for proper development and tissue homeostasis in all multicellular organisms, and its deregulation plays a key role in cancer and many other diseases. A crucial event in apoptosis is the formation of protein-permeable pores in the outer mitochondrial membrane that release cytochrome c and other apoptosis-promoting factors into the cytosol. Research efforts over the past two decades have established that apoptotic pores require BCL-2 family proteins, with the proapoptotic BAX-type proteins being direct effectors of pore formation.

Bcl-xL regulates mitochondrial energetics by stabilizing the inner membrane potential.

Mammalian Bcl-x(L) protein localizes to the outer mitochondrial membrane, where it inhibits apoptosis by binding Bax and inhibiting Bax-induced outer membrane permeabilization. Contrary to expectation, we found by electron microscopy and biochemical approaches that endogenous Bcl-x(L) also localized to inner mitochondrial cristae. Two-photon microscopy of cultured neurons revealed large fluctuations in inner mitochondrial membrane potential when Bcl-x(L) was genetically deleted or pharmacologically inhibited, indicating increased total ion flux into and out of mitochondria.

Sulforaphane protects immature hippocampal neurons against death caused by exposure to hemin or to oxygen and glucose deprivation.

Oxidative stress is a mediator of cell death following cerebral ischemia/reperfusion and heme toxicity, which can be an important pathogenic factor in acute brain injury. Induced expression of phase II detoxification enzymes through activation of the antioxidant response element (ARE)/Nrf2 pathway has emerged as a promising approach for neuroprotection. Little is known, however, about the neuroprotective potential of this strategy against injury in immature brain cells.

Sulforaphane protects astrocytes against oxidative stress and delayed death caused by oxygen and glucose deprivation.

Oxidative stress is an important molecular mechanism of astrocyte injury and death following ischemia/reperfusion and may be an effective target of intervention. One therapeutic strategy for detoxifying the many different reactive oxygen and nitrogen species that are produced under these conditions is induction of the Phase II gene response by the use of chemicals or conditions that promote the translocation of the transcriptional activating factor NRF2 from the cytosol to the nucleus, where it binds to genomic antioxidant response elements. This study tested the hypothesis that pre- or post-treatment of cultured cortical astrocytes with sulforaphane, an alkylating agent known to activate the NRF2 pathway of gene expression protects against death of astrocytes caused by transient exposure to O(2) and glucose deprivation (OGD).

Postnatal developmental regulation of Bcl-2 family proteins in brain mitochondria.

Although it has been long recognized that the relative balance of pro- and antiapoptotic Bcl-2 proteins is critical in determining the susceptibility to apoptotic death, only a few studies have examined the level of these proteins specifically at mitochondria during postnatal brain development. In this study, we examined the age-dependent regulation of Bcl-2 family proteins using rat brain mitochondria isolated at various postnatal ages and from the adult. The results indicate that a general down-regulation of most of the proapoptotic Bcl-2 proteins present in mitochondria occurs during postnatal brain development.

Mechanisms of impaired mitochondrial energy metabolism in acute and chronic neurodegenerative disorders.

Altered mitochondrial energy metabolism contributes to the pathophysiology of acute brain injury caused by ischemia, trauma, and neurotoxins and by chronic neurodegenerative disorders such as Parkinson's and Huntington's diseases. Although much evidence supports that the electron transport chain dysfunction in these metabolic abnormalities has both genetic and intracellular environmental causes, alternative mechanisms are being explored. These include direct, reversible inhibition of cytochrome oxidase by nitric oxide, release of mitochondrial cytochrome c, oxidative inhibition of mitochondrial matrix dehydrogenases and adenine nucleotide transport, the availability of NAD for dehydrogenase reactions, respiratory uncoupling by activities such as that of the permeability transition pore, and altered mitochondrial structure and intracellular trafficking.

Hypotensive hemorrhage increases calcium uptake capacity and Bcl-XL content of liver mitochondria.

We tested the hypothesis that the response of mitochondrial uptake of calcium and content of Bcl proteins to reversible hemorrhagic shock increases the vulnerability for hepatocellular death. Pentobarbital-anesthetized rats were bled to a mean arterial pressure of 30 to 40 mmHg for 1 h. A subset was then resuscitated (isotonic sodium chloride solution, three times shed volume).

The potential role of mitochondria in pediatric traumatic brain injury.

Mitochondria play a central role in cerebral energy metabolism, intracellular calcium homeostasis and reactive oxygen species generation and detoxification. Following traumatic brain injury (TBI), the degree of mitochondrial injury or dysfunction can be an important determinant of cell survival or death. Literature would suggest that brain mitochondria from the developing brain are very different from those from mature animals.

TAT-mediated endocytotic delivery of the loop deletion Bcl-2 protein protects neurons against cell death.

Protein delivery mediated by protein transduction domains (PTD) such as the HIV-1 TAT-PTD has emerged as a promising approach for neuroprotection. The objective of this study was to generate and evaluate the neuroprotective potential of TAT fusion proteins using constructs based on Bcl-2 anti-death family proteins. A TAT-Bcl-2 construct with the loop domain deleted (TAT-Bcl-2Deltaloop) was tested for its ability to transduce neuronal cells and to promote survival.

Inhibition of mitochondrial neural cell death pathways by protein transduction of Bcl-2 family proteins.

Bcl-2 and other closely related members of the Bcl-2 family of proteins inhibit the death of neurons and many other cells in response to a wide variety of pathogenic stimuli. Bcl-2 inhibition of apoptosis is mediated by its binding to pro-apoptotic proteins, e.g.

Effects of membrane attack complex of complement on apoptosis in experimental autoimmune encephalomyelitis.

Complement activation is involved in the initiation of inflammation and antibody-mediated demyelination in experimental autoimmune encephalomyelitis (EAE). We investigated the role of MAC in apoptosis in myelin-induced EAE in complement C5-deficient (C5-d) and C5-sufficient (C5-s) mice. The number of apoptotic cells assessed by TUNEL assay was significantly increased in C5-d mice during clinical recovery as compared with C5-s mice.

Sublytic terminal complement attack induces c-fos transcriptional activation in myotubes.

Sublytic C5b-9 alters the molecular phenotype of myotubes by inhibiting muscle-specific gene expression. Here, we showed that C5b-9 induced c-fos mRNA and transcription. Using c-fos promoter-CAT constructs and electrophoretic mobility shift assay (EMSA), the minimal c-fos promoter activity was shown to increase within 30-min exposure to serum C5b-9, which also induced the binding of serum response factor (SRF), along with ternary complex factor (TCF) Elk1 and Sap1a to the serum response element.

RGC-32 increases p34CDC2 kinase activity and entry of aortic smooth muscle cells into S-phase.

Proliferation of aortic smooth muscle cells contributes to atherogenesis and neointima formation. Sublytic activation of complement, particularly C5b-9, induces cell cycle progression in aortic smooth muscle cells. RGC-32 is a novel protein that may promote cell cycle progression in response to complement activation.